Coal-bed gas well production dynamic prediction method and device based on overall modeling

Abstract

The invention relates to the field of coal bed gas exploitation and development, and provides a coal bed gas well production dynamic prediction method and device based on overall modeling, and the corresponding method comprises the steps: obtaining the current coal bed pressure of a coal bed gas well and the current treatment plant inlet pressure; according to the current coal seam pressure, the current treatment plant inlet pressure and a pre-generated current production dynamic prediction model, the production dynamic state of the coal-bed gas well is predicted; wherein the current production dynamic prediction model is generated through iteration of a productivity equation of the coal-bed gas well in the production dynamic prediction model at the last moment, and the production dynamic prediction model is used for representing pressure changes and temperature changes among a coal-bed gas reservoir, a shaft, a valve, a pipeline and a treatment plant where the coal-bed gas well is located. According to the method, the more accurate production dynamic state of the coal-bed gas well can be obtained.

Description

Technical Field

[0001] The present application relates to the field of coalbed methane exploitation and development, in particular to the technical field related to coalbed methane gathering and transportation, and specifically to a method and device for predicting the production dynamics of coalbed methane wells based on overall modeling. Background Art

[0002] In the prior art, there are generally two methods for predicting the production dynamics of coalbed methane wells:

[0003] (1) Under the production conditions of fixed water production and fixed bottom flow pressure, the gas production, water production, formation pressure, etc. at a certain time in the future are predicted. The production dynamics calculation is carried out by combining the coalbed methane reservoir with the wellbore, and the annular dynamic liquid level is determined by the surface drainage and water production to describe the dynamic process of production under the combination of reservoir and wellbore.

[0004] However, it is impossible to determine the water production and bottom flow pressure during the construction process. On the other hand, the impact of ground conditions such as the inlet pressure of the processing plant and the ambient temperature on the production dynamics of the coalbed methane well is not considered. At present, there are corresponding methods for reservoir simulation and ground gathering and transportation pipeline simulation. If the overall system modeling and simulation of the reservoir and the ground is to be realized, it is necessary to combine multiple methods to realize the dynamic simulation of the entire mining process of the oil and gas well from underground to the ground, which is undoubtedly time-consuming and laborious.

[0005] (2) The surface coalbed methane gathering and transportation network was simulated, and the condensate water was separated out during the flow process to form a gas-liquid two-phase flow. The Beggs-Brill pressure drop calculation formula was used to calculate the pressure in the gathering and transportation network.

[0006] This method does not take into account the wellbore, nozzles and other equipment. In addition, this method models the wellbore, gas reservoir, surface pipeline network and wellbore separately, which has low convergence and does not combine the temperature change, condensate water precipitation and coalbed methane reservoir production dynamics during the flow process. Summary of the invention

[0007] The present application provides a method and device for predicting the production dynamics of coalbed methane wells based on overall modeling, the purpose of which is to overcome the following technical pain points in the prior art:

[0008] The combined simulation of oil and gas reservoirs and wellbores ignores the impact of surface gathering and transportation pipelines and the inlet pressure of the processing plant on the wellhead. In addition, the existing solutions are costly; coupling oil and gas reservoir simulators and surface gathering and transportation simulators is time-consuming (there is a data exchange process in the form of files; for coalbed methane containing water vapor, the black oil model cannot accurately describe the condensate water precipitation and volatilization process, and the use of component models for flash evaporation will increase the physical property calculation time).

[0009] The influence of the dynamic liquid level change of coalbed methane well on the bottom hole pressure cannot be ignored, but the existing technology does not take this into consideration.

[0010] In order to achieve the above objectives, in a first aspect, the present application provides a method for predicting the production dynamics of a coalbed methane well based on overall modeling, comprising:

[0011] Obtain the current coal seam pressure of the coal seam gas well and the current inlet pressure of the processing plant;

[0012] The production dynamics of the coalbed methane well is predicted based on the current coal seam pressure, the current processing plant inlet pressure and a pre-generated current production dynamics prediction model; wherein the current production dynamics prediction model is iteratively generated by the production capacity equation of the coalbed methane well in the production dynamics prediction model at the previous moment, and the production dynamics prediction model is used to characterize the pressure changes and temperature changes among the coalbed methane reservoir, wellbore, valves, pipelines and the processing plant in which the coalbed methane well is located.

[0013] In some embodiments of the present invention, the step of generating the current production dynamic prediction model includes:

[0014] Generate a current production capacity equation corresponding to the current production dynamic prediction model according to the current coal seam pressure, the current bottom hole pressure, the current permeability, the current coal seam gas viscosity and the wellbore parameters;

[0015] generating a current steady-state node pressure equation according to the current production capacity equation, the current node pressure of the coalbed methane reservoir, the current node pressure of the wellbore, the current node pressure of the valve, the current node pressure of the pipeline, and the current node pressure of the processing plant;

[0016] Solving the current steady-state node pressure equation to obtain the current mass flow rate of the coalbed methane well;

[0017] The current coal seam pressure, current bottom hole pressure, current permeability, and current coal seam gas viscosity are updated according to the current mass flow.

[0018] In some embodiments of the present invention, if condensate water is precipitated during the flow of coalbed methane, before solving the current steady-state node pressure equation to obtain the current mass flow rate of the coalbed methane well, the method further includes:

[0019] Calculating the amount of condensate water released according to the saturated temperature and saturated pressure of water vapor during the flow of the coalbed methane;

[0020] The current steady-state node pressure equation is modified according to the precipitation amount.

[0021] In some embodiments of the present invention, a method for predicting coalbed methane well production performance based on overall modeling further includes:

[0022] Calculating a current dynamic liquid level change in the wellbore based on a current flowing gas column and a current static liquid column in the wellbore;

[0023] The current bottom hole pressure is corrected according to the current dynamic liquid level change to correct the current steady-state node pressure equation.

[0024] In some embodiments of the present invention, a current steady-state node pressure equation is generated according to the current production capacity equation, the current node pressure of the coalbed methane reservoir, the current node pressure of the wellbore, the current node pressure of the valve, the current node pressure of the pipeline, and the current node pressure of the processing plant, including:

[0025] Generate a plurality of directed edges according to the production capacity equation, the wellbore, the valve, and the pipeline;

[0026] Generate a directed graph of the gathering and transportation system corresponding to the coalbed methane wells according to multiple directed edges;

[0027] The current steady-state node pressure equation is generated according to the current node pressure of each node in the directed graph.

[0028] In some embodiments of the present invention, a method for predicting coalbed methane well production performance based on overall modeling further includes:

[0029] Topologically sorting the directed graph according to the order in which coal seam gas flows through each node;

[0030] Iteratively update the temperature changes of each node in the directed graph after topological sorting until the preset conditions are met;

[0031] The current coal seam pressure, the current bottom hole pressure, the current permeability, and the current coal seam gas viscosity are updated according to the current mass flow and the current temperature of each node.

[0032] In a second aspect, the present application provides a device for predicting coalbed methane well production dynamics based on overall modeling, the device comprising:

[0033] A pressure acquisition module, used to obtain the current coal seam pressure of the coal seam gas well and the current inlet pressure of the processing plant;

[0034] A production dynamics prediction module is used to predict the production dynamics of the coalbed methane well based on the current coal seam pressure, the current processing plant inlet pressure and a pre-generated current production dynamics prediction model; wherein the current production dynamics prediction model is iteratively generated by the production capacity equation of the coalbed methane well in the production dynamics prediction model at the previous moment, and the production dynamics prediction model is used to characterize the pressure changes and temperature changes among the coalbed methane reservoir, wellbore, valve, pipeline and the processing plant in which the coalbed methane well is located.

[0035] In some embodiments of the present invention, a coalbed methane well production dynamic prediction device based on overall modeling further includes:

[0036] A prediction model generation module is used to generate the current production dynamic prediction model; the prediction model generation module includes:

[0037] A current production capacity equation generating unit, used to generate a current production capacity equation corresponding to the current production dynamic prediction model according to the current coal seam pressure, the current bottom hole pressure, the current permeability, the current coal seam gas viscosity and the wellbore parameters;

[0038] A current pressure equation generating unit, used for generating a current steady-state node pressure equation according to the current production capacity equation, the current node pressure of the coalbed methane reservoir, the current node pressure of the wellbore, the current node pressure of the valve, the current node pressure of the pipeline and the current node pressure of the processing plant;

[0039] A current pressure equation solving unit, used for solving the current steady-state node pressure equation to obtain the current mass flow of the coalbed methane well;

[0040] The current parameter updating unit is used to update the current coal seam pressure, the current bottom hole pressure, the current permeability, and the current coal seam gas viscosity according to the current mass flow rate.

[0041] In some embodiments of the present invention, if condensate water is precipitated during the flow of coalbed methane, before solving the current steady-state node pressure equation to obtain the current mass flow rate of the coalbed methane well, a coalbed methane well production dynamic prediction device based on overall modeling further includes:

[0042] A coalbed methane precipitation calculation unit, used to calculate the precipitation amount of condensate water according to the saturated temperature and saturated pressure of water vapor during the flow of the coalbed methane;

[0043] The current pressure equation correction unit is used to correct the current steady-state node pressure equation according to the precipitation amount.

[0044] In some embodiments of the present invention, a coalbed methane well production dynamic prediction device based on overall modeling further includes:

[0045] A current dynamic liquid level calculation module, used to calculate the current dynamic liquid level change in the wellbore according to the current flowing gas column and the current static liquid column of the wellbore;

[0046] The current node pressure equation correction module is used to correct the current bottom hole pressure according to the current dynamic liquid level change to correct the current steady-state node pressure equation.

[0047] In some embodiments of the present invention, the current pressure equation generating unit includes:

[0048] A plurality of directed edge generating units, used for generating a plurality of directed edges according to the production capacity equation, the wellbore, the valve, and the pipeline;

[0049] A directed graph generating unit, used for generating a directed graph of a gathering and transportation system corresponding to a coalbed methane well according to a plurality of directed edges;

[0050] The current pressure equation generating subunit is used to generate the current steady-state node pressure equation according to the current node pressure of each node in the directed graph.

[0051] In some embodiments of the present invention, a coalbed methane well production dynamic prediction device based on overall modeling further includes:

[0052] A directed graph sorting module, used for topologically sorting the directed graph according to the order in which coal seam gas flows through each node;

[0053] The temperature change iterative update module is used to iteratively update the temperature change of each node in the directed graph after topological sorting until the preset conditions are met;

[0054] The current parameter updating module is used to update the current coal seam pressure, the current bottom hole pressure, the current permeability, and the current coal seam gas viscosity according to the current mass flow and the current temperature of each node.

[0055] In a third aspect, the present application provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of a method for dynamic prediction of coalbed methane well production based on overall modeling.

[0056] In a fourth aspect, the present application provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of a method for dynamic prediction of coalbed methane well production based on overall modeling are implemented.

[0057] In a fifth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a method for dynamic prediction of coalbed methane well production based on overall modeling.

[0058] From the above description, it can be seen that the embodiment of the present application provides a method and device for predicting the production dynamics of a coalbed methane well based on overall modeling, and the corresponding method includes: first, obtaining the current coal seam pressure of the coalbed methane well and the current inlet pressure of the processing plant; then, predicting the production dynamics of the coalbed methane well according to the current coal seam pressure, the current inlet pressure of the processing plant and the pre-generated current production dynamics prediction model; wherein the current production dynamics prediction model is iteratively generated by the production capacity equation of the coalbed methane well in the production dynamics prediction model at the previous moment, and the production dynamics prediction model is used to characterize the pressure changes and temperature changes between the coalbed methane reservoir, wellbore, valve, pipeline, and processing plant where the coalbed methane well is located. The present application can obtain more accurate production dynamics of coalbed methane wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0060] Figure 1 A schematic diagram of a method for predicting coalbed methane well production dynamics based on overall modeling provided in an embodiment of the present application Figure 1 ;

[0061] Figure 2 A schematic diagram of a method for predicting coalbed methane well production dynamics based on overall modeling provided in an embodiment of the present application Figure 2 ;

[0062] Figure 3 The process diagram of step 300 of a method for predicting coalbed methane well production dynamics based on overall modeling provided in an embodiment of the present application is as follows: Figure 1 ;

[0063] Figure 4 The process diagram of step 300 of a method for predicting coalbed methane well production dynamics based on overall modeling provided in an embodiment of the present application is as follows: Figure 2 ;

[0064] Figure 5 A schematic diagram of a method for predicting coalbed methane well production dynamics based on overall modeling provided in an embodiment of the present application Figure 3 ;

[0065] Figure 6 A schematic flow chart of step 302 of a method for predicting coalbed methane well production dynamics based on overall modeling provided in an embodiment of the present application;

[0066] Figure 7A schematic diagram of a method for predicting coalbed methane well production dynamics based on overall modeling provided in an embodiment of the present application Figure 4 ;

[0067] Figure 8 A schematic diagram of a flow chart of a method for predicting the production dynamics of a coalbed methane well based on overall modeling provided in a specific application example of this application;

[0068] Fig. 9 This is a schematic diagram of the structure of the coalbed methane surface gathering and transportation pipeline network provided in the specific application example of this application;

[0069] Fig.10 A schematic diagram of an application scenario of a method for predicting the production dynamics of a coalbed methane well based on overall modeling provided in a specific application example of this application;

[0070] Fig.11 A technical flow chart of a method for predicting the production dynamics of a coalbed methane well based on overall modeling provided in a specific application example of this application;

[0071] Fig.12 The overall water-thermal calculation flow chart of the gathering and transportation system combined with the production capacity equation, wellbore, valve, and surface pipeline provided in the specific application example of this application;

[0072] Fig.13 A schematic diagram of the production performance results of each coalbed methane well in the next 800 days provided in the specific application example of this application (well W1, well W2, well W3, well W4 and well W5 respectively);

[0073] Fig.14 A schematic diagram of a coalbed methane well production dynamic prediction device based on overall modeling provided in a specific application example of this application Figure 1 ;

[0074] Fig.15 A schematic diagram of a coalbed methane well production dynamic prediction device based on overall modeling provided in a specific application example of this application Figure 2 ;

[0075] Fig.16 The structure of the prediction model generation module 30 provided in the embodiment of the present application is shown in FIG. Figure 1 ;

[0076] Fig.17 The structure of the prediction model generation module 30 provided in the embodiment of the present application is shown in FIG. Figure 2 ;

[0077] Fig.18 A schematic diagram of a coalbed methane well production dynamic prediction device based on overall modeling provided in a specific application example of this application Figure 3 ;

[0078] Fig.19 It is a structural schematic diagram of the current pressure equation generating unit 30b provided in the embodiment of the present application;

[0079] Fig. 20 A schematic diagram of a coalbed methane well production dynamic prediction device based on overall modeling provided in a specific application example of this application Figure 4 ;

[0080] Fig.21 It is a schematic diagram of the structure of an electronic device in an embodiment of the present application. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0082] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0083] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatuses.

[0084] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0085] The existing solution for predicting the production dynamics of coalbed methane wells in combination with the ground gathering and transportation pipeline network is to use specific software simulation or to couple the oil and gas reservoir simulation software with the ground gathering and transportation software. Data exchange is achieved through corresponding files to achieve the coupling of the oil and gas reservoir simulator and the ground gathering and transportation simulator, so as to make a more detailed prediction of the production dynamics of coalbed methane wells.

[0086] However, the above methods mostly simulate the oil and gas reservoir and the wellbore together, while ignoring the impact of the surface gathering and transportation pipeline network and the inlet pressure of the processing plant on the wellhead.

[0087] Based on this, the embodiment of the present application provides a specific implementation method of a coalbed methane well production dynamic prediction method based on overall modeling, see Figure 1 , the method specifically includes the following contents:

[0088] Step 100: Obtain the current coal seam pressure of the coal seam gas well and the current inlet pressure of the processing plant;

[0089] Step 200: Predict the production dynamics of the coalbed methane well based on the current coal seam pressure, the current processing plant inlet pressure and a pre-generated current production dynamics prediction model; wherein the current production dynamics prediction model is iteratively generated by the production capacity equation of the coalbed methane well in the production dynamics prediction model at the previous moment, and the production dynamics prediction model is used to characterize the pressure changes and temperature changes among the coalbed methane reservoir, wellbore, valve, pipeline and the processing plant in which the coalbed methane well is located.

[0090] From the above description, it can be seen that the embodiment of the present application provides a method for predicting the production dynamics of a coalbed methane well based on overall modeling, including: first obtaining the current coal seam pressure of the coalbed methane well and the current processing plant inlet pressure; then, predicting the production dynamics of the coalbed methane well based on the current coal seam pressure, the current processing plant inlet pressure and a pre-generated current production dynamics prediction model; wherein the current production dynamics prediction model is iteratively generated by the production capacity equation of the coalbed methane well in the production dynamics prediction model at the previous moment, and the production dynamics prediction model is used to characterize the pressure changes and temperature changes between the coalbed methane reservoir, wellbore, valve, pipeline, and processing plant in which the coalbed methane well is located.

[0091] The present application conducts overall modeling of the coalbed methane reservoir production capacity equation, wellbore, oil nozzle, and ground gathering and transportation pipeline network, and can perform integrated hydrothermal simulation; and in the process of hydrothermal simulation, the changes in the dynamic liquid level in the wellbore and the changes in fluid physical properties caused by the changes in temperature and pressure during the flow of coalbed methane are considered; the gas production and water production of each coalbed methane well are calculated at a fixed processing plant inlet pressure, and this gas production and water production are combined with the material balance method of the coalbed methane well, thereby realizing the production dynamic calculation of the coalbed methane well combined with the ground gathering and transportation pipeline network.

[0092] In step 100 and step 200, when the coal seam pressure and the inlet pressure of the processing plant are known, the gas production, water production and temperature change of each wellhead during the coalbed methane flow can be calculated, and the daily gas production and daily water production can be obtained based on the gas production and water production of each well, and the cumulative gas production and cumulative water production can be obtained. Combined with the material balance equation of the coalbed methane well, the formation pressure, permeability, porosity and other parameters at the next moment are calculated to update the coalbed methane related parameters, and the coalbed methane well production capacity equation is established again. Repeat this process to realize the dynamic calculation of coalbed methane well production combined with the ground gathering and transportation pipeline network.

[0093] It should be pointed out that the production dynamics calculation of coalbed methane wells refers to the combination of material balance equation, production capacity equation and gas-water relative permeability curve to predict the dynamic changes of formation pressure, water production and gas production of coalbed methane wells. The production dynamics analysis of coalbed methane wells can optimize the production strategy of oil and gas wells, improve the oil and gas recovery rate, and provide decision-making basis in extending the economic life of oil and gas wells and development and mining planning.

[0094] The method provided in step 100 and step 200 models the coalbed methane reservoir production capacity equation, wellbore, oil nozzle, and ground gathering and transportation pipeline network as a whole, so that an integrated hydrothermal simulation can be performed; and in the process of hydrothermal simulation, the changes in the dynamic liquid level in the wellbore and the changes in fluid physical properties caused by the changes in temperature and pressure during the flow of coalbed methane are considered; the gas production and water production of each coalbed methane well are calculated at a fixed processing plant inlet pressure, and the gas production and water production are combined with the material balance method of the coalbed methane well, thereby realizing the production dynamic calculation of the coalbed methane well combined with the ground gathering and transportation pipeline network.

[0095] In some embodiments of the present invention, see Figure 2 , a coalbed methane well production dynamic prediction method based on overall modeling, further comprising:

[0096] Step 300: Generate the current production dynamic prediction model;

[0097] Next, see Figure 3 , step 300 comprises:

[0098] Step 301: generating a current production capacity equation corresponding to the current production dynamic prediction model according to the current coal seam pressure, the current bottom hole pressure, the current permeability, the current coal seam gas viscosity and the wellbore parameters;

[0099] Specifically, based on the coalbed methane reservoir and wellbore parameters, the gas and water production capacity equations of each coalbed methane well are established to obtain the relationship between the volume flow rate and the formation pressure and bottom hole flow pressure under standard conditions. Under different water saturations, the relative permeabilities of the gas and water phases are different, which can be interpolated and calculated through the gas-water relative permeability curve.

[0100]

[0101] Among them, q sc ,q w are the gas production and water production of a single well under standard conditions, m 3 / s; Z sc is the gas compression factor under standard conditions, dimensionless; T sc is the gas temperature under standard conditions, K; K is the relative permeability of the coal seam, m 2 (1mD=0.987×10 -15 m 2 );K rg , K rw are the relative permeabilities of gas phase and water phase, dimensionless; h is the thickness of coal seam, m; p is the average reservoir pressure, Pa; p wf is the bottom hole flowing pressure, Pa; T is the coalbed methane reservoir temperature, K; is the compression factor under the average pressure of reservoir pressure and bottom hole flowing pressure, dimensionless; are gas viscosity at average pressure of reservoir pressure and bottom hole flow pressure, Pa·s; r w is the wellbore radius, m; r e is the outer boundary radius of the leaking area, m; s is the skin coefficient, dimensionless.

[0102] The temperature of coalbed methane remains constant during its flow from the formation to the bottom of the well, which is equal to the formation temperature, which is given at the beginning of the calculation.

[0103] Step 302: Generate a current steady-state node pressure equation according to the current production capacity equation, the current node pressure of the coalbed methane reservoir, the current node pressure of the wellbore, the current node pressure of the valve, the current node pressure of the pipeline, and the current node pressure of the processing plant;

[0104] Step 303: solving the current steady-state node pressure equation to obtain the current mass flow rate of the coalbed methane well;

[0105] Step 304: Update the current coal seam pressure, current bottom hole pressure, current permeability, and current coal seam gas viscosity according to the current mass flow rate.

[0106] In step 302 to step 304, a node steady-state equation with node pressure as the solution variable is established based on the current production capacity equation, wellbore model, valve model, and surface pipeline network; and the equation is solved to calculate the mass flow rate after convergence of each production capacity equation in the gathering and transportation system again to obtain the gas production Q for the day. g 、Water production on the day Q w ; and update the current pressure, permeability, and water saturation parameters of the coal seam, thereby continuing the initial steps and executing this process in a loop to achieve the future production dynamic calculation of the coalbed methane well combined with the ground pipeline network.

[0107] In some embodiments of the present invention, see Figure 4 If condensate water is precipitated during the coalbed methane flow process, before step 303, step 300 further includes:

[0108] Step 305: calculating the amount of condensate water released according to the saturated temperature and saturated pressure of water vapor during the flow of the coalbed methane;

[0109] For the condensate water precipitation caused by the changes of temperature and pressure during the flow of coalbed methane, the coalbed methane precipitation amount is calculated by interpolating the saturated temperature and saturated pressure of water vapor to reduce the time consumption of flash evaporation calculation.

[0110] Specifically, based on the composition of coalbed methane, the saturated pressure of saturated water vapor at different temperatures is determined, and the molar fraction and mass flow rate of condensed water precipitated from coalbed methane at a certain temperature and pressure are calculated:

[0111] y wg =p wc / p s

[0112] y wc =y w -y wg

[0113]

[0114] Among them, p wc is the saturation pressure at a certain temperature, Pa; p s is the system pressure, Pa; y w ,y wg ,y wc is the mole fraction of water vapor in the coalbed methane composition, the mole fraction of saturated water vapor, and the mole fraction of condensed water in the coalbed methane at a certain temperature and pressure, dimensionless; i is the mass fraction of each component; m i is the molar mass of each component, kg / kmol; n is the total number of coalbed methane components; w is the pipeline mass flow rate, kg / s; F is the total molar flow rate in the pipeline, kmol / s; m w is the water molar fraction, 18kg / kmol; w wc is the mass flow rate of condensate water, kg / s.

[0115] Step 306: Correct the current steady-state node pressure equation according to the precipitation amount.

[0116] In some embodiments of the present invention, see Figure 5 , a coalbed methane well production dynamic prediction method based on overall modeling, further comprising:

[0117] Step 400: Calculating a current dynamic liquid level change in the wellbore according to a current flowing gas column and a current static liquid column in the wellbore;

[0118] The wellbore pressure drop is the sum of the pressure drops of the flowing gas column and the static liquid column, which is used to consider the impact of dynamic liquid level changes on the bottom hole pressure.

[0119] Specifically, for the flow of coalbed methane in the wellbore annulus, considering that the wellbore annulus pressure drop is composed of a flowing gas column and a static liquid column, the flowing gas column pressure drop calculation formula is calculated in the following way (applicable to all inclined pipes), and the wellbore annulus is treated with an equivalent diameter, and the wellbore pressure drop is obtained as shown in the following formula. The dynamic liquid level height can be input into the field measurement data or calculated using the surface drainage and formation water production.

[0120] Δp=p wf -p c =Δp f +ρ L gh L

[0121] In the above formula, Δp is the pressure drop in the wellbore, Pa; p wf is the bottom hole pressure, Pa; p c is the wellhead casing pressure, Pa; Δp f is the pressure difference of the flowing gas column, Pa; ρ L is the water density, 1000kg / m 3 ; g is the acceleration due to gravity, 9.8m / s 2 ;h L is the dynamic liquid level height, m. For the temperature change of coalbed methane in the process of flowing in the wellbore, the same treatment method as that of the pipeline is adopted.

[0122] Step 500: Correct the current bottom hole pressure according to the current dynamic liquid level change to correct the current steady-state node pressure equation.

[0123] In some embodiments of the present invention, see Figure 6 , step 302 comprises:

[0124] Step 3021: Generate a plurality of directed edges according to the production capacity equation, the wellbore, the valve, and the pipeline;

[0125] Step 3022: Generate a directed graph of the gathering and transportation system corresponding to the coalbed methane well according to the multiple directed edges;

[0126] Step 3023: Generate the current steady-state node pressure equation according to the current node pressure of each node in the directed graph.

[0127] In steps 3021 to 3023, the coalbed methane well production capacity equation, wellbore, oil nozzle, and ground gathering and transportation pipeline are regarded as elements (directed edges). The starting and ending points of the elements are nodes. There are pressure and temperature changes in the flow of coalbed methane in the elements. The topological structure composed of them can be represented by an association matrix. Based on the conservation of mass at each node (the node inflow mass flow is equal to the outflow mass flow) and the same pressure, the current steady-state node pressure equation with the node pressure as the solution variable is obtained.

[0128] In some embodiments of the present invention, see Figure 7 , a coalbed methane well production dynamic prediction method based on overall modeling, further comprising:

[0129] Step 600: topologically sorting the directed graph according to the order in which the coal seam gas flows through each node;

[0130] Step 700: Iteratively update the temperature change of each node in the directed graph after topological sorting until a preset condition is met;

[0131] The nodes of the node-component directed graph of the gathering and transportation system are sorted by the topological sorting algorithm (the sorting order represents the order in which the coalbed gas flows through each node), and the temperature distribution in the gathering and transportation system is obtained by calculating from the starting point to the end point in sequence in combination with the temperature change of each component in the system and the energy conservation of the node. The temperature of each node is updated through the temperature calculation results, and the physical properties such as the viscosity of the coalbed gas are updated until the temperature difference of each node between two adjacent iterations is less than a certain threshold (preset condition).

[0132] Step 800: Update the current coal seam pressure, current bottom hole pressure, current permeability, and current coal seam gas viscosity according to the current mass flow and the current temperature of each node.

[0133] From the above description, it can be seen that the embodiment of the present application provides a method for predicting the production dynamics of a coalbed methane well based on overall modeling, including: first, establishing an overall hydrothermal calculation model of the gathering and transportation system, calculating the production capacity equation based on the relevant parameters of the coalbed methane reservoir, treating the coalbed methane well production capacity equation, wellbore model, valve model, and ground pipeline network as a whole for hydrothermal simulation, and combining the temperature and pressure change characteristics during the flow process, at a fixed inlet pressure of the ground processing plant, calculating the gas production and water production of each wellhead; then combining the cumulative gas production and cumulative water production with the material balance method of the coalbed methane reservoir, updating the coalbed methane reservoir formation pressure, permeability, water saturation and other parameters, and obtaining the gas well production capacity equation at the next moment; finally, combining the hydrothermal calculation model of the gathering and transportation system again to calculate the gas production of each wellhead, repeating this process, and realizing the dynamic calculation of coalbed methane well production combined with the underground and ground.

[0134] Another invention, the method proposed in this application, is to calculate the amount of coalbed methane precipitation caused by condensate precipitation due to changes in temperature and pressure during the flow of coalbed methane by interpolating the saturated temperature and saturated pressure of water vapor, thereby reducing the time consumption of flash evaporation calculations; the calculation of the wellbore pressure drop is divided into the sum of the pressure drops of the flowing gas column and the static liquid column, thereby considering the impact of the dynamic liquid level change on the bottom hole pressure.

[0135] To further illustrate this solution, this application also provides a specific application example of a coalbed methane well production dynamic prediction method based on overall modeling, see Figure 8 , specifically including the following contents.

[0136] S1: Based on the coalbed methane reservoir and wellbore parameters, the gas and water production capacity equations of each coalbed methane well are established to obtain the relationship between the volume flow rate and the formation pressure and bottom hole flow pressure under standard conditions.

[0137] S2: Calculate the effect of the change in dynamic liquid level on the wellbore pressure drop.

[0138] S3: For the gas-liquid two-phase flow caused by condensate water in the pipeline flow of coalbed methane, calculate the hydraulic force during the flow process.

[0139] For the gas-liquid two-phase flow caused by condensate water in the flow of coalbed methane in pipelines, the simulation process can couple a variety of multiphase pressure drop calculation methods to perform hydraulic calculations during the flow process. Specifically:

[0140]

[0141] Where p is the average pressure (absolute) of the pipeline, Pa; l is the axial flow distance, m; ρ L is the liquid density, kg / m 3 ρ g is the gas phase density, kg / m 3 ;H l is the liquid holdup, m 3 / m 3 ; g is the acceleration due to gravity, m / s 2 ; θ is the angle between the pipe and the horizontal, (°); λ is the friction coefficient of two-phase flow, dimensionless; G is the mass flow rate of the mixture, kg / s; v is the average flow velocity of the mixture, m / s; v sg is the converted velocity of the gas phase, m / s; D is the diameter of the tube, m; A is the cross-sectional area of ​​the tube, m 2 .

[0142] For the coalbed methane flow process in the pipeline, the temperature change can be calculated based on the enthalpy change, using:

[0143]

[0144] In the above formula, Hi+1 ,H i are the enthalpy values ​​at the end and starting point of the pipeline, J / kg; w is the coal seam gas velocity, m / s; ΔZ is the elevation change from the end point of the pipeline minus the starting point, m; K is the total heat transfer coefficient of the pipeline, W / (m·K); D is the outer diameter of the pipeline, m; T0, T av are ground temperature and average temperature of pipeline, respectively, ℃; ΔL is pipeline length, m; G is mass flow rate of pipeline, kg / s.

[0145] For the gas-liquid mixture formed by the precipitation of condensate water in the flow of coalbed methane, its enthalpy value is: H = xH G +(1-x)H L , x is the mass fraction of the gas phase.

[0146] S4: For the flow of coalbed methane in the valve, whether it is in a critical state is modeled in two cases.

[0147] Non-critical flow hydraulic model of valve:

[0148] Valve critical flow hydraulic model:

[0149] In the above formula, G is the mass flow rate flowing through the valve, kg / s; C d is the valve flow coefficient, dimensionless; A2 is the flow area of ​​the valve element, m 2 ; P1 is the pressure before the valve, Pa; ρ1 is the density of coalbed methane before the valve, kg / m 3 ; k is the adiabatic index of coalbed methane; r is P2 / P1, which is the ratio of the pressure after flowing through the valve to the pressure before flowing through the valve. For the temperature change of coalbed methane flowing through the valve, use:

[0150] In the above formula, H i+1 ,H i are the enthalpy values ​​before and after flowing through the valve, J / kg; w is the coal seam gas velocity, m / s.

[0151] S5: Establish a steady-state equation group (steady-state node pressure equation).

[0152] The coalbed methane well productivity equation, wellbore, oil nozzle, and ground gathering and transportation pipeline are regarded as components (directed edges). The starting and ending points of the components are nodes. The topological structure composed of them can be represented by the association matrix A. Based on the conservation of mass at each node (the inflow mass flow of the node is equal to the outflow mass flow) and the same pressure, the steady-state equation group with the node pressure as the solution variable is obtained:

[0153]

[0154] In the above formula, W=(W1,W2,…,Wm ) T is the vector composed of the mass flow of each element; w=(w1,w2,…w n ) is the vector composed of the mass flow load of each node; A is the node-element association matrix; ΔP=(ΔP1,ΔP2,…,ΔP m ) is the pressure drop vector of each component; F(W) is the functional relationship between the pressure drop of each component and the flow rate, that is, the relationship between the pressure drop of each component and the flow rate.

[0155] S6: Obtain the current mass flow rate of the coalbed methane well.

[0156] Based on the conservation of mass and energy at each node, we can get: the sum of the mass flowing in and out is: The sum of the energy flowing in and out is

[0157] Among them, I i represents the set of all elements connected to node i; a ij is the element in the node-element association matrix A; H j is the enthalpy value of the element at this node, J / kg; W j is the mass flow rate of the element, kg / s; w i is the mass load at the node, kg / s; H i Represents the enthalpy of the mass load at the node, kg / s.

[0158] S7: Calculate the amount of condensate water released according to the saturated temperature and saturated pressure of water vapor during the flow of coalbed methane.

[0159] S8: Calculate the physical properties of coalbed methane based on the average temperature and pressure of each component.

[0160] Assuming the mass flow value of each component and the unknown hydrothermal parameters of each node (unknown node pressure, unknown mass load, and unknown temperature), the physical properties of coalbed methane are calculated based on the average temperature and pressure of each component.

[0161] The BWRS state equation is used to calculate the gas phase density, gas phase enthalpy, and specific heat capacity parameters of coalbed methane, and the correlation formula is used to calculate the gas viscosity and gas-liquid interfacial tension parameters. The mass of liquid condensate water precipitation is calculated using the step S7 method, and the enthalpy of liquid condensate water is calculated using the following formula:

[0162]

[0163] In the above formula, H L is the condensate water enthalpy, J / kg; c pL is the heat capacity of condensate water, J / (kg·K); dT is the temperature difference relative to the reference temperature, K; η Lis the coke coefficient of condensate water, K / Pa; ρ L is the density of condensate water, kg / m 3 ; dP is the pressure difference relative to the reference pressure, Pa.

[0164] S9: Solving the pressure equations for each node established in step S6.

[0165] First, the relationship between flow and pressure (pressure equations at each node) is linearized, that is, W i =η i ΔP i .

[0166]

[0167] In the above formula, η represents the linearization coefficient between the mass flow rate and the pressure difference of the element, 1 / (m·s); W = (W1, W2, …, W m ) T is the vector composed of the mass flow of each element; w=(w1,w2,…,w n ) is the vector composed of the mass flow load of each node; A is the node-element association matrix; ΔP=(ΔP1,ΔP2,…,ΔP m ) is the pressure drop vector of each component; S is the main diagonal matrix composed of the admittance of each component; m is the number of components in the coalbed methane gathering and transportation system, and n is the number of nodes in the coalbed methane gathering and transportation system.

[0168] S10: Iteratively calculate component voltage drop.

[0169] Under the assumption of mass flow rate, the pressure drop of the element is calculated, and the element η and matrix S are obtained by using the pressure drop and mass flow rate. T P = w can get the new node pressure vector P and the pressure drop vector ΔP of each component. Through W = SΔP, the new mass flow of each component can be obtained. According to the new mass flow, the pressure drop of the component is obtained again, and the calculation is iterated until the node pressure equation group converges, and the node pressure and component mass flow Q in two adjacent iterations are obtained. w The difference is less than a certain threshold.

[0170] S11: When the mass flow rate is obtained, the temperature of each component is calculated sequentially.

[0171] The specific method is as follows: sort the nodes of the node-element directed graph of the gathering and transportation system by a topological sorting algorithm (the sorting order represents the order in which the coalbed gas flows through each node), and calculate from the starting point to the end point in sequence in combination with the temperature change of each element in the system and the energy conservation of the node to obtain the temperature distribution in the gathering and transportation system. Based on the temperature calculation results, the temperature of each node is updated, and the physical properties such as the viscosity of the coalbed gas are updated. Therefore, steps S8 to S11 need to be repeated until the temperature difference of each node in two adjacent iterations is less than a certain threshold.

[0172] Check whether the flow at the valve is in a critical flow state, and whether the mass flow after convergence is greater than the maximum mass flow. If not, there is no need to correct the production of each well; if yes, the mass flow of this valve needs to be corrected. During the correction, the valve front and valve back need to be divided into two parts, which are regarded as two directed topological graphs, and the node steady-state equations are established and solved respectively. The pressure is constant in the valve front part, and the flow is constant in the valve back part. If the mass flow obtained under the constant pressure before the valve and the critical mass under the pressure before the valve are less than a certain threshold, then the mass flow is taken as the mass flow of the valve after convergence; this mass flow is used for the constant flow after the valve, and the temperature and pressure in the valve back element are calculated.

[0173] S12: Forecast the future production performance of coalbed methane wells on a daily basis.

[0174] Based on the mass flow rate after the convergence of each production capacity equation in the gathering and transportation system, calculate the gas production Q for the day g , calculate the water production on the day according to the bottom hole pressure, and get the cumulative gas production G p , cumulative water production W p .

[0175] Specifically, after obtaining the gas and water production of each single well, the gas production Q of the day is calculated in units of days. g 、Water production on the day Q w , and the cumulative gas production G p , cumulative water production W p .

[0176] S13: Based on coal seam parameters, cumulative gas production, cumulative water production, and the material balance equation of coalbed methane wells, the Newton-Ralph iteration method is used to calculate the average formation pressure at the next moment.

[0177] The calculation process is divided into above the critical desorption pressure and below the critical desorption pressure:

[0178] (1) The coal seam pressure p is higher than the critical desorption pressure p d :

[0179]

[0180] (2) The coal seam pressure p is lower than the critical desorption pressure p d :

[0181]

[0182] Among them, G p is the cumulative gas production, sm 3 ; A represents the effective area of ​​coal seam, m 2 ; h represents the thickness of the coal seam, m; Indicates the original porosity of the coal seam; S wi Indicates the original water saturation of the coal seam; p i is the original average pressure of the coal seam, MPa; Z i Indicates the compression factor under standard conditions, dimensionless; T sc is the standard temperature, 293.15K; p sc is the pressure under standard conditions, MPa; T is the coal seam temperature, K; C p is the pore compression coefficient of coal seam, MPa -1 ; C w Indicates the compressibility of formation water, MPa -1 ; p is the coal seam pressure, MPa; W p is the accumulated water production, m3 / d; B w is the volume coefficient of formation water, dimensionless; Z is the compression factor under the current coal seam pressure, dimensionless; V L It represents the Langmiur volume constant, i.e. the maximum volume of gas that can be adsorbed by a unit volume of coal sample, m 3 / m 3 ; b represents the Langmiur pressure constant, which is the inverse of the pressure corresponding to half of the maximum adsorbed gas volume, MPa -1 ;p d Represents the critical desorption pressure of coal seam, MPa.

[0183] S14: Update the coal seam permeability, porosity and water saturation according to the calculated coal seam pressure p.

[0184] Specifically, step S14 is implemented according to the following formula:

[0185]

[0186]

[0187] in, Respectively represent the current porosity and original porosity of the coal seam; C p is the pore compression coefficient of coal seam, MPa -1 ; K, K i Respectively represent the permeability of the coal seam under the current pressure and the permeability under the original formation pressure, mD; S w , S wiThey represent the water saturation of the coal seam at the current pressure and the water saturation at the original formation pressure respectively; C w Indicates the compressibility of formation water, MPa -1 ;p i , p represents the original average pressure and current average pressure of the coal seam, MPa; A represents the effective area of ​​the coal seam, m 2 ; h represents the thickness of the coal seam, m.

[0188] S15: Calculate the future production performance of coalbed methane wells in combination with the surface pipeline network.

[0189] Based on the updated coal seam parameters, the coal seam gas well production equation is re-established, and the gas and water production of each single well is calculated again in combination with the wellbore model, valve model, and ground pipe network to obtain the cumulative gas and water production, and the coal seam parameters at the next moment are obtained in combination with the material balance method. In this way, the cycle is repeated to achieve the dynamic calculation of coal seam gas well production combined with the ground.

[0190] Specifically, under the current average coal seam pressure p, a new capacity equation can be obtained based on step S1; the capacity equation, wellbore model, valve model, and ground pipeline network are used to establish a node steady-state equation with node pressure as the solution variable based on step S5; combined with the solution calculation method in steps S8 to S11, the mass flow rate after convergence of each capacity equation in the gathering and transportation system is calculated again to obtain the gas production Q for the day. g 、Water production on the day Q w Combined with step S12 to step S14, the current pressure, permeability and water saturation parameters of the coal seam are updated, thereby continuing to execute step S1. This process is executed cyclically to realize the future production dynamic calculation of the coalbed methane well combined with the ground pipeline network.

[0191] In order to more clearly illustrate the actual application effect of the coalbed methane well production dynamic prediction method based on overall modeling provided by the present invention, further explanation is given by taking parameters in actual work as an example. Fig. 9 Taking the surface gathering and transportation pipeline network with a structural form as an example, the gas quality composition of the produced coalbed methane is shown in Table 1, the pipeline parameters are shown in Table 2, the wellbore parameters are shown in Table 3, the valve diameter is 25 mm, the flow coefficient is 0.83, the coal seam parameters corresponding to each well are shown in Table 4, the gas-water relative permeability parameters are shown in Table 5, and the inlet pressure of the ground processing plant is 100 kPag. Assuming the initial dynamic liquid level is 100 m, it will drop linearly to 30 m within 300 days and remain unchanged.

[0192] refer to Fig.10As shown, based on the basic parameters of the coal seam, the coalbed methane well production capacity equation is established; the topological structure composed of the gas well production capacity equation, wellbore, valve, and ground pipeline components, based on the pressure and temperature change equations of each component and the pressure equality, energy conservation, and mass conservation at the node, the gas production and water production of each wellhead and the temperature change in the coalbed methane flow can be calculated when the coal seam pressure and the inlet pressure of the processing plant are known; the daily gas production and daily water production are obtained based on the gas production and water production of each well, and the cumulative gas production and cumulative water production are obtained, and combined with the coalbed methane well material balance equation, the formation pressure, permeability, porosity and other parameters at the next moment are calculated; after updating the coal seam parameters, the coalbed methane well production capacity equation is established again, and this process is repeated to realize the dynamic calculation of coalbed methane well production combined with the ground gathering and transportation pipeline network.

[0193] Fig.11 The simulation flow chart of the method for predicting the production dynamics of coalbed methane wells based on overall modeling is provided for the specific application example of this application. First, the basic parameters of coalbed methane reservoirs, wellbores, valves, pipelines, and the environment are obtained; secondly, the gas well production capacity equation is established according to the coalbed methane well parameters, and the steady-state node pressure equation and the node energy conservation equation are constructed for the gathering and transportation system composed of the production capacity equation, wellbores, valves, and pipelines, and the water and heat calculation of the gathering and transportation system is performed to obtain the production of each coalbed methane well; then, according to the gas production and water production of each well, the daily gas production and daily water production are obtained, and the cumulative gas production and cumulative water production are obtained; finally, according to the cumulative gas production and cumulative water production combined with the coalbed methane well material balance equation, the coalbed methane pressure, permeability and other parameters are updated, thereby updating the coalbed methane well production capacity equation again, and the gathering and transportation system water and heat calculation, production calculation, and bottom hole pressure calculation are performed to realize the dynamic calculation of coalbed methane well production combined with the ground gathering and transportation pipeline network.

[0194] refer to Fig.12 As shown, it is a flow chart of the overall water-thermal calculation of the gathering and transportation system mentioned in the present invention in combination with the production capacity equation, wellbore, valves, and ground pipelines.

[0195] Table 1 Gas quality composition of each well

[0196] Components C1 <![CDATA[CO2]]> <![CDATA[N2]]> <![CDATA[H2O]]> volume(%) 95.66 0.29 2.16 1.89

[0197] Table 2 Pipeline parameters

[0198]

[0199]

[0200] Table 3 Wellbore parameters

[0201]

[0202] Table 4 Coal seam parameters

[0203] Basic parameters of coal seams corresponding to each well W1 W2 W3 W4 W5 Original formation pressure (MPa) 2 3 2.5 2.5 3.5 Original formation permeability (mD) 300 200 180 140 200 Coal seam thickness (m) 10 10 10 10 10 Original formation porosity 0.01 0.01 0.03 0.03 0.01 <![CDATA[Langmiur pressure constant (MPa -1 )]]> 15 15 15 15 15 <![CDATA[Langmiur volume constant (m 3 / m 3 )]]> 0.22 0.22 0.22 0.22 0.22 <![CDATA[Effective area of coal seam (m 2 )]]> 90000 90000 90000 90000 90000 Critical analytical pressure (MPa) 1.8 2.2 2.0 2.0 3 Initial water saturation 0.95 0.95 0.95 0.95 0.95 Initial gas saturation 0.05 0.05 0.05 0.05 0.05 Skin Factor 0.1 0.1 0.1 0.1 0.1 Outer boundary radius of pressure relief area (m) 200 200 200 200 200 Coal seam temperature (℃) 50 50 50 50 50

[0204] Table 5 Gas-water relative permeability parameters

[0205]

[0206]

[0207] According to the above data, the coalbed methane well production dynamic prediction model and calculation method provided by the present invention are used to calculate the coalbed methane well production data on the 100th day. The specific data are shown in Table 6 below. The production dynamic calculation results of each coalbed methane well, bottom hole flow pressure, coal seam pressure, gas production, and water production data are shown in Fig.13 shown.

[0208] Table 6 Calculation results of production of each coalbed methane well on the 100th day

[0209] <![CDATA[Daily gas production (m 3 / d)]]> <![CDATA[Daily water production (m 3 / d)]]> Formation pressure (MPa) Bottom hole pressure (MPa) W1 2408.2 21.5 1.76 1.40 W2 5613.6 17.36 2.078 1.31 W3 432.5 28.26 1.96 1.59 W4 428.1 19.42 1.96 1.59 W5 11532.8 6.16 2.09 1.28

[0210] See also Fig.13 (Production dynamic results of each coalbed methane well in the next 800 days), the inlet pressure of the ground processing plant (CGPF) remains unchanged at 100kPag, and the future production dynamic changes of the five wells are shown in the figure. The production time and production situation of the gas production peak of each well are different. Since the gas-liquid two-phase flow formed by the precipitation of condensate water in the flow of coalbed methane is taken into account, the multi-phase pressure drop calculation method is used. Some calculation results fluctuate, but the overall situation is good, and the production dynamics of coalbed methane wells are calculated more accurately.

[0211] The above examples further illustrate that the method for calculating the production dynamics of coalbed methane wells combined with the ground gathering and transportation pipeline network provided by the present invention can calculate the changes in the future gas and water production of coalbed methane wells. By combining the material balance method of coalbed methane wells with the hydrothermal simulation of the gathering and transportation system through basic parameters such as coal seams, wellbores, pipelines, valves, etc., it is possible to perform more accurate production dynamic calculations on each coalbed methane well in combination with the entire gathering and transportation system. In practical applications, the future production dynamics of coalbed methane wells under different ground processing conditions and different coalbed methane well parameters can be calculated and analyzed.

[0212] Based on the same inventive concept, the embodiments of the present application also provide a coalbed methane well production dynamic prediction device based on overall modeling, which can be used to implement the method described in the above embodiments, such as the following embodiments. Since the principle of solving the problem by the coalbed methane well production dynamic prediction device based on overall modeling is similar to the coalbed methane well production dynamic prediction method based on overall modeling, the implementation of the coalbed methane well production dynamic prediction device based on overall modeling can refer to the implementation of the coalbed methane well production dynamic prediction method based on overall modeling, and the repeated parts will not be repeated. As used below, the term "unit" or "module" can be a combination of software and / or hardware that implements predetermined functions. Although the system described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0213] The embodiment of the present application provides a specific implementation of a coalbed methane well production dynamic prediction device based on overall modeling that can realize a coalbed methane well production dynamic prediction method based on overall modeling, see Fig.14 A coalbed methane well production dynamic prediction device based on overall modeling specifically includes the following contents:

[0214] The pressure acquisition module 10 is used to obtain the current coal seam pressure of the coal seam gas well and the current inlet pressure of the processing plant;

[0215] The production dynamics prediction module 20 is used to predict the production dynamics of the coalbed methane well based on the current coal seam pressure, the current processing plant inlet pressure and a pre-generated current production dynamics prediction model; wherein the current production dynamics prediction model is iteratively generated by the production capacity equation of the coalbed methane well in the production dynamics prediction model at the previous moment, and the production dynamics prediction model is used to characterize the pressure changes and temperature changes between the coalbed methane reservoir, wellbore, valve, pipeline and the processing plant in which the coalbed methane well is located.

[0216] In some embodiments of the present invention, see Fig.15 , a coalbed methane well production dynamic prediction device based on overall modeling, further comprising:

[0217] The prediction model generation module 30 is used to generate the current production dynamic prediction model; see Fig.16 , the prediction model generation module 30 includes:

[0218] The current production capacity equation generating unit 30a is used to generate the current production capacity equation corresponding to the current production dynamic prediction model according to the current coal seam pressure, the current bottom hole pressure, the current permeability, the current coal seam gas viscosity and the wellbore parameters;

[0219] A current pressure equation generating unit 30b is used to generate a current steady-state node pressure equation according to the current production capacity equation, the current node pressure of the coalbed methane reservoir, the current node pressure of the wellbore, the current node pressure of the valve, the current node pressure of the pipeline and the current node pressure of the processing plant;

[0220] A current pressure equation solving unit 30c, used to solve the current steady-state node pressure equation to obtain the current mass flow rate of the coalbed methane well;

[0221] The current parameter updating unit 30d is used to update the current coal seam pressure, the current bottom hole pressure, the current permeability, and the current coal seam gas viscosity according to the current mass flow rate.

[0222] In some embodiments of the present invention, see Fig.17 If condensate water is precipitated during the coalbed methane flow process, the prediction model generation module 30 further includes:

[0223] A coalbed methane precipitation calculation unit 30e, used to calculate the precipitation amount of condensate water according to the saturated temperature and saturated pressure of water vapor during the flow of the coalbed methane;

[0224] The current pressure equation correction unit 30f is used to correct the current steady-state node pressure equation according to the precipitation amount.

[0225] In some embodiments of the present invention, see Fig.18 , a coalbed methane well production dynamic prediction device based on overall modeling, further comprising:

[0226] A current dynamic liquid level calculation module 40, for calculating the current dynamic liquid level change in the wellbore according to the current flowing gas column and the current static liquid column of the wellbore;

[0227] The current node pressure equation correction module 50 is used to correct the current bottom hole pressure according to the current dynamic liquid level change, so as to correct the current steady-state node pressure equation.

[0228] In some embodiments of the present invention, see Fig.19 , the current pressure equation generating unit 30b includes:

[0229] A plurality of directed edge generating units 30b1, used for generating a plurality of directed edges according to the production capacity equation, the wellbore, the valve, and the pipeline;

[0230] A directed graph generating unit 30b2, used to generate a directed graph of a gathering and transportation system corresponding to the coalbed methane well according to a plurality of directed edges;

[0231] The current pressure equation generating subunit 30b3 is used to generate the current steady-state node pressure equation according to the current node pressure of each node in the directed graph.

[0232] In some embodiments of the present invention, see Fig. 20 , a coalbed methane well production dynamic prediction device based on overall modeling, further comprising:

[0233] A directed graph sorting module 60 is used to topologically sort the directed graph according to the order in which the coal seam gas flows through each node;

[0234] The temperature change iterative update module 70 is used to iteratively update the temperature change of each node in the directed graph after topological sorting until a preset condition is met;

[0235] The current parameter updating module 80 is used to update the current coal seam pressure, the current bottom hole pressure, the current permeability, and the current coal seam gas viscosity according to the current mass flow rate and the current temperature of each node.

[0236] The embodiment of the present application also provides a specific implementation of an electronic device capable of implementing all steps in the method for predicting the production dynamics of coalbed methane wells based on overall modeling in the above embodiment, see Fig.21 , electronic equipment specifically includes the following:

[0237] Processor (processor) 1201, memory (memory) 1202, communication interface (CommunicationsInterface) 1203 and bus 1204;

[0238] The processor 1201 , the memory 1202 , and the communication interface 1203 communicate with each other via the bus 1204 ; the communication interface 1203 is used to realize information transmission between relevant devices such as the server-side device, the power measurement device, and the user-side device.

[0239] The processor 1201 is used to call the computer program in the memory 1202. When the processor executes the computer program, all the steps in the method for predicting the production dynamics of coalbed methane wells based on overall modeling in the above embodiment are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0240] Step 100: Obtain the current coal seam pressure of the coal seam gas well and the current inlet pressure of the processing plant;

[0241] Step 200: Predict the production dynamics of the coalbed methane well based on the current coal seam pressure, the current processing plant inlet pressure and a pre-generated current production dynamics prediction model; wherein the current production dynamics prediction model is iteratively generated by the production capacity equation of the coalbed methane well in the production dynamics prediction model at the previous moment, and the production dynamics prediction model is used to characterize the pressure changes and temperature changes among the coalbed methane reservoir, wellbore, valve, pipeline and the processing plant in which the coalbed methane well is located.

[0242] The embodiment of the present application also provides a computer-readable storage medium capable of implementing all the steps in the method for predicting the production dynamics of coalbed methane wells based on overall modeling in the above embodiment. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, all the steps in the method for predicting the production dynamics of coalbed methane wells based on overall modeling in the above embodiment are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0243] Step 100: Obtain the current coal seam pressure of the coal seam gas well and the current inlet pressure of the processing plant;

[0244] Step 200: Predict the production dynamics of the coalbed methane well based on the current coal seam pressure, the current processing plant inlet pressure and a pre-generated current production dynamics prediction model; wherein the current production dynamics prediction model is iteratively generated by the production capacity equation of the coalbed methane well in the production dynamics prediction model at the previous moment, and the production dynamics prediction model is used to characterize the pressure changes and temperature changes among the coalbed methane reservoir, wellbore, valve, pipeline and the processing plant in which the coalbed methane well is located.

[0245] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0246] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0247] Although the present application provides method operation steps such as embodiments or flow charts, more or fewer operation steps may be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one way of executing the order of many steps and does not represent the only execution order. When the actual device or client product is executed, it can be executed in the order of the method shown in the embodiments or the drawings or in parallel (for example, in a parallel processor or multi-threaded processing environment).

[0248] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0249] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0250] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0251] Specific embodiments are used in this application to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core idea of ​​this application. At the same time, for those skilled in the art, according to the idea of ​​this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on this application.

Claims

1. A method for predicting the production dynamics of coalbed methane wells based on overall modeling, characterized in that: include: Obtain the current coal seam pressure of the coal seam gas well and the current inlet pressure of the processing plant; The production dynamics of the coalbed methane well is predicted based on the current coal seam pressure, the current processing plant inlet pressure and a pre-generated current production dynamics prediction model; wherein the current production dynamics prediction model is iteratively generated by the production capacity equation of the coalbed methane well in the production dynamics prediction model at the previous moment, and the production dynamics prediction model is used to characterize the pressure changes and temperature changes among the coalbed methane reservoir, wellbore, valves, pipelines and the processing plant in which the coalbed methane well is located.

2. The method for predicting the production dynamics of a coalbed methane well according to claim 1, characterized in that: The steps of generating the current production dynamic prediction model include: Generate a current production capacity equation corresponding to the current production dynamic prediction model according to the current coal seam pressure, the current bottom hole pressure, the current permeability, the current coal seam gas viscosity and the wellbore parameters; generating a current steady-state node pressure equation according to the current production capacity equation, the current node pressure of the coalbed methane reservoir, the current node pressure of the wellbore, the current node pressure of the valve, the current node pressure of the pipeline, and the current node pressure of the processing plant; Solving the current steady-state node pressure equation to obtain the current mass flow rate of the coalbed methane well; The current coal seam pressure, current bottom hole pressure, current permeability, and current coal seam gas viscosity are updated according to the current mass flow.

3. The method for predicting the production dynamics of a coalbed methane well according to claim 2, characterized in that: If condensate water is precipitated during the flow of coalbed methane, before solving the current steady-state node pressure equation to obtain the current mass flow rate of the coalbed methane well, the method further includes: Calculating the amount of condensate water released according to the saturated temperature and saturated pressure of water vapor during the flow of the coalbed methane; The current steady-state node pressure equation is modified according to the precipitation amount.

4. The method for predicting the production dynamics of a coalbed methane well according to claim 2, characterized in that: Also includes: Calculating a current dynamic liquid level change in the wellbore based on a current flowing gas column and a current static liquid column in the wellbore; The current bottom hole pressure is corrected according to the current dynamic liquid level change to correct the current steady-state node pressure equation.

5. The method for predicting the production dynamics of a coalbed methane well according to claim 2, characterized in that: The current steady-state node pressure equation is generated according to the current production capacity equation, the current node pressure of the coalbed methane reservoir, the current node pressure of the wellbore, the current node pressure of the valve, the current node pressure of the pipeline, and the current node pressure of the processing plant, including: Generate a plurality of directed edges according to the production capacity equation, the wellbore, the valve, and the pipeline; Generate a directed graph of the gathering and transportation system corresponding to the coalbed methane wells according to multiple directed edges; The current steady-state node pressure equation is generated according to the current node pressure of each node in the directed graph.

6. The method for predicting the production dynamics of a coalbed methane well according to claim 5, characterized in that: Also includes: Topologically sorting the directed graph according to the order in which coal seam gas flows through each node; Iteratively update the temperature changes of each node in the directed graph after topological sorting until the preset conditions are met; The current coal seam pressure, the current bottom hole pressure, the current permeability, and the current coal seam gas viscosity are updated according to the current mass flow and the current temperature of each node.

7. A coalbed methane well production dynamic prediction device based on overall modeling, characterized in that: include: A pressure acquisition module, used to obtain the current coal seam pressure of the coal seam gas well and the current inlet pressure of the processing plant; A production dynamics prediction module is used to predict the production dynamics of the coalbed methane well based on the current coal seam pressure, the current processing plant inlet pressure and a pre-generated current production dynamics prediction model; wherein the current production dynamics prediction model is iteratively generated by the production capacity equation of the coalbed methane well in the production dynamics prediction model at the previous moment, and the production dynamics prediction model is used to characterize the pressure changes and temperature changes among the coalbed methane reservoir, wellbore, valve, pipeline and the processing plant in which the coalbed methane well is located.

8. The coalbed methane well production dynamic prediction device according to claim 7, characterized in that: Also includes: A prediction model generation module, used to generate the current production dynamic prediction model; The prediction model generation module includes: A current production capacity equation generating unit, used to generate a current production capacity equation corresponding to the current production dynamic prediction model according to the current coal seam pressure, the current bottom hole pressure, the current permeability, the current coal seam gas viscosity and the wellbore parameters; A current pressure equation generating unit, used for generating a current steady-state node pressure equation according to the current production capacity equation, the current node pressure of the coalbed methane reservoir, the current node pressure of the wellbore, the current node pressure of the valve, the current node pressure of the pipeline and the current node pressure of the processing plant; A current pressure equation solving unit, used for solving the current steady-state node pressure equation to obtain the current mass flow of the coalbed methane well; The current parameter updating unit is used to update the current coal seam pressure, the current bottom hole pressure, the current permeability, and the current coal seam gas viscosity according to the current mass flow rate.

9. The coalbed methane well production dynamic prediction device according to claim 8, characterized in that: If condensate water is precipitated during the flow of coalbed methane, before solving the current steady-state node pressure equation to obtain the current mass flow rate of the coalbed methane well, the method further includes: A coalbed methane precipitation calculation unit, used to calculate the precipitation amount of condensate water according to the saturated temperature and saturated pressure of water vapor during the flow of the coalbed methane; The current pressure equation correction unit is used to correct the current steady-state node pressure equation according to the precipitation amount.

10. The coalbed methane well production dynamic prediction device according to claim 8, characterized in that: Also includes: A current dynamic liquid level calculation module, used to calculate the current dynamic liquid level change in the wellbore according to the current flowing gas column and the current static liquid column of the wellbore; The current node pressure equation correction module is used to correct the current bottom hole pressure according to the current dynamic liquid level change to correct the current steady-state node pressure equation.

11. The coalbed methane well production dynamic prediction device according to claim 8, characterized in that: The current pressure equation generating unit comprises: A plurality of directed edge generating units, used for generating a plurality of directed edges according to the production capacity equation, the wellbore, the valve, and the pipeline; A directed graph generating unit, used for generating a directed graph of a gathering and transportation system corresponding to a coalbed methane well according to a plurality of directed edges; The current pressure equation generating subunit is used to generate the current steady-state node pressure equation according to the current node pressure of each node in the directed graph.

12. The coalbed methane well production dynamic prediction device according to claim 11, characterized in that: Also includes: A directed graph sorting module, used for topologically sorting the directed graph according to the order in which coal seam gas flows through each node; The temperature change iterative update module is used to iteratively update the temperature change of each node in the directed graph after topological sorting until the preset conditions are met; The current parameter updating module is used to update the current coal seam pressure, the current bottom hole pressure, the current permeability, and the current coal seam gas viscosity according to the current mass flow and the current temperature of each node.

13. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method for predicting the production dynamics of a coalbed methane well based on overall modeling as described in any one of claims 1 to 6 are implemented.

14. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the method for dynamic prediction of coalbed methane well production based on overall modeling as described in any one of claims 1 to 6 are implemented.

15. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for predicting the production dynamics of a coalbed methane well based on overall modeling as described in any one of claims 1 to 6 are implemented.

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