Method and device for determining recoverable reserves of shale gas and storage medium

Abstract

The invention discloses a shale gas recoverable reserve determination method and device and a storage medium, and relates to the technical field of shale gas exploitation. The method comprises the following steps: fitting parameters such as a dynamic desorption lag index, a surface site occupancy rate, an adsorption equilibrium constant, an adsorption phase volume maximum value and the like by utilizing shale gas reservoir parameters, experiment numbers of at least six groups of adsorption and desorption experiments and an adsorption and desorption model comprising the dynamic desorption lag index subjected to temperature and pressure changes; different pressure, temperature and excess adsorption capacity are used as fitting variables in the fitting process, so that the fitted parameters, especially the dynamic desorption lag index, can capture the relationship between the desorption lag effect and the temperature and pressure variables, and the relationship between the desorption lag effect and the temperature and pressure variables can be obtained. Therefore, the determination precision of the real gas adsorption amount of the target reservoir under different temperature and pressure conditions is remarkably improved, the recoverable reserves of the shale gas of the target reservoir are determined more accurately, and the accuracy of determining the recoverable reserves is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of shale gas extraction, and in particular to a method, device and storage medium for determining recoverable reserves of shale gas. Background Art

[0002] Shale gas is a significant unconventional natural gas resource. Compared to conventional natural gas, a significant portion of the gas in shale exists in an adsorbed state. When reservoir pressure decreases, this gas transitions from an adsorbed state to a desorbed state, allowing it to be recovered. However, because the adsorption and desorption processes in shale gas are not fully reversible, not all adsorbed gas is released during decompression, resulting in residual gas remaining in an adsorbed state, creating a desorption hysteresis effect. When determining recoverable shale gas reserves, the impact of desorption hysteresis needs to be considered to improve the accuracy of the results.

[0003] The Langmuir model is used in related art to describe the monolayer adsorption and desorption of gas molecules on solid surfaces. This model assumes that the adsorption process is an interaction between molecules and surface sites, ultimately reaching a dynamic equilibrium. Based on this model, a hysteresis parameter β is introduced to describe the desorption hysteresis effect of shale gas. Specifically, the hysteresis parameter β is an empirical parameter between 0 and 1. When β = 1, there is no hysteresis effect. When β = 0, there are no adsorption sites available for desorption, resulting in no gas release.

[0004] However, since the hysteresis parameter is an empirical parameter, and experimental studies have shown that the size of the hysteresis parameter is affected by temperature and maximum equilibrium pressure, describing the desorption hysteresis effect only by using the empirical hysteresis parameter cannot capture the relationship between the desorption hysteresis effect and temperature and pressure variables, thereby reducing the accuracy of adsorption and desorption simulation and making it impossible to accurately predict the recoverable reserves of shale gas. Summary of the Invention

[0005] The present invention provides a method, device, and storage medium for determining recoverable shale gas reserves to address the problem in related technologies where hysteresis parameters are merely empirical parameters and fail to capture the relationship between the desorption hysteresis effect and temperature and pressure variables, thereby reducing the accuracy of adsorption and desorption simulations and failing to accurately predict recoverable shale gas reserves. The technical solution is as follows:

[0006] In a first aspect, a method for determining recoverable reserves of shale gas is provided, the method comprising:

[0007] Obtaining average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least six sets of adsorption and desorption experiments of the target shale gas reservoir, wherein the experimental data include experimental pressure, experimental temperature, experimental excess adsorption capacity, experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density in each set of experimental data of the at least six sets of adsorption and desorption experiments are all constant values;

[0008] Determining the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir based on the experimental data of the at least six groups of adsorption and desorption experiments, the reservoir pressure, and the reservoir temperature, and based on an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure, wherein the adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure is an improved adsorption and desorption model based on the Langmuir adsorption and desorption model by introducing pressure, temperature, and excess adsorption amount to indicate the dynamic desorption hysteresis of gas in the reservoir;

[0009] The recoverable reserves of the target shale gas reservoir are determined based on the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, the average reservoir porosity, the water saturation, the rock density, the gas volume coefficient, and the reservoir pressure.

[0010] Optionally, the determining of the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir based on the experimental data of the at least six groups of adsorption and desorption experiments, the reservoir pressure, and the reservoir temperature, based on an adsorption and desorption model including a dynamic desorption hysteresis index affected by temperature and pressure, comprises:

[0011] Determine the dynamic desorption hysteresis index, the maximum adsorption phase volume, the pre-exponential factor, the adsorption energy, the theoretical maximum adsorption capacity, and the reduction coefficient of the target shale gas reservoir using a nonlinear least squares fitting method based on the experimental data of the at least six groups of adsorption and desorption experiments and an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure;

[0012] determining an adsorption equilibrium constant of the target shale gas reservoir according to the reservoir pressure, the reservoir temperature, the experimental ideal gas constant, the pre-exponential factor, and the adsorption energy;

[0013] The surface site occupancy of the target shale gas reservoir is determined according to the adsorption equilibrium constant and the reservoir pressure.

[0014] Optionally, the adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure is specifically:

[0015]

[0016] Where p is the experimental pressure, Pa; T is the experimental temperature, K; n e is the experimental excess adsorption capacity, mol·kg -1 ;p m is the experimental maximum equilibrium pressure, Pa; R is the experimental ideal gas constant, J·mol -1 ·K -1 ρ g is the experimental gas volume density, g / m 3 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; n m is the theoretical maximum adsorption capacity, mol·kg -1 ;D T is the reduction factor, K -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1 .

[0017] Optionally, determining the adsorption equilibrium constant according to the reservoir pressure, the reservoir temperature, the experimental ideal ti'j constant, the pre-exponential factor, and the adsorption energy includes:

[0018] The adsorption equilibrium constant is determined by the following formula based on the reservoir pressure, the reservoir temperature, the experimental ideal gas constant, the pre-exponential factor, and the adsorption energy:

[0019]

[0020] Where b is the adsorption equilibrium constant, dimensionless; R is the experimental ideal gas constant, J·mol -1 ·K -1 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ;p b is the reservoir pressure, Pa; T b is the reservoir temperature, K.

[0021] Optionally, determining the surface site occupancy according to the adsorption equilibrium constant and the reservoir pressure includes:

[0022] According to the adsorption equilibrium constant and the reservoir pressure, the surface site occupancy is determined by the following formula:

[0023]

[0024] Where θ is the rock surface site occupancy, dimensionless; b is the adsorption equilibrium constant, dimensionless; p b is the reservoir pressure, Pa.

[0025] Optionally, determining the recoverable reserves of the target shale gas reservoir according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, the reservoir average porosity, the water saturation, the rock density, the gas volume coefficient, and the reservoir pressure includes:

[0026] Determining the adsorbed gas volume of the target shale gas reservoir according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, and the gas volume coefficient;

[0027] Determining the free gas volume of the target shale gas reservoir according to the average porosity of the reservoir, the water saturation, the rock density and the gas volume coefficient;

[0028] The recoverable reserves of the target shale gas reservoir are determined by summing the free gas volume of the target shale gas reservoir and the adsorbed gas volume of the target shale gas reservoir.

[0029] Optionally, determining the adsorbed gas capacity of the target shale gas reservoir according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, and the gas volume coefficient includes:

[0030] The adsorbed gas volume of the target shale gas reservoir is determined according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, and the gas volume coefficient using the following formula:

[0031]

[0032] Where V a is the amount of adsorbed gas in the target shale gas reservoir under surface conditions, m 3 kg -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1; b is the adsorption equilibrium constant, dimensionless; θ is the rock surface site occupancy, dimensionless; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; p m is the maximum equilibrium pressure of the experiment, Pa; p b is the reservoir pressure, Pa; b g is the gas volume coefficient, dimensionless.

[0033] Optionally, determining the free gas volume of the target shale gas reservoir according to the average porosity of the reservoir, the water saturation, the rock density, and the gas volume coefficient includes:

[0034] The free gas volume of the target shale gas reservoir is determined according to the average reservoir porosity, the water saturation, the rock density, and the gas volume coefficient using the following formula:

[0035]

[0036] Where V f is the free gas volume of the target shale gas reservoir under surface conditions, m 3 kg -1 ;S w is the water saturation, dimensionless; ρ r is the rock density in g / m 3 ; is the average reservoir porosity, dimensionless; b g is the gas volume coefficient, dimensionless.

[0037] In a second aspect, a device for determining recoverable reserves of shale gas is provided, the device comprising:

[0038] an acquisition module, configured to acquire the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least six sets of adsorption and desorption experiments of the target shale gas reservoir, wherein the experimental data include experimental pressure, experimental temperature, experimental excess adsorption capacity, experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density in each set of experimental data of the at least six sets of adsorption and desorption experiments are all constant values;

[0039] a first determination module, configured to determine, based on the experimental data of the at least six groups of adsorption and desorption experiments, the reservoir pressure, and the reservoir temperature, a dynamic desorption hysteresis index, a surface site occupancy, an adsorption equilibrium constant, and a maximum adsorption phase volume of the target shale gas reservoir, based on an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure, wherein the adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure is an improved adsorption and desorption model based on the Langmuir adsorption and desorption model by introducing pressure, temperature, and excess adsorption amount to indicate the dynamic desorption hysteresis of gas in the reservoir;

[0040] The second determination module is used to determine the recoverable reserves of the target shale gas reservoir based on the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, the average reservoir porosity, the water saturation, the rock density, the gas volume coefficient, and the reservoir pressure.

[0041] Optionally, the first determining module includes:

[0042] A first determining unit is configured to determine the dynamic desorption hysteresis index, the maximum adsorption phase volume, the pre-exponential factor, the adsorption energy, the theoretical maximum adsorption capacity, and the reduction coefficient of the target shale gas reservoir using a nonlinear least squares fitting method based on the experimental data of the at least six groups of adsorption and desorption experiments and an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure;

[0043] a second determining unit, configured to determine an adsorption equilibrium constant of the target shale gas reservoir according to the reservoir pressure, the reservoir temperature, the experimental ideal gas constant, the pre-exponential factor, and the adsorption energy;

[0044] The third determining unit is configured to determine the surface site occupancy of the target shale gas reservoir according to the adsorption equilibrium constant and the reservoir pressure.

[0045] Optionally, the adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure changes in the first determination unit is specifically:

[0046]

[0047] Where p is the experimental pressure, Pa; T is the experimental temperature, K; n e is the experimental excess adsorption capacity, mol·kg -1 ;p m is the experimental maximum equilibrium pressure, Pa; R is the experimental ideal gas constant, J·mol -1 ·K -1 ρ g is the experimental gas volume density, g / m3 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; n m is the theoretical maximum adsorption capacity, mol·kg -1 ;D T is the reduction factor, K -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1 .

[0048] Optionally, the second determining unit includes:

[0049] The adsorption equilibrium constant is determined by the following formula based on the reservoir pressure, the reservoir temperature, the experimental ideal gas constant, the pre-exponential factor, and the adsorption energy:

[0050]

[0051] Where b is the adsorption equilibrium constant, dimensionless; R is the experimental ideal gas constant, J·mol -1 ·K -1 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ;p b is the reservoir pressure, Pa; T b is the reservoir temperature, K.

[0052] Optionally, the third determining unit includes:

[0053] According to the adsorption equilibrium constant and the reservoir pressure, the surface site occupancy is determined by the following formula:

[0054]

[0055] Where θ is the rock surface site occupancy, dimensionless; b is the adsorption equilibrium constant, dimensionless; p b is the reservoir pressure, Pa.

[0056] Optionally, the second determining module includes:

[0057] a fourth determining unit, configured to determine the adsorbed gas volume of the target shale gas reservoir according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, and the gas volume coefficient;

[0058] a fifth determining unit, configured to determine the free gas volume of the target shale gas reservoir according to the average porosity of the reservoir, the water saturation, the rock density, and the gas volume coefficient;

[0059] The sixth determining unit is configured to determine the recoverable reserves of the target shale gas reservoir by taking the sum of the free gas volume of the target shale gas reservoir and the adsorbed gas volume of the target shale gas reservoir.

[0060] Optionally, the fourth determining unit includes:

[0061] The adsorbed gas volume of the target shale gas reservoir is determined according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, and the gas volume coefficient using the following formula:

[0062]

[0063] Where V a is the amount of adsorbed gas in the target shale gas reservoir under surface conditions, m 3 kg -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1 ; b is the adsorption equilibrium constant, dimensionless; θ is the rock surface site occupancy, dimensionless; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; p m is the maximum equilibrium pressure of the experiment, Pa; p b is the reservoir pressure, Pa; b g is the gas volume coefficient, dimensionless.

[0064] Optionally, the fifth determining unit includes:

[0065] The free gas volume of the target shale gas reservoir is determined according to the average reservoir porosity, the water saturation, the rock density, and the gas volume coefficient using the following formula:

[0066]

[0067] Where V f is the free gas volume of the target shale gas reservoir under surface conditions, m 3 kg -1 ;S w is the water saturation, dimensionless; ρ r is the rock density in g / m 3 ; is the average reservoir porosity, dimensionless; b g is the gas volume coefficient, dimensionless.

[0068] In a third aspect, a device for determining recoverable reserves of shale gas is provided, wherein the device comprises:

[0069] processor;

[0070] a memory for storing processor-executable instructions;

[0071] The processor is configured to execute the above-mentioned method for determining recoverable reserves of shale gas.

[0072] The technical solutions provided in the embodiments of the present application can at least bring the following beneficial effects:

[0073] In an embodiment of the present invention, the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least 6 groups of adsorption and desorption experiments of the target shale gas reservoir are obtained, wherein the experimental data include experimental pressure, experimental temperature, experimental excess adsorption amount, experimental maximum equilibrium pressure, experimental ideal gas constant and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant and experimental gas volume density in each group of experimental data of at least 6 groups of adsorption and desorption experiments are all constant values; based on the experimental data of at least 6 groups of adsorption and desorption experiments, reservoir pressure and reservoir temperature, a dynamic desorption hysteresis coefficient including the temperature and pressure changes is obtained. An adsorption-desorption model with a post-index is used to determine the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir. The adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure is an improved adsorption-desorption model based on the Langmuir adsorption-desorption model that introduces pressure, temperature, and excess adsorption capacity to indicate the dynamic desorption hysteresis. The recoverable reserves of the target shale gas reservoir are determined based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, average reservoir porosity, water saturation, rock density, gas volume coefficient, and reservoir pressure. That is, when determining the recoverable reserves of the target shale gas reservoir, this method uses an improved adsorption-desorption model that can indicate the dynamic desorption hysteresis of gas in the reservoir to fit relevant parameters such as the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume, and calculates the recoverable reserves of the reservoir based on these parameters. Since different pressures, temperatures, and excess adsorption amounts are used as fitting variables in the fitting process, the fitted parameters, especially the dynamic desorption hysteresis index, can capture the relationship between the desorption hysteresis effect and the temperature and pressure variables, thereby significantly improving the accuracy of determining the actual adsorbed gas volume of the target reservoir under different temperature and pressure conditions, and thus more accurately determining the recoverable reserves of the target reservoir shale gas, thereby improving the accuracy of determining the recoverable reserves. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0075] Figure 1 This is a flow chart of a method for determining recoverable reserves of shale gas provided by an embodiment of the present invention;

[0076] Figure 2 This is a flow chart of another method for determining recoverable reserves of shale gas provided by an embodiment of the present invention;

[0077] Figure 3 This is a schematic structural diagram of a device for determining recoverable reserves of shale gas provided by an embodiment of the present invention;

[0078] Figure 4 It is a structural diagram of a terminal 400 provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0079] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0080] Before explaining the embodiments of the present invention in detail, the terms, application scenarios and system architecture involved in the embodiments of the present invention are explained respectively.

[0081] First, the terms involved in the embodiments of the present invention are introduced.

[0082] Average reservoir porosity

[0083] Definition: The average percentage of pore volume in reservoir rock to the total rock volume.

[0084] Note: Characterizing the reservoir's ability to store fluids is the core parameter for calculating shale gas reserves.

[0085] Water saturation

[0086] Definition: The ratio of the volume of water in the pore space of a reservoir to the total pore volume.

[0087] Note: Affects oil and gas recoverability. High water saturation, such as >50%, may reduce gas flow capacity.

[0088] Rock density

[0089] Definition: Mass of reservoir rock per unit volume (unit: g / cm 3 ).

[0090] Description: Used to calculate porosity and formation stress.

[0091] Reservoir pressure

[0092] Definition: The absolute pressure to which the pore fluid in an underground reservoir is subjected (unit: Pa).

[0093] Note: The key parameters that determine gas desorption and seepage usually increase with increasing burial depth.

[0094] Reservoir temperature

[0095] Definition: The formation temperature of the reservoir (unit: K).

[0096] Description: Affects gas adsorption / desorption equilibrium and phase behavior.

[0097] Gas volume coefficient

[0098] Definition: The ratio of the volume of gas under underground reservoir conditions to the volume of the same mass of gas under standard surface conditions (dimensionless).

[0099] Description: Used to convert underground reserves into surface measurable volumes, which decrease as pressure increases.

[0100] Adsorption and desorption experiments

[0101] Definition: A test that measures the adsorption and desorption behavior of gases on rock surfaces by simulating reservoir temperature and pressure conditions in the laboratory.

[0102] Description: Core experimental method used to establish adsorption isotherm model.

[0103] Experimental pressure

[0104] Definition: The absolute pressure range applied in adsorption-desorption experiments (unit: Pa).

[0105] Note: The reservoir pressure must be covered to the critical desorption pressure, typically in the range of 0.1–30 MPa.

[0106] Experimental temperature

[0107] Definition: The constant temperature set for adsorption and desorption experiments (unit: K).

[0108] Note: The temperature must be consistent with the reservoir temperature to maintain experimental representativeness.

[0109] Experimental excess adsorption capacity

[0110] Definition: The measured adsorption amount minus the correction value of the pore volume occupied by free gas at the same temperature and pressure (unit: mol·kg -1 ).

[0111] Note: This parameter truly reflects the adsorption capacity of the rock surface, not the absolute adsorption amount.

[0112] Experimental maximum equilibrium pressure

[0113] Definition: The highest pressure point when the adsorption experiment reaches saturation adsorption. It is set manually (unit: Pa).

[0114] Description: The key boundary conditions that determine the shape of the adsorption isotherm.

[0115] Experimental ideal gas constant

[0116] Definition: Universal constant in the gas state formula (R = 8.314 J·mol -1 ·K -1 ).

[0117] Description: Used to calculate gas density and adsorption correction.

[0118] Experimental gas volume density

[0119] Definition: The mass of gas per unit volume under experimental conditions (unit: g / m 3 ).

[0120] Note: Calculated by state formula, used for correction of excess adsorption.

[0121] Adsorption-desorption model including dynamic desorption hysteresis exponent affected by temperature and pressure

[0122] Definition: A dimensionless dynamic parameter that characterizes the strength of the hysteresis effect caused by temperature and pressure changes during the adsorption-desorption process.

[0123] Explanation: Traditional models often ignore hysteresis or assume it to be constant. This index dynamically correlates temperature and pressure changes with hysteresis, a key innovation of this embodiment. It reflects the nonequilibrium characteristics of pore structure and gas migration resistance as they change with temperature and pressure. It is used to modify adsorption models and improve the accuracy of reserve predictions and development plans.

[0124] Next, the system architecture involved in the embodiments of the present invention is introduced.

[0125] The method for determining recoverable shale gas reserves provided in an embodiment of the present invention can be applied to a terminal having a data processing function. Specifically, the terminal can be a smart phone, tablet computer, laptop computer, desktop computer, or other terminal capable of data processing.

[0126] Figure 1 This is a flow chart of a method for determining recoverable reserves of shale gas provided by an embodiment of the present invention. Figure 1 , the method comprises the following steps:

[0127] Step 101: Obtain the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least six groups of adsorption and desorption experiments of the target shale gas reservoir, wherein the experimental data include experimental pressure, experimental temperature, experimental excess adsorption amount, experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density in each group of experimental data of the at least six groups of adsorption and desorption experiments are all constant values.

[0128] Step 102: Based on the experimental data of at least 6 groups of adsorption and desorption experiments, reservoir pressure and reservoir temperature, and based on an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure, determine the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir. The adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure is an improved adsorption and desorption model based on the Langmuir adsorption and desorption model that introduces pressure, temperature, and excess adsorption amount to indicate the dynamic desorption hysteresis of gas in the reservoir.

[0129] Step 103: Determine the recoverable reserves of the target shale gas reservoir based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, reservoir average porosity, water saturation, rock density, gas volume coefficient, and reservoir pressure.

[0130] In an embodiment of the present invention, the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least 6 groups of adsorption and desorption experiments of the target shale gas reservoir are obtained, wherein the experimental data include experimental pressure, experimental temperature, experimental excess adsorption amount, experimental maximum equilibrium pressure, experimental ideal gas constant and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant and experimental gas volume density in each group of experimental data of at least 6 groups of adsorption and desorption experiments are all constant values; based on the experimental data of at least 6 groups of adsorption and desorption experiments, reservoir pressure and reservoir temperature, a dynamic desorption hysteresis coefficient including the temperature and pressure changes is obtained. An adsorption-desorption model with a post-index is used to determine the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir. The adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure is an improved adsorption-desorption model based on the Langmuir adsorption-desorption model that introduces pressure, temperature, and excess adsorption capacity to indicate the dynamic desorption hysteresis. The recoverable reserves of the target shale gas reservoir are determined based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, average reservoir porosity, water saturation, rock density, gas volume coefficient, and reservoir pressure. That is, when determining the recoverable reserves of the target shale gas reservoir, this method uses an improved adsorption-desorption model that can indicate the dynamic desorption hysteresis of gas in the reservoir to fit relevant parameters such as the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume, and calculates the recoverable reserves of the reservoir based on these parameters. Since different pressures, temperatures, and excess adsorption amounts are used as fitting variables in the fitting process, the fitted parameters, especially the dynamic desorption hysteresis index, can capture the relationship between the desorption hysteresis effect and the temperature and pressure variables, thereby significantly improving the accuracy of determining the actual adsorbed gas volume of the target reservoir under different temperature and pressure conditions, and thus more accurately determining the recoverable reserves of the target reservoir shale gas, thereby improving the accuracy of determining the recoverable reserves.

[0131] Optionally, based on experimental data from at least six sets of adsorption and desorption experiments, reservoir pressure, and reservoir temperature, and based on an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure, the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir are determined, including:

[0132] Based on experimental data from at least six sets of adsorption and desorption experiments and an adsorption and desorption model that includes a dynamic desorption hysteresis index affected by temperature and pressure, a nonlinear least squares fitting method is used to determine the dynamic desorption hysteresis index, maximum adsorption phase volume, pre-exponential factor, adsorption energy, theoretical maximum adsorption capacity, and reduction coefficient of the target shale gas reservoir;

[0133] Determine the adsorption equilibrium constant of the target shale gas reservoir based on reservoir pressure, reservoir temperature, experimental ideal gas constant, pre-exponential factor, and adsorption energy;

[0134] The surface site occupancy of the target shale gas reservoir is determined based on the adsorption equilibrium constant and reservoir pressure.

[0135] Optionally, the adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure is specifically:

[0136] Where p is the experimental pressure, Pa; T is the experimental temperature, K; n e is the experimental excess adsorption capacity, mol·kg -1 ;p m is the experimental maximum equilibrium pressure, Pa; R is the experimental ideal gas constant, J·mol -1 ·K -1 ρ g is the experimental gas volume density, g / m 3 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; n m is the theoretical maximum adsorption capacity, mol·kg -1 ;D T is the reduction factor, K -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1 .

[0137] Optionally, the adsorption equilibrium constant is determined based on the reservoir pressure, reservoir temperature, experimental ideal gas constant, pre-exponential factor, and adsorption energy, including:

[0138] According to the reservoir pressure, reservoir temperature, experimental ideal gas constant, pre-exponential factor, and adsorption energy, the adsorption equilibrium constant is determined by the following formula:

[0139]

[0140] Where b is the adsorption equilibrium constant, dimensionless; R is the experimental ideal gas constant, J·mol -1 ·K -1 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ;p b is the reservoir pressure, Pa; T b is the reservoir temperature, K.

[0141] Optionally, the surface site occupancy is determined based on the adsorption equilibrium constant and the reservoir pressure, including:

[0142] According to the adsorption equilibrium constant and reservoir pressure, the surface site occupancy is determined by the following formula:

[0143]

[0144] Where θ is the rock surface site occupancy, dimensionless; b is the adsorption equilibrium constant, dimensionless; p b is the reservoir pressure, Pa.

[0145] Optionally, the recoverable reserves of the target shale gas reservoir are determined based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, average reservoir porosity, water saturation, rock density, gas volume coefficient, and reservoir pressure, including:

[0146] Determine the adsorbed gas volume of the target shale gas reservoir based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, and gas volume coefficient;

[0147] Determine the free gas volume of the target shale gas reservoir based on the average reservoir porosity, water saturation, rock density and gas volume coefficient;

[0148] The recoverable reserves of the target shale gas reservoir are determined by adding the free gas volume and the adsorbed gas volume of the target shale gas reservoir.

[0149] Optionally, the adsorbed gas volume of the target shale gas reservoir is determined based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, and gas volume coefficient, including:

[0150] Based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, and gas volume coefficient, the adsorbed gas volume of the target shale gas reservoir is determined using the following formula:

[0151]

[0152] Where V a is the amount of adsorbed gas in the target shale gas reservoir under surface conditions, m 3 kg -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1; b is the adsorption equilibrium constant, dimensionless; θ is the rock surface site occupancy, dimensionless; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; p m is the maximum equilibrium pressure of the experiment, Pa; p b is the reservoir pressure, Pa; b g is the gas volume coefficient, dimensionless.

[0153] Optionally, the free gas volume of the target shale gas reservoir is determined based on the average reservoir porosity, water saturation, rock density, and gas volume coefficient, including:

[0154] Based on the average reservoir porosity, water saturation, rock density and gas volume coefficient, the free gas volume of the target shale gas reservoir is determined by the following formula:

[0155]

[0156] Where V f is the free gas volume of the target shale gas reservoir under surface conditions, m 3 kg -1 ;S w is the water saturation, dimensionless; ρ r is the rock density in g / m 3 ; is the average reservoir porosity, dimensionless; b g is the gas volume coefficient, dimensionless.

[0157] All of the above optional technical solutions can be combined in any way to form optional embodiments of the present invention, and the embodiments of the present invention will not be described in detail one by one.

[0158] Figure 2 This is a flow chart of another method for determining recoverable shale gas reserves provided by an embodiment of the present invention. Figure 2 , the method comprises the following steps:

[0159] Step 201: Obtain the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least six groups of adsorption and desorption experiments of the target shale gas reservoir, wherein the experimental data include experimental pressure, experimental temperature, experimental excess adsorption amount, experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density in each group of experimental data of the at least six groups of adsorption and desorption experiments are all constants.

[0160] Parameters such as the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, and gas volume coefficient of the target shale gas reservoir can be input by the user, sent by other devices, or obtained by the shale gas reservoir integrated management system. For example, before determining the recoverable reserves of the target shale gas reservoir, the user logs into the shale gas reservoir integrated management system, obtains the reservoir parameters of the target shale gas by matching the target shale gas, and extracts the parameters such as the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, and gas volume coefficient required in the embodiments of the present invention into the device for further use.

[0161] The experimental data of at least six adsorption and desorption experiments can be input by the user, sent by other devices, or obtained from the adsorption and desorption experiment management system. For example, if a user conducts at least six adsorption and desorption experiments and records the experimental results in the adsorption and desorption experiment management system, the experimental data of at least six adsorption and desorption experiments can be obtained by querying the system.

[0162] It should be noted that the method for determining recoverable shale gas reserves provided in an embodiment of the present invention is based on intermediate data determined by the adsorption-desorption model fitting method, and the final recoverable reserves are determined using the intermediate data and acquired parameters. Therefore, in the fitting step, in order to improve fitting accuracy, it is necessary to set a minimum fitting data set. At least 6 sets of experimental data are the minimum data set when fitting parameters in an embodiment of the present invention. The fitting parameters fitted with less than 6 sets of experimental data are less reliable and cannot be used. At the same time, in order to improve fitting accuracy, the number of experimental data sets can be set to be higher than 6, for example, obtaining experimental data from 20 sets of adsorption-desorption experiments.

[0163] Step 202: Based on the experimental data of at least 6 groups of adsorption and desorption experiments, reservoir pressure and reservoir temperature, and based on an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure, determine the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir. The adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure is an improved adsorption and desorption model based on the Langmuir adsorption and desorption model that introduces pressure, temperature, and excess adsorption amount to indicate the dynamic desorption hysteresis of gas in the reservoir.

[0164] It should be noted that the embodiment of the present invention provides a method for determining recoverable shale gas reserves. When determining the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir, it can be directly determined in one step through an adsorption-desorption model that includes a dynamic desorption hysteresis index affected by temperature and pressure changes, or it can be determined in three sub-steps to provide users with more detailed intermediate data information.

[0165] The adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure is the core innovation of the embodiments of the present invention. The derivation process and theory of the model are described herein.

[0166] For the Langmuir model, the adsorption rate r a and desorption rate r d Given by formula (1)-formula (4):

[0167] r a =k a p(1-θ) (1)

[0168] r d =k d θ (2)

[0169]

[0170] Where r a is the adsorption rate, mol·m -2 ·s -1 ; r d is the desorption rate, mol·m -2 ·s -1 ;k a is the adsorption rate constant, mol·m -2 ·s -1 ·Pa -1 ;k d is the desorption rate constant, mol·m -2 ·s -1 ; p is the experimental pressure, Pa; T is the experimental temperature, K; θ is the rock surface site occupancy, dimensionless; b is the adsorption equilibrium constant, dimensionless; R is the experimental ideal gas constant, J·mol -1 ·K -1 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ; n0 is the maximum adsorption capacity, mol·kg -1 ;n a is the absolute adsorption capacity, mol·kg -1 .

[0171] Considering the existence of desorption hysteresis effect, only a part of the adsorption sites are available for desorption. Therefore, the desorption rate r d It can be modified into formula (5):

[0172] r d =βk d θ (5)

[0173] Where β is the hysteresis parameter, dimensionless; r d is the desorption rate, kd is the desorption rate constant, mol·m -2 ·s -1 ; θ is the rock surface site occupancy, dimensionless.

[0174] In formula (5), β is between 0 and 1. When β = 1, formula (5) is simplified to formula (2), indicating that there is no desorption hysteresis effect. When β = 0, it means that there are no adsorption sites available for desorption, resulting in no gas release.

[0175] The desorption hysteresis mechanism can be explained by the fact that gas adsorption in the reservoir causes deformation of the reservoir pore structure, resulting in pore throat contraction. During depressurization, gas molecules can escape through these contracted pore throats, but this requires more energy than their initial entry, leading to desorption hysteresis. Increasing the amount of adsorbed gas results in greater changes in the pore structure, thereby increasing the degree of desorption hysteresis.

[0176] In order to quantify this relationship, a semi-empirical linear formula for the lag parameter β is proposed, namely formula (6):

[0177] β=aε v +b (6)

[0178] Where β is the hysteresis parameter, dimensionless; a is the intermediate fitting coefficient, dimensionless; b is the adsorption equilibrium constant, dimensionless; ε V is the volume strain due to adsorption and is dimensionless.

[0179] Volume strain ε caused by adsorption V One step can be described as:

[0180]

[0181] When ε V =0, β is equal to 1; therefore, b is equal to 1. Therefore, the formula can be expressed as:

[0182] β=aε v +1 (8)

[0183] When p approaches infinity, n a ≈n0,ε V The value reaches its maximum value, denoted as ε Vm . Accordingly, β reaches its minimum value, which can be expressed as:

[0184] β min =aε vm +1 (9)

[0185] ε vm =ε g n0 (10)

[0186] The value on the right side of formula (8) is between 0 and 1. Substituting c for this term yields:

[0187] c=aε vm +1 (11)

[0188] Combining formulas (7)-(11), we can obtain:

[0189]

[0190] Let d = 1-c, so formula (12) can be expressed as:

[0191] β=1-dθ (13)

[0192] where d is the dimensionless dynamic desorption hysteresis index, β is the dimensionless hysteresis parameter, and θ is the rock surface site occupancy, also dimensionless.

[0193] In formula (13), because c is between 0 and 1, the value of d ranges from 0 to 1. As d increases, the desorption hysteresis increases. Conversely, as d decreases, the desorption hysteresis decreases. Furthermore, as θ decreases, the desorption hysteresis decreases. When θ = 0 and β = 1, the pore structure change is completely reversible.

[0194] At equilibrium, the adsorption rate is equal to the desorption rate (r a =r d ). Therefore, combining formulas (1), (5) and (13) we get

[0195]

[0196] Where n0 is the maximum adsorption capacity, mol·kg -1 ;n a is the absolute adsorption capacity, mol·kg -1 ; p is the experimental pressure, Pa; θ is the rock surface site occupancy, dimensionless; b is the adsorption equilibrium constant, dimensionless; d is the dynamic desorption hysteresis index, dimensionless; β is the hysteresis parameter, dimensionless.

[0197] When d = 0, formula (14) is simplified to the Langmuir model, describing methane adsorption; when d ≠ 0, formula (14) describes methane desorption.

[0198] Equation (14) exhibits a singularity at the maximum equilibrium pressure. This pressure marks the end of the adsorption isotherm and the beginning of the corresponding desorption isotherm. At this point, the adsorption and desorption models should predict the same adsorption amount, but Equation (14) produces inconsistent values. To address this issue, Equation (14) was further improved to obtain the modified Langmuir model:

[0199]

[0200] Where p m is the maximum equilibrium pressure, MPa; n0 is the maximum adsorption capacity, mol·kg -1 ;n a is the absolute adsorption capacity, mol·kg -1 ; p is the experimental pressure, Pa; θ is the rock surface site occupancy, dimensionless; b is the adsorption equilibrium constant, dimensionless; d is the dynamic desorption hysteresis index, dimensionless; β is the hysteresis parameter, dimensionless.

[0201] When d = 0, Equation (15) is simplified to the Langmuir model, describing methane adsorption; when d ≠ 0, Equation (15) describes methane desorption. At the maximum adsorption equilibrium pressure, the two models yield the same results.

[0202] Furthermore, consider n0 as a temperature-dependent parameter:

[0203] n0=n m exp(-D T ×T) (16)

[0204] Where n0 is the maximum adsorption capacity, mol·kg -1 ;n m is the theoretical maximum adsorption capacity, mol·kg -1 ;D T is the reduction factor, K -1 , which is related to the temperature increase; T is the experimental temperature, K.

[0205] The adsorption capacity mentioned above refers to the absolute adsorption capacity, which is indicated by the subscript a. The absolute adsorption capacity can be used for reservoir evaluation and well production prediction. However, in adsorption experiments, the measured adsorption capacity is usually called the excess adsorption capacity. This term represents the difference between the total amount of adsorbate in the system and the adsorbed mass present in the same volume at the same temperature and pressure, assuming no adsorption occurs. In order to convert the excess adsorption capacity into absolute adsorption capacity, the Gibbs adsorption formula is used. This conversion is crucial for comparing experimental data with theoretical models. The Gibbs adsorption formula is:

[0206] n e =n a -V a ρ g (17)

[0207] Where n e is the experimental excess adsorption capacity, mol·kg -1 ; V a is the volume of the adsorbed phase, mol·kg -1 ρg is the gas volume density, g / m -3 .

[0208] V a It cannot be directly measured through experiments, so V is calculated based on the ML model. a is processed as a function of pressure and temperature, where V a V changes proportionally with coverage θ until it reaches a maximum value V m , which corresponds to the volume of the adsorbed phase at the maximum adsorption capacity.

[0209]

[0210] Where V a is the volume of the adsorbed phase, mol·kg -1 ; V m is the maximum volume of the adsorbed phase, mol·kg -1 ; p is the experimental pressure, Pa; θ is the rock surface site occupancy, dimensionless; b is the adsorption equilibrium constant, dimensionless; d is the dynamic desorption hysteresis index, dimensionless; p m is the maximum equilibrium pressure, MPa.

[0211] By combining formula (4), formula (15)-formula (18), we can obtain the adsorption and desorption model of shale gas adsorption and desorption, including the dynamic desorption hysteresis index affected by temperature and pressure changes. Among them, the experimental pressure p, the experimental temperature T, the experimental excess adsorption amount n e , experimental maximum equilibrium pressure p m , experimental ideal gas constant R and experimental gas volume density ρ g is the input parameter, the theoretical maximum adsorption capacity n m , maximum adsorption phase volume V m , dynamic desorption hysteresis index d, pre-exponential factor A, reduction coefficient D T and adsorption energy E are fitting parameters.

[0212] The above model-building approach resulted in an adsorption-desorption model that includes a dynamic desorption hysteresis exponent that varies with temperature and pressure. The hysteresis parameter is not a constant, but rather a dynamic desorption hysteresis exponent that varies with pressure and temperature. This enables the model to fit and predict gas adsorption and desorption isotherms at different temperatures. This enhances the model's applicability in various practical scenarios, such as reservoir evaluation and well production prediction.

[0213] Specifically, the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir can be determined through the following steps 21 to 223.

[0214] Step 2021: Based on the experimental data of at least 6 groups of adsorption and desorption experiments and the adsorption and desorption model including the dynamic desorption hysteresis index affected by temperature and pressure changes, a nonlinear least squares fitting method is used to determine the dynamic desorption hysteresis index, the maximum adsorption phase volume, as well as the pre-exponential factor, adsorption energy, theoretical maximum adsorption capacity and reduction coefficient of the target shale gas reservoir.

[0215] It should be noted that the experimental data for at least six sets of adsorption and desorption experiments were obtained at different temperatures and pressures, resulting in different excess adsorption capacities. This allows for more accurate fitting parameters to be derived from experimental data at different temperatures and pressures. The maximum equilibrium pressure, ideal gas constant, and gas volume density were determined based on experimental needs. These three parameters can be the same or different across experiments. To enhance comparability between experiments, they were set to the same across all experiments.

[0216] It should also be noted that when fitting the model, one of the weighted least squares method, generalized least squares method, robust regression method, or regularization method can be selected. In one possible method, a nonlinear least squares fitting method is used to fit the model. The above four fitting methods are all prior art and are not specifically described in the embodiments of the present invention.

[0217] In a possible embodiment, 6 sets of experimental data can be found in Table 1 - Adsorption and desorption experimental data table:

[0218] Table 1 - Adsorption and desorption experimental data

[0219]

[0220] It should be noted that the data in Table 1 above are only exemplary data of the embodiment of the present invention, and the embodiment of the present invention does not limit the specific values ​​of the number of experimental groups and experimental data.

[0221] Specifically, the adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure formed by combining formula (4), formula (15)-formula (18) is:

[0222]

[0223] Where p is the experimental pressure, Pa; T is the experimental temperature, K; n e is the experimental excess adsorption capacity, mol·kg -1 ;p m is the experimental maximum equilibrium pressure, Pa; R is the experimental ideal gas constant, J·mol -1 ·K -1 ρ gis the experimental gas volume density, g / m 3 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; n m is the theoretical maximum adsorption capacity, mol·kg -1 ;D T is the reduction factor, K -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1 .

[0224] It should be noted that in order to improve the fitting effect and reduce interference terms, formula (4), formula (15)-formula (18) are sorted into experimental pressure p, experimental temperature T, experimental excess adsorption amount n e , experimental maximum equilibrium pressure p m , experimental ideal gas constant R and experimental gas volume density ρ g , theoretical maximum adsorption capacity n m , maximum adsorption phase volume V m , dynamic desorption hysteresis index d, pre-exponential factor A, reduction coefficient D T And the adsorption energy E is expressed in formula (19). Among them, the experimental pressure p, the experimental temperature T, the experimental excess adsorption amount n e , experimental maximum equilibrium pressure p m , experimental ideal gas constant R and experimental gas volume density ρ g is the input parameter, the theoretical maximum adsorption capacity n m , maximum adsorption phase volume V m , dynamic desorption hysteresis index d, pre-exponential factor A, reduction coefficient D T and adsorption energy E are used as fitting parameters, and the nonlinear least squares fitting method is used for fitting.

[0225] Step 2022: Determine the adsorption equilibrium constant of the target shale gas reservoir based on the reservoir pressure, reservoir temperature, experimental ideal gas constant, pre-exponential factor, and adsorption energy.

[0226] It should be noted that after fitting the dynamic desorption hysteresis index, maximum adsorption phase volume, pre-exponential factor, adsorption energy, theoretical maximum adsorption capacity and reduction coefficient of the target shale gas reservoir, the adsorption equilibrium constant can be determined by formula (20), as well as reservoir pressure, reservoir temperature, experimental ideal gas constant, pre-exponential factor and adsorption energy.

[0227]

[0228] Where b is the adsorption equilibrium constant, dimensionless; R is the experimental ideal gas constant, J·mol -1 ·K -1 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ;p b is the reservoir pressure, Pa; T b is the reservoir temperature, K.

[0229] Step 2023: Determine the surface site occupancy of the target shale gas reservoir based on the adsorption equilibrium constant and the reservoir pressure.

[0230] It should be noted that after fitting the dynamic desorption hysteresis index, maximum adsorption phase volume, pre-exponential factor, adsorption energy, theoretical maximum adsorption capacity and reduction coefficient of the target shale gas reservoir, the surface site occupancy can be determined by formula (21), as well as the adsorption equilibrium constant and reservoir pressure.

[0231]

[0232] Where θ is the rock surface site occupancy, dimensionless; b is the adsorption equilibrium constant, dimensionless; p b is the reservoir pressure, Pa.

[0233] In a possible embodiment, for different target shale gas reservoirs, the theoretical maximum adsorption capacity n fitted according to steps 21 to 223 is m , maximum adsorption phase volume V m , dynamic desorption hysteresis index d, pre-exponential factor A, reduction coefficient D T And adsorption energy E can be seen in Table 2 - Fitting parameter data table:

[0234] Table 2 - Fitting parameter data table

[0235]

[0236]

[0237] Furthermore, the data in Table 2 were compared with data fitted by the Langmuir model with empirical lag parameters. To balance accuracy and simplicity, relative error (RE) and the modified Akaike information criterion (AICc) were used to evaluate model performance. The modified Akaike information criterion (AICc) is a modification of the original Akaike information criterion, adjusted for small sample sizes. Lower AICc values ​​indicate a better balance between goodness of fit and model simplicity. The comparison results are shown in Table 3.

[0238] Table 3 Relative errors and AICc values ​​of the fitting results of the embodiment of the present invention and the Langmuir model fitting results

[0239]

[0240]

[0241] As shown in Table 3, the average REs for the adsorption-desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure and the Langmuir model with empirical hysteresis parameters provided by the embodiment of the present invention were 3.67% and 3.72%, respectively. Although the two models exhibited similar accuracy, the AICc value (-504.94) for the adsorption-desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure provided by the embodiment of the present invention was lower than that for the Langmuir model with empirical hysteresis parameters (-497.96), indicating that the adsorption-desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure provided by the embodiment of the present invention is superior to the Langmuir model with empirical hysteresis parameters.

[0242] It should be noted that once the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir are determined, the recoverable reserves of the target shale gas reservoir can be further determined based on these parameters. Since the recoverable reserves of the target shale gas reservoir are composed of adsorbed gas and free gas, to clarify the specific values ​​of these two types of gas, the steps for determining the recoverable reserves of the target shale gas reservoir can be divided into first determining the adsorbed gas volume of the target shale gas reservoir, then determining the free gas volume of the target shale gas reservoir, and finally determining the recoverable reserves of the target shale gas reservoir.

[0243] Step 203: Determine the adsorbed gas volume of the target shale gas reservoir based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, and gas volume coefficient.

[0244] Based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, and gas volume coefficient, the adsorbed gas volume of the target shale gas reservoir is determined using the following formula:

[0245]

[0246] Where V a is the amount of adsorbed gas in the target shale gas reservoir under surface conditions, m 3 kg -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1; b is the adsorption equilibrium constant, dimensionless; θ is the rock surface site occupancy, dimensionless; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; p m is the maximum equilibrium pressure of the experiment, Pa; p b is the reservoir pressure, Pa; b g is the gas volume coefficient, dimensionless.

[0247] Step 204: Determine the free gas volume of the target shale gas reservoir based on the average reservoir porosity, water saturation, rock density, and gas volume coefficient.

[0248] Based on the average reservoir porosity, water saturation, rock density and gas volume coefficient, the free gas volume of the target shale gas reservoir is determined by the following formula:

[0249]

[0250] Where V f is the free gas volume of the target shale gas reservoir under surface conditions, m 3 kg -1 ;S w is the water saturation, dimensionless; ρ r is the rock density in g / m 3 ; is the average reservoir porosity, dimensionless; b g is the gas volume coefficient, dimensionless.

[0251] Step 205: Determine the recoverable reserves of the target shale gas reservoir by summing the free gas volume of the target shale gas reservoir and the adsorbed gas volume of the target shale gas reservoir.

[0252] In a possible embodiment, the geological parameters of the target shale gas reservoir are shown in Table 4, and the fitting results are shown in the result of No. 1 in the second row of Table 2.

[0253] Table 4. Parameters of target shale gas reservoirs

[0254]

[0255] Based on the above results, the adsorbed gas capacity of the target shale gas reservoir is finally determined to be 10.06 Sm according to formula (22). 3 ·m -3 According to formula (23), the free gas volume of the target shale gas reservoir is determined to be 8.03Sm 3 ·m -3 The recoverable reserves of the target shale gas reservoir are determined to be 18.09 Sm 3 ·m -3 That is, the standard volume of adsorbed gas per unit volume of the target shale gas reservoir is 10.06m3 The standard volume of free gas per unit volume of reservoir is 8.03m 3 Therefore, the recoverable reserves per unit volume of the target shale gas reservoir are 18.09m 3 .

[0256] It should be noted that the above data are only exemplary data of the embodiment of the present invention, and the embodiment of the present invention does not limit this.

[0257] In an embodiment of the present invention, the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least 6 groups of adsorption and desorption experiments of the target shale gas reservoir are obtained, wherein the experimental data include experimental pressure, experimental temperature, experimental excess adsorption amount, experimental maximum equilibrium pressure, experimental ideal gas constant and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant and experimental gas volume density in each group of experimental data of at least 6 groups of adsorption and desorption experiments are all constant values; based on the experimental data of at least 6 groups of adsorption and desorption experiments, reservoir pressure and reservoir temperature, a dynamic desorption hysteresis coefficient including the temperature and pressure changes is obtained. An adsorption-desorption model with a post-index is used to determine the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir. The adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure is an improved adsorption-desorption model based on the Langmuir adsorption-desorption model that introduces pressure, temperature, and excess adsorption capacity to indicate the dynamic desorption hysteresis. The recoverable reserves of the target shale gas reservoir are determined based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, average reservoir porosity, water saturation, rock density, gas volume coefficient, and reservoir pressure. That is, when determining the recoverable reserves of the target shale gas reservoir, this method uses an improved adsorption-desorption model that can indicate the dynamic desorption hysteresis of gas in the reservoir to fit relevant parameters such as the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume, and calculates the recoverable reserves of the reservoir based on these parameters. Since different pressures, temperatures, and excess adsorption amounts are used as fitting variables in the fitting process, the fitted parameters, especially the dynamic desorption hysteresis index, can capture the relationship between the desorption hysteresis effect and the temperature and pressure variables, thereby significantly improving the accuracy of determining the actual adsorbed gas volume of the target reservoir under different temperature and pressure conditions, and thus more accurately determining the recoverable reserves of the target reservoir shale gas, thereby improving the accuracy of determining the recoverable reserves.

[0258] All of the above optional technical solutions can be combined in any way to form optional embodiments of the present invention, and the embodiments of the present invention will not be described in detail one by one.

[0259] Figure 3This is a schematic diagram of the structure of a device for determining recoverable reserves of shale gas provided by an embodiment of the present invention. Figure 3 , the apparatus may include:

[0260] An acquisition module 301 is configured to acquire the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least six sets of adsorption and desorption experiments of the target shale gas reservoir, wherein the experimental data includes experimental pressure, experimental temperature, experimental excess adsorption capacity, experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density in each set of experimental data of the at least six sets of adsorption and desorption experiments are all constant values;

[0261] A first determination module 302 is configured to determine a dynamic desorption hysteresis index, a surface site occupancy, an adsorption equilibrium constant, and a maximum adsorption phase volume of a target shale gas reservoir based on experimental data from at least six sets of adsorption and desorption experiments, reservoir pressure, and reservoir temperature, and based on an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure. The adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure is an improved adsorption and desorption model based on the Langmuir adsorption and desorption model that introduces pressure, temperature, and excess adsorption capacity to indicate the dynamic desorption hysteresis of gas in the reservoir.

[0262] The second determination module 303 is used to determine the recoverable reserves of the target shale gas reservoir based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, reservoir average porosity, water saturation, rock density, gas volume coefficient, and reservoir pressure.

[0263] Optionally, the first determining module includes:

[0264] The first determination unit is configured to determine the dynamic desorption hysteresis index, the maximum adsorption phase volume, the pre-exponential factor, the adsorption energy, the theoretical maximum adsorption capacity, and the reduction coefficient of the target shale gas reservoir using a nonlinear least squares fitting method based on experimental data from at least six groups of adsorption and desorption experiments and an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure;

[0265] The second determining unit is used to determine the adsorption equilibrium constant of the target shale gas reservoir according to the reservoir pressure, reservoir temperature, experimental ideal gas constant, pre-exponential factor, and adsorption energy;

[0266] The third determining unit is used to determine the surface site occupancy of the target shale gas reservoir according to the adsorption equilibrium constant and the reservoir pressure.

[0267] Optionally, the adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure changes in the first determination unit is specifically:

[0268]

[0269] Where p is the experimental pressure, Pa; T is the experimental temperature, K; n e is the experimental excess adsorption capacity, mol·kg -1 ;p m is the experimental maximum equilibrium pressure, Pa; R is the experimental ideal gas constant, J·mol -1 ·K -1 ρ g is the experimental gas volume density, g / m 3 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; n m is the theoretical maximum adsorption capacity, mol·kg -1 ;D T is the reduction factor, K -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1 .

[0270] Optionally, the second determining unit includes:

[0271] According to the reservoir pressure, reservoir temperature, experimental ideal gas constant, pre-exponential factor, and adsorption energy, the adsorption equilibrium constant is determined by the following formula:

[0272]

[0273] Where b is the adsorption equilibrium constant, dimensionless; R is the experimental ideal gas constant, J·mol -1 ·K -1 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ;p b is the reservoir pressure, Pa; T b is the reservoir temperature, K.

[0274] Optionally, the third determining unit includes:

[0275] According to the adsorption equilibrium constant and reservoir pressure, the surface site occupancy is determined by the following formula:

[0276]

[0277] Where θ is the rock surface site occupancy, dimensionless; b is the adsorption equilibrium constant, dimensionless; p b is the reservoir pressure, Pa.

[0278] Optionally, the second determining module includes:

[0279] a fourth determination unit for determining the adsorbed gas volume of the target shale gas reservoir according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, and the gas volume coefficient;

[0280] a fifth determining unit, configured to determine the free gas volume of the target shale gas reservoir based on the average porosity, water saturation, rock density, and gas volume coefficient of the reservoir;

[0281] The sixth determining unit is configured to determine the recoverable reserves of the target shale gas reservoir by taking the sum of the free gas volume of the target shale gas reservoir and the adsorbed gas volume of the target shale gas reservoir.

[0282] Optionally, the fourth determining unit includes:

[0283] Based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, and gas volume coefficient, the adsorbed gas volume of the target shale gas reservoir is determined using the following formula:

[0284]

[0285] Where V a is the amount of adsorbed gas in the target shale gas reservoir under surface conditions, m 3 kg -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1 ; b is the adsorption equilibrium constant, dimensionless; θ is the rock surface site occupancy, dimensionless; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; p m is the maximum equilibrium pressure of the experiment, Pa; p b is the reservoir pressure, Pa; b g is the gas volume coefficient, dimensionless.

[0286] Optionally, the fifth determining unit includes:

[0287] Based on the average reservoir porosity, water saturation, rock density and gas volume coefficient, the free gas volume of the target shale gas reservoir is determined by the following formula:

[0288]

[0289] Where Vf is the free gas volume of the target shale gas reservoir under surface conditions, m 3 kg -1 ;S w is the water saturation, dimensionless; ρ r is the rock density in g / m 3 ; is the average reservoir porosity, dimensionless; b g is the gas volume coefficient, dimensionless.

[0290] In an embodiment of the present invention, the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least 6 groups of adsorption and desorption experiments of the target shale gas reservoir are obtained, wherein the experimental data include experimental pressure, experimental temperature, experimental excess adsorption amount, experimental maximum equilibrium pressure, experimental ideal gas constant and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant and experimental gas volume density in each group of experimental data of at least 6 groups of adsorption and desorption experiments are all constant values; based on the experimental data of at least 6 groups of adsorption and desorption experiments, reservoir pressure and reservoir temperature, a dynamic desorption hysteresis coefficient including the temperature and pressure changes is obtained. An adsorption-desorption model with a post-index is used to determine the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir. The adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure is an improved adsorption-desorption model based on the Langmuir adsorption-desorption model that introduces pressure, temperature, and excess adsorption capacity to indicate the dynamic desorption hysteresis. The recoverable reserves of the target shale gas reservoir are determined based on the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, maximum adsorption phase volume, experimental maximum equilibrium pressure, average reservoir porosity, water saturation, rock density, gas volume coefficient, and reservoir pressure. That is, when determining the recoverable reserves of the target shale gas reservoir, this method uses an improved adsorption-desorption model that can indicate the dynamic desorption hysteresis of gas in the reservoir to fit relevant parameters such as the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume, and calculates the recoverable reserves of the reservoir based on these parameters. Since different pressures, temperatures, and excess adsorption amounts are used as fitting variables in the fitting process, the fitted parameters, especially the dynamic desorption hysteresis index, can capture the relationship between the desorption hysteresis effect and the temperature and pressure variables, thereby significantly improving the accuracy of determining the actual adsorbed gas volume of the target reservoir under different temperature and pressure conditions, and thus more accurately determining the recoverable reserves of the target reservoir shale gas, thereby improving the accuracy of determining the recoverable reserves.

[0291] It should be noted that the apparatus for determining recoverable shale gas reserves provided in the above-mentioned embodiment only uses the division of the above-mentioned functional modules as an example to illustrate the determination of recoverable shale gas reserves. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the apparatus can be divided into different functional modules to complete all or part of the functions described above. In addition, the apparatus for determining recoverable shale gas reserves provided in the above-mentioned embodiment and the embodiment of the method for determining recoverable shale gas reserves are based on the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0292] Figure 4 The figure is a schematic diagram of the structure of a terminal 400 provided in an embodiment of the present invention. Terminal 400 may be a smartphone, a tablet computer, an MP3 player (Moving Picture Experts Group Audio Layer III), an MP4 player (Moving Picture Experts Group Audio Layer IV), a laptop computer, or a desktop computer. Terminal 400 may also be referred to as user equipment, a portable terminal, a laptop terminal, a desktop terminal, or other similar names.

[0293] Typically, the terminal 400 includes a processor 401 and a memory 402 .

[0294] The processor 401 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 401 may be implemented in at least one hardware form of DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), or PLA (Programmable Logic Array). The processor 401 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a CPU (Central Processing Unit); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 401 may be integrated with a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 401 may also include an AI (Artificial Intelligence) processor, which is used to process computing operations related to machine learning.

[0295] Memory 402 may include one or more computer-readable storage media, which may be non-transitory. Memory 402 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory storage devices. In some embodiments, the non-transitory computer-readable storage medium in memory 402 is used to store at least one instruction, which is executed by processor 401 to implement the method for determining recoverable shale gas reserves provided in the method embodiments of this application.

[0296] In some embodiments, terminal 400 may optionally include a peripheral device interface 403 and at least one peripheral device. Processor 401, memory 402, and peripheral device interface 403 may be connected via a bus or signal lines. Each peripheral device may be connected to peripheral device interface 403 via a bus, signal lines, or circuit boards. Specifically, the peripheral device may include at least one of a radio frequency circuit 404, a touch screen display 404, a camera 406, an audio circuit 407, a positioning component 408, and a power supply 409.

[0297] The peripheral device interface 403 can be used to connect at least one I / O (Input / Output)-related peripheral device to the processor 401 and the memory 402. In some embodiments, the processor 401, the memory 402, and the peripheral device interface 403 are integrated on the same chip or circuit board; in some other embodiments, any one or two of the processor 401, the memory 402, and the peripheral device interface 403 can be implemented on separate chips or circuit boards, which is not limited in this embodiment.

[0298] The radio frequency circuit 404 is used to receive and transmit RF (Radio Frequency) signals, also known as electromagnetic signals. The radio frequency circuit 404 communicates with communication networks and other communication devices via electromagnetic signals. The radio frequency circuit 404 converts electrical signals into electromagnetic signals for transmission, or converts received electromagnetic signals into electrical signals. Optionally, the radio frequency circuit 404 includes: an antenna system, an RF transceiver, one or more amplifiers, a tuner, an oscillator, a digital signal processor, a codec chipset, a user identity module card, etc. The radio frequency circuit 404 can communicate with other terminals via at least one wireless communication protocol. Such wireless communication protocols include, but are not limited to, metropolitan area networks, various generations of mobile communication networks (2G, 3G, 4G, and 5G), wireless local area networks, and / or WiFi (Wireless Fidelity) networks. In some embodiments, the radio frequency circuit 404 may also include circuits related to NFC (Near Field Communication), which is not limited in this application.

[0299] Display screen 404 is used to display a user interface (UI). This UI may include graphics, text, icons, videos, or any combination thereof. When display screen 405 is a touchscreen display, it is also capable of collecting touch signals on or above the surface of display screen 405. These touch signals can be input as control signals to processor 401 for processing. Display screen 405 can also be used to provide virtual buttons and / or a virtual keyboard, also known as soft buttons and / or a soft keyboard. In some embodiments, there can be a single display screen 405, located on the front panel of terminal 400. In other embodiments, there can be at least two display screens 405, located on different surfaces of terminal 400 or in a foldable design. In still other embodiments, display screen 405 can be a flexible display screen, located on a curved or foldable surface of terminal 400. Furthermore, display screen 405 can be configured as a non-rectangular, irregular shape, also known as a special-shaped screen. Display screen 405 can be made of materials such as LCD (Liquid Crystal Display) and OLED (Organic Light-Emitting Diode).

[0300] The camera assembly 406 is used to capture images or videos. Optionally, the camera assembly 406 includes a front camera and a rear camera. Typically, the front camera is arranged on the front panel of the terminal, and the rear camera is arranged on the back of the terminal. In some embodiments, there are at least two rear cameras, which are any one of a main camera, a depth of field camera, a wide-angle camera, and a telephoto camera, so as to realize the fusion of the main camera and the depth of field camera to realize the background blur function, the fusion of the main camera and the wide-angle camera to realize panoramic shooting and VR (Virtual Reality) shooting function or other fusion shooting functions. In some embodiments, the camera assembly 406 may also include a flash. The flash can be a monochrome temperature flash or a dual-color temperature flash. A dual-color temperature flash refers to a combination of a warm light flash and a cold light flash, which can be used for light compensation at different color temperatures.

[0301] The audio circuit 407 may include a microphone and a speaker. The microphone is used to collect sound waves from the user and the environment, and convert the sound waves into electrical signals that are input into the processor 401 for processing, or input into the radio frequency circuit 404 to achieve voice communication. For the purpose of stereo sound collection or noise reduction, there may be multiple microphones, each disposed at different locations on the terminal 400. The microphone may also be an array microphone or an omnidirectional collection microphone. The speaker is used to convert electrical signals from the processor 401 or the radio frequency circuit 404 into sound waves. The speaker may be a traditional thin film speaker or a piezoelectric ceramic speaker. When the speaker is a piezoelectric ceramic speaker, it can not only convert electrical signals into sound waves audible to humans, but also convert electrical signals into sound waves inaudible to humans for purposes such as distance measurement. In some embodiments, the audio circuit 407 may also include a headphone jack.

[0302] Positioning component 408 is used to locate the current geographic location of terminal 400 to implement navigation or LBS (Location Based Service). Positioning component 408 can be a positioning component based on the US GPS (Global Positioning System), China's Beidou system, Russia's Greninja system, or the European Union's Galileo system.

[0303] Power supply 409 is used to power various components in terminal 400. Power supply 409 can be AC ​​power, DC power, a disposable battery, or a rechargeable battery. When power supply 409 includes a rechargeable battery, the rechargeable battery can support wired charging or wireless charging. The rechargeable battery can also be used to support fast charging technology.

[0304] In some embodiments, the terminal 400 further includes one or more sensors 410 , including but not limited to: an acceleration sensor 411 , a gyroscope sensor 412 , a pressure sensor 413 , a fingerprint sensor 414 , an optical sensor 415 , and a proximity sensor 416 .

[0305] The accelerometer 411 can detect the magnitude of acceleration along the three coordinate axes of the coordinate system established by the terminal 400. For example, the accelerometer 411 can be used to detect the components of gravity acceleration along the three coordinate axes. The processor 401 can control the touch screen display 405 to display the user interface in a landscape or portrait view based on the gravity acceleration signal collected by the accelerometer 411. The accelerometer 411 can also be used to collect game or user motion data.

[0306] The gyroscope sensor 412 can detect the orientation and rotation angle of the terminal 400. It can also work with the accelerometer 411 to collect the user's 3D movements of the terminal 400. Based on the data collected by the gyroscope sensor 412, the processor 401 can implement the following functions: motion sensing (e.g., changing the UI based on the user's tilt), image stabilization during shooting, game control, and inertial navigation.

[0307] The pressure sensor 413 can be set on the side frame of the terminal 400 and / or the lower layer of the touch screen display 405. When the pressure sensor 413 is set on the side frame of the terminal 400, it can detect the user's grip signal of the terminal 400, and the processor 401 performs left and right hand recognition or shortcut operations based on the grip signal collected by the pressure sensor 413. When the pressure sensor 413 is set on the lower layer of the touch screen display 405, the processor 401 controls the operable controls on the UI interface based on the user's pressure operation on the touch screen display 405. The operable controls include at least one of a button control, a scroll bar control, an icon control, and a menu control.

[0308] The fingerprint sensor 414 is used to collect the user's fingerprint. The processor 401 identifies the user's identity based on the fingerprint collected by the fingerprint sensor 414, or the fingerprint sensor 414 identifies the user's identity based on the collected fingerprint. When the user's identity is recognized as a trusted identity, the processor 401 authorizes the user to perform relevant sensitive operations, such as unlocking the screen, viewing encrypted information, downloading software, making payments, and changing settings. The fingerprint sensor 414 can be set on the front, back, or side of the terminal 400. When a physical button or manufacturer logo is provided on the terminal 400, the fingerprint sensor 414 can be integrated with the physical button or manufacturer logo.

[0309] Optical sensor 415 is used to detect ambient light intensity. In one embodiment, processor 401 can control the display brightness of touchscreen display 405 based on the ambient light intensity detected by optical sensor 415. Specifically, when the ambient light intensity is high, the display brightness of touchscreen display 405 is increased; when the ambient light intensity is low, the display brightness of touchscreen display 405 is decreased. In another embodiment, processor 401 can also dynamically adjust the shooting parameters of camera assembly 406 based on the ambient light intensity detected by optical sensor 415.

[0310] Proximity sensor 416, also known as a distance sensor, is typically located on the front panel of terminal 400. Proximity sensor 416 is used to detect the distance between the user and the front of terminal 400. In one embodiment, when proximity sensor 416 detects that the distance between the user and the front of terminal 400 is gradually decreasing, processor 401 controls touchscreen display 405 to switch from the screen-on state to the screen-off state. When proximity sensor 416 detects that the distance between the user and the front of terminal 400 is gradually increasing, processor 401 controls touchscreen display 405 to switch from the screen-off state to the screen-on state.

[0311] That is, the embodiment of the present invention not only provides a terminal including a processor and a memory for storing processor-executable instructions, wherein the processor is configured to execute Figure 1 or Figure 2 The method in the embodiment shown in the figure, and the embodiment of the present invention also provides a computer readable storage medium, which stores a computer program, which can be implemented when the computer program is executed by the processor. Figure 1 or Figure 2 The method for determining recoverable reserves of shale gas in the embodiment shown.

[0312] Those skilled in the art will understand that Figure 4 The structure shown in the figure does not constitute a limitation on the terminal 400, and the terminal 400 may include more or fewer components than shown in the figure, or combine certain components, or adopt a different component arrangement.

[0313] Those skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware, or by a program to instruct the relevant hardware, and the program may be stored in a computer-readable storage medium, which may be a read-only memory, a disk, or an optical disk, etc.

[0314] 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 in the scope of protection of the present invention.

Claims

1. A method for determining recoverable reserves of shale gas, characterized in that: The method for determining recoverable reserves of shale gas includes: Obtaining average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least six sets of adsorption and desorption experiments of the target shale gas reservoir, wherein the experimental data include experimental pressure, experimental temperature, experimental excess adsorption capacity, experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density in each set of experimental data of the at least six sets of adsorption and desorption experiments are all constant values; Determining the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir based on the experimental data of the at least six groups of adsorption and desorption experiments, the reservoir pressure, and the reservoir temperature, and based on an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure, wherein the adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure is an improved adsorption and desorption model based on the Langmuir adsorption and desorption model by introducing pressure, temperature, and excess adsorption amount to indicate the dynamic desorption hysteresis of gas in the reservoir; The recoverable reserves of the target shale gas reservoir are determined based on the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, the average reservoir porosity, the water saturation, the rock density, the gas volume coefficient, and the reservoir pressure.

2. The method for determining recoverable shale gas reserves according to claim 1, characterized in that: The method comprises determining the dynamic desorption hysteresis index, surface site occupancy, adsorption equilibrium constant, and maximum adsorption phase volume of the target shale gas reservoir based on the experimental data of the at least six groups of adsorption and desorption experiments, the reservoir pressure, and the reservoir temperature, and based on an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure, including: Determine the dynamic desorption hysteresis index, the maximum adsorption phase volume, the pre-exponential factor, the adsorption energy, the theoretical maximum adsorption capacity, and the reduction coefficient of the target shale gas reservoir using a nonlinear least squares fitting method based on the experimental data of the at least six groups of adsorption and desorption experiments and an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure; determining an adsorption equilibrium constant of the target shale gas reservoir according to the reservoir pressure, the reservoir temperature, the experimental ideal gas constant, the pre-exponential factor, and the adsorption energy; The surface site occupancy of the target shale gas reservoir is determined according to the adsorption equilibrium constant and the reservoir pressure.

3. The method for determining recoverable shale gas reserves according to claim 2, characterized in that: The adsorption-desorption model including the dynamic desorption hysteresis index affected by temperature and pressure is specifically: Where p is the experimental pressure, Pa; T is the experimental temperature, K; n e is the experimental excess adsorption capacity, mol·kg -1 ;p m is the experimental maximum equilibrium pressure, Pa; R is the experimental ideal gas constant, J·mol -1 ·K -1 ρ g is the experimental gas volume density, g / m 3 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; n m is the theoretical maximum adsorption capacity, mol·kg -1 ; D T is the reduction factor, K -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1 .

4. The method for determining recoverable shale gas reserves according to claim 2, characterized in that: Determining the adsorption equilibrium constant according to the reservoir pressure, the reservoir temperature, the experimental ideal gas constant, the pre-exponential factor, and the adsorption energy includes: The adsorption equilibrium constant is determined by the following formula based on the reservoir pressure, the reservoir temperature, the experimental ideal gas constant, the pre-exponential factor, and the adsorption energy: Where b is the adsorption equilibrium constant, dimensionless; R is the experimental ideal gas constant, J·mol -1 ·K -1 ; A is the pre-exponential factor, Pa -1 ; E is the adsorption energy, J·mol -1 ;p b is the reservoir pressure, Pa; T b is the reservoir temperature, K.

5. The method for determining recoverable reserves of shale gas according to claim 2, characterized in that: Determining the surface site occupancy according to the adsorption equilibrium constant and the reservoir pressure includes: According to the adsorption equilibrium constant and the reservoir pressure, the surface site occupancy is determined by the following formula: Where θ is the rock surface site occupancy, dimensionless; b is the adsorption equilibrium constant, dimensionless; p b is the reservoir pressure, Pa.

6. The method for determining recoverable shale gas reserves according to claim 1, characterized in that: The method of determining the recoverable reserves of the target shale gas reservoir according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, the reservoir average porosity, the water saturation, the rock density, the gas volume coefficient, and the reservoir pressure includes: Determining the adsorbed gas volume of the target shale gas reservoir according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, and the gas volume coefficient; Determining the free gas volume of the target shale gas reservoir according to the average porosity of the reservoir, the water saturation, the rock density and the gas volume coefficient; The recoverable reserves of the target shale gas reservoir are determined by summing the free gas volume of the target shale gas reservoir and the adsorbed gas volume of the target shale gas reservoir.

7. The method for determining recoverable shale gas reserves according to claim 6, characterized in that: The step of determining the adsorbed gas volume of the target shale gas reservoir according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, and the gas volume coefficient includes: The adsorbed gas volume of the target shale gas reservoir is determined according to the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, and the gas volume coefficient using the following formula: Where V a is the amount of adsorbed gas in the target shale gas reservoir under surface conditions, m 3 kg -1 ; V m is the maximum volume of the adsorbed phase, in m 3 kg -1 ; b is the adsorption equilibrium constant, dimensionless; θ is the rock surface site occupancy, dimensionless; d is the dynamic desorption hysteresis index, dimensionless, ranging from 0 to 1; p m is the maximum equilibrium pressure of the experiment, Pa; p b is the reservoir pressure, Pa; b g is the gas volume coefficient, dimensionless.

8. The method for determining recoverable shale gas reserves according to claim 6, characterized in that: The step of determining the free gas volume of the target shale gas reservoir according to the average porosity of the reservoir, the water saturation, the rock density, and the gas volume coefficient includes: The free gas volume of the target shale gas reservoir is determined according to the average reservoir porosity, the water saturation, the rock density, and the gas volume coefficient using the following formula: Where V f is the free gas volume of the target shale gas reservoir under surface conditions, m 3 kg -1 ;S w is the water saturation, dimensionless; ρ r is the rock density in g / m 3 ; is the average reservoir porosity, dimensionless; b g is the gas volume coefficient, dimensionless.

9. A device for determining recoverable reserves of shale gas, characterized in that: The device for determining recoverable reserves of shale gas comprises: an acquisition module, configured to acquire the average reservoir porosity, water saturation, rock density, reservoir pressure, reservoir temperature, gas volume coefficient, and experimental data of at least six sets of adsorption and desorption experiments of the target shale gas reservoir, wherein the experimental data include experimental pressure, experimental temperature, experimental excess adsorption capacity, experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density, wherein the experimental maximum equilibrium pressure, experimental ideal gas constant, and experimental gas volume density in each set of experimental data of the at least six sets of adsorption and desorption experiments are all constant values; a first determination module, configured to determine, based on the experimental data of the at least six groups of adsorption and desorption experiments, the reservoir pressure, and the reservoir temperature, a dynamic desorption hysteresis index, a surface site occupancy, an adsorption equilibrium constant, and a maximum adsorption phase volume of the target shale gas reservoir, based on an adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure, wherein the adsorption and desorption model including a dynamic desorption hysteresis index that varies with temperature and pressure is an improved adsorption and desorption model based on the Langmuir adsorption and desorption model by introducing pressure, temperature, and excess adsorption amount to indicate the dynamic desorption hysteresis of gas in the reservoir; The second determination module is used to determine the recoverable reserves of the target shale gas reservoir based on the dynamic desorption hysteresis index, the surface site occupancy, the adsorption equilibrium constant, the maximum adsorption phase volume, the experimental maximum equilibrium pressure, the average reservoir porosity, the water saturation, the rock density, the gas volume coefficient, and the reservoir pressure.

10. A device for determining recoverable reserves of shale gas, characterized in that: The device comprises: processor; a memory for storing processor-executable instructions; The processor is configured to execute the steps of any one of the methods of claims 1-8.

Images