Quantitative evaluation method for adsorbed gas and free gas dynamic production of deep coalbed methane

Abstract

The application provides a deep coalbed methane adsorbed gas and free gas dynamic output quantitative evaluation method, which firstly obtains the gas released by the coalbed core sample in the experimental process and the corresponding core experiment data, thereby providing a basic data source for subsequent evaluation which is consistent with the actual reservoir characteristics of the deep coalbed. Then, the gas is subjected to isotope value testing to obtain a first methane carbon isotope value, which accurately reflects the fractionation characteristics of the methane gas in the matrix pores and fractures. The first gas pressure and the first core temperature of the coalbed methane in the matrix pores are calculated, and the second gas pressure and the second core temperature of the coalbed methane in the fractures are calculated, thereby realizing accurate characterization of the temperature and pressure field in the reservoir. Finally, the gas state equation and the isothermal adsorption equation are used to calculate the gas amount of the coalbed methane adsorbed gas and free gas, and the multi-source fitting of the simulation experiment data and the preset control equation calculation data is performed, thereby greatly improving the accuracy of the quantitative evaluation of the coalbed methane adsorbed gas and free gas output.

Description

Technical Field

[0001] This application relates to the field of coalbed methane development technology, and in particular to a method for quantitatively evaluating the dynamic production of adsorbed gas and free gas in deep coalbed methane. Background Technology

[0002] Deep coalbed methane is an unconventional natural gas resource found in coal and rock reservoirs, and its development faces challenges such as high pressure, high temperature, and complex pore structure. In deep coal and rock reservoirs, methane gas exists in both adsorbed and free forms.

[0003] In related technologies, it is difficult to achieve real-time monitoring of the entire life cycle of coalbed methane development, resulting in insufficient dynamic characterization of gas pressure evolution and gas isotope fractionation phenomena in coalbed methane in fractures and matrix pores, leading to inaccurate assessment of the amount of adsorbed and free gas in coalbed methane.

[0004] Therefore, improving the accuracy of assessing the amount of adsorbed and free gas in coalbed methane has become an urgent technical problem to be solved. Summary of the Invention

[0005] This application provides a method for quantitatively evaluating the dynamic production of adsorbed gas and free gas in deep coalbed methane, in order to solve the problem of low accuracy in the quantitative evaluation of the dynamic production of adsorbed gas and free gas in deep coalbed methane in related technologies.

[0006] In a first aspect, embodiments of this application provide a method for quantitatively evaluating the dynamic production of adsorbed gas and free gas in deep coalbed methane, including:

[0007] The experiment aimed to obtain the gases released during the experiment from coal seam core samples and the corresponding core experimental data; the core experimental data included the first gas data; the core samples contained matrix pores and fractures;

[0008] The first carbon isotope value of methane was obtained by performing isotope analysis on the gas.

[0009] The first gas data, methane gas molecular mass, ideal gas constant, and first methane carbon isotope value are input into the preset control equation. Combined with the preset geometric model, preset initial conditions, and preset boundary conditions, the first gas pressure and first core temperature of coalbed methane in the matrix pores are calculated, and the second gas pressure and second core temperature of coalbed methane in the fractures are also calculated.

[0010] The first gas pressure, the first core temperature, the second gas pressure, and the second core temperature are input into the gas state equation and the isothermal adsorption equation for calculation, and the second gas data and the second methane carbon isotope value corresponding to the coalbed methane are obtained.

[0011] Based on the first gas data, the second gas data, the first methane carbon isotope value, and the second methane carbon isotope value, the preset control equations are solved to obtain the amount of adsorbed gas and free gas in the coalbed methane.

[0012] In one possible implementation, a preset control equation is solved based on first gas data and second gas data, first methane carbon isotope value and second methane carbon isotope value to obtain the amounts of adsorbed gas and free gas in the coalbed methane, including:

[0013] When fitting the first gas data and the second gas data, and simultaneously fitting the first methane carbon isotope value and the second methane carbon isotope value, the target parameters of the preset control equation are determined.

[0014] The target parameters are input into the preset control equations for calculation to obtain the pressure field distribution data of coalbed methane.

[0015] Based on the pressure field distribution data, the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane were determined.

[0016] The gas production rate ratio of adsorbed gas and the proportion of adsorbed gas in the cumulative desorbed coalbed methane are used to solve the gas volume calculation equations for adsorbed gas and free gas, thereby determining the gas volume of adsorbed gas and free gas.

[0017] In one possible implementation, the gas released from the coal seam core sample during the experiment and the corresponding core experimental data are obtained, including:

[0018] Obtain coal seam core samples;

[0019] Methane was injected into coal seam core samples according to preset experimental parameters for pressurization and saturation treatment, and core experimental data were collected during the pressurization and saturation treatment process.

[0020] Methane after pressurized saturation treatment is subjected to depletion development, and the gas produced during the depletion development process is collected.

[0021] In one possible implementation, the core experimental data further includes the initial porosity of the matrix pores, the initial average pore diameter of the matrix pores, the initial effective stress of the matrix pores, and the gas confining pressure; the first gas data, methane gas molecular mass, ideal gas constant, and first methane carbon isotope value are input into a preset governing equation, and combined with a preset geometric model, preset initial conditions, and preset boundary conditions, the first gas pressure and first core temperature of the coalbed methane in the matrix pores are calculated, and the second gas pressure and second core temperature of the coalbed methane in the fractures are also calculated, including:

[0022] Based on the first gas data, the molecular mass of methane gas, and the ideal gas constant, the gas viscosity in the matrix pores and fractures was determined, respectively.

[0023] Based on the gas confining pressure, the stress equations for matrix pores and cracks are solved to obtain the effective stresses of matrix pores and cracks.

[0024] The effective porosity of the matrix pores is determined based on the initial porosity of the matrix pores, the initial average pore diameter of the matrix pores, and the initial effective stress of the matrix pores.

[0025] The gas viscosity in the matrix pores and fractures, the effective stress in the matrix pores and fractures, and the effective porosity of the matrix pores are input into the preset control equations. Combined with the preset geometric model, preset initial conditions and preset boundary conditions, the first gas pressure and the first core temperature of coalbed methane in the matrix pores are calculated, and the second gas pressure and the second core temperature of coalbed methane in the fractures are also calculated.

[0026] In one possible implementation, the core experimental data also includes the core radius and core height; the preset geometric model is obtained by inputting the core radius and core height into the simulation software.

[0027] In one possible implementation, the core test data also includes the initial gas pressure and the carbon isotope atomic ratio of the standard sample; the preset initial conditions are determined based on the initial gas pressure, the first methane carbon isotope value, and the carbon isotope atomic ratio of the standard sample.

[0028] In one possible implementation, the core experimental data also includes atmospheric pressure; the preset boundary conditions are determined based on atmospheric pressure, the first methane carbon isotope value, and the carbon isotope atomic ratio of the standard sample.

[0029] Secondly, embodiments of this application provide a device for quantitatively evaluating the dynamic production of adsorbed gas and free gas in deep coalbed methane, comprising:

[0030] The acquisition module is used to acquire the gases released by the coal seam core sample during the experiment and the corresponding core experimental data; the core experimental data includes the first gas data; the core has matrix pores and fractures;

[0031] The processing module is used to perform isotope value testing on the gas to obtain the first methane carbon isotope value;

[0032] The calculation module is used to input the first gas data, methane gas molecular mass, ideal gas constant, and first methane carbon isotope value into the preset control equation, and combine the preset geometric model, preset initial conditions and preset boundary conditions to calculate the first gas pressure and first core temperature of coalbed methane in the matrix pores, and to calculate the second gas pressure and second core temperature of coalbed methane in the fractures.

[0033] The calculation module is also used to input the first gas pressure, the first core temperature, the second gas pressure, and the second core temperature into the gas state equation and the isothermal adsorption equation for calculation, so as to obtain the second gas data and the second methane carbon isotope value corresponding to the coalbed methane.

[0034] The calculation module is also used to solve the preset control equations based on the first gas data and the second gas data, the first methane carbon isotope value and the second methane carbon isotope value, to obtain the amount of adsorbed gas and free gas in the coalbed methane.

[0035] In one possible implementation, the computing module is specifically used for:

[0036] When fitting the first gas data and the second gas data, and simultaneously fitting the first methane carbon isotope value and the second methane carbon isotope value, the target parameters of the preset control equation are determined.

[0037] The target parameters are input into the preset control equations for calculation to obtain the pressure field distribution data of coalbed methane.

[0038] Based on the pressure field distribution data, the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane were determined.

[0039] The gas production rate ratio of adsorbed gas and the proportion of adsorbed gas in the cumulative desorbed coalbed methane are used to solve the gas volume calculation equations for adsorbed gas and free gas, thereby determining the gas volume of adsorbed gas and free gas.

[0040] In one possible implementation, the acquisition module is used for:

[0041] Obtain coal seam core samples;

[0042] Methane was injected into coal seam core samples according to preset experimental parameters for pressurization and saturation treatment, and core experimental data were collected during the pressurization and saturation treatment process.

[0043] Methane after pressurized saturation treatment is subjected to depletion development, and the gas produced during the depletion development process is collected.

[0044] In one possible implementation, the core experimental data also includes initial matrix porosity, initial average matrix pore diameter, initial effective matrix stress, and confining gas pressure; the calculation module is specifically used for:

[0045] Based on the first gas data, the molecular mass of methane gas, and the ideal gas constant, the gas viscosity in the matrix pores and fractures was determined, respectively.

[0046] Based on the gas confining pressure, the stress equations for matrix pores and cracks are solved to obtain the effective stresses of matrix pores and cracks.

[0047] The effective porosity of the matrix pores is determined based on the initial porosity of the matrix pores, the initial average pore diameter of the matrix pores, and the initial effective stress of the matrix pores.

[0048] The gas viscosity in the matrix pores and fractures, the effective stress in the matrix pores and fractures, and the effective porosity of the matrix pores are input into the preset control equations. Combined with the preset geometric model, preset initial conditions and preset boundary conditions, the first gas pressure and the first core temperature of coalbed methane in the matrix pores are calculated, and the second gas pressure and the second core temperature of coalbed methane in the fractures are also calculated.

[0049] In one possible implementation, the core experimental data also includes the core radius and core height; the preset geometric model is obtained by inputting the core radius and core height into the simulation software.

[0050] In one possible implementation, the core test data also includes the initial gas pressure and the carbon isotope atomic ratio of the standard sample; the preset initial conditions are determined based on the initial gas pressure, the first methane carbon isotope value, and the carbon isotope atomic ratio of the standard sample.

[0051] In one possible implementation, the core experimental data also includes atmospheric pressure; the preset boundary conditions are determined based on atmospheric pressure, the first methane carbon isotope value, and the carbon isotope atomic ratio of the standard sample.

[0052] Thirdly, embodiments of this application provide an electronic device, including: a processor, and a memory communicatively connected to the processor;

[0053] The memory stores the instructions that the computer executes;

[0054] The processor executes computer-executable instructions stored in memory to implement the method as described in the first aspect or any of the above.

[0055] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the method described in the first aspect or any of the above-mentioned methods.

[0056] Fifthly, embodiments of this application provide a computer program. The computer program product includes a computer program stored in a computer-readable storage medium. At least one processor can read the computer program from the computer-readable storage medium. When the at least one processor executes the computer program, it can implement the methods described in the first aspect or any of the above-mentioned methods.

[0057] The method for quantitatively evaluating the dynamic production of adsorbed and free gases in deep coalbed methane provided in this application first acquires the gases released from coalbed core samples during the experiment and the corresponding core experimental data, providing a fundamental data source that fits the actual reservoir characteristics of deep coalbeds for subsequent evaluation, avoiding the problem of theoretical assumptions being out of touch with field conditions. Then, isotope values ​​are measured on the gases to obtain the first methane carbon isotope value, accurately reflecting the fractionation characteristics of methane gas in matrix pores and fractures, providing a key isotope identifier for distinguishing between adsorbed and free gases. Next, the first gas data, methane gas molecular mass, ideal gas constant, and first methane carbon isotope value are input into a preset control equation. Combined with a preset geometric model, preset initial conditions, and preset boundary conditions, the first gas pressure and first core temperature of coalbed methane in matrix pores are calculated, as well as the second gas pressure and second core temperature of coalbed methane in fractures. This achieves accurate characterization of the temperature and pressure field within a dual-medium reservoir, overcoming the deficiency of traditional models in distinguishing the temperature and pressure differences between matrix pores and fractures. Finally, the first gas pressure, first core temperature, second gas pressure, and second core temperature are input into the gas state equation and isothermal adsorption equation for calculation, obtaining the second gas data and second methane carbon isotope value corresponding to the coalbed methane. Then, based on the first gas data, the second gas data, the first methane carbon isotope value, and the second methane carbon isotope value, the preset control equation is solved to obtain the amount of adsorbed gas and free gas in the coalbed methane. Through multi-source fitting of simulation experimental data and calculation data from the preset control equation, the accuracy of coalbed methane volume assessment is greatly improved, and the precise quantification of adsorbed gas and free gas is achieved, providing reliable data support for the formulation of deep coalbed methane development plans. Attached Figure Description

[0058] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0059] Figure 1 A flowchart illustrating the quantitative evaluation method for the dynamic production of adsorbed and free gas in deep coalbed methane provided in this application embodiment. Figure 1 ;

[0060] Figure 2 This is a schematic diagram of a preset geometric model provided in an embodiment of this application;

[0061] Figure 3 A schematic diagram of coalbed methane volume assessed by the material balance method in an embodiment of this application;

[0062] Figure 4 A flowchart illustrating the quantitative evaluation method for the dynamic production of adsorbed and free gas in deep coalbed methane provided in this application embodiment. Figure 2 ;

[0063] Figure 5 A schematic diagram of a coal seam sample provided in Embodiment 1 of this application;

[0064] Figure 6 A schematic diagram showing the cumulative desorbed gas volume, gas production rate, core inlet and outlet pressure, and methane carbon isotope variation over time in the simulation experiment provided in Example 1 of this application.

[0065] Figure 7 This is a schematic diagram showing the fitting of the cumulative desorbed gas volume, gas production rate, inlet pressure, and methane carbon isotope value calculated by the preset control equation with the measured data in the simulation experiment, as provided in Embodiment 1 of this application.

[0066] Figure 8 A schematic diagram showing the results of evaluating coalbed methane volume using the material balance method provided in Embodiment 1 of this application;

[0067] Figure 9 A schematic diagram comparing the gas volume assessment results of the preset control equation and the material balance method provided in Embodiment 1 of this application;

[0068] Figure 10 A schematic diagram showing the fitting of cumulative desorbed gas volume, gas production rate, inlet pressure, and methane carbon isotope value calculated by a preset control equation with field data for Embodiment 2 of this application;

[0069] Figure 11 A schematic diagram showing the results of evaluating coalbed methane volume using the material balance method provided in Embodiment 2 of this application;

[0070] Figure 12 A schematic diagram comparing the gas volume assessment results of the preset control equation and the material balance method provided in Embodiment 2 of this application;

[0071] Figure 13 A schematic diagram of the structure of the quantitative evaluation device for dynamic production of adsorbed gas and free gas in deep coalbed methane provided in the embodiments of this application;

[0072] Figure 14 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0073] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0074] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0075] Before introducing the embodiments of this application, the application background of the embodiments of this application will be explained first:

[0076] Deep coalbed methane (DBM) is an unconventional natural gas resource found in coal-bearing reservoirs, and its development faces challenges such as high pressure, high temperature, and complex pore structures. In deep coal-bearing reservoirs, methane gas coexists in both adsorbed and free states. Due to significant differences in the desorption, diffusion, and flow mechanisms of adsorbed and free gas, their dynamic production ratio during development directly affects the well's production curve, development efficiency, and subsequent fracturing design optimization. For example, in deep coal-bearing reservoirs, the coupling effect between fracture or cleavage systems and matrix pores leads to complex evolutions in pressure fields and isotope fractionation, and current technologies struggle to monitor this dynamic process in real-time and continuously. Furthermore, the development cycle of deep coal-bearing reservoirs is long (typically exceeding 20 years), necessitating dynamic assessment of the adsorbed to free gas production ratio throughout its entire lifecycle to guide production strategy adjustments and reservoir stimulation measures.

[0077] However, a method combining physical experiments and multi-scale, multi-mechanism models is currently lacking that can simultaneously characterize pressure evolution and isotope fractionation effects in the dual media of fractures or cleavage-matrix pores, and predict the ratio of adsorbed gas to free gas in future production stages. Therefore, developing a dynamic quantitative evaluation method for coalbed methane based on physical experiments and isotope fractionation models throughout the entire life cycle of deep coalbed methane is of great significance for improving the development efficiency, reducing development costs, and optimizing reservoir management.

[0078] In related technologies, the mass balance method calculates the free gas content using the mass balance equation of a constant-volume gas reservoir, and then obtains the adsorbed gas content by subtracting the free gas content from the measured total gas production. This method relies on the calculation of the apparent mean pressure of the core, but its assumptions differ significantly from the actual geological conditions of deep coal-fired reservoirs, leading to large deviations in the calculation results. Furthermore, this method cannot predict the dynamic adsorbed / free gas production ratio in future production stages and is only suitable for posterior analysis of historical data.

[0079] Nuclear magnetic resonance (NMR) method involves placing a depletion development device within an NMR instrument, using a gas mass flow meter to record the gas production in real time, and then using a T2 relaxation time spectrum to distinguish between adsorbed and free gas. This method relies on experimental equipment, making continuous on-site monitoring difficult. Furthermore, the setting of the T2 cutoff value lacks industry standards and depends on subjective judgment, leading to significant uncertainty in the calculated adsorbed / free gas quantities.

[0080] Existing isotope fractionation models are mainly based on bidispersed pore structures, solving for the ratio of adsorbed gas to free gas by fitting historical parameters. However, the actual structure of deep coal and rock reservoirs contains a dual medium of fractures or cleavages and matrix pores. Existing models do not consider the coupling effect between the two, resulting in insufficient characterization of methane carbon isotope fractionation in fractures or cleavages, thus limiting the applicability of the models.

[0081] In summary, improving the accuracy of assessing the volume of adsorbed and free gas in coalbed methane has become an urgent technical problem to be solved.

[0082] To address the technical problems existing in related technologies, the inventors of this application have the following concept: Regarding the issue of low accuracy in assessing the amount of adsorbed and free gas in coalbed methane, firstly, coal seam core samples with matrix pores and fractures are obtained. The samples are pressurized according to preset parameters, and experimental data on the released gas and core samples are collected. Simultaneously, the first methane carbon isotope value of the gas is measured to provide real experimental data support for subsequent modeling. Then, a geometric model is constructed based on the core dimensions. Initial and boundary conditions of the model are set by combining the initial gas pressure, standard carbon isotope atomic ratio, and atmospheric pressure. Simultaneously, the gas viscosity in the matrix pores and fractures is calculated using the first gas data and methane molecular mass. The effective stress is solved through gas confining pressure, and the effective porosity is determined by combining the initial matrix pore parameters. These parameters are input into preset control equations to calculate the gas pressure and core temperature within the matrix pores and fractures. Finally, the second gas data and the second methane carbon isotope value are solved by the gas state equation. The experimental and calculated data are fitted to determine the target parameters of the control equation, and then the pressure field distribution data are obtained. The proportion of adsorbed gas production rate and the proportion of cumulative adsorbed gas are calculated. Finally, the gas volume calculation equation is used to achieve accurate separation of adsorbed gas and free gas volume, thereby improving the accuracy and reliability of the quantitative evaluation of the dynamic production of adsorbed gas and free gas in the overall coalbed methane.

[0083] The parts not described in detail are disclosed in the following embodiments.

[0084] The technical solution of this application will now be described in detail through specific embodiments. It should be noted that the following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0085] Figure 1A flowchart illustrating the quantitative evaluation method for the dynamic production of adsorbed and free gas in deep coalbed methane provided in this application embodiment. Figure 1 ,like Figure 1 As shown, the method may include the following steps:

[0086] Step 11: Obtain the gas released by the coal seam core sample during the experiment and the corresponding core experimental data.

[0087] The core experimental data includes first gas data; the core contains matrix pores and fractures.

[0088] Specifically, step 11 can include the following implementation methods:

[0089] Step 1: Obtain coal seam core samples.

[0090] Under this method, coal seam core samples are drilled using wire cutting technology. Areas with gaps or unevenness are filled with adhesive and polished. The samples are then placed in a drying oven to remove moisture and finally fitted with a thermoplastic sleeve to prevent the core from breaking during subsequent pressurization.

[0091] Step 2: Inject methane into the coal seam core sample according to the preset experimental parameters for pressurization and saturation treatment, and collect the core experimental data during the pressurization and saturation treatment process.

[0092] In this implementation, the experimental apparatus is first assembled. The six-way valve, intermediate container, core holder, hand pump, and other experimental components are connected via pipelines. The pressure acquisition system is debugged, and the inlet and outlet pressures and confining pressures of the core holder are monitored. A dummy core (i.e., a metal block of the same shape and size as the coal seam core sample) is installed into the holder, and helium is introduced to pressurize it to the experimental set pressure. The inlet and outlet pressures and confining pressures are monitored for 24 hours. If the pressure curve shows an upward and downward fluctuation trend without decreasing, it indicates good airtightness. Then, the coal seam core sample is installed into the holder, and confining pressure is applied using the hand pump. Methane is introduced into the intermediate container for saturation. During pressurization, the confining pressure is always maintained above the pore pressure by 8 MPa. After reaching the experimental set saturation pressure, constant pressure saturation with methane is continued in the intermediate container for 7 to 10 days until the inlet and outlet pressures of the core holder show an upward and downward fluctuation trend without decreasing, indicating that the core adsorption has reached equilibrium. The gas generated during the pressurization process is collected, and the core experimental data during pressurization are obtained.

[0093] Step 3: Perform depletion development on the pressurized saturated methane and collect the gas produced during the depletion development process.

[0094] Under this implementation, the methane after pressurized saturation treatment is depleted and developed, and the coalbed methane generated at different times during the depletion and development experiment is collected by the water displacement gas collection method.

[0095] Step 12: Perform isotope value testing on the gas to obtain the first methane carbon isotope value.

[0096] In this step, the collected gas samples are sent to professional testing equipment, and the methane carbon isotope values ​​of the gas are detected according to the industry standard testing procedures. The first methane carbon isotope value corresponding to each time period is accurately obtained. This value can reflect the fractionation characteristics of methane in matrix pores and fractures, and is the core basis for subsequent construction of isotope fractionation model (i.e., preset control equation) and differentiation of adsorbed gas and free gas in coalbed methane.

[0097] Step 13: Input the first gas data, methane gas molecular mass, ideal gas constant, and first methane carbon isotope value into the preset control equation. Combine the preset geometric model, preset initial conditions, and preset boundary conditions to calculate the first gas pressure and first core temperature of coalbed methane in the matrix pores, and calculate the second gas pressure and second core temperature of coalbed methane in the fractures.

[0098] In this step, a preset geometric model matching the actual size of the core is first constructed based on parameters such as core radius and height. The initial conditions of the model are determined by combining the initial gas pressure and the atomic ratio of carbon isotopes in the standard sample. The boundary conditions of the model are set according to atmospheric pressure. Then, the first gas data obtained in step 11, the known molecular mass of methane gas, the ideal gas constant, and the first carbon isotope value of methane obtained in step 12 are uniformly input into the preset multi-scale, multi-mechanism, and multi-field coupled isotope fractionation control equation set (i.e., the preset control equation). The equation set is solved by numerical simulation software, and finally the first gas pressure and the first core temperature of coalbed methane in the matrix pores, as well as the second gas pressure and the second core temperature in the fractures, are calculated, so as to achieve accurate characterization of the internal temperature and pressure field of the reservoir.

[0099] For example, the predefined governing equations are a methane carbon isotope fractionation model that considers multi-scale (including cracks and matrix pores), multi-mechanism (including viscous flow and Knudsen diffusion and surface diffusion), and multi-field (including seepage field and temperature field) coupling.

[0100] In this step, the pre-defined governing equations can be expressed by the following formula:

[0101]

[0102] In the formula, B1(P,T), B2(P,T), C1(P,T), and C2(P,T) can be represented by the following formulas:

[0103]

[0104] P in the above two formulas m and These represent the matrix pores.12 CH4 (also known as free gas in coalbed methane) 13 The gas pressure of CH4 (also known as the adsorbed gas in coalbed methane); P f and They represent the cracks respectively 12 CH4 13 The gas pressure of CH4, P m , P f and The first gas pressure is K; T is the first core temperature; k is K. m_stress (P,T) and These represent the matrix pores under the influence of effective stress and temperature, respectively. 12 CH4 13 CH4 penetration rate; k f_stress (P,T) and These represent the effects of effective stress and temperature on cracks, respectively. 12 CH4 13 CH4 penetration rate ; As a shape factor, when characterizing cracks (N is the number of crack groups, and L is the crack spacing in the cubic matrix); μ m (P,T) and μ f (P,T) represent the methane viscosity in the matrix pores and fractures, respectively; and Matrix porosity and fracture porosity, respectively; r m_eff r is the effective pore size of the matrix pores. m0 ρ is the initial average pore size of the matrix; c is the mass balance ratio parameter, c = ρ rock V L Z m RT / V std (ρ) rock Density of rock; V L Z represents the volume of Langmuir; m V is the gas compressibility factor in the matrix pores; R is the universal gas constant, with units of 8.3145 J / mol / K; std (where T is the molar volume of the gas under standard conditions, in units of 22.4 L / mol); K(T) and They represent 12 CH4 and 13 Langmuir constant of CH4 at different temperatures Where A = 95.17 K 2 (B=0.125 K); k T c is the thermal conductivity of the rock. T This is the specific heat capacity of the rock.

[0105] The Langmuir constant of the free gas at different temperatures can be calculated using the following formula:

[0106]

[0107] In the formula, P L (T) represents the Langmuir pressure of methane gas in the matrix pores, P L_0 ΔS is the initial Langmuir pressure of methane in the matrix pores, ΔS is the standard molar integral entropy at saturation, and ΔH is the differential adsorption enthalpy (equal to the negative of the adsorption heat).

[0108] Specifically, step 13 may include the following implementation methods:

[0109] Step 1: Determine the gas viscosity in the matrix pores and fractures based on the first gas data, methane gas molecular mass, and ideal gas constant.

[0110] Under this implementation, the first gas data is retrieved, and combined with the known molecular mass of methane gas and the ideal gas constant, and referring to the correlation formula between the viscosity of real gas and temperature and pressure, the temperature and pressure conditions corresponding to the matrix pores and the cracks are substituted respectively to calculate the viscosity of methane gas in the matrix pores and the viscosity of methane gas in the cracks.

[0111] The first gas data includes the core inlet and outlet pressures and the core temperature.

[0112] Among them, the gas viscosity calculation needs to take into account the real gas effect. By using the temperature and pressure correction formula for methane viscosity, the error caused by the ideal gas assumption is eliminated, and the gas viscosity parameters of matrix pores and fractures are matched with the actual reservoir environment of deep coal seams.

[0113] The viscosity of methane gas in the matrix pores and fractures can be expressed by the following formula:

[0114]

[0115] In the formula, The viscosity of methane gas in the matrix pores, The viscosity of methane gas in the crack. The density of methane gas in the matrix pores, The density of methane gas in the crack can be calculated using the following formula:

[0116]

[0117] In the formula: M is the molecular mass of methane gas; R is the ideal gas constant, 8.314 J∙mol⁻¹∙K⁻¹; T is the temperature, Z m Z is the compressibility factor of methane gas in the matrix pores. fLet be the compressibility factor of methane gas in the crack. The compressibility factor of methane gas can be expressed by the following formula:

[0118]

[0119] In the formula: a T to g T The function is related to temperature, as shown below:

[0120]

[0121] Step 2: Solve the stress equations for the matrix pores and cracks based on the gas confining pressure to obtain the effective stress of the matrix pores and the effective stress of the cracks.

[0122] In this implementation, based on the gas confining pressure data monitored during the experiment, the preset matrix pore and fracture stress equations are retrieved. These equations incorporate the influence mechanism of effective stress on reservoir properties, specifically using σ m_eff and σ f_eff The effective stresses of matrix pores and cracks are characterized separately by the confining pressure P. c By combining parameters such as pore pressure with a correction factor α and a constant m related to the surface roughness of the slit-like pores, the effective stresses of the matrix pores and fractures are obtained. This process can accurately quantify the stress distribution differences between the matrix pores and fractures under deep geostress environments, providing stress dimension support for subsequent correction of physical property parameters.

[0123] The influence of stress sensitivity is considered in the preset control equations, mainly manifested as the effect of effective stress on physical properties such as permeability, average pore size, and porosity. The calculation formulas for effective stress in matrix pores and effective stress in fractures are as follows:

[0124]

[0125] In the formula: σ m_eff and σ f_eff P represents the effective stress in the matrix pores and fractures, respectively; P1 is the pressure when the pores are completely closed; P c α is the confining pressure of the gas; m is a correction factor; k is a constant related to the surface roughness of the slit-like pores; α is a correction factor; m is a constant related to the surface roughness of the slit-like pores; k is a constant related to the surface roughness of the slit-like pores. m_stress (P,T) represents the apparent permeability of the matrix pores affected by effective stress, temperature, and pressure; k f_stress (P,T) represents the fracture permeability affected by effective stress, temperature, and pressure; k m_app (P, T) represents the apparent permeability of the matrix pores affected by temperature and pressure.

[0126] The apparent permeability of the matrix pores affected by temperature and pressure can be expressed by the following formula:

[0127]

[0128] In the formula: k v r represents the intrinsic permeability of the matrix pores. m_eff D is the effective average pore size of the matrix pores. s D is the initial surface diffusion coefficient; s0 The diffusion coefficient represents the diffusion coefficient when the methane gas coverage is 0; k is the blockage rate parameter; k n_real D is the Knuth number for a real gas; m_app (P, T) represents the apparent diffusion coefficient of the matrix pores affected by temperature and pressure. The diffusion coefficient of methane molecules under viscous flow transport mechanism. The diffusion coefficient of methane molecules under the Knudsen diffusion transport mechanism is given. is the diffusion coefficient of methane molecules under the surface diffusion transport mechanism.

[0129] The initial surface diffusion coefficient can be expressed by the following formula:

[0130]

[0131] Step 3: Determine the effective porosity of the matrix pores based on the initial porosity, the initial average pore diameter, and the initial effective stress of the matrix pores.

[0132] Under this implementation, fundamental parameters such as initial porosity, initial average pore diameter, and initial effective stress of the matrix pores are obtained from core experimental data. First, the average pore diameter of the matrix pores under stress is calculated using the formula for the influence of effective stress on the average pore diameter. Then, considering the shading effect of the adsorption layer on the pore diameter, the effective average pore diameter of the matrix pores is determined by introducing the methane molecule diameter and the gas coverage of adsorbed and free gas. Finally, the dual influences of effective stress and adsorption layer are integrated and substituted into the formula for calculating the effective porosity of the matrix pores to obtain the corrected effective porosity of the matrix pores, thus achieving accurate characterization of the true reservoir space of the matrix pores.

[0133] The combined effect of effective stress and adsorption layer on the effective porosity of the matrix pores can be expressed as:

[0134]

[0135] In the formula: The initial porosity of the matrix pores; The effective porosity of the matrix pores is affected by effective stress and adsorption layer.

[0136] Where, r m_eff The effective average pore size of the matrix can be expressed by the following formula:

[0137]

[0138] In the formula: r m_eff d is the effective average pore diameter of the matrix pores. m θ is the diameter of a methane molecule, typically 0.38 nm; θ and They represent 12 CH4 13 CH4 gas coverage.

[0139] Where, r m_stress The average pore size of the matrix affected by effective stress can be calculated using the following formula:

[0140]

[0141] In the formula: r m_stress r represents the average pore size of the matrix under the influence of effective stress. m0 σ is the initial average pore size of the matrix; m_eff0 This represents the initial effective stress of the matrix pores.

[0142] Step 4: Input the gas viscosity in the matrix pores and fractures, the effective stress in the matrix pores and fractures, and the effective porosity of the matrix pores into the preset control equations. Combine the preset geometric model, preset initial conditions and preset boundary conditions to calculate the first gas pressure and the first core temperature of coalbed methane in the matrix pores, and calculate the second gas pressure and the second core temperature of coalbed methane in the fractures.

[0143] In this implementation, the gas viscosity in the matrix pores and fractures, the effective stress in the matrix pores and fractures, and the effective porosity of the matrix pores are first uniformly input into a set of pre-defined control equations. Then, a pre-defined geometric model based on the core radius and height is imported, along with initial conditions determined based on the initial gas pressure and standard carbon isotope atomic ratio, and insulating boundary conditions set based on atmospheric pressure. The control equations are then solved using numerical simulation software, ultimately obtaining the first gas pressure and first core temperature of coalbed methane in the matrix pores, and the second gas pressure and second core temperature in the fractures. This lays the foundation for subsequent gas state equation solving and isotope value fitting, providing a data basis for the temperature and pressure field.

[0144] The core experimental data also includes the core radius and core height; the preset geometric model is obtained by inputting the core radius and core height into the simulation software.

[0145] For example, Figure 2 A schematic diagram of the preset geometric model provided in the embodiments of this application, such as Figure 2 As shown, r core r represents the radius of the coal and rock plunger sample. pipe This represents the pipeline radius.

[0146] The core experimental data mentioned above also include the initial gas pressure and the carbon isotope atomic ratio of the standard sample; the preset initial conditions were determined based on the initial gas pressure, the first methane carbon isotope value, and the carbon isotope atomic ratio of the standard sample.

[0147] In this implementation, the core experimental data includes the pre-collected initial gas pressure and the carbon isotope atomic ratio of the standard sample. The preset initial conditions are determined based on the above parameters and the first methane carbon isotope value obtained in step 12. Specifically, based on the initial gas pressure, the initial gas pressures of adsorbed gas and free gas in the matrix pores and in the fractures at time t=0 are first set. Then, combining the first methane carbon isotope value and the carbon isotope atomic ratio of the standard sample, the initial molar ratio of free gas to adsorbed gas in the matrix pores and fractures is determined using the isotope molar ratio conversion formula. This is used to construct the initial conditions of the model, ensuring that the isotope distribution and gas pressure field in the initial state conform to the actual original state of the reservoir before the experiment, providing an accurate initial benchmark for subsequent numerical simulations.

[0148] The preset initial conditions can be expressed by the following formula:

[0149]

[0150] In the formula: for 12 CH4 and 13 CH 4的 Initial molar ratio; δ0 is the first methane carbon isotope value; R st The carbon isotope atomic ratio of the PDB standard sample; and These represent the initial gas pressures of free gas and adsorbed gas in the matrix pores, respectively. and P1 and P2 are the initial gas pressures of free gas and adsorbed gas in the fracture, respectively; P0 is the initial pressure of coalbed methane.

[0151] The core experimental data mentioned above also include atmospheric pressure; the preset boundary conditions were determined based on atmospheric pressure, the first methane carbon isotope value, and the carbon isotope atomic ratio of the standard sample.

[0152] Under this implementation, the core experimental data synchronously includes the atmospheric pressure of the experimental environment. The preset boundary conditions are set by combining this atmospheric pressure, the first methane carbon isotope value, and the atomic ratio of the carbon isotope in the standard sample. Specifically, the boundary at the connection between the core holder outlet and the pipeline is set to an atmospheric pressure environment, i.e., the matrix pore at this location. 12 CH4 13 The gas pressure of CH4, and the crack 12 CH4 13The gas pressure of CH4 is equal to atmospheric pressure. Simultaneously, based on the carbon isotope value of the first methane and the atomic ratio of the carbon isotope of the standard sample, the pressure at the outlet boundary is determined. 12 CH4 and 13 The isotopic molar percentage of CH4, while the core side surface, excluding pipelines (such as...) Figure 2 The end face outside the connection surface (as shown) is set as an insulating boundary to prevent gas from flowing across the boundary and exchanging isotopes. This is to construct boundary conditions that fit the real working conditions of the depletion development experiment and ensure the rationality and accuracy of the numerical simulation process.

[0153] The preset boundary conditions can be expressed by the following formula:

[0154]

[0155] In the formula: P m (t), P f (t), and These represent the points where the instrument outlet connects to the pipeline. 12 CH4 and 13 Gas pressure of CH4 in matrix pores and fractures; This indicates the connection surface between the outlet end and the pipeline; This refers to the core end face at the outlet, excluding the pipeline connection surface. Indicates the core end face at the inlet; This indicates the side of the rock core.

[0156] Step 14: Input the first gas pressure, the first core temperature, the second gas pressure, and the second core temperature into the gas state equation and the isothermal adsorption equation for calculation to obtain the second gas data and the second methane carbon isotope value corresponding to the coalbed methane.

[0157] In this step, the first gas pressure, the first core temperature, the second gas pressure, and the second core temperature are substituted into the gas state equation and the isothermal adsorption equation. Simultaneously, the compressibility factor of methane gas and the correlation formula between density and temperature / pressure are used to solve for parameters such as gas volume and gas production rate within the matrix pores and fractures, respectively. These parameters are then integrated to obtain the second gas data corresponding to coalbed methane. Based on the partial pressure ratio of adsorbed gas and free gas, the second methane carbon isotope value is calculated, forming a simulated data set corresponding to the experimental data (i.e., the second gas data and second methane carbon isotope value corresponding to coalbed methane), providing a benchmark for subsequent data fitting.

[0158] The gas law can be expressed by the following formula:

[0159]

[0160] The isothermal adsorption equation can be expressed by the following formula:

[0161]

[0162] The second gas data and second methane carbon isotope values ​​corresponding to coalbed methane, calculated based on the gas state equation and isothermal adsorption equation, are shown in the following formula:

[0163]

[0164] In the formula: P in The pressure at the core inlet is represented by S; the area at the core inlet is represented by q(t). i ) indicates that at t i Gas production rate at time t; Q(t) i ) indicates that at t i Cumulative analytical gas volume at time δ 13 C 1_cal (t i ) indicates that at t i The calculated value of the carbon isotope of methane at that time (i.e., the second carbon isotope value of methane).

[0165] Step 15: Solve the preset control equation based on the first gas data, the second gas data, the first methane carbon isotope value, and the second methane carbon isotope value to obtain the amount of adsorbed gas and free gas in the coalbed methane.

[0166] In this step, the first gas data is fitted with the simulated second gas data, and the first methane carbon isotope value and the second methane carbon isotope value are matched. The minimum value of the objective function is solved by an optimization algorithm (e.g., least squares method), and the undetermined parameters in the preset control equation are determined. Then, the optimal parameters are substituted back into the control equation to calculate the pressure field distribution data inside the core. The proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane are further derived. Then, the adsorbed gas and free gas volume calculation equations are substituted into the equations to finally achieve an accurate quantitative assessment of the individual gas volume of adsorbed gas and free gas and the total gas volume in the coalbed methane.

[0167] The formulas for calculating the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane are as follows:

[0168]

[0169] In the formula: Ratio_ads ins Indicates at t i At any given time, the rate of adsorbed gas production; Ratio_ads cum The cumulative percentage of adsorbed gas in coalbed methane was analyzed.

[0170] The production rates of free gas and adsorbed gas can be calculated based on the gas production rate and the proportion of adsorbed gas in the gas production rate. Similarly, the cumulative desorbed gas volume can be calculated based on the cumulative desorbed gas volume and the proportion of adsorbed gas in the cumulative desorbed gas volume. The specific equations for calculating the volume of adsorbed gas and free gas are as follows:

[0171]

[0172] In the formula: q free (t i ) indicates that at t i The rate of gas production from downstream ionized gas at any given time; q ads (t i ) indicates that at t i At what time is the adsorbed gas production rate; Q free (t i ) indicates that at t i The cumulative desorbed gas volume of the downstream gas at time point; Q ads (t i ) indicates that at t i The cumulative amount of adsorbed gas desorbed at any given time.

[0173] In one possible implementation, the mass balance method is used to assess the amount of adsorbed and free gas in coalbed methane. First, the apparent average pressure (P / Z) of the core at any given time is calculated using simulated core inlet and outlet pressures and compressibility factors. g A scatter plot was drawn with the cumulative gas volume as the x-axis and the apparent average pressure of the core as the y-axis. The formula for the apparent average pressure of the core is:

[0174]

[0175] Where: P / Z g P represents the apparent average pressure. in Z represents the pressure at the core inlet; in P represents the compressibility factor at the core inlet. out Z represents the pressure at the core outlet; out Indicates the compressibility factor at the core outlet;

[0176] Then, based on the mass balance equation of a constant-volume gas reservoir, the data segments showing a linear downward trend in the above scatter plot are fitted to obtain the trend line of cumulative free gas desorbed volume. The intersection of this trend line with the horizontal axis represents the total free gas volume (G0). The difference between the measured cumulative desorbed gas volume and the trend line value is the cumulative desorbed adsorbed gas volume, calculated using the following formula:

[0177]

[0178] Where: G free (P), G ads (P) and G total(P) represents the cumulative desorbed gas volume of free gas, the cumulative desorbed gas volume of adsorbed gas, and the total cumulative desorbed gas volume under pressure P, respectively; P0 / Z0 is the apparent average pressure of the core at the initial moment; G ads_total and G total These represent the total adsorbed gas volume and the total cumulative desorbed gas volume, respectively.

[0179] Correspondingly, Figure 3 A schematic diagram of coalbed methane quantity assessed by the material balance method in an embodiment of this application is shown below. Figure 3 As shown, the red dashed line represents the amount of free gas under different core apparent pressures, and the value of the black solid line minus the red dashed line represents the amount of adsorbed gas.

[0180] This application provides a quantitative evaluation method for the dynamic production of adsorbed and free gases in deep coalbed methane. The method first acquires the gases released from coalbed core samples during the experiment and the corresponding core experimental data, providing a fundamental data source that aligns with the actual reservoir characteristics of deep coalbeds for subsequent evaluation, avoiding the problem of theoretical assumptions being out of sync with field conditions. Then, isotope values ​​are measured on the gases to obtain the first methane carbon isotope value, accurately reflecting the fractionation characteristics of methane gas in matrix pores and fractures, providing a crucial isotopic identifier for distinguishing between adsorbed and free gases. Next, the first gas data, methane gas molecular mass, ideal gas constant, and first methane carbon isotope value are input into a preset control equation. Combined with a preset geometric model, preset initial conditions, and preset boundary conditions, the first gas pressure and first core temperature of coalbed methane in matrix pores are calculated, as well as the second gas pressure and second core temperature of coalbed methane in fractures. This achieves accurate characterization of the temperature and pressure field within a dual-medium reservoir, overcoming the deficiency of traditional models in distinguishing the temperature and pressure differences between matrix pores and fractures. Finally, the first gas pressure, first core temperature, second gas pressure, and second core temperature are input into the gas state equation and isothermal adsorption equation for calculation, obtaining the second gas data and second methane carbon isotope value corresponding to the coalbed methane. Then, based on the first gas data, the second gas data, the first methane carbon isotope value, and the second methane carbon isotope value, the preset control equation is solved to obtain the amount of adsorbed gas and free gas in the coalbed methane. Through multi-source fitting of simulation experimental data and calculation data from the preset control equation, the accuracy of coalbed methane volume assessment is greatly improved, and the precise quantification of adsorbed gas and free gas is achieved, providing reliable data support for the formulation of deep coalbed methane development plans.

[0181] Based on the above embodiments, Figure 4 A flowchart illustrating the quantitative evaluation method for the dynamic production of adsorbed and free gas in deep coalbed methane provided in this application embodiment. Figure 2 ,like Figure 4 As shown, step 15 may include the following steps:

[0182] Step 21: When fitting the first gas data and the second gas data, and simultaneously fitting the first methane carbon isotope value and the second methane carbon isotope value, determine the target parameters of the preset control equation.

[0183] In this step, the measured first gas data (including gas production rate, cumulative desorbed gas volume, and core inlet pressure) from step 11 is compared with the simulated second gas data from step 14. Simultaneously, the first methane carbon isotope value obtained in step 12 is matched with the second methane carbon isotope value calculated in step 14. An objective function incorporating gas volume deviation and isotope deviation is constructed, with the optimization direction being minimizing the overall deviation between the two types of data. Subsequently, an optimization algorithm (e.g., a least squares function) is used to solve the objective function. When the fit between the first and second gas data meets a preset threshold, and the fitting error between the first and second methane carbon isotope values ​​is below the industry allowable range, the target parameters in the preset control equation are determined.

[0184] The target parameters of the preset control equation specifically include the intrinsic permeability of the matrix pores (k). v ), crack permeability (k f ), Langmuir volume (V L Langmuir pressure (P) L ), matrix porosity, fracture porosity, and diffusion coefficient (D) when gas coverage is 0. s0 The values ​​are: standard molar integral entropy (ΔS), differential adsorption enthalpy (ΔH), and the ratio of apparent diffusion coefficients in the matrix pores at saturation. .

[0185] Step 22: Input the target parameters into the preset control equation for calculation to obtain the pressure field distribution data of coalbed methane.

[0186] In this step, the optimal target parameters determined in step 21 are fully substituted into the preset multi-scale, multi-mechanism, and multi-field coupled isotope fractionation control equations (i.e., the preset control equations), while retaining the constructed core geometric model, initial conditions, and boundary conditions. The control equations are then solved using numerical simulation software. During the solution process, key physical properties such as permeability, porosity, and diffusion coefficient of the matrix pores and fractures are corrected based on the target parameters to accurately calculate the values ​​at different times and spatial locations. 12 CH4 and 13 The gas pressure of CH4 in the matrix pores (P) m , ) and the gas pressure (P) within the crack f , This data is integrated to form coalbed methane pressure field distribution data covering all time periods and all spaces. This data can intuitively reflect the pressure evolution law in matrix pores and fractures, providing core data support for the subsequent separation of adsorbed gas and free gas.

[0187] Step 23: Based on the pressure field distribution data, determine the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane.

[0188] In this step, the pressure field distribution data obtained in step 22 is processed by volume integration, and the gas production rate and cumulative desorbed gas volume at any given time are calculated using the gas state equation in step 14. Then, based on the calculation formulas for the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane in step 15, and considering the contribution ratio of desorbed gas from the matrix pores in the pressure field data, the proportion of adsorbed gas production rate at that time is determined, i.e., the ratio of adsorbed gas production rate to total production rate per unit time. Simultaneously, the total cumulative desorbed coalbed methane volume from the start of depletion development to the current time is statistically analyzed, and the proportion of adsorbed gas in the cumulative desorbed coalbed methane is calculated, i.e., the ratio of cumulative adsorbed gas production to cumulative total desorbed gas volume, thus achieving a dual characterization of the instantaneous and cumulative dimensions of the coalbed methane production structure.

[0189] Step 24: Solve the equations for calculating the amount of adsorbed gas and free gas based on the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane, and determine the amount of adsorbed gas and free gas.

[0190] In this step, the gas volume calculation equations for adsorbed gas and free gas from step 15 are retrieved. The proportion of adsorbed gas production rate determined in step 23 is substituted into the equations to calculate the adsorbed gas production rate and free gas production rate at any given time. This allows for the calculation of the cumulative desorbed gas volume (i.e., the amount of adsorbed gas) and the cumulative desorbed gas volume (i.e., the amount of free gas). The calculation results for both the production rate and cumulative desorbed gas are cross-validated. If the deviation between the two is less than 5%, the final determination of the adsorbed gas volume and free gas volume corresponding to the coal seam core is achieved, thus realizing a precise quantitative breakdown of the gas volume under different occurrence states of coalbed methane.

[0191] This application provides a method for quantitatively evaluating the dynamic production of adsorbed and free gas in deep coalbed methane. The method first determines the target parameters of a preset control equation by fitting first and second gas data, and simultaneously fitting first and second methane carbon isotope values. This dual-dimensional data fitting effectively avoids parameter distortion caused by single-data calibration, significantly improving the adaptability of model parameters to deep coal-rock dual-medium reservoir conditions. Then, the target parameters are input into the preset control equation for calculation, obtaining the pressure field distribution data of the coalbed methane. This accurately presents the pressure evolution differences within matrix pores and fractures, overcoming the limitation of traditional methods that cannot distinguish the pressure states of different pore spaces. Based on the pressure field distribution data, the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulatively analyzed coalbed methane are determined, achieving a dual-dimensional quantification of the instantaneous gas production structure and the entire cycle gas production composition of coalbed methane. This solves the pain point of traditional assessments, which can only calculate the total gas volume but cannot break down the occurrence state. Finally, based on the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane, the gas volume calculation equations for adsorbed gas and free gas were solved, and the gas volume of adsorbed gas and free gas were determined. This completed the accurate separation of the gas volume of adsorbed gas and free gas, significantly improving the accuracy and refinement of the gas volume assessment of deep coalbed methane, and providing reliable data support for the optimization of subsequent development schemes.

[0192] In one possible embodiment 1, taking the deep coal seam core sample F1 in area A as an example, the specific steps of the quantitative evaluation method for the dynamic production of adsorbed gas and free gas in deep coalbed methane are as follows:

[0193] S1: Pretreatment of coal seam core samples: Figure 5 This is a schematic diagram of the coal seam sample provided in Embodiment 1 of this application, as shown below. Figure 5 As shown, coal and rock plunger samples are drilled using wire cutting technology. Areas with gaps or unevenness in the samples are filled with glue and polished. After that, they are placed in a drying oven to remove moisture and finally fitted with a thermoplastic sleeve.

[0194] S2: Assemble the experimental apparatus and test its airtightness: Install a six-way valve, intermediate container, core holder, and hand pump. Monitor the inlet and outlet pressure and confining pressure of the core holder through the pressure acquisition system. Install a fake core, pressurize it to 20MPa with helium gas, and pressurize it to 30MPa with the hand pump. After monitoring the inlet and outlet pressure and confining pressure for 24 hours, the curves show an upward and downward fluctuation trend without significant decrease.

[0195] S3: Stepped pressurization saturation: The coal seam core sample is installed in the holder, and confining pressure is applied by a hand pump. Methane is introduced into the intermediate container for saturation. The confining pressure increases in stages (e.g., 8→15→20→30MPa), and the pore pressure increases in stages (e.g., 1→5→10→20MPa). Finally, the pressure is increased to the initial pressure of coalbed methane set in the experiment, 20MPa, and the confining pressure, 30MPa.

[0196] S4: Commence Depletion Development: Open the outlet valve of the core holder to initiate depressurization mining (outlet pressure is atmospheric pressure), and collect the carbon isotope values ​​of the gas produced during the extraction process. Compile and summarize the continuously monitored inlet and outlet pressures, confining pressures, and collected gas volumes during the experiment, ultimately obtaining the simulated cumulative desorbed gas volume (i.e., first gas data), gas production rate, core inlet and outlet pressures, and continuous records of methane carbon isotope (i.e., first methane carbon isotope) changes over time.

[0197] For example, Figure 6 A schematic diagram showing the cumulative desorbed gas volume, gas production rate, core inlet and outlet pressures, and methane carbon isotope variations over time in the simulation experiment provided in Example 1 of this application is shown below. Figure 6 As shown.

[0198] S5: Establish an isotope fractionation model (i.e., matrix pores and fractures) applicable to coal cores at the core scale. Set the initial and boundary conditions for the isotope fractionation model, and solve the isotope fractionation model using numerical simulation software to obtain the core sample. 12 CH4 and 13 The pressure fields of CH4 in the matrix pores and natural fractures are calculated. By integrating the pressure fields, the cumulative desorbed gas volume (i.e., the second gas data), production rate, inlet pressure, and methane carbon isotope value (i.e., the second methane carbon isotope value) are obtained. The calculated cumulative desorbed gas volume, production rate, inlet pressure, and methane carbon isotope value are then fitted with the measured data from the simulation experiment to construct an objective function (e.g., a least squares function). The minimum value of the objective function is then solved using an optimization algorithm to determine the target parameters.

[0199] in, Figure 7 This is a schematic diagram showing the fitting of the cumulative desorbed gas volume, gas production rate, inlet pressure, and methane carbon isotope value calculated by the preset control equation with the measured data in the simulation experiment, as provided in Embodiment 1 of this application.

[0200] S6: Substitute the determined target parameters into the control equation for calculation, and finally obtain the amount of adsorbed gas and free gas at any time and at any moment during the extraction process.

[0201] In related technologies, the mass balance method is used to assess the amount of adsorbed gas and free gas. Figure 8 This is a schematic diagram illustrating the results of evaluating coalbed methane volume using the material balance method provided in Embodiment 1 of this application. Specifically, the apparent average pressure (P / Zg) of the core at any given time is calculated using the simulated core inlet and outlet pressures and compressibility factor. A scatter plot is then drawn with the cumulative desorbed gas volume as the abscissa and the apparent average pressure of the core as the ordinate. Then, using the material balance equation, the data segments in the pseudo-scatter plot that exhibit a linear decreasing trend are shown below. Figure 8 As shown, the free gas volume trend line is obtained, and the adsorbed gas volume is obtained by subtracting the value on the free gas volume trend line from the total desorbed gas volume.

[0202] A comparative analysis was conducted on the cumulative desorbed gas volume of free and adsorbed gas calculated by the isotope fractionation model (i.e., the preset control equation corresponding to the dynamic production quantitative evaluation method of adsorbed gas and free gas in deep coalbed methane) and the material balance method provided in the embodiments of this application. Figure 9 This is a schematic diagram comparing the gas volume assessment results of the preset control equation and the material balance method provided in Embodiment 1 of this application, as shown in the figure. Figure 9 As shown, Figure (a) in the upper left corner is the gas volume assessment result using the mass balance method, while Figures (b), (c), and (d) are the gas volume assessment results using the isotope fractionation model. Figure (a) shows the free gas volume and adsorbed gas volume calculated by the mass balance method, but the changes in the proportion of free gas and adsorbed gas are relatively gradual, reflecting the insufficient detail of this method in depicting dual-medium reservoirs. Figure (b) shows the free gas volume and adsorbed gas volume calculated by the isotope fractionation model. The curves of total coalbed methane volume, free gas volume, and adsorbed gas show more significant differences. The proportion of free gas is high in the early stage, and the proportion of adsorbed gas gradually increases in the later stage, which more accurately matches the coalbed methane production pattern of "free gas first, then adsorbed gas" and reflects the model's adaptability to differences in reservoir media. Figure (c) shows the proportions of free gas and adsorbed gas in the cumulative and daily gas production calculated by the isotope fractionation model. In both cumulative and daily gas production, the proportion of free gas decreases over time, while the proportion of adsorbed gas increases synchronously, clearly showing the changes in gas composition at different stages and overcoming the limitation of traditional methods in distinguishing between instantaneous and cumulative proportions. Figure (d) shows the recovery rates of free gas and adsorbed gas calculated by the isotope fractionation model. The recovery rate of free gas rapidly approaches stability, while the recovery rate of adsorbed gas continues to increase, reflecting the difference in development efficiency between the two gas occurrence states.

[0203] In summary, compared with the mass balance method, the isotope fractionation method provided in this application can more accurately and dynamically characterize the coalbed methane production structure. Figure (b) clearly distinguishes the production trend differences between free gas and adsorbed gas, which conforms to the actual production law of "free gas first, then adsorbed gas". Figure (c) further realizes the quantification of gas production ratio in instantaneous and cumulative dimensions, intuitively presenting the changes in gas production composition at different stages. Figure (d) can clearly show the difference in the recovery degree of the two types of gas in the two occurrence states. At the same time, the isotope fractionation method can not only support the comparison and verification of the model accuracy with the mass balance method when the fracture is not developed, but also accurately adapt to the dual medium characteristics in reservoirs with developed fractures and high permeability, making up for the shortcomings of traditional methods in characterizing reservoir details. It provides more refined and scenario-adaptable technical support for the assessment of deep coalbed methane production.

[0204] In another possible embodiment 2, taking the deep coal seam DJ-1 in area A as an example, the specific steps of the quantitative evaluation method for the dynamic production of adsorbed gas and free gas in deep coalbed methane are as follows:

[0205] Y1: Using glass sampling bottles, gas samples from the wellhead of deep coalbed methane wells in the production wells on site are collected by the drainage gas collection method. The collected gas is subjected to methane carbon isotope testing to obtain the first methane carbon isotope value.

[0206] Y2: Collect core experimental data (including first gas data) used in isotope fractionation models.

[0207] Y3: Using the method in step S5 above, the core experimental data is processed to obtain the isotope fractionation model calculation data (i.e., the second gas data and the second methane carbon isotope value). Then, the calculated data and the measured data in the simulation experiment are fitted to determine the target parameters of the isotope fractionation model. Then, using the method in step S6 above, the amount of adsorbed gas and the amount of free gas at any time and any moment during the extraction process are calculated.

[0208] Figure 10 This is a schematic diagram showing the fitting of cumulative desorbed gas volume, gas production rate, inlet pressure, and methane carbon isotope value calculated by a preset control equation with field data, as provided in Embodiment 2 of this application. Figure 10 As shown in Figure (a), the changes in bottom hole flowing pressure are highly consistent with the field data and the exponential fitting curve. The pressure drops rapidly in the early stage, corresponding to a large amount of free gas production. It tends to stabilize in the later stage, corresponding to the desorption of adsorbed gas as the main process, reflecting the exhaustion law of reservoir pressure. In the cumulative gas production curve in Figure (b), the model calculation results are highly consistent with the field data. The growth rate is fast in the early stage and slows down in the later stage, quantifying the changes in gas production scale throughout the production cycle. The daily gas production curve in Figure (c) also shows a trend of "first steep drop and then flattening". The consistency between the model calculation and the field data verifies the prediction accuracy of the gas production rate of this technical solution. In the changes of methane carbon isotope value (i.e., δ¹³C1) in Figure (d), the model calculation curve fits the fluctuation characteristics of the field data, reflecting the law of isotope fractionation effect in actual production, further confirming the reliability of the isotope model in the technical solution.

[0209] In related technologies, Figure 11 This is a schematic diagram illustrating the results of evaluating coalbed methane volume using the material balance method provided in Embodiment 2 of this application. Figure 11As shown, the apparent coal seam pressure (p / Z) is calculated using the average coal reservoir pressure and the gas deviation factor. A scatter plot is drawn with the cumulative gas production as the abscissa and the apparent coal seam pressure as the ordinate. Then, using the material balance equation, the data segments in the pseudo-scatter plot that show a linear downward trend are used to obtain the free gas volume trend line. The adsorbed gas volume is obtained by subtracting the value on the free gas volume trend line from the cumulative gas production.

[0210] Figure 12 This is a schematic diagram comparing the gas volume assessment results of the preset control equation and the material balance method provided in Embodiment 2 of this application, as shown in the figure. Figure 12 As shown, Figure (a) in the upper left corner presents the gas volume assessment results using the mass balance method, while Figures (b), (c), and (d) present the gas volume assessment results using the isotope fractionation model (i.e., the pre-defined governing equations). Figure (a) shows the changes in total gas volume, free gas volume, and adsorbed gas volume using the mass balance method, but the curves have low discrimination and the characterization of the gas production structure is somewhat vague, reflecting the shortcomings of traditional methods in providing insufficient detailed characterization in complex reservoirs. Figure (b) shows the calculation results using the isotope fractionation method. The curves for total gas volume, free gas, and adsorbed gas show significant differences. In the early stage, free gas is produced rapidly, and in the later stage, the proportion of adsorbed gas increases, accurately matching the actual production law of coalbed methane, which is "free gas first, then adsorbed gas," demonstrating the adaptability of this technical solution to the dual-medium characteristics of the reservoir. Figure (c) further quantifies the gas production structure of the isotope fractionation method. In both cumulative gas production (i.e., cumulative coalbed methane production) and daily gas production, the proportion of free gas decreases over time, while the proportion of adsorbed gas increases simultaneously, clearly showing the changes in gas production composition at different production stages and overcoming the shortcoming of traditional methods in distinguishing between instantaneous and cumulative proportions. Figure (d) shows the gas production level under the isotope fractionation method. The production level of free gas rapidly approaches stability, while the production level of adsorbed gas continues to increase, accurately reflecting the difference in development efficiency between the two gas occurrence states. Overall, Figure 12 The results of the material balance method and the isotope fractionation method were compared to verify the accuracy of the technical solution in fractured reservoirs. The quantitative analysis of gas production structure and production level also demonstrated the refined support of the solution for the assessment of gas production in deep coalbed methane.

[0211] The following are embodiments of the apparatus described in this application, which can be used to execute the embodiments of the method described in this application. For details not disclosed in the apparatus embodiments of this application, please refer to the embodiments of the method described in this application.

[0212] Figure 13 A schematic diagram of the structure of the device for quantitatively evaluating the dynamic production of adsorbed gas and free gas in deep coalbed methane provided in this embodiment of the application. Figure 13 As shown, the device includes:

[0213] The acquisition module 130 is used to acquire the gas released by the coal seam core sample during the experiment and the corresponding core experimental data; the core experimental data includes the first gas data; the core has matrix pores and fractures;

[0214] Processing module 131 is used to perform isotope value testing on the gas to obtain the first methane carbon isotope value;

[0215] The calculation module 132 is used to input the first gas data, methane gas molecular mass, ideal gas constant, and first methane carbon isotope value into the preset control equation, and calculate the first gas pressure and first core temperature of coalbed methane in the matrix pores by combining the preset geometric model, preset initial conditions and preset boundary conditions, and calculate the second gas pressure and second core temperature of coalbed methane in the fracture.

[0216] The calculation module 132 is also used to input the first gas pressure, the first core temperature, the second gas pressure, and the second core temperature into the gas state equation and the isothermal adsorption equation for calculation, so as to obtain the second gas data and the second methane carbon isotope value corresponding to the coalbed methane.

[0217] The calculation module 132 is also used to solve the preset control equation based on the first gas data and the second gas data, the first methane carbon isotope value and the second methane carbon isotope value, to obtain the amount of adsorbed gas and free gas in the coalbed methane.

[0218] In one possible implementation, the computing module 132 is specifically used for:

[0219] When fitting the first gas data and the second gas data, and simultaneously fitting the first methane carbon isotope value and the second methane carbon isotope value, the target parameters of the preset control equation are determined.

[0220] The target parameters are input into the preset control equations for calculation to obtain the pressure field distribution data of coalbed methane.

[0221] Based on the pressure field distribution data, the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane were determined.

[0222] The gas production rate ratio of adsorbed gas and the proportion of adsorbed gas in the cumulative desorbed coalbed methane are used to solve the gas volume calculation equations for adsorbed gas and free gas, thereby determining the gas volume of adsorbed gas and free gas.

[0223] In one possible implementation, the acquisition module 130 is used for:

[0224] Obtain coal seam core samples;

[0225] The coal seam core samples were pressurized according to the preset experimental parameters, the gas generated during the pressurization process was collected, and the core experimental data during the pressurization process were obtained.

[0226] In one possible implementation, the core experimental data also includes initial matrix porosity, initial average matrix pore diameter, initial effective matrix pore stress, and gas confining pressure; the calculation module 132 is specifically used for:

[0227] Based on the first gas data, the molecular mass of methane gas, and the ideal gas constant, the gas viscosity in the matrix pores and fractures was determined, respectively.

[0228] Based on the gas confining pressure, the stress equations for matrix pores and cracks are solved to obtain the effective stresses of matrix pores and cracks.

[0229] The effective porosity of the matrix pores is determined based on the initial porosity of the matrix pores, the initial average pore diameter of the matrix pores, and the initial effective stress of the matrix pores.

[0230] The gas viscosity in the matrix pores and fractures, the effective stress in the matrix pores and fractures, and the effective porosity of the matrix pores are input into the preset control equations. Combined with the preset geometric model, preset initial conditions and preset boundary conditions, the first gas pressure and the first core temperature of coalbed methane in the matrix pores are calculated, and the second gas pressure and the second core temperature of coalbed methane in the fractures are also calculated.

[0231] In one possible implementation, the core experimental data also includes the core radius and core height; the preset geometric model is obtained by inputting the core radius and core height into the simulation software.

[0232] In one possible implementation, the core test data also includes the initial gas pressure and the carbon isotope atomic ratio of the standard sample; the preset initial conditions are determined based on the initial gas pressure, the first methane carbon isotope value, and the carbon isotope atomic ratio of the standard sample.

[0233] In one possible implementation, the core experimental data also includes atmospheric pressure; the preset boundary conditions are determined based on atmospheric pressure, the first methane carbon isotope value, and the carbon isotope atomic ratio of the standard sample.

[0234] The apparatus provided in this application embodiment can be used to execute the determination method in any of the above embodiments. Its implementation principle and technical effect are similar, and will not be described again here.

[0235] It should be noted that the division of the various modules in the above device is merely a logical functional division. In actual implementation, they can be fully or partially integrated into a single physical entity, or they can be physically separated. Furthermore, these modules can be implemented entirely in software via processing element calls; they can be fully implemented in hardware; or some modules can be implemented in software via processing element calls, while others are implemented in hardware. Additionally, these modules can be fully or partially integrated together, or implemented independently. The processing element here can be an integrated circuit with signal processing capabilities. During implementation, each step of the above method or each of the above modules can be completed through the integrated logic circuits in the hardware of the processor element or through software instructions.

[0236] Figure 14 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application, such as... Figure 14 As shown, the electronic device may include: a processor 141, a memory 142, and computer program instructions stored in the memory 142 and executable on the processor 141. When the processor 141 executes the computer program instructions, it implements the method provided in any of the foregoing embodiments.

[0237] Optionally, the various components of the electronic device can be connected via a system bus.

[0238] The memory 142 can be a separate memory unit or a memory unit integrated into the processor 141. The number of processors 141 can be one or more.

[0239] It should be understood that processor 141 can be a Central Processing Unit (CPU), or other general-purpose processor 141, digital signal processor 141 (DSP), application-specific integrated circuit (ASIC), etc. General-purpose processor 141 can be a microprocessor 141, or any conventional processor 141. The steps of the method disclosed in this application can be directly manifested as being executed by the hardware processor 141, or being executed by a combination of hardware and software modules in the processor 141.

[0240] The system bus can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The system bus can be divided into address bus, data bus, control bus, etc. For ease of representation, only one thick line is used in the diagram, but this does not indicate that there is only one bus or one type of bus. Memory 142 may include random access memory (RAM) 142, and may also include non-volatile memory (NVM) 142, such as at least one disk storage device 142.

[0241] All or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a readable memory 142. When the program is executed, it performs the steps of the above method embodiments; and the aforementioned memory 142 (storage medium) includes: read-only memory 142 (ROM), RAM, flash memory 142, hard disk, solid-state hard disk, magnetic tape, floppy disk, optical disk, and any combination thereof.

[0242] The electronic device provided in this application embodiment can be used to execute the method provided in any of the above method embodiments. Its implementation principle and technical effect are similar, and will not be repeated here.

[0243] This application provides a computer-readable storage medium storing computer instructions that, when executed on a computer, cause the computer to perform the above-described method.

[0244] The aforementioned computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory, electrically erasable programmable read-only memory, erasable programmable read-only memory, programmable read-only memory, read-only memory, magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0245] Optionally, a readable storage medium can be coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Alternatively, the readable storage medium can be an integral part of the processor. Both the processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components within the device.

[0246] This application also provides a computer program product, which includes a computer program stored in a computer-readable storage medium. At least one processor can read the computer program from the computer-readable storage medium, and the at least one processor can implement the above-described method when executing the computer program.

[0247] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for quantitatively evaluating the dynamic production of adsorbed gas and free gas in deep coalbed methane, characterized in that, include: Obtain the gases released from coal seam core samples during the experiment and the corresponding core experimental data; The core experimental data includes first gas data; the core has matrix pores and fractures; The gas was subjected to isotope value testing to obtain the first methane carbon isotope value; The first gas data, methane gas molecular mass, ideal gas constant, and first methane carbon isotope value are input into the preset control equation. Combined with the preset geometric model, preset initial conditions, and preset boundary conditions, the first gas pressure and first core temperature of the coalbed methane in the matrix pores are calculated, and the second gas pressure and second core temperature of the coalbed methane in the fracture are also calculated. The first gas pressure, the first core temperature, the second gas pressure, and the second core temperature are input into the gas state equation and the isothermal adsorption equation for calculation to obtain the second gas data and the second methane carbon isotope value corresponding to the coalbed methane. Based on the first gas data and the second gas data, the first methane carbon isotope value and the second methane carbon isotope value, the preset control equation is solved to obtain the amount of adsorbed gas and free gas in the coalbed methane.

2. The method according to claim 1, characterized in that, The step of solving the preset control equation based on the first gas data and the second gas data, the first methane carbon isotope value and the second methane carbon isotope value to obtain the gas quantities of the adsorbed gas and the free gas in the coalbed methane includes: When fitting the first gas data and the second gas data, and simultaneously fitting the first methane carbon isotope value and the second methane carbon isotope value, the target parameters of the preset control equation are determined. The target parameters are input into the preset control equation for calculation to obtain the pressure field distribution data of the coalbed methane. Based on the pressure field distribution data, the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane are determined. Based on the proportion of adsorbed gas production rate and the proportion of adsorbed gas in the cumulative desorbed coalbed methane, the gas volume calculation equations for adsorbed gas and free gas are solved to determine the gas volume of adsorbed gas and free gas.

3. The method according to claim 1, characterized in that, The acquisition of the gas released by the coal seam core sample during the experiment and the corresponding core experimental data includes: Obtain core samples from the coal seam; The coal seam core sample was injected with methane according to preset experimental parameters for pressurization and saturation treatment, and the core experimental data of the pressurization and saturation treatment process were collected. The methane after pressurized saturation treatment is subjected to depletion development, and the gas produced during the depletion development process is collected.

4. The method according to claim 2, characterized in that, The core experimental data also includes the initial porosity of the matrix pores, the initial average pore diameter of the matrix pores, the initial effective stress of the matrix pores, and the gas confining pressure; the first gas data, methane gas molecular mass, ideal gas constant, and the first methane carbon isotope value are input into a preset control equation, and combined with a preset geometric model, preset initial conditions, and preset boundary conditions, the first gas pressure and first core temperature of the coalbed methane in the matrix pores are calculated, and the second gas pressure and second core temperature of the coalbed methane in the fractures are calculated, including: Based on the first gas data, the molecular mass of the methane gas, and the ideal gas constant, the gas viscosity in the matrix pores and the cracks is determined, respectively. Based on the gas confining pressure, the stress equations for matrix pores and cracks are solved to obtain the effective stress of matrix pores and cracks. The effective porosity of the matrix pores is determined based on the initial porosity of the matrix pores, the initial average pore diameter of the matrix pores, and the initial effective stress of the matrix pores. The gas viscosity in the matrix pores and the fractures, the effective stress in the matrix pores and the effective stress in the fractures, and the effective porosity of the matrix pores are input into the preset control equations. Combined with the preset geometric model, the preset initial conditions and the preset boundary conditions, the first gas pressure and the first core temperature of the coalbed methane in the matrix pores are calculated, and the second gas pressure and the second core temperature of the coalbed methane in the fractures are also calculated.

5. The method according to claim 4, characterized in that, The core experimental data also includes the core radius and core height; the preset geometric model is obtained by inputting the core radius and core height into simulation software.

6. The method according to claim 4, characterized in that, The core experimental data also includes the initial gas pressure and the carbon isotope atomic ratio of the standard sample; the preset initial conditions are determined based on the initial gas pressure, the first methane carbon isotope value, and the carbon isotope atomic ratio of the standard sample.

7. The method according to claim 6, characterized in that, The core experimental data also includes atmospheric pressure; the preset boundary conditions are determined based on the atmospheric pressure, the first methane carbon isotope value, and the carbon isotope atomic ratio of the standard sample.

8. A device for quantitatively evaluating the dynamic production of adsorbed gas and free gas in deep coalbed methane, characterized in that, include: The acquisition module is used to acquire the gases released by coal seam core samples during the experiment and the corresponding core experimental data; The core experimental data includes first gas data; the core has matrix pores and fractures; The processing module is used to perform isotope value testing on the gas to obtain the first methane carbon isotope value; The calculation module is used to input the first gas data, methane gas molecular mass, ideal gas constant, and first methane carbon isotope value into the preset control equation, and calculate the first gas pressure and first core temperature of the coalbed methane in the matrix pores by combining the preset geometric model, preset initial conditions and preset boundary conditions, and calculate the second gas pressure and second core temperature of the coalbed methane in the fracture. The calculation module is also used to input the first gas pressure, the first core temperature, the second gas pressure, and the second core temperature into the gas state equation and the isothermal adsorption equation for calculation, so as to obtain the second gas data and the second methane carbon isotope value corresponding to the coalbed methane. The calculation module is further configured to solve the preset control equation based on the first gas data and the second gas data, the first methane carbon isotope value and the second methane carbon isotope value, to obtain the amount of adsorbed gas and free gas in the coalbed methane.

9. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1 to 7.

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