Method and apparatus for determining bottom-hole flowing pressure of coalbed methane well, and electronic device

Abstract

Embodiments of the present application provide a method and apparatus for determining a bottom-hole flowing pressure of a coalbed methane well, and an electronic device. The method comprises: acquiring a first volume value and a second volume value in a coalbed methane well, the first volume value representing a gas-phase instantaneous fluid volume in the coalbed methane well, and the second volume value representing an aqueous-phase instantaneous fluid volume in the coalbed methane well; on the basis of the first volume value and the second volume value, determining a pseudo-dynamic liquid level position in the coalbed methane well; acquiring a first temperature, a second temperature, and a liquid pressure gradient of the coalbed methane well; on the basis of the first temperature and the second temperature, determining a temperature gradient of the coalbed methane well; on the basis of the pseudo-dynamic liquid level position and the temperature gradient, determining a pseudo-dynamic liquid level temperature of the coalbed methane well; on the basis of the liquid level position and the liquid level temperature, determining a pure gas column pressure corresponding to the coalbed methane well; and, on the basis of the pure gas column pressure, the pseudo-dynamic liquid level position, and the pressure gradient, determining a bottom-hole flowing pressure of the coalbed methane well. The method is used for achieving the effect of accurately determining the bottom-hole flowing pressure of the coalbed gas well.

Description

A method, apparatus, and electronic equipment for determining the bottom hole flowing pressure of a coalbed methane well.

[0001] This application claims priority to Chinese Patent Application No. 202411603408.8, filed on November 11, 2024, entitled "A method, apparatus and electronic device for determining the bottom hole flowing pressure of a coalbed methane well", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of coalbed methane well development technology, and more specifically, to a method, apparatus, and electronic equipment for determining the bottom hole flowing pressure of a coalbed methane well. Background Technology

[0003] In the process of coalbed methane well extraction, it is necessary to determine the state of natural gas in the wellbore. In the existing technology, it is necessary to determine the bottom hole pressure of the coalbed methane well, and then model based on the bottom hole pressure to determine the state of natural gas.

[0004] Therefore, there is an urgent need for a method that can accurately determine the bottom-hole flowing pressure of coalbed methane wells. Summary of the Invention

[0005] The purpose of this application is to provide a method, apparatus, and electronic equipment for determining the bottom-hole flowing pressure of a coalbed methane well, so as to achieve the effect of accurately determining the bottom-hole flowing pressure of a coalbed methane well.

[0006] In a first aspect, this application discloses a bottomhole flowing pressure method for coalbed methane wells, comprising:

[0007] Obtain a first volume value and a second volume value in the coalbed methane well; wherein the first volume value represents the instantaneous volume of the gas phase fluid in the coalbed methane well, and the second volume value represents the instantaneous volume of the water phase fluid in the coalbed methane well; and determine the position of the pseudo-dynamic liquid level in the coalbed methane well based on the first volume value and the second volume value.

[0008] The first temperature, the second temperature, and the pressure gradient of the liquid in the coalbed methane well are obtained; wherein the first temperature represents the wellhead temperature of the coalbed methane well, and the second temperature represents the reservoir temperature at the bottom of the coalbed methane well; and the temperature gradient of the coalbed methane well is determined based on the first temperature and the second temperature.

[0009] The simulated fluid level temperature of the coalbed methane well is determined based on the simulated fluid level position and temperature gradient.

[0010] Based on the simulated liquid level position and simulated liquid level temperature, the pure gas column pressure corresponding to the coalbed methane well is determined; and based on the pure gas column pressure, simulated liquid level position and pressure gradient, the bottom-hole flowing pressure of the coalbed methane well is determined, wherein the bottom-hole flowing pressure characterizes the bottom-hole pressure when the coalbed methane well contains both coalbed methane and liquid.

[0011] In one possible implementation, obtaining a first volume value in a coalbed methane well includes:

[0012] Obtain the first pseudo-comparison pressure and the first pseudo-comparison temperature; wherein, the first pseudo-comparison pressure is determined based on the wellhead pressure of the coalbed methane well and the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas, and the first pseudo-comparison temperature is determined based on the wellhead temperature of the coalbed methane well and the initial temperature at the bottom of the well when the production wellbore of the coalbed methane well contains only gas.

[0013] The first compressibility factor is determined based on the first pseudo-comparison pressure and the first pseudo-comparison temperature.

[0014] The volume coefficient of coalbed methane is determined based on the first compressibility factor, standard pressure, and standard temperature; where standard pressure represents the coalbed methane pressure under standard conditions, and standard temperature represents the coalbed methane temperature under standard conditions.

[0015] The first volume value is determined based on the volume coefficient of coalbed methane and the preset daily coalbed methane production.

[0016] In one possible implementation, obtaining the first pseudo-comparison pressure and the first pseudo-comparison temperature includes:

[0017] The wellhead pressure, wellhead temperature, initial bottom temperature, and coalbed methane density of a coalbed methane well are obtained. The initial bottom temperature represents the initial temperature at the bottom of the well when the production wellbore contains only gas.

[0018] The initial pressure at the bottom of the well is determined based on the density of coalbed methane, gravitational acceleration, and the production well depth of the coalbed methane well. The initial pressure at the bottom of the well represents the initial pressure at the bottom of the well when the production wellbore contains only gas.

[0019] The average pressure inside the first wellbore of the coalbed methane well is determined based on the wellhead pressure and the initial bottom pressure; the average temperature inside the first wellbore of the coalbed methane well is determined based on the wellhead temperature and the initial bottom temperature.

[0020] The first simulated comparison pressure is determined based on the average pressure in the first wellbore and the preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and the first simulated comparison temperature is determined based on the average temperature in the first wellbore and the preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane.

[0021] In one possible implementation, determining the position of the pseudo-dynamic liquid level in the coalbed methane well based on a first volume value and a second volume value includes:

[0022] The third volume value is obtained by summing the first and second volume values.

[0023] The position of the simulated fluid level is determined based on the second and third volume values ​​and the production well depth of the coalbed methane well.

[0024] In one possible implementation, determining the temperature gradient of the coalbed methane well based on a first temperature and a second temperature includes:

[0025] The temperature gradient of the coalbed methane well is determined based on the first temperature, the second temperature, and the production well depth of the coalbed methane well.

[0026] In one possible implementation, determining the pure gas column pressure corresponding to the coalbed methane well based on the simulated liquid level position and simulated liquid level temperature includes:

[0027] Repeat the following steps until the first preset condition is met, wherein the initial pressure obtained for the first time is determined based on the pseudo-dynamic liquid level position and the wellhead pressure of the coalbed methane well:

[0028] Based on the wellhead pressure and initial pressure of the coalbed methane well, the average pressure in the second wellbore of the coalbed methane well is determined, where the initial pressure represents the pressure of the initially obtained pure gas column; the average pressure in the second wellbore represents the average pressure of the pure gas column in the production wellbore of the coalbed methane well; based on the wellhead temperature and pseudo-dynamic liquid level temperature of the coalbed methane well, the average temperature in the second wellbore of the coalbed methane well is determined, where the average temperature in the second wellbore represents the average temperature of the pure gas column in the production wellbore of the coalbed methane well.

[0029] The second simulated comparison pressure is determined based on the average pressure inside the second wellbore and the preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and the second simulated comparison temperature is determined based on the average temperature inside the second wellbore and the preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane.

[0030] The second compressibility factor is determined based on the second comparative pressure and the second comparative temperature; and the target pressure is determined based on the second compressibility factor.

[0031] If the difference between the target pressure and the initial pressure meets the first preset condition, then the target pressure is determined as the pure gas column pressure corresponding to the coalbed methane well.

[0032] If the difference between the target pressure and the initial pressure does not meet the first preset condition, the initial pressure is updated to the target pressure.

[0033] In one possible implementation, determining the target pressure based on a second compressibility factor includes:

[0034] The parameter factors are determined based on the production well depth of the coalbed methane well, the position of the simulated moving liquid level, the average temperature inside the second wellbore, the preset relative gas density value, and the second compressibility factor.

[0035] The Reynolds number in the production wellbore of the coalbed methane well is determined based on the preset gas flow rate, preset gas relative density value, preset coalbed methane viscosity, inner diameter of the casing of the coalbed methane well, and outer diameter of the tubing of the coalbed methane well; wherein, the preset gas flow rate characterizes the gas flow rate under standard conditions.

[0036] The friction coefficient of the coalbed methane well is determined based on the preset absolute roughness of the pipe, the inner diameter of the casing of the coalbed methane well, the outer diameter of the tubing of the coalbed methane well, and the Reynolds number in the production wellbore of the coalbed methane well.

[0037] The target pressure is determined based on the wellhead pressure, friction coefficient, average temperature inside the second wellbore, second compressibility factor, preset gas flow rate, casing inner diameter, and tubing outer diameter of the coalbed methane well.

[0038] In one possible implementation, the bottomhole flowing pressure of the coalbed methane well is determined based on the pure gas column pressure, the pseudo-dynamic liquid level position, and the pressure gradient, including:

[0039] Repeat the following steps until the first preset condition is met, wherein the initial bottomhole flowing pressure obtained for the first time is determined based on the pure gas column pressure, pressure gradient, and pseudo-dynamic liquid level position of the coalbed methane well; wherein the pressure gradient is determined by the liquid density and gravitational acceleration:

[0040] The average pressure within the third wellbore of the coalbed methane well is determined based on the pure gas column pressure and the initial bottom hole flowing pressure. The initial bottom hole flowing pressure represents the initially obtained bottom hole flowing pressure. The average pressure within the third wellbore represents the average pressure of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well. The average temperature within the third wellbore of the coalbed methane well is determined based on the pseudo-dynamic liquid surface temperature and the initial bottom hole temperature. The average temperature within the third wellbore represents the average temperature of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well.

[0041] The third simulated comparison pressure is determined based on the average pressure in the third wellbore and the preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and the third simulated comparison temperature is determined based on the average temperature in the third wellbore and the preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane.

[0042] The third compressibility factor is determined based on the third pseudo-comparison pressure and the third pseudo-comparison temperature; and the target bottom hole flowing pressure is determined based on the third compressibility factor.

[0043] If the difference between the target bottom-hole flowing pressure and the initial bottom-hole flowing pressure meets the first preset condition, then the target bottom-hole flowing pressure is determined to be the bottom-hole flowing pressure corresponding to the coalbed methane well.

[0044] If the difference between the target bottom hole pressure and the initial bottom hole pressure is determined to be inconsistent with the first preset condition, the initial bottom hole pressure will be updated to the target bottom hole pressure.

[0045] In one possible implementation, determining the target bottomhole flowing pressure based on a third compressibility factor includes:

[0046] The apparent gas velocity is determined based on the preset gas flow rate, the average temperature inside the third wellbore of the coalbed methane well, the average pressure inside the third wellbore of the coalbed methane well, the third compressibility factor, the standard pressure, the standard temperature, and the annular cross-sectional area between the casing and the tubing of the coalbed methane well; wherein, the annular cross-sectional area between the casing and the tubing of the coalbed methane well is determined by the inner diameter of the casing and the outer diameter of the tubing of the coalbed methane well.

[0047] If the apparent gas flow rate is determined to meet the second preset condition, then the preset parameter is determined to be the first preset parameter.

[0048] If it is determined that the apparent gas flow rate does not meet the second preset condition, then the preset parameter is determined to be the second preset parameter.

[0049] The porosity is determined based on preset parameters and the apparent gas flow rate.

[0050] The third relevant parameters are determined based on the preset gas flow rate, standard temperature, average temperature inside the third wellbore, third compressibility factor, standard pressure, and the annular cross-sectional area between the casing and tubing of the coalbed methane well.

[0051] The first relevant parameter is determined based on the third relevant parameter, porosity, preset parameters, wellhead pressure of the coalbed methane well, pressure difference of the pure gas column, pseudo-dynamic liquid level position, and pressure gradient; wherein, the pressure difference of the pure gas column is obtained by the difference between the wellhead pressure of the coalbed methane well and the corresponding pure gas column pressure of the coalbed methane well.

[0052] The second correlation coefficient is determined based on the third correlation coefficient, porosity, preset parameters, preset gas constant, preset molar mass, pseudo-dynamic liquid level position, third compressibility factor, third wellbore average temperature, pressure gradient, wellhead pressure of coalbed methane well, and pressure difference of pure gas column; among them, the gas constant represents the general gas constant; the preset molar mass represents the molar mass of natural gas.

[0053] The target bottom hole flowing pressure is determined based on the wellhead pressure, pressure difference of the pure gas column, pressure gradient, pseudo-dynamic liquid level position, first relevant parameter, and second relevant parameter of the coalbed methane well.

[0054] Secondly, this application discloses a device for determining the bottom hole flowing pressure of a coalbed methane well, comprising:

[0055] The first acquisition module is used to acquire a first volume value and a second volume value in the coalbed methane well; wherein the first volume value represents the instantaneous volume of gas phase fluid in the coalbed methane well, and the second volume value represents the instantaneous volume of water phase fluid in the coalbed methane well; and to determine the position of the pseudo-dynamic liquid level in the coalbed methane well based on the first volume value and the second volume value.

[0056] The second acquisition module is used to acquire the first temperature, the second temperature, and the pressure gradient of the liquid in the coalbed methane well; wherein the first temperature represents the wellhead temperature of the coalbed methane well, and the second temperature represents the reservoir temperature at the bottom of the coalbed methane well; and the temperature gradient of the coalbed methane well is determined based on the first temperature and the second temperature.

[0057] The first determining module is used to determine the simulated fluid level temperature of the coalbed methane well based on the simulated fluid level position and temperature gradient.

[0058] The second determining module is used to determine the pure gas column pressure corresponding to the coalbed methane well based on the simulated moving liquid surface position and simulated moving liquid surface temperature; and to determine the bottom hole flowing pressure of the coalbed methane well based on the pure gas column pressure, simulated moving liquid surface position and pressure gradient, wherein the bottom hole flowing pressure characterizes the bottom hole pressure of the coalbed methane well when it includes coalbed methane and liquid.

[0059] In one possible implementation, the first acquisition module includes:

[0060] The first acquisition submodule is used to acquire the first simulated comparison pressure and the first simulated comparison temperature; wherein, the first simulated comparison pressure is determined based on the wellhead pressure of the coalbed methane well and the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas, and the first simulated comparison temperature is determined based on the wellhead temperature of the coalbed methane well and the initial temperature at the bottom of the well when the production wellbore of the coalbed methane well contains only gas.

[0061] The third determining module is used to determine the first compressibility factor based on the first simulated comparison pressure and the first simulated comparison temperature.

[0062] The fourth confirmation module is used to determine the volume coefficient of coalbed methane based on the first compressibility factor, standard pressure, and standard temperature; wherein, the standard pressure represents the coalbed methane pressure under standard conditions, and the standard temperature represents the coalbed methane temperature under standard conditions.

[0063] The fifth confirmation module is used to determine the first volume value based on the coalbed methane volume coefficient and the preset daily coalbed methane production.

[0064] In one possible implementation, the first acquisition submodule includes:

[0065] The second acquisition submodule is used to acquire the wellhead pressure, wellhead temperature, initial bottom temperature, and coalbed methane density of the coalbed methane well. The initial bottom temperature represents the initial temperature at the bottom of the well when the production wellbore of the coalbed methane well contains only gas.

[0066] The sixth confirmation module is used to determine the initial pressure at the bottom of the well based on the coalbed methane density, gravitational acceleration, and the production well depth of the coalbed methane well; wherein, the initial pressure at the bottom of the well represents the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas.

[0067] The seventh confirmation module is used to determine the average pressure inside the first wellbore of the coalbed methane well based on the wellhead pressure and the initial bottom pressure; and to determine the average temperature inside the first wellbore of the coalbed methane well based on the wellhead temperature and the initial bottom temperature.

[0068] The eighth confirmation module is used to determine the first pseudo-comparison pressure based on the average pressure in the first wellbore and the preset pressure, wherein the preset pressure represents the critical pressure of coalbed methane; and to determine the first pseudo-comparison temperature based on the average temperature in the first wellbore and the preset temperature, wherein the preset temperature represents the critical temperature of coalbed methane.

[0069] In one possible implementation, the first acquisition module further includes:

[0070] The calculation module is used to obtain the third volume value based on the sum of the first and second volume values.

[0071] The ninth confirmation module is used to determine the position of the simulated liquid level based on the second volume value, the third volume value, and the production well depth of the coalbed methane well.

[0072] In one possible implementation, the second acquisition module includes:

[0073] The tenth confirmation module is used to determine the temperature gradient of the coalbed methane well based on the first temperature, the second temperature, and the production well depth of the coalbed methane well.

[0074] In one possible implementation, the second determining module includes:

[0075] The first loop module is used to repeatedly execute the following steps until the first preset condition is reached, wherein the initial pressure obtained for the first time is determined based on the pseudo-dynamic liquid level position and the wellhead pressure of the coalbed methane well:

[0076] The first confirmation submodule is used to determine the average pressure inside the second wellbore of the coalbed methane well based on the wellhead pressure and the initial pressure. The initial pressure represents the initially obtained pure gas column pressure. The average pressure inside the second wellbore represents the average pressure of the pure gas column inside the production wellbore of the coalbed methane well. The module also determines the average temperature inside the second wellbore of the coalbed methane well based on the wellhead temperature and the pseudo-dynamic liquid level temperature. The average temperature inside the second wellbore represents the average temperature of the pure gas column inside the production wellbore of the coalbed methane well.

[0077] The second confirmation submodule is used to determine the second simulated comparison pressure based on the average pressure inside the second wellbore and the preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and to determine the second simulated comparison temperature based on the average temperature inside the second wellbore and the preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane.

[0078] The third confirmation submodule is used to determine the second compressibility factor based on the second simulated comparison pressure and the second simulated comparison temperature; and to determine the target pressure based on the second compressibility factor.

[0079] The fourth confirmation submodule is used to determine the target pressure as the pure gas column pressure corresponding to the coalbed methane well if the difference between the target pressure and the initial pressure meets the first preset condition.

[0080] The first update module is used to update the initial pressure to the target pressure if it is determined that the difference between the target pressure and the initial pressure does not meet the first preset condition.

[0081] In one possible implementation, the third confirmation submodule includes:

[0082] The fourth confirmation submodule is used to determine the parameter factors based on the production well depth of the coalbed methane well, the position of the simulated moving liquid level, the average temperature inside the second wellbore, the preset gas relative density value, and the second compressibility factor.

[0083] The fifth confirmation submodule is used to determine the Reynolds number in the production wellbore of a coalbed methane well based on the preset gas flow rate, preset gas relative density value, preset coalbed methane viscosity, inner diameter of the casing of the coalbed methane well, and outer diameter of the tubing of the coalbed methane well; wherein, the preset gas flow rate represents the gas flow rate under standard conditions.

[0084] The sixth confirmation submodule is used to determine the friction coefficient of a coalbed methane well based on the preset absolute roughness of the pipe, the inner diameter of the casing of the coalbed methane well, the outer diameter of the tubing of the coalbed methane well, and the Reynolds number in the production wellbore of the coalbed methane well.

[0085] The seventh confirmation submodule is used to determine the target pressure based on the wellhead pressure of the coalbed methane well, the friction coefficient of the coalbed methane well, the average temperature inside the second wellbore, the second compressibility factor, the preset gas flow rate, the inner diameter of the casing of the coalbed methane well, and the outer diameter of the tubing of the coalbed methane well.

[0086] In one possible implementation, the second determining module further includes:

[0087] The second repeating module is used to repeatedly execute the following steps until the first preset condition is reached, wherein the initial bottom hole flowing pressure obtained for the first time is determined based on the pure gas column pressure, pressure gradient, and pseudo-dynamic liquid level position of the coalbed methane well; wherein the pressure gradient is determined by the liquid density and gravitational acceleration:

[0088] The eighth confirmation submodule is used to determine the average pressure in the third wellbore of the coalbed methane well based on the pure gas column pressure and the initial bottom hole flowing pressure. The initial bottom hole flowing pressure represents the initially obtained bottom hole flowing pressure. The average pressure in the third wellbore represents the average pressure of the gas-water two-phase liquid column in the production wellbore of the coalbed methane well. The average temperature in the third wellbore of the coalbed methane well is determined based on the pseudo-dynamic liquid surface temperature and the initial bottom hole temperature. The average temperature in the third wellbore represents the average temperature of the gas-water two-phase liquid column in the production wellbore of the coalbed methane well.

[0089] The ninth confirmation submodule is used to determine the third pseudo-comparison pressure based on the average pressure in the third wellbore and the preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and to determine the third pseudo-comparison temperature based on the average temperature in the third wellbore and the preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane.

[0090] The tenth confirmation submodule is used to determine the third compressibility factor based on the third pseudo-comparison pressure and the third pseudo-comparison temperature; and to determine the target bottom hole flowing pressure based on the third compressibility factor.

[0091] The eleventh confirmation submodule is used to determine the target bottom-hole pressure as the bottom-hole pressure corresponding to the coalbed methane well if the difference between the target bottom-hole pressure and the initial bottom-hole pressure meets the first preset condition.

[0092] The second update module is used to update the initial bottom-hole flowing pressure to the target bottom-hole flowing pressure if the difference between the target bottom-hole flowing pressure and the initial bottom-hole flowing pressure does not meet the first preset condition.

[0093] In one possible implementation, the tenth confirmation submodule includes:

[0094] The twelfth confirmation submodule is used to determine the apparent gas velocity based on the preset gas flow rate, the average temperature inside the third wellbore of the coalbed methane well, the average pressure inside the third wellbore of the coalbed methane well, the third compressibility factor, the standard pressure, the standard temperature, and the annular cross-sectional area between the casing and the tubing of the coalbed methane well; wherein, the annular cross-sectional area between the casing and the tubing of the coalbed methane well is determined by the inner diameter of the casing and the outer diameter of the tubing of the coalbed methane well.

[0095] The thirteenth confirmation submodule is used to determine the preset parameter as the first preset parameter if the apparent gas flow rate meets the second preset condition.

[0096] The fourteenth confirmation submodule is used to determine the preset parameter as the second preset parameter if it is determined that the apparent gas flow rate does not meet the second preset condition.

[0097] The fifteenth confirmation submodule is used to determine the porosity based on preset parameters and the apparent gas flow rate.

[0098] The sixteenth confirmation submodule is used to determine the third relevant parameters based on the preset gas flow rate, standard temperature, average temperature inside the third wellbore, third compressibility factor, standard pressure, and the annular cross-sectional area between the casing and tubing of the coalbed methane well.

[0099] The seventeenth confirmation submodule is used to determine the first relevant parameter based on the third relevant parameter, porosity, preset parameter, wellhead pressure of coalbed methane well, pressure difference of pure gas column, pseudo-dynamic liquid level position, and pressure gradient; wherein, the pressure difference of pure gas column is obtained by the difference between the wellhead pressure of coalbed methane well and the corresponding pure gas column pressure of coalbed methane well.

[0100] The eighteenth confirmation submodule is used to determine the second correlation coefficient based on the third correlation coefficient, porosity, preset parameters, preset gas constant, preset molar mass, pseudo-dynamic liquid level position, third compressibility factor, third average temperature in the wellbore, pressure gradient, wellhead pressure of coalbed methane well, and pressure difference of pure gas column; wherein, the gas constant represents the general gas constant; and the preset molar mass represents the molar mass of natural gas.

[0101] The nineteenth confirmation submodule is used to determine the target bottom hole flowing pressure based on the wellhead pressure, pure gas column pressure difference, pressure gradient, pseudo-dynamic liquid level position, first relevant parameter, and second relevant parameter of the coalbed methane well.

[0102] Thirdly, embodiments of this application provide an apparatus, including: a memory and a processor.

[0103] The memory stores the instructions that the computer executes.

[0104] The processor executes computer execution instructions stored in memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0105] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0106] Fifthly, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect.

[0107] Based on the above technical solutions, this application provides a method, apparatus, and electronic equipment for determining the bottom-hole flowing pressure of a coalbed methane well. The method first acquires the instantaneous volumes of the gas phase and water phase fluids in the coalbed methane well to determine the position of the pseudo-moving liquid level. Then, it acquires the wellhead temperature, bottom-hole reservoir temperature, and liquid pressure gradient to calculate the temperature gradient of the coalbed methane well. Next, it combines the position of the pseudo-moving liquid level and the temperature gradient to derive the pseudo-moving liquid level temperature. Then, it determines the corresponding pure gas column pressure based on the pseudo-moving liquid level position and temperature. Finally, it comprehensively considers the pure gas column pressure, the pseudo-moving liquid level position, and the pressure gradient to accurately calculate the bottom-hole flowing pressure of the coalbed methane well containing both coalbed methane and liquid. This method achieves accurate and efficient determination of the bottom-hole flowing pressure of coalbed methane wells, effectively solving the problem of inaccurate measurement of bottom-hole flowing pressure in previous coalbed methane wells. Attached Figure Description

[0108] Figure 1 is a flowchart illustrating a method for determining the bottom-hole flowing pressure of a coalbed methane well according to an embodiment of this application.

[0109] Figure 2 is a wellbore flow model diagram of a coalbed methane well provided in an embodiment of this application;

[0110] Figure 3 is a schematic flowchart of a method for determining the bottom flow pressure of a coalbed methane well according to an embodiment of this application.

[0111] Figure 4 is a flowchart of step S301 in a method for determining the bottom flow pressure of a coalbed methane well according to an embodiment of this application.

[0112] Figure 5 is a diagram showing the conversion result of the simulated liquid level position according to an embodiment of this application;

[0113] Figure 6 is a graph showing the conversion result of the simulated liquid surface temperature according to an embodiment of this application;

[0114] Figure 7 is a flowchart of step S304 in a method for determining the bottom flow pressure of a coalbed methane well according to an embodiment of this application.

[0115] Figure 8 is a flowchart of step S305 in a method for determining the bottom flow pressure of a coalbed methane well according to an embodiment of this application.

[0116] Figure 9 is a comparison chart of calculated bottom-hole flowing pressure and measured bottom-hole flowing pressure provided in an embodiment of this application;

[0117] Figure 10 is a schematic diagram of a device for determining the bottom flow pressure of a coalbed methane well according to an embodiment of this application;

[0118] Figure 11 is a schematic diagram of the structure of a device for determining the bottom flow pressure of a coalbed methane well according to an embodiment of this application;

[0119] Figure 12 is a schematic diagram of the structure of an electronic device for determining the bottom flow pressure of a coalbed methane well provided in this application. Detailed Implementation

[0120] In recent years, significant breakthroughs have been achieved in deep coalbed methane (CBM) exploration at depths greater than 2000m. Preliminary assessments of my country's deep CBM resources exceed 30 trillion cubic meters, indicating enormous exploration and development potential. To accurately assess deep CBM production capacity and estimate Estimated Ultimate Recovery (EUR), techniques such as refined numerical simulations using reservoir engineering methods or analysis of production dynamic data characteristic curves are typically employed, often involving the bottom-hole flowing pressure of CBM wells. Bottom-hole flowing pressure, also known as flow pressure or kinetic pressure, is the pressure at the bottom of an oil or gas well during production. It represents the pressure remaining after oil or gas flows from the formation to the bottom of the well; for flowing wells, it is also the initial pressure at which oil and gas flow from the bottom to the surface. Changes in bottom-hole flowing pressure affect the desorption rate and migration path of CBM, thus impacting the production capacity of CBM wells. In numerical simulations, bottom-hole flowing pressure is one of the key parameters for simulating CBM migration processes. By setting a reasonable bottom hole flowing pressure, the entire process of coalbed methane desorbing from the coal matrix, diffusing into the fracture system, and finally being extracted through the wellbore can be simulated.

[0121] Existing methods for obtaining bottom hole flowing pressure in coalbed methane wells mainly include the measured method and the wellhead pressure reduction method. The measured method mainly uses a downhole pressure gauge to measure the bottom hole flowing pressure of the coalbed methane well. However, the operation cost of using a downhole pressure gauge is high and it will affect the production. The wellhead pressure reduction method mainly uses the wellhead pressure, wellbore pressure gradient, and gas layer depth to calculate the bottom hole flowing pressure. However, this wellhead pressure reduction method does not fully consider the two-phase flow of gas and water in the wellbore and is only applicable to some production stages, with a very limited scope of application.

[0122] Therefore, the method, apparatus, and equipment for determining the bottom-hole flowing pressure of a coalbed methane well provided in this application can solve the above-mentioned problems.

[0123] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0124] Figure 1 is a flowchart illustrating a method for determining the bottom hole flowing pressure of a coalbed methane well according to an embodiment of this application. As shown in Figure 1, the method includes:

[0125] S101. Obtain the first volume value and the second volume value in the coalbed methane well; wherein, the first volume value represents the instantaneous volume of the gas phase fluid in the coalbed methane well, and the second volume value represents the instantaneous volume of the water phase fluid in the coalbed methane well; and determine the position of the pseudo-dynamic liquid level in the coalbed methane well based on the first volume value and the second volume value.

[0126] For example, Figure 2 is a wellbore flow model diagram of a coalbed methane well provided in an embodiment of this application. As shown in Figure 2, a wellbore flow calculation model of a coalbed methane well is established, and according to the flow pattern, it is divided into a pure gas column 201 and a gas-water two-phase liquid column 202 from top to bottom. The dividing point between the pure gas column and the gas-water two-phase liquid column is the simulated moving liquid surface position 203. Liquid (groundwater) is extracted from the wellbore opening 204 from bottom to top, and coalbed methane is extracted from the wellbore opening 205 from bottom to top. The pure gas column is the part of the wellbore completely occupied by coalbed methane during the coalbed methane extraction process, without water or other liquids. This part is usually located in the upper part of the wellbore, and the specific location is affected by the gas content of the coal seam, the extraction stage, and the production control principles. The gas-water two-phase liquid column refers to the part of the wellbore where gas and liquid (mainly groundwater) coexist during the coalbed methane extraction process. This part is usually located in the middle or lower part of the shaft, and the specific location depends on the gas content of the coal seam, water saturation, mining stage, and production control principles.

[0127] For example, the first volume value characterizes the instantaneous gaseous fluid volume in a coalbed methane well, which refers to the volume occupied by the gaseous fluid (i.e., coalbed methane) flowing through the wellbore at a specific instant during the coalbed methane extraction process. This volume changes continuously over time, hence it is an "instantaneous" fluid volume. The second volume value characterizes the instantaneous aqueous fluid volume in a coalbed methane well, which refers to the volume occupied by the aqueous fluid (i.e., groundwater in the coal seam) flowing through the wellbore at a specific instant during the coalbed methane extraction process. This volume also changes continuously over time, hence it is an "instantaneous" fluid volume. In coalbed methane extraction, the pseudo-dynamic liquid level position refers to the depth of the water surface in the wellbore from the ground surface during the coalbed methane drainage process. This depth gradually changes as the formation water is continuously drained.

[0128] For example, the position of the pseudo-dynamic fluid level in the coalbed methane well is calculated based on the first volume value and the second volume value. The calculation formula is as follows:

[0129] Among them, h L Indicates the position of the pseudo-dynamic fluid level in a coalbed methane well; V w V represents the second volume value, i.e., the instantaneous volume of the aqueous phase fluid in the coalbed methane well; g The first volume value represents the instantaneous volume of gas phase fluid in the coalbed methane well; H represents the production well depth of the coalbed methane well; α represents the conversion factor, which generally ranges from 1.0 to 2.0.

[0130] S102. Obtain the first temperature, the second temperature, and the pressure gradient of the liquid in the coalbed methane well; wherein, the first temperature represents the wellhead temperature of the coalbed methane well, and the second temperature represents the reservoir temperature at the bottom of the coalbed methane well; and determine the temperature gradient of the coalbed methane well based on the first temperature and the second temperature.

[0131] For example, the first temperature characterizes the wellhead temperature of the coalbed methane well, which refers to the actual measured temperature at the wellhead; the second temperature characterizes the reservoir temperature at the bottom of the coalbed methane well, which refers to the actual temperature of the reservoir where the well is located; the temperature gradient of the coalbed methane well refers to the rate of temperature change with depth within the wellbore or coal seam reservoir. In a coalbed methane well, the temperature gradient reflects the variation of formation temperature with depth.

[0132] For example, the temperature gradient of a coalbed methane well is calculated based on a first temperature and a second temperature. The calculation formula is as follows:

[0133] Where, γ T T represents the temperature gradient of a coalbed methane well. C T represents the wellhead temperature of a coalbed methane well. m H represents the reservoir temperature at the bottom of the coalbed methane well; H represents the production well depth of the coalbed methane well.

[0134] S103. Determine the pseudo-dynamic liquid level temperature of the coalbed methane well based on the pseudo-dynamic liquid level position and temperature gradient.

[0135] For example, the temperature of the pseudo-dynamic liquid surface can be obtained by multiplying the pseudo-dynamic liquid surface position and the temperature gradient. The calculation formula is as follows: T L =h L ×γ T

[0136] Among them, T L The pseudo-dynamic fluid level temperature (h) of a coalbed methane well. L Indicates the position of the pseudo-dynamic fluid level in a coalbed methane well, γ TThis represents the temperature gradient of a coalbed methane well.

[0137] S104. Determine the pure gas column pressure corresponding to the coalbed methane well based on the simulated moving liquid surface position and simulated moving liquid surface temperature; and determine the bottom flow pressure of the coalbed methane well based on the pure gas column pressure, simulated moving liquid surface position and pressure gradient, wherein the bottom flow pressure characterizes the bottom pressure of the coalbed methane well when it contains both coalbed methane and liquid.

[0138] For example, when determining the pure gas column pressure of a coalbed methane well, an initial value is first calculated using the wellhead pressure and the position of the simulated fluid level. Then, the compressibility factor is determined based on the average temperature and pressure of the pure gas column. Finally, the target value is obtained by combining the simulated fluid level temperature. If the difference between the initial value and the target value is within the acceptable range, the target value is used; otherwise, the target value is used instead of the initial value, and the calculation is repeated until the accuracy requirements are met.

[0139] For example, when determining the bottom-hole flowing pressure of a coalbed methane well, an initial value is first calculated using the pure gas column pressure, pressure gradient, and pseudo-moving liquid level position. Then, the compressibility factor is obtained based on the average temperature and pressure of the gas-water two-phase liquid column, thereby determining the target value. If the difference between the initial value and the target value is within the acceptable range, the target value is taken; otherwise, the target value is used instead of the initial value, and the calculation is repeated until the accuracy requirements are met.

[0140] This application provides a method for determining the bottom-hole flowing pressure of a coalbed methane well. First, the instantaneous volumes of the gas phase and water phase fluids in the coalbed methane well are obtained to determine the location of the pseudo-moving fluid level. Then, the wellhead temperature, bottom-hole reservoir temperature, and pressure gradient of the fluid are obtained to calculate the temperature gradient of the coalbed methane well. Next, the pseudo-moving fluid level temperature is obtained by combining the pseudo-moving fluid level location and temperature gradient. Then, the corresponding pure gas column pressure is determined based on the pseudo-moving fluid level location and temperature. Finally, by combining the pure gas column pressure, pseudo-moving fluid level location, and pressure gradient, the bottom-hole flowing pressure of the coalbed methane well containing both coalbed methane and fluid is accurately calculated. This method achieves accurate and efficient determination of the bottom-hole flowing pressure of coalbed methane wells, effectively solving the problem of inaccurate measurement of bottom-hole flowing pressure in previous coalbed methane wells.

[0141] Figure 3 is a schematic flowchart (II) of a method for determining the bottom-hole flowing pressure of a coalbed methane well according to an embodiment of this application. As shown in Figure 3, the method includes:

[0142] S301. Obtain the first volume value and the second volume value in the coalbed methane well; wherein, the first volume value represents the instantaneous volume of the gas phase fluid in the coalbed methane well, and the second volume value represents the instantaneous volume of the water phase fluid in the coalbed methane well.

[0143] In one example, Figure 4 is a flowchart illustrating step S301 of a method for determining the bottom hole flowing pressure of a coalbed methane well according to an embodiment of this application. As shown in Figure 4, step S301 includes:

[0144] S3011. Obtain the wellhead pressure, wellhead temperature, initial bottom temperature, and coalbed methane density of the coalbed methane well. The initial bottom temperature represents the initial temperature at the bottom of the well when the production wellbore of the coalbed methane well contains only gas.

[0145] S3012. Determine the initial pressure at the bottom of the well based on the coalbed methane density, gravitational acceleration, and the production well depth of the coalbed methane well; wherein, the initial pressure at the bottom of the well represents the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas.

[0146] S3013. Determine the average pressure inside the first wellbore of the coalbed methane well based on the wellhead pressure and the initial bottom pressure; determine the average temperature inside the first wellbore of the coalbed methane well based on the wellhead temperature and the initial bottom temperature.

[0147] S3014. Determine the first pseudo-comparison pressure based on the average pressure in the first wellbore and the preset pressure; wherein the preset pressure characterizes the critical pressure of coalbed methane; and determine the first pseudo-comparison temperature based on the average temperature in the first wellbore and the preset temperature; wherein the preset temperature characterizes the critical temperature of coalbed methane.

[0148] S3015. Obtain the first pseudo-comparison pressure and the first pseudo-comparison temperature; wherein, the first pseudo-comparison pressure is determined based on the wellhead pressure of the coalbed methane well and the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas, and the first pseudo-comparison temperature is determined based on the wellhead temperature of the coalbed methane well and the initial temperature at the bottom of the well when the production wellbore of the coalbed methane well contains only gas.

[0149] S3016. Determine the first compressibility factor based on the first pseudo-comparison pressure and the first pseudo-comparison temperature;

[0150] S3017. Determine the volume coefficient of coalbed methane based on the first compressibility factor, standard pressure, and standard temperature; wherein, standard pressure represents the coalbed methane pressure under standard conditions, and standard temperature represents the coalbed methane temperature under standard conditions.

[0151] S3018. Determine the first volume value based on the coalbed methane volume coefficient and the preset daily coalbed methane production.

[0152] For example, the wellhead pressure, production well depth, and coalbed methane density of a coalbed methane well are obtained, and the initial bottom-hole pressure of the coalbed methane well is calculated using the following formula: p w =p c +ρgH

[0153] Where, p w p represents the initial pressure at the bottom of a coalbed methane well when the wellbore contains only gas; cρ represents the wellhead pressure of the coalbed methane well; g represents the density of the coalbed methane; and g is the acceleration due to gravity, taken as 9.8 m / s². -2 H represents the production well depth of a coalbed methane well.

[0154] For example, the average pressure inside the wellbore of a coalbed methane well is calculated based on the wellhead pressure and the initial bottom-hole pressure; the average temperature inside the wellbore of a coalbed methane well is calculated based on the wellhead temperature and the initial bottom-hole temperature, using the following formulas:

[0155] in, p represents the average pressure within the wellbore of a coalbed methane well. c p represents the wellhead pressure of a coalbed methane well. w This represents the initial pressure at the bottom of a coalbed methane well when the wellbore contains only gas. T represents the average temperature inside the wellbore of a coalbed methane well. c T represents the wellhead temperature of a coalbed methane well. w This indicates the initial temperature at the bottom of a coalbed methane well when the wellbore contains only gas.

[0156] For example, the first simulated pressure is calculated based on the average pressure inside the wellbore of the coalbed methane well and a preset pressure.

[0157] The preset pressure represents the critical pressure of coalbed methane; and the first pseudo-comparison temperature is calculated based on the average temperature inside the coalbed methane well and the preset temperature; the preset temperature represents the critical temperature of coalbed methane. The calculation formula is as follows:

[0158] Where, p pr1 This indicates the first comparative pressure, which is the comparative pressure of the production wellbore of the coalbed methane well. p represents the average pressure within the wellbore of a coalbed methane well. pc T represents the critical pressure of coalbed methane. pr1 This indicates the first comparative temperature, which is the comparative temperature of the production wellbore of the coalbed methane well. T represents the average temperature inside the wellbore of a coalbed methane well. pc This indicates the critical temperature of coalbed methane.

[0159] For example, a first compressibility factor is calculated based on a first pseudo-comparison pressure and a first pseudo-comparison temperature. This first compressibility factor characterizes the compressibility factor within the wellbore of a coalbed methane well. The calculation formula is as follows:

[0160] Where Z1 represents the first compression factor; p pr1 Indicates the first relative pressure; T pr1Indicates the first comparative temperature.

[0161] For example, the volume factor of coalbed methane is calculated based on the first compressibility factor, standard pressure, and standard temperature. The calculation formula is as follows:

[0162] Among them, B g Z1 represents the volume factor of coalbed methane; p represents the first compressibility factor. sc This represents the standard pressure, i.e., the coalbed methane pressure under standard conditions, typically taken as 0.101325 MPa; T sc This represents the temperature of coalbed methane under standard conditions, typically taken as 288.16 K. This indicates the average temperature inside the wellbore of a coalbed methane well.

[0163] For example, the first volume value is calculated based on the coalbed methane volume factor and the preset daily coalbed methane production, using the following formula:

[0164] Among them, V g q represents the first volume value, which characterizes the instantaneous gas phase fluid volume in a coalbed methane well; g Indicates daily coalbed methane production; B g This represents the volume coefficient of coalbed methane.

[0165] S302. Obtain the third volume value based on the sum of the first and second volume values; determine the position of the simulated moving liquid level based on the second and third volume values ​​and the production well depth of the coalbed methane well.

[0166] For example, the third volume value is calculated based on the sum of the first and second volume values. The calculation formula is as follows: V m =V g +V w

[0167] Among them, V m V represents the third volume value, which characterizes the sum of the instantaneous volumes of the gas and water phases; g V represents the first volume value, which characterizes the instantaneous gas phase fluid volume in a coalbed methane well; w This represents the second volume value, which characterizes the instantaneous volume of the water phase fluid in a coalbed methane well.

[0168] For example, the simulated fluid level position is calculated based on the second volume value, the third volume value, and the production well depth of the coalbed methane well. The calculation formula is as follows:

[0169] Among them, h L V represents the position of the pseudo-dynamic fluid level in a coalbed methane well. wV represents the instantaneous volume of the aqueous phase fluid in a coalbed methane well. m The value represents the instantaneous volume of gas phase fluid in a coalbed methane well, H represents the production well depth of the coalbed methane well, and α represents the conversion factor, which generally ranges from 1.0 to 2.0.

[0170] For example, a coalbed methane well in the proven deep coalbed methane reserve area of ​​the Daning-Jixian block on the eastern edge of the Ordos Basin is taken as the research object. The reservoir temperature of the coalbed methane well is 70℃. Figure 5 is a diagram showing the conversion result of the pseudo-dynamic liquid level position provided in an embodiment of this application. Based on the instantaneous volume of gas phase fluid and the instantaneous volume of water phase fluid in the coalbed methane well, the daily pseudo-dynamic liquid level position in the coalbed methane well is calculated. The calculation results are shown in Figure 5.

[0171] S303. Determine the temperature gradient of the coalbed methane well based on the first temperature, the second temperature, and the production well depth; determine the pseudo-dynamic liquid level temperature of the coalbed methane well based on the pseudo-dynamic liquid level position and the temperature gradient.

[0172] For example, the temperature gradient of the coalbed methane well is calculated based on the first temperature, the second temperature, and the production well depth of the coalbed methane well, using the following formula:

[0173] Where, γ T T represents the temperature gradient of a coalbed methane well. C T represents the wellhead temperature of a coalbed methane well. m H represents the reservoir temperature at the bottom of the coalbed methane well; H represents the production well depth of the coalbed methane well.

[0174] For example, the pseudo-dynamic fluid level temperature of a coalbed methane well is calculated based on the pseudo-dynamic fluid level position and temperature gradient. The calculation formula is as follows: T L =h L ×γ T

[0175] Among them, T L The pseudo-dynamic fluid level temperature (h) of a coalbed methane well. L Indicates the position of the pseudo-dynamic fluid level in a coalbed methane well, γ T This represents the temperature gradient of a coalbed methane well.

[0176] For example, a coalbed methane well in the proven deep coalbed methane reserve area of ​​the Daning-Jixian block on the eastern edge of the Ordos Basin is taken as the research object. The reservoir temperature of the coalbed methane well is 70℃. Figure 6 is a diagram showing the conversion result of the pseudo-dynamic liquid level temperature provided in an embodiment of this application. Based on the temperature gradient of the deep coalbed methane and the position of the pseudo-dynamic liquid level, the daily pseudo-dynamic liquid level temperature in the coalbed methane well is calculated. The calculation results are shown in Figure 6.

[0177] S304. Determine the pure gas column pressure corresponding to the coalbed methane well based on the simulated moving liquid level position and simulated moving liquid level temperature.

[0178] In one example, Figure 7 is a flowchart illustrating step S304 of a method for determining the bottom hole flowing pressure of a coalbed methane well according to an embodiment of this application. As shown in Figure 7, step S304 includes:

[0179] S3041. Repeat the following steps until the first preset condition is met, wherein the initial pressure obtained for the first time is determined based on the pseudo-dynamic liquid level position and the wellhead pressure of the coalbed methane well:

[0180] S3042. Based on the wellhead pressure and initial pressure of the coalbed methane well, determine the average pressure inside the second wellbore of the coalbed methane well, wherein the initial pressure represents the initially obtained pure gas column pressure; the average pressure inside the second wellbore represents the average pressure of the pure gas column inside the production wellbore of the coalbed methane well; based on the wellhead temperature and pseudo-dynamic liquid level temperature of the coalbed methane well, determine the average temperature inside the second wellbore of the coalbed methane well, wherein the average temperature inside the second wellbore represents the average temperature of the pure gas column inside the production wellbore of the coalbed methane well.

[0181] S3043. Determine the second simulated comparison pressure based on the average pressure inside the second wellbore and the preset pressure; wherein the preset pressure characterizes the critical pressure of coalbed methane; and determine the second simulated comparison temperature based on the average temperature inside the second wellbore and the preset temperature; wherein the preset temperature characterizes the critical temperature of coalbed methane.

[0182] S3044. Determine the second compressibility factor based on the second pseudo-comparison pressure and the second pseudo-comparison temperature; and determine the target pressure based on the second compressibility factor.

[0183] S3045. If the difference between the target pressure and the initial pressure meets the first preset condition, then the target pressure is determined to be the pure gas column pressure corresponding to the coalbed methane well.

[0184] S3046. If it is determined that the difference between the target pressure and the initial pressure does not meet the first preset condition, then the initial pressure is updated to the target pressure.

[0185] In one example, step S3043 further includes the following process:

[0186] The first step of step S3043 is to determine the parameter factors based on the production well depth of the coalbed methane well, the position of the simulated liquid level, the average temperature inside the second wellbore, the preset gas relative density value, and the second compressibility factor.

[0187] The second step of step S3043 is to determine the Reynolds number in the production wellbore of the coalbed methane well based on the preset gas flow rate, the preset gas relative density value, the preset coalbed methane viscosity, the inner diameter of the casing of the coalbed methane well, and the outer diameter of the tubing of the coalbed methane well; wherein, the preset gas flow rate represents the gas flow rate under standard conditions.

[0188] The third step of step S3043 is to determine the friction coefficient of the coalbed methane well based on the preset absolute roughness of the pipe, the inner diameter of the casing of the coalbed methane well, the outer diameter of the tubing of the coalbed methane well, and the Reynolds number in the production wellbore of the coalbed methane well.

[0189] The fourth step of step S3043 is to determine the target pressure based on the wellhead pressure of the coalbed methane well, the friction coefficient of the coalbed methane well, the average temperature inside the second wellbore, the second compressibility factor, the preset gas flow rate, the inner diameter of the casing of the coalbed methane well, and the outer diameter of the tubing of the coalbed methane well.

[0190] For example, the initial pressure is calculated based on the pseudo-dynamic liquid level position and the wellhead pressure of the coalbed methane well. The calculation formula is as follows: p g1 =p c +ρgh L

[0191] Where, p g1 This represents the initial pressure, i.e., the initial value of the pure gas column pressure in a coalbed methane well; p c ρ represents the wellhead pressure of the coalbed methane well; g represents the density of the coalbed methane; and g is the acceleration due to gravity, taken as 9.8 m / s². -2 h L Indicates the position of the simulated moving liquid surface.

[0192] For example, the average pressure within the second wellbore of the coalbed methane well is calculated based on the wellhead pressure and initial pressure; where the initial pressure represents the initially obtained pure gas column pressure (pseudo-dynamic fluid level pressure); and the average pressure within the second wellbore of the coalbed methane well represents the average pressure of the pure gas column within the production wellbore of the coalbed methane well. The average temperature within the second wellbore of the coalbed methane well is calculated based on the wellhead temperature and pseudo-dynamic fluid level temperature; where the average temperature within the second wellbore of the coalbed methane well represents the average temperature of the pure gas column within the production wellbore of the coalbed methane well. The calculation formula is as follows:

[0193] in, This represents the average pressure within the second wellbore of a coalbed methane well, which is the average pressure of the pure gas column within the production wellbore of the coalbed methane well; p c p represents the wellhead pressure of a coalbed methane well. g1 Indicates the initial pressure; T represents the average temperature within the second wellbore of a coalbed methane well, i.e., the average temperature of the pure gas column within the production wellbore of the coalbed methane well. c T represents the wellhead temperature of a coalbed methane well. L This indicates the temperature of the pseudo-dynamic liquid surface.

[0194] For example, a second pseudo-comparison pressure is calculated based on the average pressure inside the second wellbore and a preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and a second pseudo-comparison temperature is calculated based on the average temperature inside the second wellbore and a preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane. The calculation formula is as follows:

[0195] Where, p pr2 This represents the second pseudo-comparison pressure, which is the pseudo-comparison pressure of the pure gas column in the production wellbore of a coalbed methane well. p represents the average pressure of the pure gas column within the production wellbore of a coalbed methane well. pc This indicates the preset pressure, i.e., the critical pressure of coalbed methane; T pr2 This indicates the second pseudo-comparison temperature, which is the pseudo-comparison temperature of the pure gas column in the production wellbore of the coalbed methane well. T represents the average temperature of the pure gas column within the production wellbore of a coalbed methane well. pc This indicates the preset temperature, which is the critical temperature of coalbed methane.

[0196] For example, a second compressibility factor is calculated based on a second pseudo-comparison pressure and a second pseudo-comparison temperature. This second compressibility factor characterizes the compressibility of the pure gas column within the production wellbore of a coalbed methane well. The calculation formula is shown below:

[0197] Where Z2 represents the second compressibility factor, which is the compressibility factor of the pure gas column in the production wellbore of a coalbed methane well; p pr2 This represents the second pseudo-comparison pressure, i.e., the pseudo-comparison pressure of the pure gas column within the production wellbore of a coalbed methane well; T pr2 This indicates the second pseudo-comparison temperature, which is the pseudo-comparison temperature of the pure gas column in the production wellbore of a coalbed methane well.

[0198] For example, the parameter factor is calculated based on the production well depth of the coalbed methane well, the position of the simulated fluid level, the average temperature inside the second wellbore, the preset relative gas density value, and the second compressibility factor. The calculation formula is as follows:

[0199] Where S represents the parameter factor; γ g The relative density of the gas, i.e., the ratio of the molar mass of deep coalbed methane to the molar mass of air, can be obtained experimentally and is dimensionless; H represents the production well depth of the coalbed methane well; h L Indicates the position of the pseudo-moving liquid surface; Z1 represents the average temperature of the pure gas column in the production wellbore of a coalbed methane well; Z2 represents the second compressibility factor, which is the compressibility factor of the pure gas column in the production wellbore of a coalbed methane well.

[0200] For example, the Reynolds number within the production wellbore of a coalbed methane well is calculated based on a preset gas flow rate, a preset gas relative density value, a preset coalbed methane viscosity, the casing inner diameter of the coalbed methane well, and the tubing outer diameter of the coalbed methane well; wherein, the preset gas flow rate characterizes the gas flow rate under standard conditions. The calculation formula is as follows:

[0201] Where Re represents the Reynolds number within the production wellbore of the coalbed methane well; q sc This indicates the preset gas flow rate, i.e., the gas flow rate under standard conditions; γ g This represents the preset relative density value of the gas, i.e., the ratio of the molar mass of deep coalbed methane to the molar mass of air, which can be obtained experimentally; μ g d1 represents the preset coalbed methane viscosity; d2 represents the outer diameter of the tubing in the coalbed methane well; d3 represents the inner diameter of the casing in the coalbed methane well.

[0202] For example, the friction coefficient of a coalbed methane well is calculated based on preset absolute pipe roughness, casing inner diameter, tubing outer diameter, and Reynolds number within the production wellbore. The calculation formula is as follows:

[0203] Where f represents the friction coefficient of the coalbed methane well; E represents the preset absolute roughness of the pipe, which can be obtained through fluid dynamics experiments; d1 represents the outer diameter of the tubing in the coalbed methane well; d2 represents the inner diameter of the casing in the coalbed methane well; and Re represents the Reynolds number in the production wellbore of the coalbed methane well.

[0204] For example, the target pressure is calculated based on the wellhead pressure of the coalbed methane well, the friction coefficient of the coalbed methane well, the average temperature inside the second wellbore, the second compressibility factor, the preset gas flow rate, the inner diameter of the casing of the coalbed methane well, and the outer diameter of the tubing of the coalbed methane well.

[0205] Where, p g2 This represents the target pressure, specifically the target value of the pure gas column pressure in a coalbed methane well; p c The value represents the wellhead pressure of the coalbed methane well; e is the natural constant, approximately equal to 2.718; S represents the parameter factor; f represents the friction coefficient of the coalbed methane well. Z1 represents the average temperature within the second wellbore of a coalbed methane well, i.e., the average temperature of the pure gas column within the production wellbore of the coalbed methane well; Z2 represents the second compressibility factor, i.e., the compressibility factor of the pure gas column within the production wellbore of the coalbed methane well; q sc d1 represents the preset gas flow rate, i.e., the gas flow rate under standard conditions; d2 represents the outer diameter of the tubing in the coalbed methane well; d3 represents the inner diameter of the casing in the coalbed methane well.

[0206] For example, if the target pressure p is determined g2 With initial pressure p g1The difference between |p g2 -p g1 |Meets the first preset condition, i.e., |p g2 -p g1 |<10 -12 Then determine the target pressure p g2 , which is the pure gas column pressure corresponding to the coalbed methane well.

[0207] For example, if the target pressure p is determined g2 With initial pressure p g1 The difference between |p g2 -p g1 |Does not meet the first preset condition, i.e.,|p g2 -p g1 |≥10 -12 Then the target pressure p cannot be determined. g2 , where p is the pure gas column pressure corresponding to the coalbed methane well, and the initial pressure p needs to be... g1 Updated to target pressure p g2 Repeat the above steps to recalculate the target pressure value until the first preset condition is met, and determine the pure gas column pressure corresponding to the coalbed methane well.

[0208] S305. Determine the bottom-hole flowing pressure of a coalbed methane well based on the pure gas column pressure, the position of the pseudo-dynamic liquid level, and the pressure gradient. The bottom-hole flowing pressure characterizes the bottom-hole pressure when the coalbed methane well contains both coalbed methane and liquid.

[0209] In one example, Figure 8 is a flowchart illustrating step S305 of a method for determining the bottom hole flowing pressure of a coalbed methane well according to an embodiment of this application. As shown in Figure 8, step S305 includes:

[0210] S3051. Repeat the following steps until the first preset condition is met, wherein the initial bottom hole flowing pressure obtained for the first time is determined based on the pure gas column pressure, pressure gradient, and pseudo-dynamic liquid level position of the coalbed methane well; wherein the pressure gradient is determined by the liquid density and gravitational acceleration:

[0211] S3052. Based on the pure gas column pressure and initial bottom hole flowing pressure of the coalbed methane well, determine the average pressure in the third wellbore of the coalbed methane well, wherein the initial bottom hole flowing pressure represents the initially obtained bottom hole flowing pressure; the average pressure in the third wellbore represents the average pressure of the gas-water two-phase liquid column in the production wellbore of the coalbed methane well; based on the pseudo-dynamic liquid surface temperature and the initial bottom hole temperature of the coalbed methane well, determine the average temperature in the third wellbore of the coalbed methane well, wherein the average temperature in the third wellbore represents the average temperature of the gas-water two-phase liquid column in the production wellbore of the coalbed methane well.

[0212] S3053. Based on the average pressure in the third wellbore and the preset pressure, determine the third pseudo-comparison pressure; wherein, the preset pressure characterizes the critical pressure of coalbed methane; and based on the average temperature in the third wellbore and the preset temperature, determine the third pseudo-comparison temperature; wherein, the preset temperature characterizes the critical temperature of coalbed methane.

[0213] S3054. Determine the third compressibility factor based on the third pseudo-comparison pressure and the third pseudo-comparison temperature; and determine the target bottom hole flowing pressure based on the third compressibility factor.

[0214] S3055. If the difference between the target bottom-hole flowing pressure and the initial bottom-hole flowing pressure meets the first preset condition, then the target bottom-hole flowing pressure is determined to be the bottom-hole flowing pressure corresponding to the coalbed methane well.

[0215] S3056. If it is determined that the difference between the target bottom hole pressure and the initial bottom hole pressure does not meet the first preset condition, then the initial bottom hole pressure is updated to the target bottom hole pressure.

[0216] In one example, step S3054 further includes the following process:

[0217] The first step of step S3054 is to determine the apparent gas velocity based on the preset gas flow rate, the average temperature inside the third wellbore of the coalbed methane well, the average pressure inside the third wellbore of the coalbed methane well, the third compressibility factor, the standard pressure, the standard temperature, and the annular cross-sectional area between the casing and the tubing of the coalbed methane well; wherein, the annular cross-sectional area between the casing and the tubing of the coalbed methane well is determined by the inner diameter of the casing and the outer diameter of the tubing of the coalbed methane well.

[0218] In the second step of step S3054, if it is determined that the apparent gas flow rate meets the second preset condition, then the preset parameter is determined to be the first preset parameter; if it is determined that the apparent gas flow rate does not meet the second preset condition, then the preset parameter is determined to be the second preset parameter.

[0219] The third step of step S3054 is to determine the porosity based on preset parameters and the apparent gas flow rate.

[0220] The fourth step of step S3054 is to determine the third relevant parameters based on the preset gas flow rate, standard temperature, average temperature inside the third wellbore, third compressibility factor, standard pressure, and the annular cross-sectional area between the casing and tubing of the coalbed methane well.

[0221] In the fifth step of step S3054, the first relevant parameter is determined based on the third relevant parameter, porosity, preset parameter, wellhead pressure of coalbed methane well, pressure difference of pure gas column, pseudo-dynamic liquid level position, and pressure gradient; wherein, the pressure difference of pure gas column is obtained by the difference between the wellhead pressure of coalbed methane well and the corresponding pure gas column pressure of coalbed methane well.

[0222] In step S3054, the sixth step is to determine the second correlation coefficient based on the third correlation coefficient, porosity, preset parameters, preset gas constant, preset molar mass, pseudo-dynamic liquid level position, third compressibility factor, third average temperature in the wellbore, pressure gradient, wellhead pressure of the coalbed methane well, and pressure difference of the pure gas column; wherein, the gas constant represents the general gas constant; and the preset molar mass represents the molar mass of natural gas.

[0223] Step S3054, the seventh step, determines the target bottom hole flowing pressure based on the wellhead pressure, pure gas column pressure difference, pressure gradient, pseudo-dynamic liquid level position, first relevant parameter, and second relevant parameter of the coalbed methane well.

[0224] For example, the initial bottomhole flowing pressure is calculated based on the pure gas column pressure, pressure gradient, and pseudo-dynamic fluid level position of the coalbed methane well. The calculation formula is as follows: p wf1 =p g +r L ×h L

[0225] Where, p wf1 p represents the initial bottom hole flowing pressure; g This represents the pure gas column pressure of the coalbed methane well, i.e., the pure gas column pressure of the coalbed methane well finally calculated in step S303; r L The pressure gradient is represented by the product of the liquid density and the gravitational acceleration. The liquid density can be obtained through physical experiments, and the gravitational acceleration can be taken as 9.8 m / s². -2 h L Indicates the position of the simulated moving liquid surface.

[0226] For example, the average pressure within the third wellbore of a coalbed methane well is calculated based on the pure gas column pressure and the initial bottomhole flowing pressure. This average pressure within the third wellbore characterizes the average pressure of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well. The average temperature within the third wellbore of the coalbed methane well is determined based on the pseudo-dynamic liquid surface temperature and the initial bottomhole temperature, where the average temperature within the third wellbore characterizes the average temperature of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well. The calculation formula is as follows:

[0227] in, This represents the average pressure within the third wellbore of a coalbed methane well, i.e., the average pressure of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well; p g p represents the pure gas column pressure of a coalbed methane well. wf1 Indicates the initial bottom hole flowing pressure; This represents the average temperature within the third wellbore of a coalbed methane well, i.e., the average temperature of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well; T L T represents the pseudo-dynamic fluid level temperature of a coalbed methane well. wf This indicates the initial temperature at the bottom of the well.

[0228] For example, the third simulated comparison pressure is calculated based on the average pressure inside the third wellbore and the preset pressure; and the third simulated comparison temperature is calculated based on the average temperature inside the third wellbore and the preset temperature. The calculation formulas are as follows:

[0229] Where, p pr3 This indicates the third pseudo-comparison pressure, which is the pseudo-comparison pressure of the gas-water two-phase liquid column in the production wellbore of a coalbed methane well. This represents the average pressure within the third wellbore of a coalbed methane well, i.e., the average pressure of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well; p pc This indicates the preset pressure, i.e., the critical pressure of coalbed methane; T pr3 This indicates the third pseudo-comparison temperature, which is the pseudo-comparison temperature of the gas-water two-phase liquid column in the production wellbore of a coalbed methane well. This represents the average temperature within the third wellbore of a coalbed methane well, i.e., the average temperature of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well; T pc This indicates the preset temperature, which is the critical temperature of coalbed methane.

[0230] For example, the third compressibility factor is calculated based on the third pseudo-comparison pressure and the third pseudo-comparison temperature. The calculation formula is as follows:

[0231] Where Z3 represents the third compressibility factor, which is the compressibility factor of the gas-water two-phase liquid column in the production wellbore of a coalbed methane well; p pr3 This represents the third pseudo-comparison pressure, i.e., the pseudo-comparison pressure of the gas-water two-phase liquid column within the production wellbore of a coalbed methane well; T pr3 This indicates the third pseudo-comparison temperature, which is the pseudo-comparison temperature of the gas-water two-phase liquid column in the production wellbore of a coalbed methane well.

[0232] For example, the apparent gas velocity is calculated based on a preset gas flow rate, the average temperature within the third wellbore of the coalbed methane well, the average pressure within the third wellbore of the coalbed methane well, the third compressibility factor, the standard pressure, the standard temperature, and the annular cross-sectional area between the casing and tubing of the coalbed methane well; wherein, the annular cross-sectional area between the casing and tubing of the coalbed methane well is determined by the inner diameter of the casing and the outer diameter of the tubing of the coalbed methane well. The calculation formula is as follows:

[0233] Among them, v sg q represents the apparent flow rate of the gas; sc This indicates the preset gas flow rate, i.e., the gas flow rate under standard conditions; Z3 represents the average temperature within the third wellbore of a coalbed methane well, i.e., the average temperature of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well; Z3 represents the third compressibility factor, i.e., the compressibility factor of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well; psc The standard pressure is the coalbed methane pressure under standard conditions, typically taken as 0.101325 MPa; A represents the annular cross-sectional area between the casing and tubing, determined by the inner diameter of the casing and the outer diameter of the tubing in the coalbed methane well; T sc This represents the temperature of coalbed methane under standard conditions, typically taken as 288.16 K. This represents the average pressure within the third wellbore of a coalbed methane well, which is the average pressure of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well.

[0234] For example, if the apparent gas velocity is less than 0.61 m·s -1 When the gas-liquid two-phase column is in a bubbly flow state, the preset parameters a and b are the first preset parameters, i.e., a = 0.6 and b = 1.2; when the apparent gas velocity is greater than or equal to 0.61 m·s -1 When the flow rate is 1, it indicates that the gas-water two-phase liquid column is a slug flow. Therefore, the preset parameters a and b are the second preset parameters, i.e., a = b = 1.0.

[0235] For example, porosity is calculated based on preset parameters and apparent gas flow rate. The calculation formula is as follows:

[0236] Among them, f g Indicates porosity; v sg represents the apparent gas flow rate; a and b represent preset parameters whose values ​​are determined by the apparent gas flow rate.

[0237] For example, the third relevant parameter is calculated based on the preset gas flow rate, standard temperature, average temperature within the third wellbore, third compressibility factor, standard pressure, and the annular cross-sectional area between the casing and tubing of the coalbed methane well. The calculation formula is as follows:

[0238] Where C represents the third relevant parameter; q sc This indicates the preset gas flow rate, i.e., the gas flow rate under standard conditions; Z3 represents the average temperature within the third wellbore of a coalbed methane well, i.e., the average temperature of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well; Z3 represents the third compressibility factor, i.e., the compressibility factor of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well; p sc The standard pressure is the coalbed methane pressure under standard conditions, typically taken as 0.101325 MPa; A represents the annular cross-sectional area between the casing and tubing, determined by the inner diameter of the casing and the outer diameter of the tubing in the coalbed methane well; T sc This represents the temperature of coalbed methane under standard conditions, typically taken as 288.16 K.

[0239] For example, the first relevant parameter is calculated based on the third relevant parameter, porosity, preset parameters, wellhead pressure of the coalbed methane well, pressure difference of the pure gas column, pseudo-dynamic liquid level position, and pressure gradient; wherein, the pressure difference of the pure gas column is obtained by the difference between the wellhead pressure of the coalbed methane well and the corresponding pure gas column pressure of the coalbed methane well. The calculation formula is as follows:

[0240] Where I1 represents the first relevant parameter; C represents the third relevant parameter; a and b represent preset parameters, the values ​​of which are determined by the apparent gas flow rate; f g Indicates porosity; p c Δp represents the wellhead pressure of a coalbed methane well. g This represents the pressure difference of the pure gas column, which is obtained by dividing the wellhead pressure of the coalbed methane well by the corresponding pure gas column pressure; h L Indicates the position of the pseudo-moving liquid surface; r L The pressure gradient is represented by the product of the liquid density and the gravitational acceleration. The liquid density can be obtained through physical experiments, and the gravitational acceleration can be taken as 9.8 m / s². -2 .

[0241] For example, the second correlation coefficient is calculated based on the third correlation coefficient, porosity, preset parameters, preset gas constant, preset molar mass, pseudo-fluid level position, third compressibility factor, third average temperature within the wellbore, pressure gradient, wellhead pressure of the coalbed methane well, and pressure difference of the pure gas column; wherein, the gas constant represents the general gas constant; and the preset molar mass represents the molar mass of natural gas. The calculation formula is as follows:

[0242] Where I2 represents the second correlation coefficient; C represents the third correlation parameter; M represents the molar mass of natural gas; and g represents the gravitational acceleration, taken as 9.8 m·s⁻¹. -2 h L The position of the simulated liquid level is indicated; a and b represent preset parameters, the values ​​of which are determined by the apparent gas velocity; Z3 represents the third compressibility factor, i.e., the compressibility factor of the gas-water two-phase liquid column in the production wellbore of the coalbed methane well; R represents the preset gas constant, i.e., the universal gas constant, which is generally taken as 8.314 kJ·kmol. -1 ·K -1 ; This represents the average temperature within the third wellbore of a coalbed methane well, i.e., the average temperature of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well; f g Indicates porosity; r L The pressure gradient is represented by the product of the liquid density and the gravitational acceleration. The liquid density can be obtained through physical experiments, and the gravitational acceleration can be taken as 9.8 m / s². -2 ;p c Δp represents the wellhead pressure of a coalbed methane well. gThis represents the pressure difference of the pure gas column, which is the difference between the wellhead pressure of the coalbed methane well and the corresponding pure gas column pressure.

[0243] For example, the target bottom hole flowing pressure is calculated based on the wellhead pressure of the coalbed methane well, the pressure difference of the pure gas column, the pressure gradient, the position of the pseudo-dynamic liquid level, the first relevant parameter, and the second relevant parameter. wf2 =p c +Δp g +r L ·h L -I l +I2

[0244] Where, p wf2 p represents the target bottom hole flowing pressure. c Δp represents the wellhead pressure of a coalbed methane well. g This represents the pressure difference of the pure gas column, which is obtained by dividing the wellhead pressure of the coalbed methane well by the corresponding pure gas column pressure; r L The pressure gradient is represented by the product of the liquid density and the gravitational acceleration. The liquid density can be obtained through physical experiments, and the gravitational acceleration can be taken as 9.8 m / s². -2 h L I1 represents the position of the simulated liquid surface; I2 represents the first correlation parameter; and I2 represents the second correlation coefficient.

[0245] For example, if the target bottom hole flowing pressure p is determined wf2 With the initial bottom hole flowing pressure p wf1 The difference between |p wf2 -p wf1 |Meets the first preset condition, i.e., |p wf2 -p wf1 |<10 -12 When the target bottom hole flowing pressure p is determined, wf2 , which is the bottom hole flowing pressure corresponding to the coalbed methane well;

[0246] For example, if the target bottom hole flowing pressure p is determined wf2 With the initial bottom hole flowing pressure p wf1 The difference between

[0247] |p wf2 -p wf1 |Does not meet the first preset condition, that is, |p g2 -p g1 |≥10 -12 At that time, the target bottom hole flowing pressure p cannot be determined. wf2 , which is the bottom hole flowing pressure corresponding to the coalbed methane well, requires the initial bottom hole flowing pressure p to be... wf1 Updated to target bottom hole flowing pressure p wf2Repeat the above steps to recalculate the target bottom hole pressure until it meets the first preset condition, and determine that the target bottom hole pressure is the bottom hole pressure corresponding to the coalbed methane well.

[0248] For example, a coalbed methane well in the proven deep coalbed methane reserve area of ​​the Daning-Jixian block on the eastern edge of the Ordos Basin is taken as the research object. The reservoir temperature of the coalbed methane well is 70℃. Figure 9 is a comparison diagram of the calculated bottom-hole flowing pressure and the measured bottom-hole flowing pressure provided in an embodiment of this application. The bottom-hole flowing pressure is calculated using the method for determining the bottom-hole flowing pressure of a coalbed methane well provided in an embodiment of this application, while the measured bottom-hole flowing pressure is data obtained through on-site measurement using instruments. The comparison results are shown in Figure 9.

[0249] This application provides a method for determining the bottom-hole flowing pressure of a coalbed methane well. Through a series of precise calculation steps, firstly, the compressibility factor within the production wellbore of the coalbed methane well is calculated using parameters such as wellhead pressure, wellhead temperature, bottom-hole temperature, and bottom-hole pressure. Then, based on the compressibility factor, the volume coefficient of the coalbed methane is obtained, thereby determining the instantaneous gas phase fluid volume in the coalbed methane well. The position of the pseudo-moving liquid level is calculated by combining this with the instantaneous water phase fluid volume. Next, the pseudo-moving liquid level temperature is determined based on the position and temperature gradient, completing the accurate calculation of the pseudo-moving liquid level data. Subsequently, an initial pressure value is set using the wellhead pressure and the position of the pseudo-moving liquid level. The compressibility factor of the pure gas column within the production wellbore of the coalbed methane well is calculated again using parameters such as wellhead pressure, wellhead temperature, the initial pressure value, and the pseudo-moving liquid level temperature to obtain the target pressure value. This process is iterated multiple times until the initial pressure value and the target pressure value meet the accuracy requirements, thereby accurately calculating the pressure of the pure gas column. Finally, the initial bottom-hole flowing pressure is calculated using the pure gas column pressure, pressure gradient, and pseudo-dynamic liquid level position. Similarly, the compressibility factor of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well is calculated using parameters such as the initial bottom-hole temperature, pure gas column pressure, and pseudo-dynamic liquid level temperature. This yields the target bottom-hole flowing pressure value. The process is iterated multiple times until both the initial and target bottom-hole flowing pressure values ​​meet the accuracy requirements, thus accurately calculating the bottom-hole flowing pressure of the coalbed methane well. This method achieves accurate and efficient determination of the bottom-hole flowing pressure of coalbed methane wells, unaffected by production status or stage, and is applicable to the entire production stage of deep coalbed methane wells. The calculation is simple and convenient.

[0250] Figure 10 is a schematic diagram of a device for determining the bottom flow pressure of a coalbed methane well according to an embodiment of this application. As shown in Figure 10, the device 100 for determining the bottom flow pressure of a coalbed methane well provided in this embodiment includes:

[0251] The first acquisition module 1001 is used to acquire a first volume value and a second volume value in the coalbed methane well; wherein the first volume value represents the instantaneous volume of the gas phase fluid in the coalbed methane well, and the second volume value represents the instantaneous volume of the water phase fluid in the coalbed methane well; and to determine the position of the pseudo-dynamic liquid level in the coalbed methane well based on the first volume value and the second volume value.

[0252] The second acquisition module 1002 is used to acquire the first temperature, the second temperature, and the pressure gradient of the liquid in the coalbed methane well; wherein the first temperature represents the wellhead temperature of the coalbed methane well, the second temperature represents the reservoir temperature at the bottom of the coalbed methane well, and the temperature gradient of the coalbed methane well is determined based on the first temperature and the second temperature.

[0253] The first determining module 1003 is used to determine the simulated liquid level temperature of the coalbed methane well based on the simulated liquid level position and temperature gradient.

[0254] The second determining module 1004 is used to determine the pure gas column pressure corresponding to the coalbed methane well based on the simulated moving liquid surface position and simulated moving liquid surface temperature; and to determine the bottom flow pressure of the coalbed methane well based on the pure gas column pressure, simulated moving liquid surface position and pressure gradient, wherein the bottom flow pressure characterizes the bottom pressure of the coalbed methane well when it includes coalbed methane and liquid.

[0255] This embodiment provides a device for determining the bottom-hole flowing pressure of a coalbed methane well, which can execute the method provided in the above-described method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0256] Figure 11 is a schematic diagram of the structure of a device for determining the bottom flow pressure of a coalbed methane well according to an embodiment of this application. As shown in Figure 11, the device 110 for determining the bottom flow pressure of a coalbed methane well provided in this embodiment includes:

[0257] The first acquisition module 1101 is used to acquire a first volume value and a second volume value in the coalbed methane well; wherein, the first volume value represents the instantaneous volume of the gas phase fluid in the coalbed methane well, and the second volume value represents the instantaneous volume of the water phase fluid in the coalbed methane well; and determine the position of the pseudo-dynamic liquid surface in the coalbed methane well based on the first volume value and the second volume value.

[0258] The second acquisition module 1102 is used to acquire the first temperature, the second temperature, and the pressure gradient of the liquid in the coalbed methane well; wherein the first temperature represents the wellhead temperature of the coalbed methane well, the second temperature represents the reservoir temperature at the bottom of the coalbed methane well, and the temperature gradient of the coalbed methane well is determined based on the first temperature and the second temperature.

[0259] The first determining module 1103 is used to determine the simulated liquid level temperature of the coalbed methane well based on the simulated liquid level position and temperature gradient.

[0260] The second determining module 1104 is used to determine the pure gas column pressure corresponding to the coalbed methane well based on the simulated moving liquid surface position and simulated moving liquid surface temperature; and to determine the bottom flow pressure of the coalbed methane well based on the pure gas column pressure, simulated moving liquid surface position and pressure gradient, wherein the bottom flow pressure characterizes the bottom pressure of the coalbed methane well when it includes coalbed methane and liquid.

[0261] In one possible implementation, the first acquisition module 1101 includes:

[0262] The first acquisition submodule 11011 is used to acquire the first simulated comparison pressure and the first simulated comparison temperature; wherein, the first simulated comparison pressure is determined based on the wellhead pressure of the coalbed methane well and the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas, and the first simulated comparison temperature is determined based on the wellhead temperature of the coalbed methane well and the initial temperature at the bottom of the well when the production wellbore of the coalbed methane well contains only gas;

[0263] The third determining module 11012 is used to determine the first compressibility factor based on the first simulated comparison pressure and the first simulated comparison temperature;

[0264] The fourth confirmation module 11013 is used to determine the volume coefficient of coalbed methane based on the first compressibility factor, standard pressure, and standard temperature; wherein, the standard pressure represents the coalbed methane pressure under standard conditions, and the standard temperature represents the coalbed methane temperature under standard conditions.

[0265] The fifth confirmation module 11014 is used to determine the first volume value based on the coalbed methane volume coefficient and the preset daily coalbed methane production.

[0266] In one possible implementation, the first acquisition submodule 11011 includes:

[0267] The second acquisition submodule 110111 is used to acquire the wellhead pressure, wellhead temperature, bottom initial temperature and coalbed methane density of the coalbed methane well. The bottom initial temperature represents the initial temperature at the bottom of the well when the production wellbore of the coalbed methane well contains only gas.

[0268] The sixth confirmation module 110112 is used to determine the initial pressure at the bottom of the well based on the coalbed methane density, gravitational acceleration, and the production well depth of the coalbed methane well; wherein, the initial pressure at the bottom of the well represents the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas.

[0269] The seventh confirmation module 110113 is used to determine the average pressure inside the first wellbore of the coalbed methane well based on the wellhead pressure and the initial bottom pressure; and to determine the average temperature inside the first wellbore of the coalbed methane well based on the wellhead temperature and the initial bottom temperature.

[0270] The eighth confirmation module 110114 is used to determine the first pseudo-comparison pressure based on the average pressure in the first wellbore and the preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and to determine the first pseudo-comparison temperature based on the average temperature in the first wellbore and the preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane.

[0271] In one possible implementation, the first acquisition module 1101 further includes:

[0272] The calculation module 11015 is used to obtain the third volume value based on the sum of the first volume value and the second volume value;

[0273] The ninth confirmation module 11016 is used to determine the position of the simulated liquid level based on the second volume value, the third volume value, and the production well depth of the coalbed methane well.

[0274] In one possible implementation, the second acquisition module 1102 includes:

[0275] The tenth confirmation module 11021 is used to determine the temperature gradient of the coalbed methane well based on the first temperature, the second temperature and the production well depth of the coalbed methane well.

[0276] In one possible implementation, the second determining module 1104 includes:

[0277] The first loop module 11041 is used to repeatedly execute the following steps until a first preset condition is reached, wherein the initial pressure obtained for the first time is determined based on the pseudo-dynamic liquid level position and the wellhead pressure of the coalbed methane well:

[0278] The first confirmation submodule 11042 is used to determine the average pressure inside the second wellbore of the coalbed methane well based on the wellhead pressure and the initial pressure, wherein the initial pressure represents the initially obtained pure gas column pressure; the average pressure inside the second wellbore represents the average pressure of the pure gas column inside the production wellbore of the coalbed methane well; and to determine the average temperature inside the second wellbore of the coalbed methane well based on the wellhead temperature and the pseudo-dynamic liquid level temperature, wherein the average temperature inside the second wellbore represents the average temperature of the pure gas column inside the production wellbore of the coalbed methane well.

[0279] The second confirmation submodule 11043 is used to determine the second simulated comparison pressure based on the average pressure inside the second wellbore and the preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and to determine the second simulated comparison temperature based on the average temperature inside the second wellbore and the preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane.

[0280] The third confirmation submodule 11044 is used to determine the second compressibility factor based on the second simulated comparison pressure and the second simulated comparison temperature; and to determine the target pressure based on the second compressibility factor.

[0281] The fourth confirmation submodule 11044 is used to determine the target pressure as the pure gas column pressure corresponding to the coalbed methane well if the difference between the target pressure and the initial pressure meets the first preset condition.

[0282] The first update module 11045 is used to update the initial pressure to the target pressure if it is determined that the difference between the target pressure and the initial pressure does not meet the first preset condition.

[0283] In one possible implementation, the third confirmation submodule 11044 includes:

[0284] The fourth confirmation submodule 110441 is used to determine the parameter factors based on the production well depth of the coalbed methane well, the position of the simulated moving liquid level, the average temperature inside the second wellbore, the preset gas relative density value, and the second compressibility factor.

[0285] The fifth confirmation submodule 110442 is used to determine the Reynolds number in the production wellbore of the coalbed methane well based on the preset gas flow rate, preset gas relative density value, preset coalbed methane viscosity, casing inner diameter of the coalbed methane well, and tubing outer diameter of the coalbed methane well; wherein, the preset gas flow rate characterizes the gas flow rate under standard conditions.

[0286] The sixth confirmation submodule 110443 is used to determine the friction coefficient of the coalbed methane well based on the preset absolute roughness of the pipe, the inner diameter of the casing of the coalbed methane well, the outer diameter of the tubing of the coalbed methane well, and the Reynolds number in the production wellbore of the coalbed methane well.

[0287] The seventh confirmation submodule 110444 is used to determine the target pressure based on the wellhead pressure of the coalbed methane well, the friction coefficient of the coalbed methane well, the average temperature inside the second wellbore, the second compressibility factor, the preset gas flow rate, the inner diameter of the casing of the coalbed methane well, and the outer diameter of the tubing of the coalbed methane well.

[0288] In one possible implementation, the second determining module 1104 further includes:

[0289] The second repeating module 11046 is used to repeatedly execute the following steps until the first preset condition is reached, wherein the initial bottom hole flowing pressure obtained for the first time is determined based on the pure gas column pressure, pressure gradient, and pseudo-dynamic liquid level position of the coalbed methane well; wherein the pressure gradient is determined by the liquid density and gravitational acceleration:

[0290] The eighth confirmation submodule 11047 is used to determine the average pressure in the third wellbore of the coalbed methane well based on the pure gas column pressure and the initial bottom hole flowing pressure. The initial bottom hole flowing pressure represents the initially obtained bottom hole flowing pressure. The average pressure in the third wellbore represents the average pressure of the gas-water two-phase liquid column in the production wellbore of the coalbed methane well. The average temperature in the third wellbore of the coalbed methane well is determined based on the pseudo-dynamic liquid surface temperature and the initial bottom hole temperature. The average temperature in the third wellbore represents the average temperature of the gas-water two-phase liquid column in the production wellbore of the coalbed methane well.

[0291] The ninth confirmation submodule 11048 is used to determine the third pseudo-comparison pressure based on the average pressure in the third wellbore and the preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and to determine the third pseudo-comparison temperature based on the average temperature in the third wellbore and the preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane.

[0292] The tenth confirmation submodule 11049 is used to determine the third compressibility factor based on the third pseudo-comparison pressure and the third pseudo-comparison temperature; and to determine the target bottom hole flowing pressure based on the third compressibility factor.

[0293] The eleventh confirmation submodule 110410 is used to determine the target bottom flow pressure as the bottom flow pressure corresponding to the coalbed methane well if the difference between the target bottom flow pressure and the initial bottom flow pressure meets the first preset condition.

[0294] The second update module 110411 is used to update the initial bottom hole pressure to the target bottom hole pressure if the difference between the target bottom hole pressure and the initial bottom hole pressure does not meet the first preset condition.

[0295] In one possible implementation, the tenth confirmation submodule 11049 includes:

[0296] The twelfth confirmation submodule 110491 is used to determine the apparent gas velocity based on the preset gas flow rate, the average temperature inside the third wellbore of the coalbed methane well, the average pressure inside the third wellbore of the coalbed methane well, the third compressibility factor, the standard pressure, the standard temperature, and the annular cross-sectional area between the casing and the tubing of the coalbed methane well; wherein, the annular cross-sectional area between the casing and the tubing of the coalbed methane well is determined by the inner diameter of the casing and the outer diameter of the tubing of the coalbed methane well.

[0297] The thirteenth confirmation submodule 110492 is used to determine the preset parameter as the first preset parameter if the apparent gas flow rate meets the second preset condition.

[0298] The fourteenth confirmation submodule 110493 is used to determine the preset parameter as the second preset parameter if it is determined that the apparent flow rate of the gas does not meet the second preset condition.

[0299] The fifteenth confirmation submodule 110494 is used to determine the porosity based on preset parameters and apparent gas flow rate;

[0300] The sixteenth confirmation submodule 110495 is used to determine the third relevant parameters based on the preset gas flow rate, standard temperature, average temperature inside the third wellbore, third compressibility factor, standard pressure, and the annular cross-sectional area between the casing and tubing of the coalbed methane well.

[0301] The seventeenth confirmation submodule 110496 is used to determine the first relevant parameter based on the third relevant parameter, porosity, preset parameter, wellhead pressure of coalbed methane well, pressure difference of pure gas column, pseudo-dynamic liquid level position, and pressure gradient; wherein, the pressure difference of pure gas column is obtained by the difference between the wellhead pressure of coalbed methane well and the corresponding pure gas column pressure of coalbed methane well.

[0302] The eighteenth confirmation submodule 110497 is used to determine the second correlation coefficient based on the third correlation coefficient, porosity, preset parameters, preset gas constant, preset molar mass, pseudo-dynamic liquid level position, third compressibility factor, third wellbore average temperature, pressure gradient, wellhead pressure of coalbed methane well, and pressure difference of pure gas column; wherein, the gas constant represents the general gas constant; the preset molar mass represents the molar mass of natural gas;

[0303] The nineteenth confirmation submodule 110498 is used to determine the target bottom hole flowing pressure based on the wellhead pressure, pure gas column pressure difference, pressure gradient, pseudo-dynamic liquid level position, first relevant parameter, and second relevant parameter of the coalbed methane well.

[0304] Figure 12 is a schematic diagram of the structure of an electronic device for determining the bottom hole flowing pressure of a coalbed methane well according to this application. As shown in Figure 12, the electronic device 120 provided in this embodiment includes at least one processor 1201 and a memory 1202. Optionally, the device 120 also includes a communication component 1203. The processor 1201, the memory 1202, and the communication component 1203 are connected via a bus 1204.

[0305] In a specific implementation, at least one processor 1201 executes computer execution instructions stored in memory 1202, causing at least one processor 1201 to perform the above-described method.

[0306] The specific implementation process of processor 1201 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0307] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0308] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0309] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0310] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0311] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0312] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0313] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0314] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0315] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0316] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0317] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0318] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0319] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for determining the bottom hole flowing pressure of a coalbed methane well, characterized in that, include: Obtain a first volume value and a second volume value in the coalbed methane well; wherein the first volume value represents the instantaneous volume of the gas phase fluid in the coalbed methane well, and the second volume value represents the instantaneous volume of the water phase fluid in the coalbed methane well; and determine the position of the pseudo-dynamic liquid level in the coalbed methane well based on the first volume value and the second volume value. The first temperature, the second temperature, and the pressure gradient of the liquid in the coalbed methane well are obtained; wherein the first temperature represents the wellhead temperature of the coalbed methane well, and the second temperature represents the reservoir temperature at the bottom of the coalbed methane well; and the temperature gradient of the coalbed methane well is determined based on the first temperature and the second temperature. The simulated fluid level temperature of the coalbed methane well is determined based on the simulated fluid level position and the temperature gradient. Based on the simulated liquid level position and the simulated liquid level temperature, the pure gas column pressure corresponding to the coalbed methane well is determined; and based on the pure gas column pressure, the simulated liquid level position, and the pressure gradient, the bottom-hole flowing pressure of the coalbed methane well is determined, wherein the bottom-hole flowing pressure characterizes the bottom-hole pressure when the coalbed methane well contains both coalbed methane and liquid.

2. The method according to claim 1, characterized in that, Obtaining the first volume value in the coalbed methane well includes: Obtain the first pseudo-comparison pressure and the first pseudo-comparison temperature; wherein, the first pseudo-comparison pressure is determined based on the wellhead pressure of the coalbed methane well and the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas, and the first pseudo-comparison temperature is determined based on the wellhead temperature of the coalbed methane well and the initial temperature at the bottom of the well when the production wellbore of the coalbed methane well contains only gas. The first compressibility factor is determined based on the first pseudo-comparison pressure and the first pseudo-comparison temperature; The volume factor of coalbed methane is determined based on the first compressibility factor, standard pressure, and standard temperature; wherein, standard pressure represents the coalbed methane pressure under standard conditions, and standard temperature represents the coalbed methane temperature under standard conditions. The first volume value is determined based on the volume coefficient of the coalbed methane and the preset daily coalbed methane production.

3. The method according to any one of claims 1-2, characterized in that, Obtaining the first pseudo-comparison pressure and the first pseudo-comparison temperature includes: The wellhead pressure, wellhead temperature, initial bottom temperature, and coalbed methane density of the coalbed methane well are obtained. The initial bottom temperature represents the initial temperature at the bottom of the well when the production wellbore contains only gas. The initial pressure at the bottom of the well is determined based on the coalbed methane density, gravitational acceleration, and the production well depth of the coalbed methane well; wherein, the initial pressure at the bottom of the well represents the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas. The average pressure inside the first wellbore of the coalbed methane well is determined based on the wellhead pressure and the initial bottom pressure; the average temperature inside the first wellbore of the coalbed methane well is determined based on the wellhead temperature and the initial bottom temperature. A first comparative pressure is determined based on the average pressure inside the first wellbore and a preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and a first comparative temperature is determined based on the average temperature inside the first wellbore and a preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane.

4. The method according to any one of claims 1-3, characterized in that, Determining the position of the pseudo-dynamic liquid level in the coalbed methane well based on the first volume value and the second volume value includes: The third volume value is obtained by summing the first volume value and the second volume value; The position of the simulated fluid level is determined based on the second volume value, the third volume value, and the production well depth of the coalbed methane well.

5. The method according to any one of claims 1-4, characterized in that, Determining the temperature gradient of the coalbed methane well based on the first temperature and the second temperature includes: The temperature gradient of the coalbed methane well is determined based on the first temperature, the second temperature, and the production well depth of the coalbed methane well.

6. The method according to any one of claims 1-5, characterized in that, Determining the pure gas column pressure corresponding to the coalbed methane well based on the simulated liquid level position and the simulated liquid level temperature includes: Repeat the following steps until the first preset condition is met, wherein the initial pressure obtained for the first time is determined based on the pseudo-dynamic liquid level position and the wellhead pressure of the coalbed methane well: The average pressure inside the second wellbore of the coalbed methane well is determined based on the wellhead pressure and the initial pressure, wherein the initial pressure represents the initially obtained pure gas column pressure; the average pressure inside the second wellbore represents the average pressure of the pure gas column inside the production wellbore of the coalbed methane well; the average temperature inside the second wellbore of the coalbed methane well is determined based on the wellhead temperature and the pseudo-dynamic liquid level temperature, wherein the average temperature inside the second wellbore represents the average temperature of the pure gas column inside the production wellbore of the coalbed methane well; A second comparative pressure is determined based on the average pressure inside the second wellbore and a preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and a second comparative temperature is determined based on the average temperature inside the second wellbore and a preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane. Based on the second simulated pressure and the second simulated temperature, a second compressibility factor is determined; and based on the second compressibility factor, a target pressure is determined. If the difference between the target pressure and the initial pressure is determined to meet the first preset condition, then the target pressure is determined to be the pure gas column pressure corresponding to the coalbed methane well. If it is determined that the difference between the target pressure and the initial pressure does not meet the first preset condition, then the initial pressure is updated to the target pressure.

7. The method according to any one of claims 1-6, characterized in that, Based on the second compressibility factor, the target pressure is determined, including: The parameter factors are determined based on the production well depth of the coalbed methane well, the position of the pseudo-dynamic liquid level, the average temperature inside the second wellbore, the preset relative gas density value, and the second compressibility factor. The Reynolds number in the production wellbore of the coalbed methane well is determined based on the preset gas flow rate, preset gas relative density value, preset coalbed methane viscosity, inner diameter of the casing of the coalbed methane well, and outer diameter of the tubing of the coalbed methane well; wherein, the preset gas flow rate characterizes the gas flow rate under standard conditions. The friction coefficient of the coalbed methane well is determined based on the preset absolute roughness of the pipe, the inner diameter of the casing of the coalbed methane well, the outer diameter of the tubing of the coalbed methane well, and the Reynolds number in the production wellbore of the coalbed methane well. The target pressure is determined based on the wellhead pressure of the coalbed methane well, the friction coefficient of the coalbed methane well, the average temperature inside the second wellbore, the second compressibility factor, the preset gas flow rate, the inner diameter of the casing of the coalbed methane well, and the outer diameter of the tubing of the coalbed methane well.

8. The method according to any one of claims 1-7, characterized in that, The bottomhole flowing pressure of the coalbed methane well is determined based on the pure gas column pressure, the pseudo-dynamic liquid level position, and the pressure gradient, including: Repeat the following steps until the first preset condition is reached, wherein the initial bottomhole flowing pressure obtained for the first time is determined based on the pure gas column pressure, pressure gradient, and the position of the pseudo-dynamic liquid level of the coalbed methane well; wherein the pressure gradient is determined by the liquid density and gravitational acceleration: The average pressure within the third wellbore of the coalbed methane well is determined based on the pure gas column pressure and the initial bottom hole flowing pressure, wherein the initial bottom hole flowing pressure represents the initially obtained bottom hole flowing pressure; the average pressure within the third wellbore represents the average pressure of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well; and the average temperature within the third wellbore of the coalbed methane well is determined based on the pseudo-dynamic liquid surface temperature and the initial bottom hole temperature, wherein the average temperature within the third wellbore represents the average temperature of the gas-water two-phase liquid column within the production wellbore of the coalbed methane well. The third simulated comparison pressure is determined based on the average pressure in the third wellbore and the preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and the third simulated comparison temperature is determined based on the average temperature in the third wellbore and the preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane. Based on the third simulated pressure and the third simulated temperature, a third compressibility factor is determined; and based on the third compressibility factor, the target bottom hole flowing pressure is determined. If the difference between the target bottom-hole flowing pressure and the initial bottom-hole flowing pressure meets the first preset condition, then the target bottom-hole flowing pressure is determined to be the bottom-hole flowing pressure corresponding to the coalbed methane well. If it is determined that the difference between the target bottom hole pressure and the initial bottom hole pressure does not meet the first preset condition, then the initial bottom hole pressure is updated to the target bottom hole pressure.

9. The method according to any one of claims 1-8, characterized in that, The target bottom hole flowing pressure is determined based on the third compressibility factor, including: The apparent gas velocity is determined based on the preset gas flow rate, the average temperature inside the third wellbore of the coalbed methane well, the average pressure inside the third wellbore of the coalbed methane well, the third compressibility factor, the standard pressure, the standard temperature, and the annular cross-sectional area between the casing and the tubing of the coalbed methane well; wherein, the annular cross-sectional area between the casing and the tubing of the coalbed methane well is determined by the inner diameter of the casing and the outer diameter of the tubing of the coalbed methane well. If it is determined that the apparent flow rate of the gas meets the second preset condition, then the preset parameter is determined to be the first preset parameter; If it is determined that the apparent flow rate of the gas does not meet the second preset condition, then the preset parameter is determined to be the second preset parameter; The porosity is determined based on the preset parameters and the apparent gas flow rate. The third relevant parameter is determined based on the preset gas flow rate, standard temperature, average temperature inside the third wellbore, third compressibility factor, standard pressure, and the annular cross-sectional area between the casing and tubing of the coalbed methane well. The first relevant parameter is determined based on the third relevant parameter, the porosity, the preset parameter, the wellhead pressure of the coalbed methane well, the pressure difference of the pure gas column, the position of the pseudo-dynamic liquid level, and the pressure gradient; wherein, the pressure difference of the pure gas column is obtained by the difference between the wellhead pressure of the coalbed methane well and the corresponding pure gas column pressure of the coalbed methane well. The second correlation coefficient is determined based on the third correlation coefficient, the porosity, the preset parameters, the preset gas constant, the preset molar mass, the pseudo-dynamic liquid level position, the third compressibility factor, the third average temperature inside the wellbore, the pressure gradient, the wellhead pressure of the coalbed methane well, and the pressure difference of the pure gas column; wherein, the gas constant represents the general gas constant; and the preset molar mass represents the molar mass of natural gas. The target bottom hole flowing pressure is determined based on the wellhead pressure of the coalbed methane well, the pressure difference of the pure gas column, the pressure gradient, the position of the pseudo-dynamic liquid level, the first relevant parameter, and the second relevant parameter.

10. A device for determining the bottom hole flowing pressure of a coalbed methane well, characterized in that, include: The first acquisition module is used to acquire a first volume value and a second volume value in the coalbed methane well; wherein the first volume value represents the instantaneous volume of gas phase fluid in the coalbed methane well, and the second volume value represents the instantaneous volume of water phase fluid in the coalbed methane well; and to determine the position of the pseudo-dynamic liquid level in the coalbed methane well based on the first volume value and the second volume value. The second acquisition module is used to acquire the first temperature, the second temperature, and the pressure gradient of the liquid in the coalbed methane well; wherein the first temperature represents the wellhead temperature of the coalbed methane well, and the second temperature represents the reservoir temperature at the bottom of the coalbed methane well; and to determine the temperature gradient of the coalbed methane well based on the first temperature and the second temperature. The first determining module is used to determine the simulated liquid level temperature of the coalbed methane well based on the simulated liquid level position and the temperature gradient. The second determining module is used to determine the pure gas column pressure corresponding to the coalbed methane well based on the simulated liquid surface position and the simulated liquid surface temperature; and to determine the bottom flow pressure of the coalbed methane well based on the pure gas column pressure, the simulated liquid surface position and the pressure gradient, wherein the bottom flow pressure characterizes the bottom pressure of the coalbed methane well when it includes coalbed methane and liquid.

11. The apparatus according to claim 10, characterized in that, The first acquisition module includes: The first acquisition submodule is used to acquire the first simulated comparison pressure and the first simulated comparison temperature; wherein, the first simulated comparison pressure is determined based on the wellhead pressure of the coalbed methane well and the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas, and the first simulated comparison temperature is determined based on the wellhead temperature of the coalbed methane well and the initial temperature at the bottom of the well when the production wellbore of the coalbed methane well contains only gas. The third determining module is used to determine the first compressibility factor based on the first simulated comparison pressure and the first simulated comparison temperature; The fourth confirmation module is used to determine the volume factor of coalbed methane based on the first compressibility factor, standard pressure, and standard temperature; wherein, the standard pressure represents the coalbed methane pressure under standard conditions, and the standard temperature represents the coalbed methane temperature under standard conditions. The fifth confirmation module is used to determine the first volume value based on the volume coefficient of the coalbed methane and the preset daily coalbed methane production.

12. The apparatus according to any one of claims 10-11, characterized in that, The first acquisition submodule includes: The second acquisition submodule is used to acquire the wellhead pressure, wellhead temperature, bottom initial temperature and coalbed methane density of the coalbed methane well. The bottom initial temperature represents the initial temperature at the bottom of the well when the production wellbore of the coalbed methane well contains only gas. The sixth confirmation module is used to determine the initial pressure at the bottom of the well based on the coalbed methane density, gravitational acceleration, and the production well depth of the coalbed methane well; wherein, the initial pressure at the bottom of the well represents the initial pressure at the bottom of the well when the production wellbore of the coalbed methane well contains only gas. The seventh confirmation module is used to determine the average pressure inside the first wellbore of the coalbed methane well based on the wellhead pressure and the initial bottom pressure; and to determine the average temperature inside the first wellbore of the coalbed methane well based on the wellhead temperature and the initial bottom temperature. The eighth confirmation module is used to determine a first comparative pressure based on the average pressure in the first wellbore and a preset pressure, wherein the preset pressure represents the critical pressure of coalbed methane; and to determine a first comparative temperature based on the average temperature in the first wellbore and a preset temperature, wherein the preset temperature represents the critical temperature of coalbed methane.

13. The apparatus according to any one of claims 10-12, characterized in that, The first acquisition module also includes: The calculation module is used to obtain a third volume value based on the sum of the first volume value and the second volume value; The ninth confirmation module is used to determine the position of the simulated liquid level based on the second volume value, the third volume value, and the production well depth of the coalbed methane well.

14. The apparatus according to any one of claims 10-13, characterized in that, The second acquisition module includes: The tenth confirmation module is used to determine the temperature gradient of the coalbed methane well based on the first temperature, the second temperature, and the production well depth of the coalbed methane well.

15. The apparatus according to any one of claims 10-14, characterized in that, The second determining module includes: The first loop module is used to repeatedly execute the following steps until a first preset condition is reached, wherein the initial pressure obtained for the first time is determined based on the pseudo-dynamic liquid level position and the wellhead pressure of the coalbed methane well: The first confirmation submodule is used to determine the average pressure inside the second wellbore of the coalbed methane well based on the wellhead pressure and the initial pressure, wherein the initial pressure represents the initially obtained pure gas column pressure; the average pressure inside the second wellbore represents the average pressure of the pure gas column inside the production wellbore of the coalbed methane well; and to determine the average temperature inside the second wellbore of the coalbed methane well based on the wellhead temperature and the pseudo-dynamic liquid level temperature, wherein the average temperature inside the second wellbore represents the average temperature of the pure gas column inside the production wellbore of the coalbed methane well. The second confirmation submodule is used to determine a second simulated comparison pressure based on the average pressure inside the second wellbore and a preset pressure, wherein the preset pressure represents the critical pressure of coalbed methane; and to determine a second simulated comparison temperature based on the average temperature inside the second wellbore and a preset temperature, wherein the preset temperature represents the critical temperature of coalbed methane; The third confirmation submodule is used to determine the second compressibility factor based on the second simulated comparison pressure and the second simulated comparison temperature; and to determine the target pressure based on the second compressibility factor. The fourth confirmation submodule is used to determine the target pressure as the pure gas column pressure corresponding to the coalbed methane well if the difference between the target pressure and the initial pressure meets the first preset condition. The first update module is used to update the initial pressure to the target pressure if it is determined that the difference between the target pressure and the initial pressure does not meet the first preset condition.

16. The apparatus according to any one of claims 10-15, characterized in that, The third confirmation submodule includes: The fourth confirmation submodule is used to determine the parameter factors based on the production well depth of the coalbed methane well, the position of the pseudo-dynamic liquid level, the average temperature inside the second wellbore, the preset gas relative density value, and the second compressibility factor. The fifth confirmation submodule is used to determine the Reynolds number in the production wellbore of the coalbed methane well based on the preset gas flow rate, the preset gas relative density value, the preset coalbed methane viscosity, the casing inner diameter of the coalbed methane well, and the tubing outer diameter of the coalbed methane well; wherein, the preset gas flow rate represents the gas flow rate under standard conditions. The sixth confirmation submodule is used to determine the friction coefficient of the coalbed methane well based on the preset absolute roughness of the pipe, the inner diameter of the casing of the coalbed methane well, the outer diameter of the tubing of the coalbed methane well, and the Reynolds number in the production wellbore of the coalbed methane well. The seventh confirmation submodule is used to determine the target pressure based on the wellhead pressure of the coalbed methane well, the friction coefficient of the coalbed methane well, the average temperature inside the second wellbore, the second compressibility factor, the preset gas flow rate, the inner diameter of the casing of the coalbed methane well, and the outer diameter of the tubing of the coalbed methane well.

17. The apparatus according to any one of claims 10-16, characterized in that, The second determining module also includes: The second repeating module is used to repeatedly execute the following steps until the first preset condition is reached, wherein the initial bottom hole flowing pressure obtained for the first time is determined based on the pure gas column pressure, pressure gradient, and the position of the pseudo-dynamic liquid level of the coalbed methane well; wherein the pressure gradient is determined by the liquid density and gravitational acceleration: The eighth confirmation submodule is used to determine the average pressure in the third wellbore of the coalbed methane well based on the pure gas column pressure and the initial bottom hole flowing pressure, wherein the initial bottom hole flowing pressure represents the initially obtained bottom hole flowing pressure; the average pressure in the third wellbore represents the average pressure of the gas-water two-phase liquid column in the production wellbore of the coalbed methane well; and to determine the average temperature in the third wellbore of the coalbed methane well based on the pseudo-dynamic liquid surface temperature and the initial bottom hole temperature, wherein the average temperature in the third wellbore represents the average temperature of the gas-water two-phase liquid column in the production wellbore of the coalbed methane well. The ninth confirmation submodule is used to determine the third simulated comparison pressure based on the average pressure in the third wellbore and the preset pressure; wherein the preset pressure represents the critical pressure of coalbed methane; and to determine the third simulated comparison temperature based on the average temperature in the third wellbore and the preset temperature; wherein the preset temperature represents the critical temperature of coalbed methane. The tenth confirmation submodule is used to determine the third compressibility factor based on the third pseudo-comparison pressure and the third pseudo-comparison temperature; and to determine the target bottom hole flowing pressure based on the third compressibility factor. The eleventh confirmation submodule is used to determine the target bottom flow pressure as the bottom flow pressure corresponding to the coalbed methane well if the difference between the target bottom flow pressure and the initial bottom flow pressure meets the first preset condition. The second update module is used to update the initial bottom hole pressure to the target bottom hole pressure if the difference between the target bottom hole pressure and the initial bottom hole pressure does not meet the first preset condition.

18. The apparatus according to any one of claims 10-17, characterized in that, The tenth confirmation submodule includes: The twelfth confirmation submodule is used to determine the apparent gas velocity based on the preset gas flow rate, the average temperature inside the third wellbore of the coalbed methane well, the average pressure inside the third wellbore of the coalbed methane well, the third compressibility factor, the standard pressure, the standard temperature, and the annular cross-sectional area between the casing and the tubing of the coalbed methane well; wherein, the annular cross-sectional area between the casing and the tubing of the coalbed methane well is determined by the inner diameter of the casing and the outer diameter of the tubing of the coalbed methane well. The thirteenth confirmation submodule is used to determine the preset parameter as the first preset parameter if it is determined that the apparent flow rate of the gas meets the second preset condition. The fourteenth confirmation submodule is used to determine the preset parameter as the second preset parameter if it is determined that the apparent flow rate of the gas does not meet the second preset condition. The fifteenth confirmation submodule is used to determine the porosity based on the preset parameters and the apparent gas flow rate. The sixteenth confirmation submodule is used to determine the third relevant parameters based on the preset gas flow rate, standard temperature, average temperature inside the third wellbore, third compressibility factor, standard pressure, and the annular cross-sectional area between the casing and tubing of the coalbed methane well. The seventeenth confirmation submodule is used to determine the first relevant parameter based on the third relevant parameter, the porosity, the preset parameter, the wellhead pressure of the coalbed methane well, the pressure difference of the pure gas column, the position of the pseudo-dynamic liquid level, and the pressure gradient; wherein, the pressure difference of the pure gas column is obtained by the difference between the wellhead pressure of the coalbed methane well and the pressure of the pure gas column corresponding to the coalbed methane well. The eighteenth confirmation submodule is used to determine the second correlation coefficient based on the third correlation coefficient, the porosity, the preset parameters, the preset gas constant, the preset molar mass, the pseudo-dynamic liquid level position, the third compressibility factor, the third average temperature inside the wellbore, the pressure gradient, the wellhead pressure of the coalbed methane well, and the pressure difference of the pure gas column; wherein, the gas constant represents the general gas constant; and the preset molar mass represents the molar mass of natural gas; The nineteenth confirmation submodule is used to determine the target bottom hole flowing pressure based on the wellhead pressure of the coalbed methane well, the pressure difference of the pure gas column, the pressure gradient, the position of the pseudo-dynamic liquid level, the first relevant parameter, and the second relevant parameter.

19. An electronic device, characterized in that, include: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any one of claims 1-9.

20. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that, when executed on a computer, cause the computer to perform the method described in any one of claims 1-9.

21. A computer program, characterized in that, Includes program code that, when the computer runs the computer program, performs the method as described in any one of claims 1-9.

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