Method for measuring fluid composition and fluid phase state in nanopore

Abstract

The invention provides a method for measuring fluid composition and fluid phase state in a nanopore. The method comprises the following steps: measuring the molar composition of each component in a nanopore through Monte Carlo experiments of preset times to obtain an initial fluid composition set; randomly selecting a plurality of groups of compositions meeting a preset condition from the initial fluid composition set to serve as a candidate fluid composition set of the nanopores; according to the initial pressure of the nanopore and the basic characteristic parameters of the fluid in the crack area, calculating the fugacity of each component in each composition in the candidate fluid composition set; the fugacity of each component in each composition in the candidate fluid composition set is compared with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component. According to the scheme, the fluid composition and the fluid phase state in the nanopore can be accurately determined, so that the behavior characteristics of the fluid in the nanopore can be accurately reflected.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas field exploration and development, and in particular to a method for determining the composition and phase state of fluid in nanopores. Background Art

[0002] Shale reservoirs are typical multi-scale spaces with widely distributed nano-scale pores and millimeter-scale fractures. The oil and gas compositions in different scales are different. Accurately determining the composition and phase state of the fluid in shale reservoirs can more accurately evaluate resources and determine more reasonable development plans.

[0003] The composition of the fluid in the fracture can be determined by collecting the output fluid of the fracture, but it is more difficult to determine the composition of the fluid in the nanopore. At present, the fluid phase (gaseous, liquid or mixed state) in nanopores of different sizes is generally determined by pressure coring combined with nuclear magnetic resonance, and the fluid components in the nanopores are determined. However, this method cannot accurately determine the specific composition of the fluid in the nanopore.

[0004] There is currently no effective solution for how to accurately determine the specific composition of the fluid in the nanopores. Summary of the invention

[0005] The present specification provides a method for determining the composition and phase state of fluid in nanopores, so as to achieve the purpose of accurately determining the composition and phase state of fluid in nanopores.

[0006] This specification provides a method for determining the composition and phase state of fluid in nanopores, which is achieved by:

[0007] A method for determining fluid composition and fluid phase in nanopores, comprising:

[0008] Determine the pressure in the fracture area, the fugacity of each component in the fracture area, and the basic characteristic parameters of the fluid in the fracture area;

[0009] The pressure in the fracture region is used as the initial pressure of the nanopore, the molar composition of each component in the nanopore is measured by a preset number of Monte Carlo experiments, and the measurement result of each Monte Carlo experiment is used as the initial fluid composition set of the nanopore;

[0010] Randomly selecting a plurality of groups of compositions satisfying preset conditions from the initial fluid composition set as candidate fluid composition sets for the nanopores;

[0011] According to the initial pressure of the nanopores and the basic characteristic parameters of the fluid in the fracture area, the fugacity of each component in each composition of the candidate fluid composition set is calculated;

[0012] The fugacity of each component in each composition in the candidate fluid composition set is compared with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component.

[0013] In one embodiment, the fugacity of each component in each composition in the candidate fluid composition set is compared with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component, including:

[0014] respectively calculating the first fugacity difference between the fugacity of each component in each composition in the candidate fluid composition set and the fugacity of the same component in the fracture region to obtain a plurality of first fugacity differences;

[0015] According to the multiple first fugacity differences, two groups of fluid compositions with the smallest first fugacity differences are selected from the candidate fluid composition set as the first fluid composition and the second fluid composition of the nanopores, wherein the first fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture region is smaller than the first fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture region;

[0016] respectively calculating a second fugacity difference between the fugacity of each component in the first fluid composition and the second fluid composition and the fugacity of the same component in the fracture region;

[0017] According to the first fluid composition, the second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture area, the second fluid composition, the second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture area, iterative operations are performed using the chord-intercept method formula to calculate the fluid composition in the nanopores and the molar composition of each component.

[0018] In one embodiment, after calculating the fluid composition and the molar composition of each component in the nanopores by the chord-intercept method formula, the method further includes:

[0019] Compare and verify the first fugacity difference between the calculated fugacity of each component in the fluid composition in the nanopores and the fugacity of the same component in the fracture area, and the calculated molar composition of each component in the fluid composition in the nanopores with the preset conditions;

[0020] In the case where the verification fails, the initial pressure of the nanopore is adjusted, and the fluid composition and the molar composition of each component in the nanopore are recalculated by the adjusted initial pressure of the nanopore until the verification passes;

[0021] The fluid composition in the nanopore and the molar composition of each component when the verification is passed are taken as the determined fluid composition in the nanopore and the molar composition of each component and outputted;

[0022] Conduct single-phase stability tests on the fluid composition within the defined nanopores;

[0023] If the test fails, the nanopore is determined to be in a two-phase state, a two-phase flash calculation is performed on the fluid composition of the determined nanopore region, and a gas phase composition, a liquid phase composition, a gas phase mole fraction, and a liquid phase mole fraction are output;

[0024] If the test passes, it is determined that the nanopore is in a single-phase state, and the fluid composition in the nanopore region is output.

[0025] In one embodiment, the fugacity of each component in each composition in the candidate fluid composition set is calculated based on the initial pressure of the nanopores and the basic characteristic parameters of the fluid in the fracture region, including:

[0026] Obtaining the temperature of the oil reservoir where the nanopore is located, the gas constant, the diameter of the molecule in the nanopore, and the radius of the nanopore;

[0027] Determine basic characteristic parameters of the fluid in the fracture area according to production data; the basic characteristic parameters of the fluid include at least one of the following: critical pressure, critical temperature and eccentricity factor;

[0028] According to the initial pressure of the nanopore, the temperature of the reservoir, the gas constant, the diameter of the molecule in the nanopore, the radius of the nanopore, the critical pressure of the fracture area, the critical temperature of the fracture area and the eccentricity factor of the fracture area, the deviation factor of the nanopore is calculated according to the following formula:

[0029] Z 3 -(1-B)Z 2 +(A-2B-3B 2 )Z-(AB-B 2 -B 3 )=0

[0030] Where Z is the deviation factor, P m is the initial pressure in the nanopores, R is the gas constant, T is the temperature of the reservoir, σ LJ is the diameter of the molecule in the nanopore, R p is the radius of the nanopore, P c is the critical pressure in the crack region, T c is the critical temperature of the crack region, ω is the eccentricity factor of the crack region;

[0031] According to the deviation factor of the nanopores, the fugacity of each component in each composition in the candidate fluid composition set is calculated.

[0032] In one embodiment, a plurality of groups of compositions satisfying preset conditions are randomly selected from the initial fluid composition set as the candidate fluid composition set of the nanopores, including:

[0033] A plurality of groups of compositions satisfying the following conditions are randomly selected from the initial fluid composition set:

[0034] 0<z mi <1

[0035]

[0036] Among them, z mi is the molar composition of component i in composition m.

[0037] In one embodiment, the first fugacity difference between the fugacity of each component in each composition in the candidate fluid composition set and the fugacity of the same component in the fracture region is calculated respectively to obtain a plurality of first fugacity difference values, including:

[0038] The first fugacity difference between the fugacity of each component in each composition in the candidate fluid composition set and the fugacity of the same component in the fracture area is calculated according to the following formula:

[0039]

[0040] Among them, diff i is the first fugacity difference between the fugacity of component i in candidate fluid composition m and the fugacity of component i in the fracture region, f mi is the fugacity of component i in candidate fluid composition m, f bi is the fugacity of component i in the fracture region.

[0041] In one embodiment, respectively calculating the second fugacity difference between the fugacity of each component in the first fluid composition and the second fluid composition and the fugacity of the same component in the fracture region comprises:

[0042] The second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture area is calculated according to the following formula:

[0043] Δf mai =f mai -f mbi

[0044] Where Δf mai is the fugacity difference between the fugacity of component i in the first fluid composition and the fugacity of component i in the fracture region, f maiis the fugacity of component i in the first fluid composition, f bi is the fugacity of component i in the fracture area;

[0045] The second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture area is calculated according to the following formula:

[0046] Δf mbi =f mbi -f bi

[0047] Where Δf mbi is the fugacity difference between the fugacity of component i in the second fluid composition and the fugacity of component i in the fracture region, f mbi is the fugacity of component i in the second fluid composition.

[0048] In one embodiment, the chord-intercept method formula is used to perform an iterative operation to calculate the fluid composition in the nanopores and the molar composition of each component, including:

[0049] According to the first fluid composition and the second fluid composition, obtaining the molar composition of each component in the first fluid composition and the second fluid composition;

[0050] According to the molar composition of each component in the first fluid composition and the second fluid composition, the second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture area, and the second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture area, the initial value of the iterative calculation of the chord-intercept method formula is calculated according to the following formula:

[0051]

[0052] in, is the initial value of the iterative calculation of the chord-intercept method formula, z mai is the molar composition of component i in the first fluid composition, z mbi is the molar composition of component i in the second fluid composition, Δf mai is the second fugacity difference between the fugacity of component i in the first fluid composition and the fugacity of component i in the fracture region, Δf mbi is the second fugacity difference between the fugacity of component i in the second fluid composition and the fugacity of component i in the fracture region;

[0053] Get the error accuracy of the preset chord-intercept method formula;

[0054] According to the second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture region, the second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture region, and the calculated initial value of the chord-intercept method formula for iterative calculation, the fluid composition in the nanopores is iteratively calculated according to the following chord-intercept method formula:

[0055]

[0056] in, is the fluid composition in the nanopores calculated at the kth iteration, is the fluid composition in the nanopores calculated at the k-1th iteration, k is a non-negative number that increases with the number of iterations starting from 0. is the second fugacity difference between the fugacity of component i in the fluid composition in the nanopores and the fugacity of component i in the fracture area calculated at the k-1th iteration;

[0057] When the second fugacity difference between the fugacity of each component in the calculated fluid composition in the nanopores and the fugacity of the same component in the fracture area is less than the error precision, the iterative calculation is terminated and the calculated fluid composition in the nanopores and the molar composition of each component are output.

[0058] In one embodiment, the first fugacity difference between the calculated fugacity of each component in the fluid composition in the nanopore and the fugacity of the same component in the fracture region, and the calculated molar composition of each component in the fluid composition in the nanopore are compared and verified with preset conditions, including:

[0059] determining a specified error of a first fugacity difference between the fugacity of each component in the fluid composition within the nanopores and the fugacity of the same component in the fracture region and an allowable error of a sum of the molar compositions of each component in the fluid composition within the nanopores;

[0060] The first fugacity difference between the fugacity of each component in the fluid composition in the nanopore and the fugacity of the same component in the fracture region is compared with the specified error according to the following formula:

[0061]

[0062] Among them, diff i is the first fugacity difference between the fugacity of each component in the fluid composition in the nanopore and the fugacity of the same component in the fracture area, ε is the specified error, and f i is the fugacity of component i in the fluid composition in the nanopore, f bi is the fugacity of component i in the fracture area;

[0063] The sum of the molar compositions of the components in the fluid composition within the nanopores is compared with the allowable error according to the following formula:

[0064]

[0065] Where δ is the allowable error, z i is the molar composition of component i in the fluid composition in the nanopore;

[0066] When the first fugacity difference between the fugacity of each component in the fluid composition in the nanopore and the fugacity of the same component in the fracture area is less than the specified error, and the difference between the sum of the molar composition of each component in the fluid composition in the nanopore and 1 is less than the allowable error, the verification is determined to be passed; otherwise, the verification is determined to be failed.

[0067] In one embodiment, a single-phase stability test is performed on the fluid composition in the determined nanopores, comprising:

[0068] According to the pressure in the nanopore, the gas-liquid equilibrium constant of each component in the fluid composition in the nanopore is calculated according to the following formula:

[0069]

[0070] in, is the gas-liquid equilibrium constant of component i in the fluid composition in the nanopores, P m is the pressure inside the nanopore, T ci is the critical temperature of component i, P ci is the critical pressure of component i, ω i is the eccentricity factor of component i, exp(·) is an exponential function with the natural number e as the base;

[0071] According to the gas-liquid equilibrium constant of each component in the fluid composition in the nanopore, the gas-liquid equilibrium constant of each component in the fluid composition in the nanopore is initialized according to the following formula to obtain an initialization set:

[0072]

[0073] Among them, K i Initialize the set of gas-liquid equilibrium constants of component i in the fluid composition in the nanopore;

[0074] According to the initialization set of gas-liquid equilibrium constants of each component in the fluid composition in the nanopore, the intermediate variable of each value in the initialization set of gas-liquid equilibrium constants of each component in the fluid composition in the nanopore is calculated according to the following formula:

[0075]

[0076] Among them, X i The intermediate variable z is the initialization value of each value in the set of gas-liquid equilibrium constants of component i in the fluid composition in the nanopore. i is the molar composition of component i in the fluid composition within the nanopores;

[0077] The intermediate variables of each value in the set are initialized according to the gas-liquid equilibrium constant of each component in the fluid composition in the nanopores, and the intermediate variables are iteratively calculated according to the following formula:

[0078]

[0079] in, is the result calculated at the kth iteration, is the fugacity coefficient of component i in the fluid composition of the nanopore region, is the result calculated at the k-1th iteration, is the fugacity coefficient of component i in the fluid composition of the nanopore region corresponding to the intermediate composition calculated in the k-1th iteration, and Z is an integer set;

[0080] According to the result obtained by the k-th iteration and the result obtained by the k-1-th iteration, the iteration error is calculated according to the following formula:

[0081]

[0082] Among them, err is the iteration error;

[0083] According to the iteration error, when the iteration error is greater than 1×10 -8 In the case of , continue iterative calculation, and when the iteration error is less than or equal to 1×10 -8 In the case of, the TPD function value is calculated according to the following formula:

[0084]

[0085] Among them, TPD i is the TPD function value of component i in the fluid composition in the nanopores;

[0086] According to the TPD function value, all values ​​in the gas-liquid equilibrium constant initialization set of each component in the fluid composition in the nanopore make the TPD function value greater than or equal to -1×10 -8 In the case of , the test is judged to pass when any value in the initialization set of the gas-liquid equilibrium constant of each component in the fluid composition in the nanopore makes the TPD function value less than -1×10 -8 In this case, the test is judged to have failed.

[0087] A device for measuring fluid composition and fluid phase in nanopores, comprising:

[0088] A determination module, used to determine the pressure in the fracture area, the fugacity of each component in the fracture area, and basic characteristic parameters of the fluid in the fracture area;

[0089] A determination module, for taking the pressure of the fracture area as the initial pressure of the nanopore, determining the molar composition of each component in the nanopore through a preset number of Monte Carlo experiments, and taking the determination result of each Monte Carlo experiment as the initial fluid composition set of the nanopore;

[0090] A selection module, used for randomly selecting a plurality of groups of compositions satisfying preset conditions from the initial fluid composition set as candidate fluid composition sets for the nanopores;

[0091] A first calculation module is used to calculate the fugacity of each component in each composition in the candidate fluid composition set according to the initial pressure of the nanopores and the basic characteristic parameters of the fluid in the fracture area;

[0092] The second calculation module is used to compare the fugacity of each component in each composition in the candidate fluid composition set with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component.

[0093] An electronic device comprises a processor and a memory for storing instructions executable by the processor, wherein the steps of the above method are implemented when the processor executes the instructions.

[0094] A computer-readable storage medium stores a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0095] The present application provides a method for determining the composition and phase state of fluid in nanopores, by determining the pressure of the fracture area, the fugacity of each component in the fracture area and the basic characteristic parameters of the fluid in the fracture area; taking the pressure of the fracture area as the initial pressure of the nanopore, determining the molar composition of each component in the nanopore through a preset number of Monte Carlo experiments, and taking the determination results of each Monte Carlo experiment as the initial fluid composition set of the nanopore; randomly selecting multiple groups of compositions that meet the preset conditions in the initial fluid composition set as the candidate fluid composition set of the nanopore; according to the initial pressure of the nanopore and the basic characteristic parameters of the fluid in the fracture area, calculating the fugacity of each component in each composition in the candidate fluid composition set; comparing the fugacity of each component in each composition in the candidate fluid composition set with the fugacity of each component in the fracture area to determine the fluid composition and the molar composition of each component in the nanopore. The above scheme can realize the accurate determination of the fluid composition and phase state in the nanopore, thereby accurately reflecting the behavior characteristics of the fluid in the nanopore. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] In order to more clearly illustrate the embodiments of this specification, the drawings required for use in the embodiments will be briefly introduced below. The drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0097] Figure 1 It is a method flow chart of an embodiment of a method for determining fluid composition and fluid phase state in nanopores provided by the present application;

[0098] Figure 2 It is a hardware structure block diagram of an electronic device for a method for determining fluid composition and fluid phase state in a nanopore provided by the present application;

[0099] Figure 3 It is a schematic diagram of the module structure of an embodiment of a device for measuring fluid composition and fluid phase state in nanopores provided in the present application. DETAILED DESCRIPTION

[0100] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this specification.

[0101] In view of the existing method for determining the fluid in the nanopore, the phase state and fluid components of the fluid in the nanopores of different sizes can only be directional judged by pressure coring combined with nuclear magnetic resonance, but the specific composition of the fluid in the nanopore cannot be accurately determined. In this example, a method for determining the composition and phase state of the fluid in the nanopore is provided. Although the present application provides the method operation steps or device structure shown in the following embodiments or drawings, more or less operation steps or module units may be included in the method or device based on routine or no creative labor. In the steps or structures where there is no necessary causal relationship logically, the execution order of these steps or the module structure of the device is not limited to the execution order or module structure described in the embodiments of the present application and shown in the drawings. When the method or module structure is applied to the actual device or terminal product, it can be connected according to the method or module structure shown in the embodiment or drawings for sequential execution or parallel execution (for example, a parallel processor or a multi-threaded processing environment, or even a distributed processing environment).

[0102] Specifically, Figure 1 As shown, the above-mentioned method for determining the fluid composition and fluid phase state in the nanopores may include the following steps:

[0103] S101: Determine the pressure in the fracture area, the fugacity of each component in the fracture area, and the basic characteristic parameters of the fluid in the fracture area.

[0104] Among them, the fugacity of each component in the fracture area can be determined according to the fluid phase parameters in the fracture area. Specifically, the gas phase mole fraction can be obtained by phase equilibrium calculation, and the fluid phase parameters in the fracture area can be judged according to the gas phase mole fraction, including:

[0105] When the gas phase mole fraction is greater than or equal to 1, or less than or equal to 0, the fluid is single-phase, and the fugacity of each component in the output fluid is used as the fugacity of each component in the fracture area;

[0106] When the gas phase mole fraction is between 0 and 1, the fluid is two-phase, and the gas phase composition, liquid phase composition, gas phase fugacity and liquid phase fugacity are output, and the gas phase fugacity is used as the fugacity of each component in the fracture area.

[0107] Specifically, the fugacity of each component in the fracture region determined above is used as a reference fugacity required to determine the fluid composition in the nanopores.

[0108] Specifically, the basic characteristic parameters of the fluid in the fracture area can be determined based on production data, and the basic characteristic parameters of the fluid in the fracture area at least include: fluid components, molar composition of each component, critical pressure, critical temperature and eccentricity factor. However, it is worth noting that the above-listed methods for determining the basic characteristic parameters of the fluid in the fracture area and the parameters included in the basic characteristic parameters of the fluid in the fracture area are only an exemplary description and do not constitute an improper limitation on the present application. In actual implementation, other appropriate methods can be selected according to needs and on-site conditions, and the present application does not limit this.

[0109] S102: taking the pressure of the fracture area as the initial pressure of the nanopore, measuring the molar composition of each component in the nanopore through a preset number of Monte Carlo experiments, and taking the measurement result of each Monte Carlo experiment as the initial fluid composition set of the nanopore.

[0110] S103: Randomly select multiple groups of compositions that meet preset conditions from the initial fluid composition set as candidate fluid composition sets for the nanopores.

[0111] Specifically, the multiple groups of compositions randomly selected from the initial fluid composition set satisfy the following conditions:

[0112] 0<z mi <1

[0113]

[0114] Among them, z mi is the molar composition of component i in composition m.

[0115] S104: Calculate the fugacity of each component in each composition in the candidate fluid composition set according to the initial pressure of the nanopores and the basic characteristic parameters of the fluid in the fracture area.

[0116] Before calculating the fugacity of each component in the fluid composition in the nanopore, it is necessary to first calculate the deviation factor of the nanopore. Specifically, the deviation factor of the nanopore can be calculated by the initial pressure of the nanopore and the basic characteristic parameters of the fluid in the fracture area, including:

[0117] Obtaining the temperature of the oil reservoir where the nanopore is located, the gas constant, the diameter of the molecule in the nanopore, and the radius of the nanopore;

[0118] Determine basic characteristic parameters of the fluid in the fracture area according to production data; the basic characteristic parameters of the fluid include at least one of the following: critical pressure, critical temperature and eccentricity factor;

[0119] According to the initial pressure of the nanopore, the temperature of the reservoir, the gas constant, the diameter of the molecule in the nanopore, the radius of the nanopore, the critical pressure of the fracture area, the critical temperature of the fracture area and the eccentricity factor of the fracture area, the deviation factor of the nanopore can be calculated according to the following formula:

[0120] Z 3 -(1-B)Z 2 +(A-2B-3B 2 )Z-(AB-B 2 -B 3 )=0

[0121] Where Z is the deviation factor, P m is the initial pressure in the nanopores, R is the gas constant, T is the temperature of the reservoir, σ LJ is the diameter of the molecule in the nanopore, R p is the radius of the nanopore, P c is the critical pressure in the crack region, T c is the critical temperature of the crack region, and ω is the eccentricity factor of the crack region.

[0122] Furthermore, after the deviation factor of the nanopore is determined, the fugacity of each component in the fluid composition in the nanopore is calculated according to the deviation factor of the nanopore through a phase state model based on the A-PR state equation taking into account the nanoconfinement effect.

[0123] S105: Compare the fugacity of each component in each composition in the candidate fluid composition set with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component.

[0124] Specifically, before determining the fluid composition and the molar composition of each component in the nanopore, it is necessary to compare the fugacity of each component in each composition in the candidate fluid composition set with the fugacity of each component in the fracture region, which may include the following steps (S1 to S4):

[0125] S1: respectively calculating the first fugacity difference between the fugacity of each component in each composition in the candidate fluid composition set and the fugacity of the same component in the fracture region to obtain a plurality of first fugacity differences.

[0126] Specifically, the first fugacity difference may be calculated according to the following formula:

[0127]

[0128] Among them, diff iis the first fugacity difference between the fugacity of component i in candidate fluid composition m and the fugacity of component i in the fracture region, f mi is the fugacity of component i in candidate fluid composition m, f bi is the fugacity of component i in the fracture region.

[0129] S2: Based on the multiple first fugacity differences, two groups of fluid compositions with the smallest first fugacity differences are selected from the candidate fluid composition set as the first fluid composition and the second fluid composition in the nanopores, wherein the first fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture region is smaller than the first fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture region.

[0130] S3: respectively calculating the second fugacity difference between the fugacity of each component in the first fluid composition and the second fluid composition and the fugacity of the same component in the fracture region.

[0131] Specifically, the second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture area can be calculated according to the following formula:

[0132] Δf mai =f mai -f mbi

[0133] Where Δf mai is the fugacity difference between the fugacity of component i in the first fluid composition and the fugacity of component i in the fracture region, f mai is the fugacity of component i in the first fluid composition, f bi is the fugacity of component i in the fracture region.

[0134] Specifically, the second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture area can be calculated according to the following formula:

[0135] Δf mbi =f mbi -f bi

[0136] Where Δf mbi is the fugacity difference between the fugacity of component i in the second fluid composition and the fugacity of component i in the fracture region, f mbi is the fugacity of component i in the second fluid composition.

[0137] S4: According to the first fluid composition, the second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture area, the second fluid composition, the second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture area, iterative operations are performed through the chord-intercept method formula to calculate the fluid composition in the nanopores and the molar composition of each component.

[0138] Specifically, before performing iterative calculations using the chord-intercept method formula, it is necessary to first determine the initial value of the iterative calculation of the chord-intercept method, including:

[0139] According to the first fluid composition and the second fluid composition, obtaining the molar composition of each component in the first fluid composition and the second fluid composition;

[0140] According to the molar composition of each component in the first fluid composition and the second fluid composition, the second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture region, and the second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture region, the initial value of the iterative calculation of the chord-intercept method formula can be calculated according to the following formula:

[0141]

[0142] in, is the initial value of the iterative calculation of the chord-intercept method formula, z mai is the molar composition of component i in the first fluid composition, z mbi is the molar composition of component i in the second fluid composition, Δf mai is the second fugacity difference between the fugacity of component i in the first fluid composition and the fugacity of component i in the fracture region, Δf mbi is the second fugacity difference between the fugacity of component i in the second fluid composition and the fugacity of component i in the fracture region.

[0143] Furthermore, for the chord-intercept method formula, it is also necessary to obtain the error accuracy of the preset chord-intercept method formula to determine whether to continue iterating or terminate the iteration of the chord-intercept method formula.

[0144] Further, after determining the initial value of the iterative calculation of the chord intercept formula and the error accuracy of the chord intercept formula, according to the second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture area, the second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture area, and the calculated initial value of the iterative calculation of the chord intercept formula, the fluid composition in the nanopores can be iteratively calculated according to the following chord intercept formula:

[0145]

[0146] in, is the fluid composition in the nanopores calculated at the kth iteration, is the fluid composition in the nanopores calculated at the k-1th iteration, k is a non-negative number that increases with the number of iterations starting from 0. is the second fugacity difference between the fugacity of component i in the fluid composition in the nanopores and the fugacity of component i in the fracture region calculated at the k-1th iteration; for Fugacity of component i, f bi is the fugacity of component i in the fracture region.

[0147] Further, according to the second fugacity difference between the fugacity of each component in the fluid composition in the nanopores calculated in the chord-intercept method formula and the fugacity of the same component in the fracture area and the error accuracy of the chord-intercept method formula, the continued iteration or termination iteration of the chord-intercept method formula is judged, including:

[0148] When the calculated second fugacity difference between the fugacity of each component in the fluid composition in the nanopores and the fugacity of the same component in the fracture region is greater than or equal to the error precision, continuing the iterative calculation;

[0149] When the second fugacity difference between the fugacity of each component in the calculated fluid composition in the nanopores and the fugacity of the same component in the fracture area is less than the error precision, the iterative calculation is terminated and the calculated fluid composition in the nanopores and the molar composition of each component are output.

[0150] Furthermore, the fluid composition in the nanopores and the molar composition of each component calculated by the chord-intercept method formula need to be verified and tested to ensure that the calculated fluid composition in the nanopores and the molar composition of each component meet the preset conditions.

[0151] Specifically, the first fugacity difference between the calculated fugacity of each component in the fluid composition in the nanopores and the fugacity of the same component in the fracture area, as well as the calculated molar composition of each component in the fluid composition in the nanopores and the preset conditions are compared and verified, including:

[0152] determining a specified error of a first fugacity difference between the fugacity of each component in the fluid composition within the nanopores and the fugacity of the same component in the fracture region and an allowable error of a sum of the molar compositions of each component in the fluid composition within the nanopores;

[0153] The first fugacity difference between the fugacity of each component in the fluid composition in the nanopore and the fugacity of the same component in the fracture region is compared with the specified error according to the following formula:

[0154]

[0155] Among them, diff i is the first fugacity difference between the fugacity of each component in the fluid composition in the nanopore and the fugacity of the same component in the fracture area, ε is the specified error, and f i is the fugacity of component i in the fluid composition in the nanopore, f bi is the fugacity of component i in the fracture area;

[0156] The sum of the molar compositions of the components in the fluid composition within the nanopores is compared with the allowable error according to the following formula:

[0157]

[0158] Where δ is the allowable error, z i is the molar composition of component i in the fluid composition within the nanopores.

[0159] Specifically, when the first fugacity difference between the fugacity of each component in the fluid composition in the nanopore and the fugacity of the same component in the fracture area is less than the specified error, and the difference between the sum of the molar composition of each component in the fluid composition in the nanopore and 1 is less than the allowable error, the verification is determined to be passed; otherwise, the verification is determined to be failed.

[0160] If the verification fails, the initial pressure of the nanopores is adjusted, and the fluid composition and the molar composition of each component in the nanopores are recalculated based on the adjusted initial pressure of the nanopores. Specifically, the initial pressure of the nanopores is lowered, and the fluid composition in the nanopores is remeasured through the Monte Carlo experiment to obtain a new initial fluid composition set. A new candidate fluid composition set that meets the preset conditions is selected from the new initial fluid composition set, and the fugacity of each component in each composition in the new candidate fluid composition set is compared with the fugacity of the same component in the fracture area. The fluid composition and the molar composition of each component in the nanopores are re-determined by the chord-intercept method formula, and the re-determined fluid composition and the molar composition of each component in the nanopores are verified again until the verification passes.

[0161] Furthermore, when the verification is passed, the fluid composition in the nanopore and the molar composition of each component when the verification is passed are taken as the determined fluid composition in the nanopore and the molar composition of each component and outputted.

[0162] Furthermore, in order to accurately determine the phase parameters of the fluid composition in the nanopores, it is also necessary to perform a single-phase stability test on the determined fluid composition in the nanopores.

[0163] Specifically, the single-phase stability test is performed on the determined fluid composition in the nanopores in the following manner, including:

[0164] According to the pressure in the nanopore, the gas-liquid equilibrium constant of each component in the fluid composition in the nanopore is calculated according to the following equation:

[0165]

[0166] in, is the gas-liquid equilibrium constant of component i in the fluid composition in the nanopores, P m is the pressure inside the nanopore, T ci is the critical temperature of component i, P ci is the critical pressure of component i, ω i is the eccentricity factor of component i, exp(·) is an exponential function with the natural number e as the base;

[0167] Further, according to the gas-liquid equilibrium constant of each component in the fluid composition in the nanopore, the gas-liquid equilibrium constant of each component in the fluid composition in the nanopore is initialized according to the following formula to obtain an initialization set:

[0168]

[0169] Among them, K i Initialize the set of gas-liquid equilibrium constants of component i in the fluid composition in the nanopore;

[0170] Further, according to the initialization set of gas-liquid equilibrium constants of each component in the fluid composition in the nanopore, the intermediate variable of each value in the initialization set of gas-liquid equilibrium constants of each component in the fluid composition in the nanopore is calculated according to the following formula:

[0171]

[0172] Among them, X i The intermediate variable z is the initialization value of each value in the set of gas-liquid equilibrium constants of component i in the fluid composition in the nanopore. i is the molar composition of component i in the fluid composition within the nanopores;

[0173] Furthermore, an intermediate variable of each value in the set is initialized according to the gas-liquid equilibrium constant of each component in the fluid composition in the nanopores, and the intermediate variable is iteratively calculated according to the following formula:

[0174]

[0175] in, is the result calculated at the kth iteration, is the fugacity coefficient of component i in the fluid composition of the nanopore region, is the fugacity coefficient of component i in the fluid composition of the nanopore region corresponding to the intermediate composition calculated in the k-1th iteration, is the result calculated at the k-1th iteration, and Z is a set of integers;

[0176] According to the result obtained by the k-th iteration and the result obtained by the k-1-th iteration, the iteration error is calculated according to the following formula:

[0177]

[0178] Among them, err is the iteration error;

[0179] According to the iteration error, when the iteration error is greater than 1×10 -8 In the case of , continue iterative calculation, and when the iteration error is less than or equal to 1×10 -8 In the case of, the TPD function value is calculated according to the following formula:

[0180]

[0181] Among them, TPD i is the TPD function value of component i in the fluid composition in the nanopores;

[0182] Further, according to the TPD function value, all values ​​in the gas-liquid equilibrium constant initialization set of each component in the fluid composition in the nanopore make the TPD function value greater than or equal to -1×10 -8 In the case of , the test is judged to pass when any value in the initialization set of the gas-liquid equilibrium constant of each component in the fluid composition in the nanopore makes the TPD function value less than -1×10 -8 In this case, the test is judged to have failed.

[0183] Furthermore, if the test fails, it is determined that the nanopores are in a two-phase state, and a two-phase flash calculation is performed on the fluid composition of the nanopore region determined above, and the gas phase composition, liquid phase composition, gas phase mole fraction and liquid phase mole fraction are output. If the test passes, it is determined that the nanopores are in a single-phase state, and the fluid composition of the nanopore region is output.

[0184] The above method is described below in conjunction with a specific embodiment. However, it should be noted that this specific embodiment is only for better illustrating the present application and does not constitute an improper limitation on the present application.

[0185] In this example, considering that the existing method for measuring fluids in nanopores can only make directional judgments on the phase state and fluid components of fluids in nanopores of different sizes by pressure-maintaining coring combined with nuclear magnetic resonance, but cannot accurately determine the specific composition of the fluids in the nanopores, in this example, a method for measuring the composition and phase state of fluids in nanopores is provided. This method can accurately determine the composition of the fluid in the nanopores based on the pressure in the fracture area, the fugacity of each component in the fracture area, and the basic characteristic parameters of the fluid in the fracture area, and accurately determine the fluid phase state of the fluid in the nanopores based on the molar composition of each component in the determined fluid composition in the nanopores, thereby accurately reflecting the behavior characteristics of the fluid in the nanopores and optimizing the development plan of shale oil reservoirs.

[0186] Specifically, the method for determining the fluid composition and fluid phase state in the nanopores may include the following steps:

[0187] S1: Determine the temperature of the reservoir and the pressure in the fracture area, and clarify the basic characteristic parameters of the fluid in the fracture area based on production data.

[0188] The above basic characteristic parameters at least include: fluid components in the fracture area, molar composition of each component in the fracture area, critical pressure, critical temperature and eccentricity factor.

[0189] S2: Use the traditional phase model to perform phase equilibrium calculations to obtain the gas phase mole fraction. Based on the gas phase mole fraction, determine the fluid phase parameters in the fracture area and the fugacity of each component in the fracture area.

[0190] When the gas phase mole fraction is greater than or equal to 1, or less than or equal to 0, the fluid is determined to be single-phase, and when the gas phase mole fraction is between 0 and 1, the fluid is determined to be two-phase.

[0191] When the fluid is single-phase, the fugacity of each component in the output fluid is used as the fugacity of each component in the fracture area; when the fluid is two-phase, the gas phase composition, liquid phase composition, gas phase fugacity and liquid phase fugacity are output, and the gas phase fugacity is used as the fugacity of each component in the fracture area.

[0192] S3: Set the pressure in the nanopore to be equal to the pressure in the fracture area, assume that the fluid in the nanopore is in a single-phase state, use the Monte Carlo method to measure the molar composition range in the nanopore multiple times, and obtain multiple groups of initial fluid compositions. Randomly select several groups of compositions that meet the following requirements from all the initial fluid compositions as candidate fluid composition sets:

[0193] 0<z mi <1

[0194]

[0195] Among them, z mi is the molar composition of component i in composition m.

[0196] S4: For each composition in the above candidate fluid composition set, the phase state model considering the nanoconfinement effect based on the A-PR state equation is used, combined with the basic characteristic parameters of the fluid in the fracture area, to calculate the fugacity of each component in each composition in the candidate fluid composition set, and the first fugacity difference between the fugacity of each component in each composition in the candidate fluid composition set and the same fugacity in the fracture area is calculated respectively, and two groups of compositions with smaller fugacity differences are selected. mai and z mbi .

[0197] Specifically, in order to determine the fugacity of each component of each composition in the candidate fluid composition set, the deviation factor of the nanopore may be calculated first. For example, the deviation factor of the nanopore may be calculated according to the following formula:

[0198] Z 3 -(1-B)Z 2 +(A-2B-3B 2 )Z-(AB-B 2 -B 3 )=0

[0199] Where Z is the deviation factor, P m is the initial pressure in the nanopores, R is the gas constant, T is the temperature of the reservoir, σ LJ is the diameter of the molecule in the nanopore, R p is the radius of the nanopore, P c is the critical pressure in the crack region, T c is the critical temperature of the crack region, and ω is the eccentricity factor of the crack region.

[0200] Further, according to the above deviation factor, the fugacity of each component of each composition in the above candidate fluid composition set can be calculated using the phase state model based on the A-PR state equation taking into account the nanoconfinement effect. Then, the first fugacity difference between the fugacity of each component of each composition in the candidate fluid composition set and the fugacity of the same component in the fracture area can be calculated according to the following formula:

[0201]

[0202] Among them, diff i is the first fugacity difference between the fugacity of component i in candidate fluid composition m and the fugacity of component i in the fracture region, f mi is the fugacity of component i in candidate fluid composition m, f bi is the fugacity of component i in the fracture region.

[0203] S5: According to z mai and z mbi The fugacity f corresponding to each component in mai and f mbi , calculate f mai and f mbi The second fugacity difference Δf between the fugacity of the same component in the fracture area mai and Δf mbi , z iam 、z mbi , Δf mai and Δf mbi Substitute the chord-intercept method formula and iteratively solve the fluid composition in the nanopores.

[0204] Specifically, f can be calculated according to the following formula mai The second fugacity difference between the fugacity of the same component in the fracture area:

[0205] Δf mai =f mai -f bi

[0206] Calculate f according to the following formula mbi The second fugacity difference between the fugacity of the same component in the fracture area:

[0207] Δf mbi =f mbi -f bi

[0208] Specifically, the fluid composition in the nanopores is iteratively calculated according to the following formula:

[0209]

[0210] Among them, the initial value of the iterative calculation of the chord intercept method formula is is the second fugacity difference between the fugacity of component i in the fluid composition in the nanopores and the fugacity of component i in the fracture region calculated at the k-1th iteration; for Fugacity of component i, f bi is the fugacity of component i in the fracture region.

[0211] Further, in In the case of , the chord-intercept method formula terminates the iteration, where μ is the error accuracy of the chord-intercept method formula.

[0212] S6: In order to determine whether the calculated fluid composition of the nanopores meets the preset conditions, the calculated fluid composition of the nanopores needs to be verified, including:

[0213] Condition 1. Verify whether the fugacity difference between the fugacity of each component in the fracture area and the fugacity difference of each component in the nanopores is less than the specified error, that is:

[0214]

[0215] Among them, ε is the specified error;

[0216] Condition 2: Verify whether the sum of the molar compositions of the components in the fluid composition in the nanopores is 1, that is:

[0217]

[0218] Here, δ is the allowable error.

[0219] Specifically, when the calculated fluid composition of the nanopores satisfies both condition 1 and condition 2, it is determined that the verification is passed; when the calculated fluid composition of the nanopores does not satisfy any of the above conditions, it is determined that the verification is failed.

[0220] Furthermore, if the verification fails, the pressure in the nanopore region is reduced, and steps S3-S6 are repeated to recalculate the fluid composition in the nanopore until the calculated fluid composition in the nanopore satisfies both the above conditions 1 and 2, and then the fluid composition in the nanopore is output.

[0221] S7: In order to determine the fluid phase parameters of the fluid composition in the nanopores outputted above, a single-phase stability test is required, as follows:

[0222] The gas-liquid equilibrium constant of each component in the fluid composition in the nanopores is calculated by the following equation:

[0223] in, is the gas-liquid equilibrium constant of component i in the fluid composition in the nanopores, P m is the pressure inside the nanopore, T ci is the critical temperature of component i, P ci is the critical pressure of component i, ω i is the eccentricity factor of component i, exp(·) is an exponential function with the natural number e as the base;

[0224] According to the following formula Initialize and get the initialization set:

[0225]

[0226] Among them, K i Initialize the set of gas-liquid equilibrium constants of component i in the fluid composition in the nanopore;

[0227] For each K in the above set i The intermediate variable X is calculated according to the following formula i :

[0228] X i =z i K i

[0229] Among them, X i The intermediate variable z is the initialization value of each value in the set of gas-liquid equilibrium constants of component i in the fluid composition in the nanopore. i is the molar composition of component i in the fluid composition within the nanopores;

[0230] According to the following formula, the intermediate variable X i Perform an iterative solution:

[0231]

[0232] in, is the result calculated at the kth iteration, is the fugacity coefficient of component i in the fluid composition of the nanopore region, is the result calculated at the k-1th iteration, is the fugacity coefficient of component i in the fluid composition of the nanopore region corresponding to the intermediate composition calculated in the k-1th iteration, and Z is an integer set;

[0233] According to the following formula, the intermediate variable X i The iterative error err is evaluated:

[0234]

[0235] Where err is the iteration error; when err>1×10 -8 In the case of err≤1×10 -8 In the case of , the iteration terminates;

[0236] When the iteration is terminated, the TPD function value is calculated according to the following formula:

[0237]

[0238] Among them, TPD i is the TPD function value of component i in the fluid composition within the nanopores.

[0239] S8: Determine the phase state of the fluid in the nanopores according to the calculated TPD function value, including:

[0240] In the initialization set, all K i The TPD value is calculated i The values ​​are all greater than or equal to -1×10 -8 In the case of , the test is judged to have failed, the nanopore is determined to be in a single-phase state, and the calculation ends.

[0241] When using any K in the initialization set i The TPD value is calculated i The values ​​are all less than -1×10 -8 In the case of the above, the test is judged as failed, and the nanopore is determined to be in a two-phase state. Based on the phase model of the A-PR state equation taking into account the nanoconfinement effect, the two-phase flash calculation is performed using the fluid composition in the nanopore output in step S6, and the gas phase composition, oil phase composition, gas phase mole fraction and liquid phase mole fraction are output.

[0242] In the above example, the fluid composition in the nanopores is accurately determined based on the pressure in the fracture area, the fugacity of each component in the fracture area, and the basic characteristic parameters of the fluid in the fracture area. The fluid phase state of the fluid in the nanopores is accurately determined based on the molar composition of each component in the determined fluid composition in the nanopores. This can accurately reflect the behavioral characteristics of the fluid in the nanopores and optimize the development plan of the shale oil reservoir.

[0243] The method for determining the composition and phase of the fluid in the nanopores is described as follows using a specific embodiment:

[0244] Step 1: Taking the hydrocarbon mixture system as an example, determine the pressure P in the fracture area b =34MPa, reservoir temperature T = 374.72K, nanopore radius R p =30nm, the fluid components and component properties in the fracture area are obtained according to the production data, and the specific parameter values ​​are shown in Table 1.

[0245] Table 1 Fluid components and properties in the fracture area

[0246] Components <![CDATA[z b ]]> <![CDATA[T c (Unit: K)]]> <![CDATA[P c (Unit: MPa)]]> ω C1 0.6509 190.6000 4.6002 0.0080 C2-C3 0.1926 324.2000 4.7097 0.1126 C4-C6 0.0274 452.7720 3.5246 0.2251 C7-C18 0.0977 652.1195 2.0739 0.5743 C19-C38 0.0313 805.5042 1.5263 1.0060

[0247] Step 2: The calculated saturation pressure of the fluid in the fracture area is 34.96 MPa, which is higher than the system pressure, indicating that the fluid is two-phase. Output the gas phase composition and oil phase composition of each component in the fracture area as well as the gas phase fugacity and oil phase fugacity, and use the gas phase fugacity as the fracture area fugacity f bi The gas phase composition and oil phase composition of each component in the fracture area are shown in Table 2, and the gas phase fugacity and oil phase fugacity of each component in the fracture area are shown in Table 3.

[0248] Table 2 Gas phase composition and oil phase composition of each component in the fracture area

[0249] Components C1 C2-C3 C4-C6 C7-C18 C19-C38 Gas phase composition 0.7515 0.1843 0.0204 0.0394 0.0045 Liquid phase composition 0.6232 0.1950 0.0294 0.1138 0.0387

[0250] Table 3 Gas phase fugacity and oil phase fugacity of each component in the fracture area

[0251] Components C1 C2-C3 C4-C6 C7-C18 C19-C38 Gas phase fugacity 2.3567E+04 2.4087E+03 8.4488E+01 6.2446 7.9588E-03 Liquid phase fugacity 2.3567E+04 2.4087E+03 8.4488E+01 6.2446 7.9588E-03

[0252] Step 3: Assuming that the crude oil in the nanopore is in a single-phase state, the Monte Carlo method is used to estimate the molar composition in the nanopore. Here, two sets of values ​​are taken as examples, as shown in Table 4:

[0253] Table 4 Composition of two groups obtained using Monte Carlo method

[0254] Components C1 C2-C3 C4-C6 C7-C18 C19-C38 Composition 1 0.782585876 0.175557601 0.017154612 0.023068455 0.001633457 Composition 2 0.785137115 0.174827644 0.016913374 0.022152497 0.00096937

[0255] Step 4: For the above two compositions, calculate the fugacity f of each component mi and the difference between the fugacity in the fracture area As shown in Table 5:

[0256] Table 5 Fugacity corresponding to different fluid compositions in nanopores

[0257] Components C1 C2-C3 C4-C6 C7-C18 C19-C38 diff Composition 1 Fugacity 2.388E+04 2435 85.37 6.329 8.652E-03 319.2481 Composition 2 Fugacity 2.390E+04 2437 85.4 6.32 5.530E-03 333.853

[0258] Step 5: Select the above components as the initial value z mai and z mbi , calculate f respectively mai and f mbi and the fracture area fugacity f bi The difference Δf mai =f mai -f bi and Δf mbi =f mbi -f bi , as shown in Table 6.

[0259] Table 6 The difference between the fugacity of the components in the nanopores and the fugacity of the fracture area

[0260] <![CDATA[Δf mai ]]> 3.181E+02 26.7485 0.8859 0.0846 6.934E-04 <![CDATA[Δf mbi ]]> 3.327E+02 27.8416 0.9132 0.0757 -2.428E-03

[0261] z mai 、z mbi 、f mai 、f mbi , Δf mai , Δf mbi Substitute the chord-intercept method formula to iteratively solve the fluid composition in the nanopores. The specific results are shown in Table 7.

[0262] Table 7. Chord-intercept method iteration initial values ​​and final calculation results

[0263]

[0264] Step 6: Verify whether the difference in fugacity between the fracture area and the components in the nanopores is less than the specified error, and whether the sum of the molar composition of the components in the nanopores is 1. The verification results are shown in Table 8.

[0265] Table 8 Compliance verification of calculation results

[0266]

[0267] As can be seen from Table 8, if the verification fails, the pressure in the nanopore area is reduced and steps S3 to S6 are repeated;

[0268] After several pressure drops, when the pressure in the nanopore area drops to 33.516 MPa, the above judgment conditions are met. The fluid composition in the nanopores at this time is shown in Table 9, and the compliance verification results are shown in Table 10.

[0269] Table 9 Fluid composition of nanopores that meet the conditions

[0270] Components C1 C2-C3 C4-C6 C7-C18 C19-C38 composition 0.7856 0.1747 0.0169 0.0208 0.0015 fugacity 23567.64 2408.65 84.4952 5.9297 0.0086

[0271] Table 10 Compliance verification of qualified nanopore composition

[0272]

[0273] Step 7: Perform a single-phase stability test on the above composition, as follows:

[0274] Calculate the gas-liquid equilibrium constants of each component in the nanopores What you get The values ​​are shown in Table 11:

[0275] Table 11 Gas-liquid equilibrium constants of each component

[0276]

[0277] right Initialize to get K i The values ​​are shown in Table 12.

[0278] Table 12 Initialize K of each component i value

[0279] Components C1 C2-C3 C4-C6 C7-C18 C19-C38 <![CDATA[K1]]> 0.5040 3.0118 33.1996 6104.7089 2.830E+06 <![CDATA[K2]]> 1.9842 0.3320 0.0301 0.0002 3.534E-07 <![CDATA[K3]]> 0.7958 1.4441 3.2140 18.2763 1.414E+02 <![CDATA[K4]]> 1.2566 0.6925 0.3111 0.0547 7.070E-03

[0280] For K1~K4, the following calculation is performed (each group K i The calculation process is similar, and only K is described in detail here. i Calculation process): Calculate the initial value of the intermediate variable As shown in Table 13:

[0281] Table 13 Initial values ​​of intermediate variables

[0282]

[0283] Iterative solution X i , the results of the first iteration are shown in Table 14:

[0284] Table 14 Intermediate variables after the first iteration

[0285]

[0286] The iteration results are evaluated and the iteration error err = 4240.07, which is greater than 1×10 -8 , continue to iterate;

[0287] The final iterative calculation results are The values ​​are shown in Table 15:

[0288] Table 15 Final values ​​of intermediate variables

[0289]

[0290] At this time, err = 8.31 × 10 -10 , less than 1×10 -8 , stop iteration;

[0291] calculate The TPD function value at , we get TPD = 0.00046, which is greater than -1×10 -8 , the test passed;

[0292] Repeat this step using the same algorithm to calculate the TPD function values ​​corresponding to K2~K4. The calculation results are shown in Table 16:

[0293] Table 16 TPD function values ​​corresponding to K2~K4

[0294] <![CDATA[K i ]]> <![CDATA[K2]]> <![CDATA[K3]]> <![CDATA[K4]]> TPD function value 0.00046 0.00046 0.00046

[0295] It can be seen from Table 16 that all TPD function values ​​are greater than -1×10 -8, it can be determined that the fluid in the nanopore is in a single-phase state. The program ends and the fluid composition in the nanopore is output.

[0296] In the above embodiments, the fluid composition in the nanopores is accurately determined based on the pressure in the fracture area, the fugacity of each component in the fracture area and the basic characteristic parameters of the fluid in the fracture area. Based on the molar composition of each component in the determined fluid composition in the nanopores, the fluid phase state of the fluid in the nanopores is accurately determined, thereby accurately reflecting the behavioral characteristics of the fluid in the nanopores and optimizing the development plan of the shale oil reservoir.

[0297] The method embodiments provided in the above embodiments of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. Taking running on an electronic device as an example, Figure 2 This is a hardware structure block diagram of an electronic device for a method of determining fluid composition and fluid phase in a nanopore provided by the present application. Figure 2 As shown, the electronic device 10 may include one or more (only one is shown in the figure) processors 02 (the processor 02 may include but is not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA), a memory 04 for storing data, and a transmission module 06 for communication functions. It can be understood by those skilled in the art that Figure 2 The structure shown is only for illustration and does not limit the structure of the above electronic device. Figure 2 More or fewer components as shown, or with Figure 2 Different configurations are shown.

[0298] The memory 04 can be used to store software programs and modules of application software, such as program instructions / modules corresponding to the method for determining the composition of fluid in nanopores and the phase state of fluid in the embodiment of the present application. The processor 02 executes various functional applications and data processing by running the software programs and modules stored in the memory 04, that is, the method for determining the composition of fluid in nanopores and the phase state of fluid in the above-mentioned application program is realized. The memory 04 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 04 may further include a memory remotely arranged relative to the processor 02, and these remote memories may be connected to the electronic device 10 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0299] The transmission module 06 is used to receive or send data via a network. The specific example of the above network may include a wireless network provided by a communication provider of the electronic device 10. In one example, the transmission module 06 includes a network adapter (Network Interface Controller, NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission module 06 can be a radio frequency (Radio Frequency, RF) module, which is used to communicate with the Internet wirelessly.

[0300] Based on the same inventive concept as the above-mentioned method for determining the composition and phase state of fluid in nanopores, a device for determining the composition and phase state of fluid in nanopores is also provided in the embodiment of the present application. The device for determining the composition and phase state of fluid in nanopores can be as follows: Figure 3 Shown include:

[0301] Determination module 301, for determining the pressure of the fracture area, the fugacity of each component in the fracture area and the basic characteristic parameters of the fluid in the fracture area;

[0302] A determination module 302 is used to use the pressure of the fracture area as the initial pressure of the nanopore, determine the molar composition of each component in the nanopore through a preset number of Monte Carlo experiments, and use the determination result of each Monte Carlo experiment as the initial fluid composition set of the nanopore;

[0303] A selection module 303 is used to randomly select a plurality of groups of compositions satisfying preset conditions from the initial fluid composition set as candidate fluid composition sets for the nanopores;

[0304] A first calculation module 304 is used to calculate the fugacity of each component in each composition in the candidate fluid composition set according to the initial pressure of the nanopores and the basic characteristic parameters of the fluid in the fracture area;

[0305] The second calculation module 305 is used to compare the fugacity of each component in each composition in the candidate fluid composition set with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component.

[0306] Since the principle of solving the problem by the device for measuring fluid composition and fluid phase state in nanopores is similar to that of the method for measuring fluid composition and fluid phase state in nanopores, the implementation of the device for measuring fluid composition and fluid phase state in nanopores can refer to the implementation of the method for measuring fluid composition and fluid phase state in nanopores, and the repeated parts will not be repeated here.

[0307] The embodiments of the present application also provide a specific implementation of an electronic device capable of implementing all the steps in the method for determining the composition and phase state of the fluid in the nanopores in the above embodiments. The electronic device specifically includes the following contents: a processor, a memory, a communication interface and a bus; wherein the processor, the memory and the communication interface communicate with each other through the bus; the processor is used to call a computer program in the memory, and when the processor executes the computer program, all the steps in the method for determining the composition and phase state of the fluid in the nanopores in the above embodiments are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0308] Step 1: Determine the pressure in the fracture area, the fugacity of each component in the fracture area, and the basic characteristic parameters of the fluid in the fracture area;

[0309] Step 2: taking the pressure of the fracture area as the initial pressure of the nanopore, measuring the molar composition of each component in the nanopore through a preset number of Monte Carlo experiments, and taking the measurement result of each Monte Carlo experiment as the initial fluid composition set of the nanopore;

[0310] Step 3: randomly selecting a plurality of groups of compositions satisfying preset conditions from the initial fluid composition set as candidate fluid composition sets for the nanopores;

[0311] Step 4: Calculate the fugacity of each component in each composition in the candidate fluid composition set according to the initial pressure of the nanopores and the basic characteristic parameters of the fluid in the fracture area;

[0312] Step 5: Compare the fugacity of each component in each composition in the candidate fluid composition set with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component.

[0313] The embodiments of the present application also provide a computer-readable storage medium capable of implementing all the steps in the method for determining the composition and phase state of the fluid in the nanopores in the above embodiments. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, all the steps in the method for determining the composition and phase state of the fluid in the nanopores in the above embodiments are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0314] Step 1: Determine the pressure in the fracture area, the fugacity of each component in the fracture area, and the basic characteristic parameters of the fluid in the fracture area;

[0315] Step 2: taking the pressure of the fracture area as the initial pressure of the nanopore, measuring the molar composition of each component in the nanopore through a preset number of Monte Carlo experiments, and taking the measurement result of each Monte Carlo experiment as the initial fluid composition set of the nanopore;

[0316] Step 3: randomly selecting a plurality of groups of compositions satisfying preset conditions from the initial fluid composition set as candidate fluid composition sets for the nanopores;

[0317] Step 4: Calculate the fugacity of each component in each composition in the candidate fluid composition set according to the initial pressure of the nanopores and the basic characteristic parameters of the fluid in the fracture area;

[0318] Step 5: Compare the fugacity of each component in each composition in the candidate fluid composition set with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component.

[0319] From the above description, it can be seen that the present application determines the pressure of the fracture area, the fugacity of each component in the fracture area and the basic characteristic parameters of the fluid in the fracture area; takes the pressure of the fracture area as the initial pressure of the nanopore, and measures the molar composition of each component in the nanopore through a preset number of Monte Carlo experiments, and takes the measurement results of each Monte Carlo experiment as the initial fluid composition set of the nanopore; randomly selects multiple groups of compositions that meet the preset conditions from the initial fluid composition set as the candidate fluid composition set of the nanopore; calculates the fugacity of each component in each composition in the candidate fluid composition set according to the initial pressure of the nanopore and the basic characteristic parameters of the fluid in the fracture area; compares the fugacity of each component in each composition in the candidate fluid composition set with the fugacity of each component in the fracture area to determine the fluid composition and the molar composition of each component in the nanopore. The above scheme can realize the accurate determination of the fluid composition and fluid phase state in the nanopore, thereby accurately reflecting the behavior characteristics of the fluid in the nanopore.

[0320] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0321] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0322] Although the present application provides method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one way of executing the order of many steps and does not represent the only execution order. When the actual device or client product is executed, it can be executed in the order of the method shown in the embodiments or the drawings or in parallel (for example, in a parallel processor or multi-threaded processing environment).

[0323] Although the present specification embodiment provides the method operation steps as described in the embodiment or flow chart, more or less operation steps may be included based on conventional or non-creative means. The order of steps listed in the embodiment is only one way in the order of execution of many steps, and does not represent a unique execution order. When the device or terminal product in practice is executed, it can be executed in sequence or in parallel (such as a parallel processor or a multi-threaded processing environment, or even a distributed data processing environment) according to the method shown in the embodiment or the accompanying drawings. The term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, product or equipment including a series of elements not only includes those elements, but also includes other elements not clearly listed, or also includes elements inherent to such process, method, product or equipment. In the absence of more restrictions, it is not excluded that there are other identical or equivalent elements in the process, method, product or equipment including the elements.

[0324] For the convenience of description, the above devices are described in various modules according to their functions. Of course, when implementing the embodiments of this specification, the functions of each module can be implemented in the same or more software and / or hardware, or the module implementing the same function can be implemented by a combination of multiple sub-modules or sub-units. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0325] Those skilled in the art also know that, in addition to implementing the controller in a purely computer-readable program code, the controller can be made to implement the same function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, such a controller can be considered as a hardware component, and the devices for implementing various functions included therein can also be considered as structures within the hardware component. Or even, the devices for implementing various functions can be considered as both software modules for implementing the method and structures within the hardware component.

[0326] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0327] Those skilled in the art will appreciate that the embodiments of this specification may be provided as methods, systems or computer program products. Therefore, the embodiments of this specification may take the form of complete hardware embodiments, complete software embodiments or embodiments combining software and hardware. Moreover, the embodiments of this specification may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0328] The present specification embodiments may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The present specification embodiments may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0329] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. In the description of this specification, the description of the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of this specification. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, in the absence of contradiction, a person skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0330] The above is only an example of the embodiment of the present specification and is not intended to limit the embodiment of the present specification. For those skilled in the art, the embodiment of the present specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiment of the present specification shall be included in the scope of the claims of the embodiment of the present specification.

Claims

1. A method for determining fluid composition and fluid phase in nanopores, characterized in that: include: Determine the pressure in the fracture area, the fugacity of each component in the fracture area, and the basic characteristic parameters of the fluid in the fracture area; The pressure in the fracture region is used as the initial pressure of the nanopore, the molar composition of each component in the nanopore is measured by a preset number of Monte Carlo experiments, and the measurement result of each Monte Carlo experiment is used as the initial fluid composition set of the nanopore; Randomly selecting a plurality of groups of compositions satisfying preset conditions from the initial fluid composition set as candidate fluid composition sets for the nanopores; According to the initial pressure of the nanopores and the basic characteristic parameters of the fluid in the fracture area, the fugacity of each component in each composition of the candidate fluid composition set is calculated; The fugacity of each component in each composition in the candidate fluid composition set is compared with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component.

2. The method according to claim 1, characterized in that Comparing the fugacity of each component in each composition in the candidate fluid composition set with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component, including: respectively calculating the first fugacity difference between the fugacity of each component in each composition in the candidate fluid composition set and the fugacity of the same component in the fracture region to obtain a plurality of first fugacity differences; According to the multiple first fugacity differences, two groups of fluid compositions with the smallest first fugacity differences are selected from the candidate fluid composition set as the first fluid composition and the second fluid composition of the nanopores, wherein the first fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture region is smaller than the first fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture region; respectively calculating a second fugacity difference between the fugacity of each component in the first fluid composition and the second fluid composition and the fugacity of the same component in the fracture region; According to the first fluid composition, the second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture area, the second fluid composition, the second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture area, iterative operations are performed using the chord-intercept method formula to calculate the fluid composition in the nanopores and the molar composition of each component.

3. The method according to claim 2, characterized in that After the fluid composition and the molar composition of each component in the nanopores are calculated by the chord-intercept method formula, it also includes: Compare and verify the first fugacity difference between the calculated fugacity of each component in the fluid composition in the nanopores and the fugacity of the same component in the fracture area, and the calculated molar composition of each component in the fluid composition in the nanopores with the preset conditions; In the case where the verification fails, the initial pressure of the nanopore is adjusted, and the fluid composition and the molar composition of each component in the nanopore are recalculated by the adjusted initial pressure of the nanopore until the verification passes; The fluid composition in the nanopore and the molar composition of each component when the verification is passed are taken as the determined fluid composition in the nanopore and the molar composition of each component and outputted; Conduct single-phase stability tests on the fluid composition within the defined nanopores; If the test fails, the nanopore is determined to be in a two-phase state, a two-phase flash calculation is performed on the fluid composition of the determined nanopore region, and a gas phase composition, a liquid phase composition, a gas phase mole fraction, and a liquid phase mole fraction are output; If the test passes, it is determined that the nanopore is in a single-phase state, and the fluid composition in the nanopore region is output.

4. The method according to claim 1, characterized in that According to the initial pressure of the nanopores and the basic characteristic parameters of the fluid in the fracture area, the fugacity of each component in each composition in the candidate fluid composition set is calculated, including: Obtaining the temperature of the oil reservoir where the nanopore is located, the gas constant, the diameter of the molecule in the nanopore, and the radius of the nanopore; Determine basic characteristic parameters of the fluid in the fracture area according to production data; the basic characteristic parameters of the fluid include at least one of the following: critical pressure, critical temperature and eccentricity factor; According to the initial pressure of the nanopore, the temperature of the reservoir, the gas constant, the diameter of the molecule in the nanopore, the radius of the nanopore, the critical pressure of the fracture area, the critical temperature of the fracture area and the eccentricity factor of the fracture area, the deviation factor of the nanopore is calculated according to the following formula: Z 3 -(1-B)Z 2 +(A-2B-3B 2 )Z-(AB-B 2 -B 3 )=0 Where Z is the deviation factor, P m is the initial pressure in the nanopores, R is the gas constant, T is the temperature of the reservoir, σ LJ is the diameter of the molecule in the nanopore, R p is the radius of the nanopore, P c is the critical pressure in the crack region, T c is the critical temperature of the crack region, ω is the eccentricity factor of the crack region; According to the deviation factor of the nanopores, the fugacity of each component in each composition in the candidate fluid composition set is calculated.

5. The method according to claim 1, characterized in that A plurality of groups of compositions satisfying preset conditions are randomly selected from the initial fluid composition set as candidate fluid composition sets for the nanopores, including: A plurality of groups of compositions satisfying the following conditions are randomly selected from the initial fluid composition set: 0＜z mi ＜1 Among them, z mi is the molar composition of component i in composition m.

6. The method according to claim 2, characterized in that The first fugacity difference between the fugacity of each component in each composition in the candidate fluid composition set and the fugacity of the same component in the fracture region is calculated respectively to obtain a plurality of first fugacity difference values, including: The first fugacity difference between the fugacity of each component in each composition in the candidate fluid composition set and the fugacity of the same component in the fracture area is calculated according to the following formula: Among them, diff i is the first fugacity difference between the fugacity of component i in candidate fluid composition m and the fugacity of component i in the fracture region, f mi is the fugacity of component i in candidate fluid composition m, f bi is the fugacity of component i in the fracture region.

7. The method according to claim 2, characterized in that Respectively calculating the second fugacity difference between the fugacity of each component in the first fluid composition and the second fluid composition and the fugacity of the same component in the fracture region, comprising: The second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture area is calculated according to the following formula: Δf mai =f mai -f bi Where Δf mai is the fugacity difference between the fugacity of component i in the first fluid composition and the fugacity of component i in the fracture region, f mai is the fugacity of component i in the first fluid composition, f bi is the fugacity of component i in the fracture area; The second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture area is calculated according to the following formula: Δf mbi =f mbi -f bi Where Δf mbi is the fugacity difference between the fugacity of component i in the second fluid composition and the fugacity of component i in the fracture region, f mbi is the fugacity of component i in the second fluid composition.

8. The method according to claim 2, characterized in that: The chord-intercept method formula is used for iterative calculation to calculate the fluid composition in the nanopores and the molar composition of each component, including: According to the first fluid composition and the second fluid composition, obtaining the molar composition of each component in the first fluid composition and the second fluid composition; According to the molar composition of each component in the first fluid composition and the second fluid composition, the second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture area, and the second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture area, the initial value of the iterative calculation of the chord-intercept method formula is calculated according to the following formula: in, is the initial value of the iterative calculation of the chord-intercept method formula, z mai is the molar composition of component i in the first fluid composition, z mbi is the molar composition of component i in the second fluid composition, Δf mai is the second fugacity difference between the fugacity of component i in the first fluid composition and the fugacity of component i in the fracture region, Δf mbi is the second fugacity difference between the fugacity of component i in the second fluid composition and the fugacity of component i in the fracture region; Get the error accuracy of the preset chord-intercept method formula; According to the second fugacity difference between the fugacity of each component in the first fluid composition and the fugacity of the same component in the fracture region, the second fugacity difference between the fugacity of each component in the second fluid composition and the fugacity of the same component in the fracture region, and the calculated initial value of the chord-intercept method formula for iterative calculation, the fluid composition in the nanopores is iteratively calculated according to the following chord-intercept method formula: in, is the fluid composition in the nanopores calculated at the kth iteration, is the fluid composition in the nanopores calculated at the k-1th iteration, k is a non-negative number that increases with the number of iterations starting from 0. is the second fugacity difference between the fugacity of component i in the fluid composition in the nanopores and the fugacity of component i in the fracture region calculated at the k-1th iteration, where for Fugacity of component i, f bi is the fugacity of component i in the fracture area; When the second fugacity difference between the fugacity of each component in the calculated fluid composition in the nanopores and the fugacity of the same component in the fracture area is less than the error precision, the iterative calculation is terminated and the calculated fluid composition in the nanopores and the molar composition of each component are output.

9. The method according to claim 3, characterized in that: The first fugacity difference between the calculated fugacity of each component in the fluid composition in the nanopores and the fugacity of the same component in the fracture area, as well as the calculated molar composition of each component in the fluid composition in the nanopores are compared and verified with the preset conditions, including: determining a specified error of a first fugacity difference between the fugacity of each component in the fluid composition within the nanopores and the fugacity of the same component in the fracture region and an allowable error of a sum of the molar compositions of each component in the fluid composition within the nanopores; The first fugacity difference between the fugacity of each component in the fluid composition in the nanopore and the fugacity of the same component in the fracture region is compared with the specified error according to the following formula: Among them, diff i is the first fugacity difference between the fugacity of each component in the fluid composition in the nanopore and the fugacity of the same component in the fracture area, ε is the specified error, and f i is the fugacity of component i in the fluid composition in the nanopore, f bi is the fugacity of component i in the fracture area; The sum of the molar compositions of the components in the fluid composition within the nanopores is compared with the allowable error according to the following formula: Where δ is the allowable error, z i is the molar composition of component i in the fluid composition in the nanopore; When the first fugacity difference between the fugacity of each component in the fluid composition in the nanopore and the fugacity of the same component in the fracture area is less than the specified error, and the difference between the sum of the molar composition of each component in the fluid composition in the nanopore and 1 is less than the allowable error, the verification is determined to be passed; otherwise, the verification is determined to be failed.

10. A device for measuring fluid composition and fluid phase in nanopores, characterized in that: include: A determination module, used to determine the pressure in the fracture area, the fugacity of each component in the fracture area, and basic characteristic parameters of the fluid in the fracture area; A determination module, for taking the pressure of the fracture area as the initial pressure of the nanopore, determining the molar composition of each component in the nanopore through a preset number of Monte Carlo experiments, and taking the determination result of each Monte Carlo experiment as the initial fluid composition set of the nanopore; A selection module, used for randomly selecting a plurality of groups of compositions satisfying preset conditions from the initial fluid composition set as candidate fluid composition sets for the nanopores; A first calculation module is used to calculate the fugacity of each component in each composition in the candidate fluid composition set according to the initial pressure of the nanopores and the basic characteristic parameters of the fluid in the fracture area; The second calculation module is used to compare the fugacity of each component in each composition in the candidate fluid composition set with the fugacity of each component in the fracture region to determine the fluid composition in the nanopores and the molar composition of each component.

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