Coal bed gas horizontal well bottom hole flowing pressure control method and device and storage medium

Abstract

The invention relates to a coal-bed gas horizontal well bottom hole flowing pressure control method and device and a storage medium. The method comprises the steps that data of a coal-bed gas well in a first time period when production starts are obtained; drawing a first curve according to the data; calculating quasi-steady-state water production parameters according to the data and the first curve; gradually reducing the flowing bottomhole pressure to the critical desorption pressure of the reservoir; recording the second-day water yield of each day; reducing the flowing bottomhole pressure day by day; the pressure value in the sleeve is adjusted; and calculating the daily gas-water relative permeability ratio. According to the method, the defect of a template scheme with the static parameters of the reservoir as the system basis in an existing method is overcome, the heterogeneity of the coal-bed gas well is fully considered, the flexible indexed parameter determination method is adopted according to the actual gas-water flow characteristics of the single well, the optimal underground seepage state of the single well can be achieved, and the underground seepage rate of the single well is increased. And stratum supply and ground production achieve supply and production balance, single well long-term stable production is achieved, and reference is provided for coal-bed gas well drainage and production control refinement.

Description

Technical Field

[0001] The present invention relates to the technical field of coalbed methane development, and particularly to a method, device and storage medium for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well. Background Art

[0002] The main development mode for surface coalbed methane extraction is the drainage depressurization - desorption gas production mode. Through continuous drainage depressurization of the coalbed methane well, when the coal reservoir pressure drops to the methane desorption pressure, the adsorbed methane gas in the coal matrix begins to desorb and be produced. The core purpose of this development process is to establish a production pressure difference by controlling the decline of the bottom-hole flowing pressure, so as to achieve the decline of the coal reservoir pressure. If the method for the decline of the bottom-hole flowing pressure is set unreasonably and the pressure node is controlled inaccurately, it will cause corresponding reservoir damage, resulting in a poor development effect and a decline in economic benefits. Therefore, during the drainage production process of a coalbed methane well, corresponding drainage production methods need to be determined at different drainage production stages, and key parameter nodes such as the casing pressure and the bottom-hole flowing pressure need to be accurately controlled to ensure the efficient development of the coalbed methane well.

[0003] Currently, a variety of drainage production methods for coalbed methane wells have been disclosed. Chinese Patent CN114658390A discloses a method and system for controlling the drainage production of a coalbed methane well, which mainly determines the pressure drop mode of the bottom-hole flowing pressure according to the coal body structure of the coalbed methane well. The worse the coal body structure of the coalbed methane well, the slower the pressure drop mode is selected; Chinese Patent CN114622875A discloses a drainage production control method and device for a fractured horizontal well of high-rank coalbed methane, which mainly uses three specific flow pressure drop rates for drainage production control at different nodes of the bottom-hole flowing pressure. However, in the above technical solutions, since the data basis for parameter formulation comes from the static data of the coal reservoir or the wellbore pressure data, the actual seepage state of the coal reservoir is not considered throughout the development process. Therefore, the drainage production methods described in the above patents often adopt a batch templatized control method based on the block scale, and cannot make parameter fine-tuning for each well according to the actual seepage state of a single well and perform real-time optimization and correction of parameters during the drainage production process. Therefore, improvement is needed. Summary of the Invention

[0004] In view of this, the present invention provides a method, device and storage medium for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well.

[0005] Specifically, the present invention is realized through the following technical solutions:

[0006] According to a first aspect of the present invention, there is provided a method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well, the method comprising the steps of:

[0007] Obtain data of the coalbed methane well within a first time period at the start of production;

[0008] Draw a first curve according to the data;

[0009] Calculate the pseudo-steady state water production parameters based on the said data and the first curve;

[0010] Gradually reduce the bottom-hole flowing pressure to the critical desorption pressure of the reservoir;

[0011] Record the second daily water production;

[0012] Gradually lower the bottom-hole flowing pressure day by day;

[0013] Adjust the pressure value in the casing;

[0014] Calculate the gas-water relative permeability ratio daily.

[0015] Preferably, the obtaining of the data of the coalbed methane well in the first time period at the start of production includes the steps of:

[0016] Obtain the bottom-hole flowing pressure data of the coalbed methane well in the first time period at the start of production;

[0017] Obtain the water production parameters of the coalbed methane well in the first time period at the start of production.

[0018] Preferably, the drawing of the first curve based on the said data includes the steps of:

[0019] Obtain the bottom-hole flowing pressure data in the said data;

[0020] Obtain the water production parameters in the said data;

[0021] Draw the first curve according to the bottom-hole flowing pressure data and the water production parameters.

[0022] Preferably, the calculation of the pseudo-steady state water production parameters based on the said data and the first curve includes the steps of:

[0023] Obtain the bottom-hole flowing pressure data in the said data;

[0024] Obtain the first curve;

[0025] Calculate the pseudo-steady state water production parameters according to the bottom-hole flowing pressure data and the first curve.

[0026] Preferably, the gradually lowering of the bottom-hole flowing pressure day by day includes the steps of:

[0027] Obtain the second daily water production;

[0028] Judge whether the second daily water production tends to be stable;

[0029] If so, gradually lower the bottom-hole flowing pressure day by day at an adjustment amplitude of 0.01 MPa / d.

[0030] Preferably, the adjustment of the pressure value in the casing includes the steps of:

[0031] Obtain the pressure value inside the casing;

[0032] Determine whether the pressure value is lower than 0.2 MPa;

[0033] If so, maintain the current pressure value;

[0034] If not, lower the pressure value and return to the step of determining whether the pressure value is lower than 0.2 MPa.

[0035] Preferably, the calculation of the daily gas-water relative permeability ratio includes the steps of:

[0036] Record the daily gas production during the adjustment period;

[0037] Record the daily water production during the adjustment period;

[0038] Obtain the reservoir boundary type;

[0039] Calculate the daily gas-water relative permeability ratio according to the reservoir boundary type.

[0040] According to the second aspect of the present invention, there is provided a bottom-hole flowing pressure control device for a coalbed methane horizontal well, the device comprising:

[0041] A data acquisition module for acquiring data of the coalbed methane well during a first time period at the start of production;

[0042] A curve plotting module for plotting a first curve according to the data;

[0043] A parameter calculation module for calculating the pseudo-steady state water production parameters according to the data and the first curve;

[0044] A pressure reduction module for gradually reducing the bottom-hole flowing pressure to the critical desorption pressure of the reservoir;

[0045] A water production recording module for recording the second-day water production every day;

[0046] A flowing pressure lowering module for lowering the bottom-hole flowing pressure day by day;

[0047] A pressure value adjustment module for adjusting the pressure value inside the casing;

[0048] A relative permeability ratio calculation module for calculating the daily gas-water relative permeability ratio.

[0049] According to the third aspect of the present invention, there is provided an electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein when the processor executes the program, the steps of the bottom-hole flowing pressure control method for a coalbed methane horizontal well in the first aspect or any possible implementation manner of the first aspect are implemented.

[0050] According to a fourth aspect of the present invention, there is provided a storage medium having a computer program stored thereon, and when the program is executed by a processor, the steps of the bottom hole flowing pressure control method for a coalbed methane horizontal well in the first aspect or any possible implementation manner of the first aspect are implemented.

[0051] The technical solution provided by the present invention at least brings the following beneficial effects:

[0052] A bottom hole flowing pressure control method, device and storage medium for a coalbed methane horizontal well provided by the present application eliminate the disadvantages of the templatized scheme that uses reservoir static parameters as the basis for the system in the existing methods, fully consider the heterogeneity of coalbed methane wells, and adopt a flexible method for determining indexed parameters according to the actual gas-water flow characteristics of a single well, which can achieve the optimal underground seepage state of a single well, balance the formation supply and surface production, ensure long-term stable production of a single well, and provide a reference for realizing refined drainage control of coalbed methane wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present invention, and are used together with the specification to explain the principles of the present invention.

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or related technologies. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0055] Figure 1 It is a schematic flow chart of a bottom hole flowing pressure control method for a coalbed methane horizontal well provided by an embodiment of the present invention;

[0056] Figure 2 It is a schematic structural diagram of a bottom hole flowing pressure control device for a coalbed methane horizontal well provided by an embodiment of the present invention;

[0057] Figure 3 It is a schematic structural diagram of an electronic device provided by an embodiment of the present invention;

[0058] Figure 4 It is a schematic structural diagram of a storage medium provided by an embodiment of the present invention;

[0059] Figure 5 It is a schematic diagram of a production curve model of a bottom hole flowing pressure control method for a coalbed methane horizontal well provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0060] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0061] Figure 1 FIG. schematically shows a flow diagram of a method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well applicable to an embodiment of the present invention.

[0062] See Figure 1 , an embodiment of the present invention provides a method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well. This method can be applied to electronic devices, such as PCs, servers, terminals, etc. This method may include the following steps:

[0063] S1: Obtain data of the coalbed methane well within a first time period at the start of production;

[0064] In an embodiment of the present application, the obtaining of data of the coalbed methane well within a first time period at the start of production includes the steps of:

[0065] Obtain the bottom-hole flowing pressure data of the coalbed methane well within a first time period at the start of production;

[0066] Obtain the water production parameters of the coalbed methane well within a first time period at the start of production.

[0067] Specifically, obtain the bottom-hole flowing pressure data and water production parameters of the coalbed methane well within a first time period at the start of production.

[0068] S2: Draw a first curve according to the data;

[0069] In an embodiment of the present application, the drawing of a first curve according to the data includes the steps of:

[0070] Obtain the bottom-hole flowing pressure data in the data;

[0071] Obtain the water production parameters in the data;

[0072] Draw the first curve according to the bottom-hole flowing pressure data and the water production parameters.

[0073] Specifically, draw a first curve based on the bottom-hole flowing pressure data and water production data. The first curve is used to reflect the coupling relationship between the bottom-hole flowing pressure data and the water production data.

[0074] S3: Calculate the pseudo-steady-state water production parameters according to the data and the first curve;

[0075] In an embodiment of the present application, calculating the pseudo-steady-state water production parameter according to the data and the first curve includes the steps of:

[0076] Obtain the bottom-hole flowing pressure data in the data;

[0077] Obtain the first curve;

[0078] Calculate the pseudo-steady-state water production parameter according to the bottom-hole flowing pressure data and the first curve.

[0079] Specifically, the pseudo-steady-state water production parameter is calculated from the first curve and the bottom-hole flowing pressure. The first curve is used to reflect the coupling relationship between the bottom-hole flowing pressure data and the water production data.

[0080] S4: Gradually reduce the bottom-hole flowing pressure to the critical desorption pressure of the reservoir;

[0081] Specifically, after the pseudo-steady-state water production parameter is determined and when the pseudo-steady-state water production is determined, with the constant water production as the control target, gradually reduce the bottom-hole flowing pressure to the critical desorption pressure of the reservoir.

[0082] S5: Record the second-day water production every day;

[0083] Specifically, after the bottom-hole flowing pressure is reduced to the preset critical desorption pressure of the reservoir, record the second-day water production every day in sequence.

[0084] S6: Gradually lower the bottom-hole flowing pressure day by day;

[0085] In an embodiment of the present application, gradually lowering the bottom-hole flowing pressure day by day includes the steps of:

[0086] Obtain the second-day water production;

[0087] Judge whether the second-day water production tends to be stable;

[0088] If so, gradually lower the bottom-hole flowing pressure day by day at an adjustment amplitude of 0.01 MPa / d.

[0089] Specifically, after the second-day production tends to be stable, gradually lower the bottom-hole flowing pressure day by day, and the adjustment amplitude each time is 0.01 MPa / d.

[0090] S7: Adjust the pressure value in the casing;

[0091] In an embodiment of the present application, adjusting the pressure value in the casing includes the steps of:

[0092] Obtain the pressure value in the casing;

[0093] Judge whether the pressure value is lower than 0.2 MPa;

[0094] If so, maintain the current pressure value;

[0095] If not, lower the pressure value and return to the step of determining whether the pressure value is lower than 0.2 MPa.

[0096] Specifically, adjust the pressure value in the casing to keep it always below 0.2 MPa.

[0097] S8: Calculate the daily gas-water relative permeability ratio.

[0098] In the embodiment of the present application, the calculation of the daily gas-water relative permeability ratio includes the steps of:

[0099] Record the daily gas production during the adjustment period;

[0100] Record the daily water production during the adjustment period;

[0101] Obtain the reservoir boundary type;

[0102] Calculate the daily gas-water relative permeability ratio according to the reservoir boundary type.

[0103] Specifically, record the daily gas production and water production during the adjustment period, and calculate the daily gas-water relative permeability ratio based on the reservoir boundary type.

[0104] In the embodiment of the present application, when the gas-water relative permeability ratio = 0.02, control the bottom-hole flowing pressure to continuously decrease and increase production by releasing the casing pressure, thereby gradually increasing the gas-water relative permeability ratio day by day, and record the daily gas-water relative permeability ratio during this period; when the gas-water relative permeability ratio = 1, at this time, the underground gas-water seepage state reaches the isosmotic point, end the operation of controlling the casing pressure to increase production, and maintain the bottom-hole flowing pressure the same as the pipeline pressure.

[0105] In the embodiment of the present application, the calculation of the pseudo-steady-state water production parameter according to the data and the first curve includes the steps of:

[0106] (1) Calculate the ordinate intercept of the first curve based on the first curve, and calculate the pseudo-steady-state water production parameter based on the ordinate intercept of the first curve and the bottom-hole flowing pressure, where the calculation formula is:

[0107]

[0108] In the formula, Q n is the steady-state water production parameter, P e is the ordinate intercept of the first curve, P wf is the bottom-hole flowing pressure.

[0109] (2) During the process of gradually lowering the bottom-hole flowing pressure to the reservoir critical desorption pressure, the daily water production of a single well is always consistent with the pseudo-steady-state water production parameter, and record the daily bottom-hole flowing pressure.

[0110] (3) Calculating the daily gas-water relative permeability includes the steps of:

[0111] If the reservoir boundary type is a constant-pressure boundary, calculate the corresponding gas-water relative permeability based on the daily gas production and water production through the first calculation formula;

[0112] If the reservoir boundary type is a closed boundary, calculate the corresponding gas-water relative permeability based on the daily gas production and water production through the second calculation formula.

[0113] Among them, the first calculation formula is:

[0114]

[0115] In the formula: K is the gas-water relative permeability, Pj is the critical desorption pressure of the reservoir, PW is the bottom-hole flowing pressure on the current day, Pe is the intercept of the first curve on the vertical coordinate, Qg is the gas production on the current day, and Qw is the water production on the current day.

[0116] Among them, the second calculation formula is:

[0117]

[0118] In the formula: K is the gas-water relative permeability, P j is the critical desorption pressure of the reservoir, P W is the bottom-hole flowing pressure on the current day, P e is the intercept of the first curve on the vertical coordinate, Q g is the gas production on the current day, Q w is the water production on the current day.

[0119] Among them, controlling the continuous decline of the bottom-hole flowing pressure to increase production by means of reducing the casing pressure to increase production, and then gradually increasing the gas-water relative permeability day by day, includes:

[0120] Gradually lower the bottom-hole flowing pressure day by day, and the adjustment range each time is 0.01 - 0.02 MPa / d. At the same time, adjust the opening and closing degree of the casing valve to control the flowing fluid level below 10 m, and record the daily gas production and water production during this period.

[0121] The present invention provides a method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well. Its main purpose is to improve the reservoir diversion ability, maximize the pressure drop expansion, and improve the recovery rate by controlling the processes of pressure reduction, water production, and gas production. Its main characteristics are: During the drainage period, based on the principle of efficient decline of the formation pressure, two fixed processes of fixed water production and pressure reduction and fixed pressure water control are carried out before and after critical desorption. During the production increase period, based on the principle of maintaining continuous gas and water production, two lifting processes of controlling the fluid level to lift water and controlling the casing pressure to lift gas are carried out before and after the equal mobility point. There are a total of 6 main production drainage stages:

[0122] (1) Parameter determination stage:

[0123] This stage starts from the production start of the coalbed methane well and ends after obtaining the pseudo-steady state water production parameters (Q n ), generally lasting for 5 - 7 days. Obtain the pseudo-steady state water production parameters of the coalbed methane well within the first time period after the start of production.

[0124] During this stage, drain water by adopting the method of constant flowing pressure drop, record the relationship between the bottom-hole flowing pressure (P wf ) and water production, draw the reservoir IPR curve, and record the original formation pressure of the reservoir (the vertical intercept P e ) of the IPR curve, and the water production index (the negative reciprocal of the slope of the IPR curve) after the drawing is completed. The pseudo-steady state water production parameters (Q n ) are obtained through Formula 1:

[0125]

[0126] (2) Constant water pressure reduction stage:

[0127] This stage starts from the determination of the pseudo-steady state water production parameters and ends when the bottom-hole flowing pressure drops to the critical desorption pressure (P j ) of the reservoir. (After obtaining the pseudo-steady state water production parameters of the reservoir, gradually reduce the bottom-hole flowing pressure to the critical desorption pressure of the reservoir. During this period, the daily water production of a single well is always consistent with the pseudo-steady state water production, and record the second bottom-hole flowing pressure every day. During the process of draining water and reducing pressure in this stage, always keep the daily water production of a single well (Q) = pseudo-steady state water production (Q n ), and record the bottom-hole flowing pressure (P wf ) every day.

[0128] (3) Constant pressure drainage stage:

[0129] This stage starts from when the bottom-hole flowing pressure drops to the critical desorption pressure (P j ) of the reservoir and ends after the daily water production change range ΔQ = 0. After the bottom-hole flowing pressure drops to the critical desorption pressure of the reservoir, record the daily water production volume in turn, and after the fluctuation value of the daily water production volume between two adjacent days is 0, always keep the bottom-hole flowing pressure (P wf ) = critical desorption pressure (P j ) during the process of draining water and reducing pressure in this stage, record the daily water production (Q w ), and the daily water production change range ΔQw = the daily water production Q i on the i-th day - the daily water production Q i-1 on the (i - 1)-th day.

[0130] (4) Liquid level control and water lifting stage:

[0131] This stage starts from when the daily water production change range ΔQw = 0 and ends until the gas-water relative permeability ratio reaches the equal mobility point.

[0132] After the daily water production change range ΔQ = 0, adopt ΔPwf Control the bottom-hole flowing pressure to decrease at a rate of 0.01 MPa / d, keep the casing valve fully open, control the casing pressure below 0.2 MPa, and record the daily gas production (Q g ), daily water production (Q w ). According to different reservoir boundary types, calculate the gas-water relative permeability ratio K daily (using formula 2 for constant-pressure boundary and formula 3 for closed boundary). Gradually lower the bottom-hole flowing pressure by 0.01 MPa / d each day, and adjust the pressure value inside the casing to keep it always below 0.2 MPa. Record the daily gas production and water production during the adjustment period, and calculate the daily gas-water relative permeability ratio based on the reservoir boundary type.

[0133]

[0134]

[0135] In the formula, K is the gas-water relative permeability ratio, P j is the critical desorption pressure of the reservoir, P W is the bottom-hole flowing pressure on that day, P e is the intercept of the first curve on the vertical axis, Q g is the daily gas production, Q w is the daily water production.

[0136] When K = 0.02 (equal mobility point), this stage ends.

[0137] (5) Casing pressure control and production increase stage:

[0138] This stage starts from K = 0.02 (the first preset value) and ends when K reaches the isosmotic point. When the gas-water relative permeability ratio = 0.02, lower the flowing fluid level and increase the casing pressure in this stage. Control the bottom-hole flowing pressure to continue decreasing and increase production by releasing the casing pressure. Use a system of ΔP wf = 0.01 - 0.02 MPa / d to control the decrease of the bottom-hole flowing pressure. Appropriately control the opening of the casing valve, control the flowing fluid level below 10 m, and record the daily gas production (Q g ), daily water production (Q w ). According to different reservoir boundary types, calculate the gas-water relative permeability ratio K daily (using formula 2 for constant-pressure boundary and formula 3 for closed boundary), and the maximum daily gas production (Q max ).

[0139] When K = 1, the underground gas-water seepage state reaches the isosmotic point, and the casing pressure control and production increase stage ends.

[0140] (6) Casing pressure control and stable production stage:

[0141] This stage starts from K = 1 (the second preset value) and lasts until the P of this well wfEqual to the pipeline pressure P s At this point, the production stage of artificial pressure control for the coalbed methane well ends, and the coalbed methane well enters the natural production stage with uncontrollable pressure.

[0142] In this stage, by regulating Q g and ΔP wf pressure reduction and production control are achieved. After K = 1, by controlling ΔP wf , Q g = Q max is achieved. When ΔP wf = 0, Q g = Q max can be guaranteed. When 0 < ΔP wf < 0.01 MPa / d, the daily gas production can be further increased by increasing the gas venting amplitude.

[0143] The technical basis of this invention is as follows:

[0144] During the drainage stage, due to the differences in the reservoir boundary types and formation water content of each coalbed methane well, if a templatized drainage system or empirical parameters obtained based on some evaluation well parameters are used to formulate drainage, it may lead to a decrease in the adaptability and pertinence of the drainage parameters, and may further cause reservoir damage. Therefore, based on the traditional drainage model, this invention designs a parameter acquisition stage at the initial stage of single-well drainage. By obtaining the pseudo-steady state water production of a single well, the optimal water production suitable for its own geological conditions is obtained for pressure reduction, so as to establish the production pressure difference with the highest efficiency and improve the pressure drop funnel expansion efficiency. After the bottom hole flowing pressure drops to the critical desorption pressure, due to the lag of pressure conduction, the actual formation pressure is still relatively high at this time. If the desorption and production increase stage is entered rashly, a large amount of water will not be discharged, affecting the production increase efficiency and the ultimate recovery rate in the production increase stage. Therefore, this invention designs a constant pressure water production link when the bottom hole flowing pressure is close to the critical desorption pressure. When the water production no longer changes during the constant pressure process, it indicates that the formation pressure drop expansion has reached the maximum range under the current pressure difference condition. At this time, entering the production increase stage can obtain a higher methane desorption efficiency in a short time and improve the development effect of the coalbed methane well.

[0145] During the production increase stage, the production of gas will change the formation flow state from single-phase water flow to gas-water two-phase flow. Methane will supplement the formation energy in the form of gas elastic energy at the initial stage of desorption, promoting the production of water. After the gas-water co-flow is formed, the relative permeability of gas and water changes with the change of gas-water saturation. The production of gas will inhibit the water production, and thus inhibit the continuous drainage and pressure reduction. Therefore, at the initial stage of drainage and production, start pumping with low parameters, calculate the gas-water relative permeability ratio of the reservoir based on the water production and gas production, balance the gas-water relative permeability relationship, maintain the optimal gas-water ratio, and keep the continuous production of gas and water. Maintain the stable gas saturation in the reservoir. When the water-phase seepage is strong: hold the casing pressure to increase the gas saturation in the formation; when the gas-phase seepage is strong: release gas at low casing pressure to reduce the gas saturation in the formation. In the later stage of drainage and production, as the gas volume increases, the decline rate of the pressure conductivity coefficient gradually slows down, the water production continues to decline, and the gas production gradually enters the stable production stage. Maintain the underground gas saturation, rely on the self-improvement of the reservoir, guide the continuous production of gas, and achieve long-term stable production of gas wells. Therefore, the present invention controls the division of the drainage and production stage and the bottom-hole flowing pressure control method by introducing the gas-water relative permeability ratio parameter, and realizes the optimal underground seepage state of a single well through this technology, so that the formation supply and surface production reach the supply-production balance.

[0146] Example 2

[0147] Such as Figure 5 , Well CP10 in the CZ well area is a coalbed methane horizontal well using an electric submersible screw pump for extraction. This well develops the coalbed methane in the No. 3 coal seam, with a burial depth of 1000 m. The reservoir pressure P e of the No. 3 coal seam is 8.0 MPa. According to the production situation of adjacent wells, the desorption pressure P j is predicted to be 2.7 MPa. Apply the method provided by the present invention and operate specifically according to the following steps:

[0148] (1) Parameter determination stage:

[0149] After the well is put into production, the flowing pressure P wf = 10 MPa. Draw the IPR curve after 5 days of trial pumping, determine the water production index J = -40, Pe = 8.0 MPa. Therefore, determine that the well Q n = 40 m 3 / d.

[0150] (2) Fixed water pressure reduction stage:

[0151] In this stage, maintain a daily water production of 40 m 3 / d for drainage and pressure reduction, and keep it until P wf = P j＝ 2.7 MPa.

[0152] (3) Fixed pressure drainage stage:

[0153] Keep P wf = P j= 2.7 MPa, the daily water production will continue to show a downward trend. The daily water production of this well decreases from 40 m 3 / d to 20 m 3 / d and stops decreasing. At this time, ΔQw = 0, and this drainage stage ends.

[0154] (4) Bottom-hole flowing pressure control with liquid level control stage:

[0155] Adopt a system of ΔP wf = 0.01 MPa / d to control the decrease of the bottom-hole flowing pressure, keep the casing valve fully open, and control the casing pressure at 0.05 MPa. At this time, both the daily gas production and the daily water production show a natural upward trend, and no specific control is made on the gas production increase.

[0156] (5) Casing pressure control for production increase stage:

[0157] When K = 0.02 for Well CP10, gradually adjust the casing valve back to increase the casing pressure. The casing pressure gradually rises to 0.5 MPa, and maintain a system of ΔP wf = 0.01 MPa / d to control the decrease of the bottom-hole flowing pressure. At this time, the daily gas production shows a natural upward trend and the daily water production shows a natural downward trend.

[0158] (6) Casing pressure control for stable production stage:

[0159] When K = 1 for Well CP10, the daily gas production is 4500 m 3 / d. By controlling 0 < ΔP wf < 0.01 MPa / d, keep this well producing at a daily production of 4500 m 3 / d.

[0160] For example Figure 2 , this application provides a bottom-hole flowing pressure control device for a coalbed methane horizontal well. The device includes:

[0161] A data acquisition module 10 for acquiring data of the coalbed methane well during the first time period when production starts;

[0162] A curve plotting module 20 for plotting a first curve according to the data;

[0163] A parameter calculation module 30 for calculating the pseudo-steady state water production parameters according to the data and the first curve;

[0164] A pressure reduction module 40 for gradually reducing the bottom-hole flowing pressure to the critical desorption pressure of the reservoir;

[0165] A water production recording module 50 for recording the second daily water production;

[0166] A flowing pressure reduction module 60 for reducing the bottom-hole flowing pressure day by day;

[0167] The pressure value adjustment module 70 is used to adjust the pressure value inside the casing;

[0168] The gas-water relative permeability ratio calculation module 80 is used to calculate the daily gas-water relative permeability ratio.

[0169] A bottom-hole flowing pressure control device for a coalbed methane horizontal well provided by this application can execute a bottom-hole flowing pressure control method for a coalbed methane horizontal well provided by the above steps.

[0170] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principles of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all variations and modifications that fall within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

[0171] Next, refer to Figure 3 , which shows a schematic structural diagram of an electronic device 100 suitable for implementing the embodiments of the present disclosure. The electronic devices in the embodiments of the present disclosure may include, but are not limited to, mobile terminals such as mobile phones, laptop computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Tablet Computers), PMPs (Portable Multimedia Players), in-vehicle terminals (such as in-vehicle navigation terminals), etc., and fixed terminals such as digital TVs, desktop computers, etc. Figure 3 The electronic device shown is only an example and should not bring any limitations to the functions and usage scope of the embodiments of the present disclosure.

[0172] As Figure 3 shown, the electronic device 100 may include a processing device (such as a central processing unit, a graphics processing unit, etc.) 101, which can execute various appropriate actions and processes according to the program stored in the read-only memory (ROM) 102 or the program loaded from the storage device 108 into the random access memory (RAM) 103. In the RAM 103, various programs and data required for the operation of the electronic device 100 are also stored. The processing device 101, the ROM 102, and the RAM 103 are connected to each other through a bus 104. The input / output (I / O) interface 105 is also connected to the bus 104.

[0173] Typically, the following devices can be connected to the I / O interface 105: an input device 106 including, for example, a touch screen, a touchpad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 107 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; a storage device 108 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 109. The communication device 109 can allow the electronic device 100 to communicate with other devices wirelessly or wiredly to exchange data. Although the electronic device 100 with various devices is shown in the figure, it should be understood that it is not required to implement or have all the shown devices. More or fewer devices can be alternatively implemented or had.

[0174] In particular, according to an embodiment of the present disclosure, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present disclosure includes a computer program product that includes a computer program carried on a computer-readable medium, and the computer program contains program codes for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication device 109, or installed from the storage device 108, or installed from the ROM 102. When the computer program is executed by the processing device 101, the above-mentioned functions defined in the method of the embodiment of the present disclosure are executed.

[0175] Reference is made below to Figure 4 , which shows a schematic structural diagram of a computer-readable storage medium suitable for implementing an embodiment of the present disclosure. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it can implement the coalbed methane horizontal well bottom hole flowing pressure control method as described in any one of the above.

[0176] A coalbed methane horizontal well bottom hole flowing pressure control method, device and storage medium provided by the present application eliminate the drawbacks of the templated scheme in the existing method that uses reservoir static parameters as the system basis, fully consider the heterogeneity of coalbed methane wells, and adopt a flexible method for determining indexed parameters according to the actual gas-water flow characteristics of a single well, which can achieve the optimal underground seepage state of a single well, the formation supply and surface production reach the supply-production balance, and the single well has long-term stable production, providing a reference for realizing the refinement of the drainage control of coalbed methane wells. A coalbed methane horizontal well bottom hole flowing pressure control method, device and storage medium provided by the present application can be applied to coalbed methane wells developed by the surface drainage method, and have good application effects and great popularization value.

[0177] It should be noted that, in this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0178] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well, characterized in that, the method comprises the steps of: obtaining data of the coalbed methane well during a first time period at the start of production; drawing a first curve based on the data; calculating the pseudo-steady-state water production parameters according to the data and the first curve; gradually reducing the bottom-hole flowing pressure to the critical desorption pressure of the reservoir; recording the second daily water production; gradually lowering the bottom-hole flowing pressure day by day; adjusting the pressure value in the casing; calculating the daily gas-water relative permeability ratio.

2. The method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well according to claim 1, characterized in that, the obtaining of the data of the coalbed methane well during a first time period at the start of production comprises the steps of: obtaining the bottom-hole flowing pressure data of the coalbed methane well during a first time period at the start of production; obtaining the water production parameters of the coalbed methane well during a first time period at the start of production.

3. The method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well according to claim 1, characterized in that, the drawing of the first curve according to the data comprises the steps of: obtaining the bottom-hole flowing pressure data in the data; obtaining the water production parameters in the data; drawing the first curve according to the bottom-hole flowing pressure data and the water production parameters.

4. The method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well according to claim 1, characterized in that, the calculating of the pseudo-steady-state water production parameters according to the data and the first curve comprises the steps of: obtaining the bottom-hole flowing pressure data in the data; obtaining the first curve; calculating the pseudo-steady-state water production parameters according to the bottom-hole flowing pressure data and the first curve.

5. The method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well according to claim 1, characterized in that, the gradually lowering of the bottom-hole flowing pressure day by day comprises the steps of: obtaining the second daily water production; judging whether the second daily water production tends to be stable; if so, gradually lowering the bottom-hole flowing pressure day by day at an adjustment amplitude of 0.01 MPa / d.

6. The method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well according to claim 1, characterized in that, the adjusting of the pressure value in the casing comprises the steps of: obtaining the pressure value in the casing; judging whether the pressure value is lower than 0.2 MPa; if so, maintaining the current pressure value; if not, lowering the pressure value and returning to the step of judging whether the pressure value is lower than 0.2 MPa.

7. The method for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well according to claim 1, characterized in that, the calculating of the daily gas-water relative permeability ratio comprises the steps of: recording the daily gas production during the adjustment period; recording the daily water production during the adjustment period; obtaining the reservoir boundary type; calculating the daily gas-water relative permeability ratio according to the reservoir boundary type.

8. A device for controlling the bottom-hole flowing pressure of a coalbed methane horizontal well, characterized in that, the device comprises: a data acquisition module for obtaining data of the coalbed methane well during a first time period at the start of production; a curve drawing module for drawing a first curve according to the data; a parameter calculation module for calculating the pseudo-steady-state water production parameters according to the data and the first curve; a pressure reduction module for gradually reducing the bottom-hole flowing pressure to the critical desorption pressure of the reservoir; a water production recording module for recording the second daily water production; The flowing pressure reduction module is used to gradually reduce the bottom-hole flowing pressure day by day; The pressure value adjustment module is used to adjust the pressure value in the casing; The gas-water relative permeability ratio calculation module is used to calculate the daily gas-water relative permeability ratio.

9. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein, when the processor executes the program, the steps of the method according to any one of claims 1-7 are implemented.

10. A storage medium, on which a computer program is stored, wherein, when the program is executed by the processor, the steps of the method according to any one of claims 1-7 are implemented.

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