A Method for Establishing a Calculation Model for Total Gas Content in High-Temperature and High-Pressure Methane-Bearing Rocks

Abstract

This invention provides a method for establishing a calculation model for the total gas content of high-temperature, high-pressure methane-bearing rocks, belonging to the field of geophysical logging and reservoir evaluation technology in oil and gas exploration. The method includes the following steps: preparing aqueous solutions of dissolved methane-bearing formations with different proportions, and measuring the resistivity of these solutions; obtaining a formation hydroelectric response model based on multivariate linear coupling fitting of data from multiple experimental conditions; constructing a gas abundance model containing only dissolved gas when the water saturation Sw=1; and constructing a total gas abundance model with both dissolved and free gas when the water saturation Sw<1. The relationship between resistivity and gas abundance is established and compared with core resistivity to determine the gas abundance of the core. The reliability of the model is verified in an implementation case. This invention avoids the problem of directly measuring gas content in traditional pressure-dissolved gas reservoirs, and helps improve the accuracy of gas content identification and evaluation in exploration and development wells.

Description

Technical Field

[0001] This invention relates to the field of geophysical logging and reservoir evaluation technology for oil and gas exploration, and in particular to a method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks. Background Technology

[0002] As oil and gas exploration and development advances into deeper, higher-temperature, and higher-pressure areas, the solubility of methane gas in rock pore water is increasing, leading to larger errors in the calculation of total gas content. In these reservoirs, methane exists not only as free gas but also in large quantities as dissolved gas in the formation water, giving the reservoir complex electrical characteristics controlled by both dissolved and free gas. Existing Archie and Indonesian formulas primarily address free gas reservoirs and struggle to accurately describe the resistivity increase effect caused by dissolved gas, resulting in significant errors in the inversion of total gas content in high-temperature and high-pressure reservoirs.

[0003] Currently, there is a lack of computational models that can consider changes in methane solubility under conditions of temperature, pressure, and salinity, and simultaneously reflect the combined effects of dissolved and free methane on the electrical properties of rocks. Therefore, the total gas content is difficult to accurately characterize, which seriously affects the resource assessment of this type of reservoir. Summary of the Invention

[0004] In view of this, the present invention aims to propose a method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-containing rocks, which can solve the problem that the rock resistivity and gas content are difficult to respond accurately when dissolved methane and free methane coexist, as well as the technical bottleneck that the total gas content of high-temperature and high-pressure reservoirs is difficult to quantify.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks, comprising the following steps: Step S1: Prepare formation aqueous solutions containing dissolved methane in different proportions, and measure the resistivity of the formation aqueous solutions for different proportions of dissolved methane. Step S2: Based on data from multiple experimental conditions, the formation hydroelectric response model Rw is obtained through multivariate linear coupling fitting. Step S3: The total gas content is expressed as gas abundance. When the water saturation Sw=1, the formation hydroelectric response model Rw is substituted into the Indonesian formula to construct a model of the relationship between gas abundance and core resistivity containing only dissolved gas. Step S4: When the water saturation Sw < 1, substitute the formation hydroelectric response model Rw into the Indonesian formula, replace the water saturation with gas abundance and solubility, and construct a model relating the total gas abundance to the core resistivity. Step S5: Based on the model established in steps S3 and S4, establish the relationship between resistivity and gas abundance, and compare it with the core resistivity to determine the gas abundance of the core.

[0006] Furthermore, step S1 includes: Step S11: Inject a known volume of formation water into the sample preparation system, and then introduce a set volume of methane gas into the sample preparation system. Step S12: Adjust the temperature and pressure of the sample preparation system to the experimental conditions. After the temperature and pressure have been stabilized for 2 hours, start the stirring device of the sample preparation system and stir for more than 60 minutes to obtain water containing dissolved methane. Step S13: The prepared aqueous solution containing dissolved methane is transported to the water resistivity measurement system. After setting the same temperature, pressure and salinity conditions as in steps S11 and S12, the resistivity of the simulated formation water is measured to obtain experimental data on the relationship between the amount of dissolved methane and the resistivity. Step S14: Repeat steps S11-S13. Each time steps S11-S13 are repeated, adjust at least one of the parameters of the three experimental conditions: the volume of methane gas introduced into the sample preparation system, the temperature of the sample preparation system, and the pressure. Then measure the resistivity of the simulated formation water. Finally, obtain multiple sets of experimental data on the relationship between methane dissolution and resistivity under different temperatures, pressures, and salinity conditions.

[0007] Furthermore, step S2 includes: based on the resistivity of the formation water containing dissolved methane gas in the experiment. The relationship between methane solubility and different mineralization, pressures, and temperatures was analyzed using multivariate linear coupling to obtain the relationship between temperature T, pressure P, mineralization S, and dissolved methane content R for any given conditions. G Formation water resistivity under certain conditions The model and calculation formula are as follows: Where T is temperature (°C); P is pressure (MPa); S is mineralization (g / L); R G is the dissolved methane content, L / L; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution, obtained from experimental data, and are dimensionless.

[0008] Furthermore, step S3 includes: when SW=1, there is no free gas, the formation gas exists in a dissolved state, and the gas abundance GA is less than or equal to the solubility R of methane gas in formation water. G max Simultaneously, the rock resistivity during the dissolved gas stage was established using the classic Indonesian formula. The relationship between the total gas content and the total gas content is calculated using the following formula: in, is the rock resistivity, Ω·m; GA is the gas abundance, L / L; The mud content is %; ρ is the resistivity of the clay, in Ω·m; denoted as porosity (%), m as cementation index, n as saturation index, and a as a constant, all dimensionless; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution, dimensionless.

[0009] Furthermore, step S4 includes: when SW < 1, the formation methane gas exists in both dissolved and free states, and the total gas abundance GA is greater than the solubility R of formation water methane gas. G max Simultaneously, the rock resistivity during the coexistence stage of dissolved gas and free gas was established using the Indonesian formula. The relationship between the total gas content and the total gas content is calculated using the following formula: in, is the rock resistivity, Ω·m; GA is the gas abundance, L / L; The mud content is %; ρ is the resistivity of the clay, in Ω·m; denoted as porosity (%), m as cementation index, n as saturation index, and a as a constant, all dimensionless; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution, dimensionless. This represents the maximum solubility of methane in the current formation water, in L / L.

[0010] Furthermore, step S5 includes: based on the core resistivity-gas abundance relationship model established in steps S3 and S4, performing a monotonically increasing curve of core resistivity and gas abundance, where each resistivity value in the curve corresponds to a unique gas abundance value; based on the actual core resistivity value, finding the gas abundance value corresponding to the actual core resistivity value on the monotonically increasing curve of resistivity and gas abundance, which is the total gas content calculated by the model.

[0011] Compared with existing technologies, the method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks described in this invention has the following advantages: This invention utilizes the influence of methane dissolution on formation water resistivity under high-temperature and high-pressure conditions, and combines this with core resistivity response data to establish a model relating the total gas content (gas abundance) of the core to the core resistivity. This model can accurately invert the total gas content (including dissolved and free gas) in the rock pore space when resistivity data is obtained from well logging. This invention not only solves the problem of large errors in the evaluation of the total gas content of high-temperature and high-pressure reservoirs using the traditional Archie / Indonesian formula, but also helps in the identification and resource evaluation of this type of reservoir in well logging evaluation. Attached Figure Description

[0012] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the overall process of the method described in this invention; Figure 2 The experimental relationship curves of formation water resistivity versus methane dissolution under different temperatures, pressures, and salinity conditions are shown. Figure 3 To construct a graph showing the relationship between gas abundance and rock resistivity based on the newly established integrated model for forward modeling; Figure 4 A comparison chart of measured and retrieved gas abundance (GA≤R) was used to validate the model. G max ); Figure 5 A comparison chart of measured gas abundance and inverted gas abundance (GA>R) is used to validate the model. G max ). Detailed Implementation

[0013] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0014] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0015] like Figures 1-5 As shown, this invention provides a method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks. Using this method, the total gas content of dissolved and free methane within the rock can be rapidly and accurately inverted using parameters such as resistivity obtained from well logging under high-temperature and high-pressure conditions. This invention establishes a formation water resistivity model with arbitrary temperature, pressure, salinity, and dissolved gas volume through high-temperature and high-pressure formation water experiments containing dissolved methane. This model is then combined with the classic Indonesian formula to innovatively establish an integrated inversion model for the total gas content of dissolved and free gas in multiple states. This achieves quantitative inversion of the total gas content of high-temperature and high-pressure methane-bearing rocks. The reliability of the model is verified by establishing the relationship between resistivity and total gas content (gas abundance) through high-temperature and high-pressure core experiments. This method avoids the problem of difficulty in directly measuring gas content in traditional pressure-dissolved gas reservoirs, and helps improve the accuracy of gas content identification and evaluation in exploration and development wells. Specifically, the method of this invention includes the following steps: The total gas content is expressed as gas abundance; gas abundance refers to the total volume of dissolved methane and free methane contained in a unit pore volume under standard conditions.

[0016] Step S1 involves preparing formation aqueous solutions containing dissolved methane in different proportions, and simultaneously measuring the resistivity of the formation aqueous solutions with different proportions. Specifically, the solution experimental equipment includes a sample preparation system, a water resistivity measurement system, and a data acquisition system. Step S11: Inject a known volume of formation water into the sample preparation system, and then introduce a set volume of methane gas into the sample preparation system. Step S12: Adjust the temperature and pressure of the sample preparation system to the experimental conditions. After the temperature and pressure have been stabilized for 2 hours, start the stirring device of the sample preparation system and stir for more than 60 minutes to ensure that the methane gas is fully dissolved in the water, thereby obtaining water containing dissolved methane. Step S13: The prepared aqueous solution containing dissolved methane is transported to the water resistivity measurement system. After setting the same temperature, pressure and salinity conditions as in steps S11 and S12, the resistivity of the simulated formation water is measured to obtain experimental data on the relationship between the amount of dissolved methane and the resistivity. Step S14: Repeat steps S11-S13. Each time steps S11-S13 are repeated, adjust at least one of the parameters of the three experimental conditions: the volume of methane gas introduced into the sample preparation system, the temperature of the sample preparation system, and the pressure. Then measure the resistivity of the simulated formation water. Finally, obtain multiple sets of experimental data on the relationship between methane dissolution and resistivity under different temperatures (110℃~170℃), pressures (60MPa~100MPa), and salinity conditions.

[0017] Step S2: Based on data from multiple experimental conditions, the relationship between the resistivity Rw of formation water containing dissolved methane and temperature, pressure, methane dissolution, and formation water salinity is obtained through multivariate linear coupling fitting. Specifically, based on the experimental relationship between formation water resistivity and methane dissolution at different salinities, pressures, and temperatures, multivariate linear coupling fitting is used to obtain the relationship between arbitrary temperature T, pressure P, salinity S, and dissolved methane content Rw. G Formation water resistivity under certain conditions The model and calculation formula are as follows: Where T is temperature (°C); P is pressure (MPa); S is mineralization (g / L); R G is the dissolved methane content, L / L; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution, obtained from experimental data, and are dimensionless.

[0018] Step S3: The total gas content is expressed as gas abundance. When the water saturation Sw=1, the formation hydroelectric response model Rw is substituted into the Indonesian formula to construct a model relating gas abundance to core resistivity containing only dissolved gas. Specifically, when SW=1, there is no free gas, and the formation gas exists in a dissolved state. The gas abundance GA (methane content per unit pore volume under standard conditions, L / L) is less than or equal to the solubility of methane in formation water R. G max Simultaneously, the rock resistivity during the dissolved gas stage was established using the classic Indonesian formula. The relationship between total gas content (GA) and total gas content is calculated using the following formula: in, is the rock resistivity, Ω·m; GA is the gas abundance, L / L; The mud content is %; ρ is the resistivity of the clay, in Ω·m; denoted as porosity (%), m as cementation index, n as saturation index, and a as a constant, all dimensionless; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution, dimensionless.

[0019] Step S4: When the water saturation Sw < 1, substitute the formation hydroelectric response model Rw into the Indonesian formula, and replace the water saturation with gas abundance and solubility to construct a model relating total gas abundance to core resistivity. Specifically, when SW < 1, free gas is present, and formation methane gas exists in both dissolved and free states. The total gas abundance GA is greater than the solubility R of formation water methane gas. G max Simultaneously, the rock resistivity during the coexistence stage of dissolved gas and free gas was established by combining the classic Indonesian formula. The Indonesian formula, which is the existing technology, is a model relating the relationship between total gas content (i.e., gas abundance GA) and the total gas content. The calculation formula is as follows: Wherein, GA represents gas abundance, in L / L; The content of clay is expressed as % (%). The resistivity of clay is expressed in Ω·m. Porosity is expressed as %; m is the cementation index; n is the saturation index; a is a constant, all dimensionless; A, B, and C are the fitting coefficients for the resistivity of the aqueous solution containing dissolved methane gas. This represents the maximum solubility of methane in the current formation water, expressed in L / L.

[0020] Step S5: Based on the core resistivity-gas abundance relationship model established in steps S3 and S4, a monotonically increasing curve of core resistivity and gas abundance is generated. Each resistivity value in this curve corresponds to a unique gas abundance value. Based on the actual core resistivity value, the gas abundance value corresponding to the actual core resistivity value on the monotonically increasing curve of resistivity and gas abundance is found. This gas abundance value is the total gas content calculated by the model.

[0021] Example 1 The method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks, as described in this embodiment, includes the following steps: Step 1: Preparation of aqueous solution containing dissolved methane. Inject a known volume of formation water (e.g., 10000 ppm, 14000 ppm, 32000 ppm) into the mixing system, and introduce methane gas of different predetermined volumes into the mixing system. Adjust the temperature and pressure of the mixing system to the experimental conditions. After the temperature (e.g., 80℃~180℃) and pressure (e.g., 40MPa~120MPa) have stabilized for 2 hours, start the stirring device of the mixing system and stir for at least 60 minutes to ensure that the methane gas is fully dissolved in the water.

[0022] A pre-prepared aqueous solution containing dissolved methane is delivered to a water resistivity measurement system. After setting multiple different temperature (e.g., 80℃~180℃), pressure (e.g., 40MPa~120MPa), and salinity (e.g., 10000ppm, 14000ppm, 32000ppm) conditions, the resistivity of the simulated formation water is measured to obtain experimental data on the relationship between methane dissolution and resistivity.

[0023] It should be noted that the various proportions of dissolved methane-containing aqueous solutions are prepared separately. After preparing one proportion of the dissolved methane-containing aqueous solution, it is necessary to set the temperature (e.g., 80℃~180℃), pressure (e.g., 40MPa~120MPa), and salinity (e.g., 10000ppm, 14000ppm, 32000ppm) conditions for that proportion of aqueous solution, and measure the resistivity of the simulated formation water. Then, experimental data on the relationship between methane dissolution and resistivity are obtained. After completing the experiment with this proportion of dissolved methane-containing aqueous solution, another proportion of dissolved methane-containing aqueous solution is prepared and tested according to step 1. This process is repeated until multiple proportions of dissolved methane-containing aqueous solutions are prepared and multiple sets of experimental data on the relationship between methane dissolution and resistivity under different temperature, pressure, and salinity conditions are obtained.

[0024] Step 2: Combine the formation water resistivity data obtained in Step 1 under different temperature, pressure, and salinity conditions with the corresponding methane dissolution amount R. G Organize, such as Figure 2 As shown. Where RG To characterize the methane content dissolved in simulated formation water, a nonlinear least squares fitting method was used to analyze the formation water resistivity as a function of R. G By fitting the relationship between the changes, we obtain empirical formulas describing the hydroelectric behavior of formations under different temperature, pressure, and salinity conditions: Where Rw is the resistivity of formation water, and the coefficients A, B, and C vary with temperature, pressure, and salinity, respectively.

[0025] Since the above three variables and formation water resistivity all follow an exponential function law, a formation water electrical response model applicable to different T-P-S and dissolved gas conditions is further obtained through multivariate linear coupling fitting. The calculation formula is as follows: Where T is temperature (°C); P is pressure (MPa); S is mineralization (g / L); R G is the dissolved methane content, L / L; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution, obtained from experimental data, and are dimensionless.

[0026] Step 3: Under the condition of SW=1 water saturation, there is no free gas in the core pores, only methane dissolved in the formation water. Substituting the formation hydroelectric response model Rw obtained in Step 2 into the Indonesian formula, and given parameters such as rock porosity, clay content, clay resistivity, cementation index, and saturation index, a rock resistivity-gas abundance relationship model under dissolved gas conditions is constructed, the expression of which is: Wherein, GA represents gas abundance, in L / L; The content of clay is expressed as % (%). The resistivity of clay is expressed in Ω·m. Porosity is expressed as %; m is the cementation index; n is the saturation index; a is a constant, all dimensionless; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution, dimensionless.

[0027] Step 4: When SW < 1, free gas is present. Formation methane gas exists in both dissolved and free states, and the total gas abundance GA is greater than the solubility R of formation water methane gas. G max Substitute the formation hydroelectric response model Rw obtained in step 3 into the Indonesian formula, and replace the water saturation Sw with (1 - (total gas saturation - dissolved gas saturation)). Both the total gas saturation and free gas saturation need to be verified by GA and R. G maxPerform volume conversion under standard conditions to determine the rock resistivity during the stage where dissolved and free gases coexist. The calculation formula for the relationship model between total gas content (i.e., gas abundance GA) and total gas content is as follows: Wherein, GA represents gas abundance, in L / L; The content of clay is expressed as % (%). The resistivity of clay is expressed in Ω·m. Porosity is expressed as %; m is the cementation index; n is the saturation index; a is a constant, all dimensionless; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution. This represents the maximum solubility of methane in the current formation water, expressed in L / L.

[0028] Step 5: Prepare aqueous solutions with different methane dissolution amounts using a sample mixing system at the target experimental temperature and pressure, and inject the aqueous solutions with different methane dissolution amounts into the core to measure resistivity data; after all cores have completed resistivity measurements under the condition of saturated aqueous solutions with dissolved methane, use methane gas to displace the aqueous solutions containing dissolved methane in the core for different amounts of methane dissolution, thereby obtaining the core resistivity under different water saturation levels.

[0029] Using a series of data measured in experiments, through formulas The measured gas abundance is obtained. Based on the core resistivity-gas abundance relationship model established in steps S3 and S4, a monotonically increasing curve of core resistivity versus gas abundance is derived. Each resistivity value in this curve corresponds to a unique gas abundance value. Figure 3 Based on the actual resistivity value of the core sample, find the corresponding gas abundance value on the monotonically increasing curve of resistivity versus gas abundance. This value is the total gas content obtained from the model inversion. Compare the relationship between the gas abundance obtained from the core experiment and the gas abundance obtained from the model inversion to verify the model (GA≤R). G max and GA>R G max The validity of GA≤R. G max The gas abundance inverted by the time model and the actual gas abundance in the experimental core are as follows: Figure 4 As shown; GA>R G max The gas abundance inverted by the time model and the actual gas abundance in the experimental core are as follows: Figure 5 As shown, the average relative error between the model's calculated values ​​and the actual values ​​is less than 5%, proving the model's effectiveness.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks, characterized in that, Includes the following steps: Step S1: Prepare formation aqueous solutions containing dissolved methane in different proportions, and measure the resistivity of the formation aqueous solutions for different proportions of dissolved methane. Step S2: Based on data from multiple experimental conditions, the formation hydroelectric response model Rw is obtained through multivariate linear coupling fitting. Step S3: The total gas content is expressed as gas abundance. When the water saturation Sw=1, the formation hydroelectric response model Rw is substituted into the Indonesian formula to construct a model of the relationship between gas abundance and core resistivity containing only dissolved gas. Step S4: When the water saturation Sw < 1, substitute the formation hydroelectric response model Rw into the Indonesian formula, replace the water saturation with gas abundance and solubility, and construct a model relating the total gas abundance to the core resistivity. Step S5: Based on the model established in steps S3 and S4, establish the relationship between resistivity and gas abundance, and compare it with the core resistivity to determine the gas abundance of the core.

2. The method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks according to claim 1, characterized in that, Step S1 includes: Step S11: Inject a known volume of formation water into the sample preparation system, and then introduce a set volume of methane gas into the sample preparation system. Step S12: Adjust the temperature and pressure of the sample preparation system to the experimental conditions. After the temperature and pressure have been stabilized for 2 hours, start the stirring device of the sample preparation system and stir for more than 60 minutes to obtain water containing dissolved methane. Step S13: The prepared aqueous solution containing dissolved methane is transported to the water resistivity measurement system. After setting the same temperature, pressure and salinity conditions as in steps S11 and S12, the resistivity of the simulated formation water is measured to obtain experimental data on the relationship between the amount of dissolved methane and the resistivity. Step S14: Repeat steps S11-S13. Each time steps S11-S13 are repeated, adjust at least one of the parameters of the three experimental conditions: the volume of methane gas introduced into the sample preparation system, the temperature of the sample preparation system, and the pressure. Then measure the resistivity of the simulated formation water. Finally, obtain multiple sets of experimental data on the relationship between methane dissolution and resistivity under different temperatures, pressures, and salinity conditions.

3. The method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks according to claim 1, characterized in that, Step S2 includes: based on the resistivity of formation water containing dissolved methane gas in the experiment. The relationship between methane solubility and different mineralization, pressures, and temperatures was analyzed using multivariate linear coupling to obtain the relationship between temperature T, pressure P, mineralization S, and dissolved methane content R for any given conditions. G Formation water resistivity under certain conditions The model and calculation formula are as follows: Where T is temperature (°C); P is pressure (MPa); S is mineralization (g / L); R G is the dissolved methane content, L / L; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution, obtained from experimental data, and are dimensionless.

4. The method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks according to claim 1, characterized in that, Step S3 includes: when SW=1, there is no free gas, the formation gas exists in a dissolved state, and the gas abundance GA is less than or equal to the solubility R of methane gas in formation water. G max Simultaneously, the rock resistivity during the dissolved gas stage was established using the classic Indonesian formula. The relationship between the total gas content and the total gas content is calculated using the following formula: in, is the rock resistivity, Ω·m; GA is the gas abundance, L / L; The mud content is %; ρ is the resistivity of the clay, in Ω·m; denoted as porosity (%), m as cementation index, n as saturation index, and a as a constant, all dimensionless; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution, dimensionless.

5. The method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks according to claim 1, characterized in that, Step S4 includes: when SW < 1, the formation contains free gas, with methane gas existing in both dissolved and free states, and the total gas abundance GA is greater than the solubility R of methane gas in formation water. G max Simultaneously, the rock resistivity during the coexistence stage of dissolved gas and free gas was established using the Indonesian formula. The relationship between the total gas content and the total gas content is calculated using the following formula: in, is the rock resistivity, Ω·m; GA is the gas abundance, L / L; The mud content is %; ρ is the resistivity of the clay, in Ω·m; denoted as porosity (%), m as cementation index, n as saturation index, and a as a constant, all dimensionless; A, B, and C are the fitting coefficients for the resistivity of the pressurized dissolved gas solution, dimensionless. This represents the maximum solubility of methane in the current formation water, in L / L.

6. The method for establishing a calculation model for the total gas content of high-temperature and high-pressure methane-bearing rocks according to claim 1, characterized in that, Step S5 includes: based on the core resistivity-gas abundance relationship model established in steps S3 and S4, performing a monotonically increasing curve of core resistivity and gas abundance, where each resistivity value in the curve corresponds to a unique gas abundance value; based on the actual core resistivity value, finding the gas abundance value corresponding to the actual core resistivity value on the monotonically increasing curve of resistivity and gas abundance, which is the total gas content calculated by the model.

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