A method and system for determining the cooperative deformation law of multi-induced dynamic nanopores

Abstract

The present invention discloses a method for determining the law of multi-inducement dynamic nanopore cooperative deformation, including calculating the stress-induced deformation of shale reservoirs under different conditions; constructing a quantitative model corresponding to shale reservoirs and adsorbed molecules; calculating the corresponding adsorption-induced deformation through the quantitative model, and combining iterative algorithms to obtain the true deformation; combining the stress-induced deformation of shale reservoirs and the adsorption-induced deformation, comprehensively calculating the deformation of shale reservoirs under the synergistic effect of multiple inducements, and determining the law of multi-inducement dynamic nanopore cooperative deformation. The present invention uses molecular simulation methods combined with formula derivation to obtain the stress-induced deformation and adsorption-induced deformation of shale reservoirs under different conditions, thereby obtaining the deformation of shale reservoirs under the synergistic effect of multiple inducements, providing a theoretical basis for the dynamic nanopore deformation law under the synergistic effect of multiple inducements, and for the efficient development of shale oil reservoirs.

Description

Technical Field

[0001] The present invention relates to the technical field of unconventional oil and gas exploration and development, and in particular to a method and system for determining a multi-inducing dynamic nanopore cooperative deformation law. Background Art

[0002] As the development of conventional oil and gas resources becomes increasingly difficult, the large-scale development of shale oil has attracted widespread attention at home and abroad as the exploration and development technology of shale oil resources has gradually matured. However, due to the special occurrence form of shale oil reservoirs, it is generally believed that the occurrence form of shale oil in shale reservoirs is mainly adsorbed or free, with a small amount of dissolved (or miscible) state. Therefore, there is a problem of low availability during the development process. The CO2 throughput of shale oil reservoirs can not only improve the recovery rate of shale oil, but also achieve effective storage of CO2, thereby achieving the purpose of controlling CO2 emissions.

[0003] However, in the process of developing shale oil reservoirs using CO2 huff and puff, the pore pressure field in the shale reservoir (hereinafter referred to as pore pressure field) will change due to the injection and production of fluids, which will cause changes in adsorption characteristics and pore throat structure; and there is a complex coupling and synergy between the pore pressure field, adsorption characteristics and nanopore throat deformation field (hereinafter referred to as deformation field). Therefore, the relationship between the pore pressure field, adsorption characteristics and deformation field is relatively complex: the change in adsorption characteristics is the result of the synergy between the pore pressure field and the deformation field; the deformation field is caused by the synergy between the pore pressure field and the adsorption characteristics, and there is a coupling effect between the deformation field and the adsorption characteristics. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] The present invention is proposed in view of the existing problem that the pore pressure changes due to the inflow and output of fluids in the above-mentioned and / or existing shale oil development process, thereby affecting the pore deformation characteristics and adsorption properties of shale.

[0006] Therefore, the problem to be solved by the present invention is how to determine the deformation law of pores under the action of multiple factors.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In the first aspect, an embodiment of the present invention provides a method for determining the law of multi-inducement dynamic nanopore collaborative deformation, which includes calculating the stress-induced deformation of shale reservoirs under different conditions; constructing a model corresponding to the shale reservoir and the adsorbed molecules; obtaining the corresponding adsorption-induced deformation through quantitative model calculation, and combining iterative algorithm to approach the true deformation; combining the stress-induced deformation and adsorption-induced deformation of the shale reservoir, comprehensively calculating the deformation of the shale reservoir under the synergistic action of multiple factors, and determining the law of multi-inducement dynamic nanopore collaborative deformation.

[0009] As a preferred solution of the method for determining the multi-induced dynamic nanopore cooperative deformation law of the present invention, the stress-induced deformation of the shale reservoir under different conditions is calculated, and the specific formula is as follows:

[0010]

[0011] in, is the average normal stress acting on the pore, V φ-r is the pore volume under a certain pressure, α is the Biot coefficient, K is the bulk modulus, φ is the porosity, and p i is the original formation pressure, p is the current formation pressure, L t is the length of the curved pore, τ is the tortuosity, L0 is the length of the straight pore, r i is the pore radius under the initial pressure condition.

[0012] As a preferred scheme of the method for determining the multi-inducing dynamic nanopore cooperative deformation law described in the present invention, constructing a model corresponding to a shale reservoir and adsorbed molecules includes the following steps: constructing a graphene sheet to characterize the shale reservoir organic matter model; determining simulation parameters; calculating the adsorption amount corresponding to the simulation; conducting multiple groups of simulation experiments and taking the average value.

[0013] As a preferred scheme of the method for determining the cooperative deformation law of multi-induced dynamic nanopores described in the present invention, the corresponding adsorption induced deformation is obtained by quantitative model calculation, and combined with an iterative algorithm, approaching the true deformation includes the following steps: calculating the comprehensive fluid-solid coupling coefficient; setting initial conditions, and calculating the adsorption induced deformation based on molecular simulation method.

[0014] As a preferred solution of the method for determining the cooperative deformation law of multi-inducing dynamic nanopores of the present invention, the specific formula of the comprehensive fluid-solid coupling coefficient is as follows:

[0015]

[0016] Among them, C mix is the weighted comprehensive fluid-structure coupling coefficient, k is the number of terms, C xis the fluid-solid coupling coefficient of a single component, n1 is the total adsorption of the mixture in the system under different pressures, and n x is the adsorption amount of a single component in the system under different pressures.

[0017] The specific formula for adsorption-induced deformation is as follows:

[0018]

[0019] Among them, C mix is the weighted comprehensive fluid-structure coupling coefficient, V ε is the volumetric strain, C mix is the comprehensive fluid-solid coupling coefficient, K is the bulk modulus, n2 is the absolute adsorption amount of the model under zero strain, f is the fluid fugacity, T is the temperature, R is the universal constant, f1 is the lower limit of the interval fugacity, and f2 is the upper limit of the interval fugacity.

[0020] As a preferred solution of the method for determining the multi-inducing dynamic nanopore cooperative deformation law of the present invention, the specific formula of the shale reservoir deformation under the synergistic action of multiple inducements is as follows:

[0021]

[0022] in, is the average normal stress acting on the pores, α is the Biot coefficient, K is the bulk modulus, φ is the porosity, and p i is the original formation pressure, p is the current formation pressure, C mix is the weighted comprehensive fluid-solid coupling coefficient, f is the fluid fugacity, T is the temperature, R is the universal constant, f1 is the lower limit of the interval fugacity, f2 is the upper limit of the interval fugacity, and n2 is the absolute adsorption amount of the model under zero strain.

[0023] As a preferred scheme of the method for determining the collaborative deformation law of multi-inducing dynamic nanopores described in the present invention, wherein: the calculation of the adsorption induced deformation includes the following steps: the calculation of the adsorption induced deformation also includes the following steps: the adsorption induced deformation of the shale reservoir is Δr1, and the simulated adsorption induced deformation is Δr2; if the difference between Δr1 and Δr2 is within the error range, Δr2 is one of the adsorption or desorption induced deformations; if the difference between Δr1 and Δr2 is not within the error range, Δr1 is replaced by Δr2; repeat the above steps until the iteration ends.

[0024] In the second aspect, an embodiment of the present invention provides a method system for determining the collaborative deformation law of multi-inducement dynamic nanopores, which includes: a stress calculation module, used to calculate the stress-induced deformation of shale reservoirs under different conditions; a molecular simulation module, used to construct a model corresponding to the shale reservoir and the adsorbed molecules; an adsorption calculation module, used to calculate the corresponding adsorption-induced deformation through a quantitative model, and combine it with an iterative algorithm to gradually approach the actual deformation; a comprehensive calculation module, used to combine the stress-induced deformation of the shale reservoir and the adsorption-induced deformation to obtain the deformation of the shale reservoir under the synergistic action of multiple factors, thereby determining the collaborative deformation law of multi-inducement dynamic nanopores.

[0025] In a third aspect, an embodiment of the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: the processor implements any step of the above method when executing the computer program.

[0026] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: the computer program implements any step of the above method when executed by a processor.

[0027] The beneficial effects of the present invention are as follows: the present invention clarifies the dynamic change characteristics of nanopores in shale reservoirs by means of molecular simulation combined with formula derivation, firstly derives the corresponding stress-induced deformation according to the formula, and calculates the corresponding adsorption-induced deformation according to the adsorption amount obtained by molecular simulation, and determines the mathematical model of shale pore deformation under multi-factor coupling conditions based on the two different deformation amounts, thereby obtaining the shale nanopore deformation under multi-factor coupling conditions, which plays a key role in determining the pore deformation characteristics of shale reservoir pores during the development process, thereby determining the adsorption characteristics of shale under multi-factor coupling conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0029] Figure 1 This is a flow chart of the method for determining the cooperative deformation law of multi-induced dynamic nanopores in Example 1.

[0030] Figure 2 Schematic diagram of stress-induced deformation of the method for determining the cooperative deformation law of multi-inducing dynamic nanopores in Example 1.

[0031] Figure 3This is a graphene model of the method for determining the cooperative deformation law of multi-induced dynamic nanopores in Example 2.

[0032] Figure 4 This is the molecular model of the adsorbate in the method for determining the cooperative deformation law of multi-inducing dynamic nanopores in Example 2.

[0033] Figure 5 This is a deformation contribution diagram under cooperative strain of the method for determining the cooperative deformation law of multi-inducing dynamic nanopores in Example 2. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0035] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0037] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0038] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0039] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] Example 1

[0041] Reference Figure 1-2 , which is the first embodiment of the present invention, provides a method and system for determining the cooperative deformation law of multi-inducing dynamic nanopores, including:

[0042] S1: Calculate the stress-induced deformation of shale reservoirs under different conditions.

[0043] First, calculate the pore volume change. The specific formula is as follows:

[0044] ΔV φ =V φ-0 (1-φ)(ε t -ε φ )

[0045] Where φ is the porosity, ΔV φ is the change in pore volume, V φ-0 is the pore volume under surface pressure conditions, ε t is the volume deformation ratio of porous media, ε φ is the pore volume deformation ratio.

[0046] Preferably, the average normal stress acting on the pores is specifically expressed as follows:

[0047]

[0048] Where φ is the porosity, is the average normal stress acting on the porous rock, K s is the bulk modulus of the solid skeleton, ε s is the solid skeleton deformation rate, Δp f is the change in fluid pressure.

[0049] Preferably, the volume deformation ratio of the porous medium is specifically expressed as follows:

[0050]

[0051] Among them, α is the Biot coefficient, K is the bulk modulus, ε t is the volume deformation ratio of porous media, is the average normal stress acting on the pore, Δpf is the change in fluid pressure, K s is the bulk modulus of the solid skeleton.

[0052] Furthermore, the specific formula for the pore volume under a certain pressure is as follows:

[0053]

[0054] Among them, α is the Biot coefficient, K is the bulk modulus, φ is the porosity, ΔV φ is the change in pore volume, V φ-0 is the pore volume under surface pressure conditions, is the average normal stress acting on the pore, Δp f is the change in fluid pressure, K s is the bulk modulus of the solid skeleton.

[0055] Furthermore, due to the complexity of the pore morphology, the movement of the liquid in the pore is not a straight line, but a curve. Therefore, the concept of tortuosity is introduced to reflect the tortuosity of the pore. The specific formula of tortuosity is as follows:

[0056]

[0057] Among them, L o is the linear pore length, L t is the length of the curved pore.

[0058] Therefore, the stress-induced deformation can be obtained, and the specific formula is as follows:

[0059]

[0060] in, is the average normal stress acting on the pore, V φ-r is the pore volume under a certain pressure, α is the Biot coefficient, K is the bulk modulus, φ is the porosity, and p i is the original formation pressure, p is the current formation pressure, L t is the length of the curved pore, τ is the tortuosity, L0 is the length of the straight pore, r i is the pore radius under the initial pressure condition.

[0061] It should be noted that after changing the Biot parameter, the obtained pore size changes with the pressure deformation as shown in Figure 2 shown.

[0062] S2: Construct a model corresponding to the shale reservoir and adsorbed molecules.

[0063] Specifically, the following steps are included:

[0064] S2.1: In Materials Studio, the input parameter of the adsorption module is fugacity instead of pressure. Therefore, in order to obtain the required parameters, the actual pressure needs to be converted into fugacity value according to the corresponding conditions (including temperature, pressure, component ratio, etc.) before simulation.

[0065] Furthermore, it is necessary to first calculate the fugacity of each component in the mixture at the corresponding temperature / pressure, including the single-component fugacity and the mixture fugacity.

[0066] Specifically, the single-component fugacity calculation formula is as follows:

[0067]

[0068] Where f is the single component fugacity, p is the critical pressure, V is the volume, R is the gas constant, 8.3143 J / (mol·K), T is the temperature, and P is the pressure.

[0069] Specifically, the mixture fugacity calculation formula is as follows:

[0070]

[0071] in, is the fugacity of component i in the mixture, y i is the mole fraction of component i of the mixture, f is the fugacity of the mixture, and N is the number of components.

[0072] S2.2: Construct graphene sheets to characterize the organic matter model of shale reservoirs.

[0073] Specifically, the graphene single cell structure is imported from the Material Studio software database, and the lattice parameters are established through the supercell module: The supercell model (20a0×10b0×1c0) with α=90°, β=90°, and γ=120° is obtained by cleaving the surface to obtain a single graphene sheet, and then building vacuum by building layers. The initial graphene slit model is used for simulation. The width of the vacuum layer is the size of the aperture. The initial aperture is And construct models corresponding to the adsorbate molecules, such as carbon dioxide, methane, n-hexane, and n-dodecane models. In the Visualizer module, molecular models of CO2, CH4, C6H14, and C12H26 are constructed. Then, the smart method in the Forcite module is used to optimize the model structure and finally obtain a stable configuration. This process is carried out under the COMPASS force field.

[0074] S2.3 Determine simulation parameters.

[0075] Specifically, the simulation uses the Sorption module in Materials studio, and the parameters are set as follows: select the Metropolis method of Grand Canonical Monte Carlo, use the Fixed Pressure task, set the fixed pressure, select the COMPASS force field for simulation, the system pressure is 0MPa~30MPa, the pressure points are 0.1MPa, 5MPa, 10MPa, 15MPa, 20MPa, 25MPa, 30MPa, the temperature is 333K-433K, and the model aperture is The molar ratio of the components is (3:1:1:1 / 3:1:1:1). The production step and the equilibrium step are both 2×106. The van der Waals interaction between molecules uses the Atom summation method, and the electrostatic interaction uses the Ewald summation method. The cutoff radius is The model system studied is a periodic boundary.

[0076] S2.4 Calculate the adsorption amount corresponding to the simulation.

[0077] Preferably, by setting up multiple groups of simulations with different temperatures, different pore sizes, and different component molar ratios, the adsorption amount corresponding to each group of simulations is calculated based on the obtained data.

[0078] It should be noted that the data here also refers to the adsorption amount, and the unit is average molecules / cell, that is, the number of adsorbates under the current unit cell, while the data obtained in the experiment is generally in mmol / g or mg / g. Therefore, the adsorption amount obtained by simulation needs to be converted, and each group must be simulated multiple times instead of just once.

[0079] S2.5 Conduct multiple sets of simulation experiments and take the average value.

[0080] Specifically, on the basis of step S2.3, multiple groups of simulation experiments of step S2.4 are carried out and the average value is taken to ensure the accuracy of the simulation.

[0081] S3: The corresponding adsorption-induced deformation is calculated by quantitative model, and combined with iterative algorithm to obtain the actual deformation.

[0082] Further, the following steps are included:

[0083] S3.1 Calculate the comprehensive fluid-structure coupling coefficient.

[0084] Preferably, the comprehensive fluid-solid coupling coefficient is as follows:

[0085]

[0086] Among them, C mixis the weighted comprehensive fluid-structure coupling coefficient, k is the number of terms, C x is the fluid-solid coupling coefficient of a single component, n1 is the total adsorption of the mixture in the system under different pressures, and n x is the adsorption amount of a single component in the system under different pressures.

[0087] Specifically, C. mix It is a weighted fluid-solid coupling coefficient. C under different conditions can be determined according to the different proportions of the components, where C is the fluid-solid coupling coefficient corresponding to each component and is a fixed value. For example Represents the different components of C.

[0088] It should be noted that in this example, as well as

[0089] S3.2 sets the initial conditions and calculates the adsorption-induced deformation based on the molecular simulation method.

[0090] Specifically, the initial conditions are set, and it is assumed that the shale pore deformation caused by the adsorption / desorption effect under the pressure and pore size conditions is Δr1. Based on the assumed deformed pore size, a pore model corresponding to the studied pressure is constructed. Based on the molecular simulation method, the adsorption / desorption law of the multi-component alkane system in the shale nanopores under the next pressure condition is simulated and analyzed, and quantitative indicators such as the molecular composition of the adsorption phase, adsorption amount, adsorption heat, adsorption layer thickness and density are obtained. Based on the simulation results of the adsorption molecules, the adsorption-induced deformation at this time is calculated, which is recorded as Δr2.

[0091] Further, the comparison between Δr1 and Δr2 includes the following contents:

[0092] If the difference between the two is within the error range, Δr2 is the adsorption / desorption induced deformation;

[0093] If the difference between the two is not within the error range, Δr1 is replaced by Δr2;

[0094] Repeat the above steps until the iteration ends.

[0095] It should be noted that at the end of the iteration, a value is obtained that tends to the actual adsorption-induced deformation. The number of iterations is determined according to the result of each iteration. For example, the result of the first iteration is 10%. Substituting the deformation into the original aperture can obtain a new aperture. Using the new aperture for simulation, the iterative result is 2%. Multiple iterations can obtain more accurate data.

[0096] Preferably, the adsorption-induced deformation is calculated using the following formula:

[0097]

[0098] Among them, V ε is the volumetric strain, C mix is the comprehensive fluid-solid coupling coefficient, K is the bulk modulus, n2 is the absolute adsorption amount of the model under zero strain, f is the fugacity, T is the temperature, and R is the universal constant.

[0099] It should be noted that, in this embodiment, K=2.65, R=8.314, and f needs to be obtained through calculation.

[0100] S4: Combine the stress-induced deformation and adsorption-induced deformation of the shale reservoir to comprehensively calculate the deformation of the shale reservoir under the synergistic effect of multiple factors and determine the law of multi-inducing dynamic nanopore synergistic deformation.

[0101] Specifically, the stress-induced deformation of the shale reservoir and the adsorption-induced deformation in step S3.2 are combined to comprehensively calculate the deformation of the shale reservoir under the synergistic effect of multiple factors. The specific formula is as follows:

[0102]

[0103] Where Δσ is the average normal stress acting on the pores, α is the Biot coefficient, K is the bulk modulus, φ is the porosity, and p is the i is the original formation pressure, p is the current formation pressure, C mix is the weighted comprehensive fluid-solid coupling coefficient, f is the fluid fugacity, T is the temperature, R is the universal constant, f1 is the lower limit of the interval fugacity, f2 is the upper limit of the interval fugacity, and r i is the pore radius under the initial pressure condition, and n2 is the absolute adsorption amount of the model under zero strain.

[0104] It should be noted that the pore pressure field and deformation field of shale pores will have a synergistic effect on the fluid adsorption / desorption law, and there is a coupling effect between the adsorption and deformation fields. Therefore, combining the adsorption-induced deformation and the stress-induced deformation can obtain a shale deformation that is closer to the actual situation.

[0105] Furthermore, the present embodiment also provides a system for determining the cooperative deformation law of multi-inducing dynamic nanopores, including: a stress calculation module, used to calculate the stress-induced deformation of shale reservoirs under different conditions; a molecular simulation module, used to construct a model corresponding to the shale reservoir and the adsorbed molecules; an adsorption calculation module, used to calculate the corresponding adsorption-induced deformation through a quantitative model, and combine it with an iterative algorithm to gradually approach the actual deformation; a comprehensive calculation module, used to combine the stress-induced deformation of the shale reservoir and the adsorption-induced deformation to obtain the deformation of the shale reservoir under the synergistic action of multiple factors, thereby determining the cooperative deformation law of multi-inducing dynamic nanopores.

[0106] This embodiment also provides a computer device, which is applicable to the method for determining the cooperative deformation law of multi-inducing dynamic nanopores, including:

[0107] Memory and processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the method for identifying the relationship between power substations and household transformers as proposed in the above embodiment.

[0108] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0109] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the following steps are implemented:

[0110] Calculate stress-induced deformation of shale reservoirs under different conditions;

[0111] Construct a model of shale reservoirs corresponding to adsorbed molecules;

[0112] The corresponding adsorption-induced deformation is calculated by quantitative model, and combined with iterative algorithm, the real deformation is obtained;

[0113] Combined with the stress-induced deformation and adsorption-induced deformation of the shale reservoir, the deformation of the shale reservoir under the synergistic effect of multiple factors is comprehensively calculated, and the law of multi-inducing dynamic nanopore synergistic deformation is determined.

[0114] In summary, the present invention clarifies the dynamic change characteristics of nanopores in shale reservoirs through molecular simulation combined with formula derivation. First, the corresponding stress-induced deformation is derived according to the formula, and the corresponding adsorption-induced deformation is calculated based on the adsorption amount obtained by molecular simulation, thereby obtaining the shale nanopore deformation under multi-factor coupling conditions, which plays a key role in determining the recoverable reserves of shale oil reservoirs and evaluating their mining potential.

[0115] Example 2

[0116] Reference Figure 3 to Figure 5 Tables 1 to 4 are the second embodiment of the present invention, which provides a method for determining the cooperative deformation law of multi-inducing dynamic nanopores. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0117] Specifically, Table 1 shows the data under the initial conditions of the shale reservoir. At this time, there is no influence of external factors and the shale reservoir is in a flat state. The Biot coefficient is the effective stress coefficient, which is the proportion of the liquid part and the solid part in the medium that contribute to energy transfer. Porosity refers to the ratio of the sum of the volumes of all pore spaces in the rock sample to the volume of the rock sample. The bulk modulus is a measure of the degree of deformation of the material due to the pressure around the surface. The tortuosity reflects the degree of tortuosity in the porous medium.

[0118] Table 1 Basic parameters of shale reservoir

[0119]

[0120] Furthermore, by substituting the data in Table 1 into the stress-induced deformation formula of the shale reservoir in step S1, the deformation values ​​of the shale pore size with the change of pressure under the basic parameters can be obtained, as shown in Table 2.

[0121] Table 2 Numerical table of pore deformation with pressure

[0122]

[0123] Preferably, Table 2 shows the change of pore size under basic parameters. As the current formation pressure changes, the difference with the original formation pressure increases, and the corresponding pore size change increases accordingly.

[0124] Furthermore, the main controlling factor analysis is carried out to determine the influence of shale reservoir physical properties on the pore stress-induced deformation law, where the influencing factors include effective stress coefficient, bulk modulus, tortuosity, and the shale reservoir organic matter model is characterized by graphene sheets, and the model corresponding to the adsorbate molecules is constructed, such as Figure 3 and Figure 4 As shown, determine the number of simulation steps, force field, and calculation method.

[0125] Furthermore, multiple simulations with different temperatures, pore sizes, and component molar ratios were set up to calculate the fugacity of each component in the mixture at the corresponding temperature / pressure. The corresponding adsorption-induced deformation was obtained through quantitative model calculation, and combined with the iterative algorithm, it gradually approached the actual deformation, as shown in Table 3.

[0126] Table 3 Schematic diagram of deformation iteration in the range of 25-20MPa

[0127]

[0128] Furthermore, the adsorption amount and pore size at 25 MPa are taken as the basic values. At this time, the temperature is set to 20 MPa and the pore size is the assumed deformation pore size. Then, the simulation is performed to obtain the corresponding adsorption amount, and the difference between the adsorption amount at 25 MPa and the adsorption amount at 25 MPa is calculated. The deformation can be obtained by substituting the difference into the formula, and the deformation at this time is substituted into the original pore size to obtain According to The simulation is performed and the above steps are repeated.

[0129] Furthermore, the deformation of the shale reservoir induced by stress and the deformation induced by adsorption are comprehensively calculated to obtain the deformation of the shale reservoir under the synergistic effect of multiple factors. The relationship of the synergistic effect of multiple factors is as follows:

[0130]

[0131] Among them, V ε is the adsorption-induced deformation, r c is the deformation of shale reservoir under the synergistic effect of multiple factors, r s is the stress-induced deformation of the shale reservoir.

[0132] Furthermore, after substituting the stress-induced deformation model, the relationship changes as follows:

[0133]

[0134] in, is the average normal stress acting on the pores, α is the Biot coefficient, K is the bulk modulus, φ is the porosity, and p i is the original formation pressure, p is the current formation pressure, V ε is the adsorption-induced deformation, r i is the pore radius under the initial pressure condition.

[0135] Furthermore, the calculation formula of adsorption-induced deformation is as follows:

[0136]

[0137] in, is the average normal stress acting on the pores, α is the Biot coefficient, K is the bulk modulus, φ is the porosity, and p i is the original formation pressure, p is the current formation pressure, C mix is the weighted comprehensive fluid-solid coupling coefficient, f is the fluid fugacity, T is the temperature, R is the universal constant, f1 is the lower limit of the interval fugacity, f2 is the upper limit of the interval fugacity, and r i is the pore radius under the initial pressure condition.

[0138] Preferably, the change in pore size based on the synergistic effect of pressure and adsorption can be calculated according to the change in adsorption amount according to the above formula, as shown in Table 4.

[0139] Table 4 Schematic table of coordinated deformation

[0140]

[0141] Specifically, Table 4 is a schematic diagram of the pore cooperative deformation amount in this embodiment. The initial pore size is the pore size under the influence of stress-induced deformation, and the cooperative deformation amount is the deformation amount corresponding to the simulated adsorption amount under the pore size under the influence of stress-induced deformation, so that the current pore size can be calculated.

[0142] Furthermore, by changing the temperature, pore size, component molar ratio, etc., the deformation of shale nanopores under multi-factor coupling conditions can be calculated, such as Figure 5 It is the deformation contribution diagram under cooperative strain. According to the cooperative deformation amount of shale in different cases and the influence of the two deformations on the pores, the multi-induced dynamic nanopore cooperative deformation law can be obtained.

[0143] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for determining the cooperative deformation law of multi-inducing dynamic nanopores, characterized in that: include, Calculate stress-induced deformation of shale reservoirs under different conditions; Construct a quantitative model corresponding to the shale reservoir and adsorbed molecules; The corresponding adsorption-induced deformation is calculated by quantitative model, and combined with iterative algorithm, it approaches the real deformation. Combined with the stress-induced deformation and adsorption-induced deformation of shale reservoirs, the deformation of shale reservoirs under the synergistic effect of multiple factors is comprehensively calculated to determine the law of synergistic deformation of dynamic nanopores caused by multiple factors. The construction of the quantitative model corresponding to the shale reservoir and the adsorbed molecules comprises the following steps: Constructing graphene sheets to characterize organic matter models in shale reservoirs; Determine simulation parameters; Calculate the adsorption amount corresponding to the simulation; Conduct multiple sets of simulation experiments and take the average value; The method of obtaining the corresponding adsorption-induced deformation by using a quantitative model and approaching the actual deformation by using an iterative algorithm comprises the following steps: Calculate the comprehensive fluid-structure coupling coefficient; Set the initial conditions and calculate the adsorption-induced deformation based on the molecular simulation method; The specific formula for the deformation of shale reservoir under the synergistic effect of multiple factors is as follows: in, is the average normal stress acting on the pores, α is the Biot coefficient, K is the bulk modulus, φ is the porosity, and p i is the original formation pressure, p is the current formation pressure, C mix is the weighted comprehensive fluid-solid coupling coefficient, f is the fluid fugacity, T is the temperature, R is the universal constant, f1 is the lower limit of the interval fugacity, f2 is the upper limit of the interval fugacity, and n2 is the absolute adsorption amount of the model under zero strain; The specific formula for calculating the stress-induced deformation of shale reservoirs under different conditions is as follows: in, is the average normal stress acting on the pore, V φ—r is the pore volume under a certain pressure, α is the Biot coefficient, K is the bulk modulus, φ is the porosity, and p i is the original formation pressure, p is the current formation pressure, L t is the length of the curved pore, τ is the tortuosity, L0 is the length of the straight pore, r i is the pore radius under the initial pressure condition.

2. The method for determining the cooperative deformation law of multi-inducing dynamic nanopores according to claim 1, characterized in that: The specific formula of the comprehensive fluid-solid coupling coefficient is as follows: Among them, C mix is the weighted comprehensive fluid-structure coupling coefficient, k is the number of terms, C x is the fluid-solid coupling coefficient of a single component, n1 is the total adsorption of the mixture in the system under different pressures, and n x is the adsorption amount of a single component in the system under different pressures; The specific formula of the adsorption-induced deformation is as follows: Among them, C mix is the weighted comprehensive fluid-structure coupling coefficient, V ε is the volumetric strain, C mix is the comprehensive fluid-solid coupling coefficient, K is the bulk modulus, n2 is the absolute adsorption amount of the model under zero strain, f is the fluid fugacity, T is the temperature, R is the universal constant, f1 is the lower limit of the interval fugacity, and f2 is the upper limit of the interval fugacity.

3. The method for determining the cooperative deformation law of multi-inducing dynamic nanopores according to claim 1, characterized in that: The calculation of the adsorption-induced deformation comprises the following steps: The adsorption-induced deformation of the shale reservoir is Δr1, and the simulated adsorption-induced deformation is Δr2; If the difference between Δr1 and Δr2 is within the error range, Δr2 is one of the adsorption- or desorption-induced deformations; If the difference between Δr1 and Δr2 is not within the error range, Δr1 is replaced by Δr2; Repeat the above steps until the iteration ends.

4. A method system for determining the cooperative deformation law of multi-inducing dynamic nanopores, based on the method for determining the cooperative deformation law of multi-inducing dynamic nanopores according to any one of claims 1 to 3, characterized in that: include, Stress calculation module, used to calculate the stress-induced deformation of shale reservoirs under different conditions; Molecular simulation module, used to build quantitative models corresponding to shale reservoirs and adsorbed molecules; The adsorption calculation module is used to calculate the corresponding adsorption-induced deformation through a quantitative model, and combine it with an iterative algorithm to gradually approach the actual deformation; The comprehensive calculation module is used to combine the stress-induced deformation and adsorption-induced deformation of the shale reservoir to obtain the deformation of the shale reservoir under the synergistic effect of multiple inducements, thereby determining the law of multi-inducing dynamic nanopore synergistic deformation.

5. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 3 are implemented.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 3 are implemented.

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