Gas drive oil extraction research method, device and equipment based on pore connectivity and medium

Abstract

The embodiment of the invention discloses a gas drive oil extraction research method, device and equipment based on pore connectivity and a medium. The method comprises the following steps: constructing at least two shale communicating pore models, wherein the shale communicating pore models are shale micro-nano-scale pore structure software models containing different numbers and / or different positions of communicating cracks; injecting pre-constructed crude oil molecules into the shale connected pore model, and performing equilibrium molecular dynamics simulation on the shale connected pore model to obtain a crude oil stable adsorption model; injecting pre-constructed oil displacement gas molecules into the crude oil stable adsorption model, and performing unbalanced molecular dynamics simulation on the crude oil stable adsorption model; and based on an unbalanced molecular dynamics simulation process, analyzing the influence of shale pore connectivity on the gas drive oil production process. According to the technical scheme, the influence of shale pore channel connectivity on the gas oil displacement effect can be studied from the microcosmic perspective by utilizing a molecular dynamics simulation method, and the shale oil recovery rate can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of tertiary oil recovery, and in particular to a gas drive oil recovery research method, device, equipment and medium based on pore connectivity. Background Art

[0002] After primary and secondary oil recovery, crude oil can no longer be extracted by relying on all the energy in the reservoir and the conventional means before. Crude oil extraction is facing the situation of urgently needing to improve the recovery rate to meet people's increasing energy needs. At present, shale oil has gradually entered people's field of vision due to its huge reserves. If shale reservoirs can be efficiently mined, it will greatly alleviate the huge energy pressure currently faced.

[0003] Artificial development of shale oil technology (such as hydraulic fracturing technology) will lead to changes in the structure of shale reservoirs. Many results show that the connectivity of shale reservoirs will change, which will lead to changes in the efficiency of crude oil extraction in the reservoir. By studying the changes in pore connectivity in shale reservoirs, we can better explore the flow laws during gas displacement, thereby optimizing gas displacement effects and improving shale oil recovery. At present, a large number of experiments have been conducted on the gas displacement process. Nanoscale pores are widely distributed in shale reservoirs, but it is currently impossible to study nanoscale channels experimentally. Summary of the invention

[0004] The present invention provides a gas drive oil recovery research method, device, equipment and medium based on pore connectivity, which can use molecular dynamics simulation method to study the influence of shale pore connectivity on gas drive oil effect from a microscopic perspective, so as to improve shale oil recovery rate by optimizing gas drive oil effect.

[0005] According to one aspect of the present invention, a method for studying gas drive oil recovery based on pore connectivity is provided, the method comprising:

[0006] Constructing at least two shale interconnected pore models, wherein the shale interconnected pore models are software models of shale micro-nanoscale pore structures containing interconnected fractures of different numbers and / or different positions;

[0007] Injecting pre-constructed crude oil molecules into the shale interconnected pore model, and performing equilibrium molecular dynamics simulation on the shale interconnected pore model to obtain a crude oil stable adsorption model; wherein the crude oil stable adsorption model is a model when the crude oil in the shale interconnected pore model reaches a stable state;

[0008] Injecting pre-constructed oil displacement gas molecules into the crude oil stable adsorption model, and performing non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model;

[0009] Based on the nonequilibrium molecular dynamics simulation process, the effect of shale pore connectivity on gas drive oil recovery process is analyzed.

[0010] According to another aspect of the present invention, there is provided a gas drive oil recovery research device based on pore connectivity, comprising:

[0011] A shale interconnected pore model construction module, used to construct at least two shale interconnected pore models, wherein the shale interconnected pore models are shale micro-nanoscale pore structure software models containing interconnected fractures of different numbers and / or different positions;

[0012] A balanced molecular dynamics simulation module is used to inject pre-constructed crude oil molecules into the shale interconnected pore model, and perform a balanced molecular dynamics simulation on the shale interconnected pore model to obtain a crude oil stable adsorption model; wherein the crude oil stable adsorption model is a model when the crude oil in the shale interconnected pore model reaches a stable state;

[0013] A non-equilibrium molecular dynamics simulation module, used for injecting pre-constructed oil displacement gas molecules into the crude oil stable adsorption model to perform non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model;

[0014] The gas drive oil production process analysis module is used to analyze the impact of shale pore connectivity on the gas drive oil production process based on the non-equilibrium molecular dynamics simulation process.

[0015] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising:

[0016] at least one processor; and

[0017] a memory communicatively connected to the at least one processor; wherein,

[0018] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the gas drive oil production research method based on pore connectivity described in any embodiment of the present invention.

[0019] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the gas drive oil production research method based on pore connectivity described in any embodiment of the present invention when executed.

[0020] The technical solution of the embodiment of the present invention is to construct at least two shale interconnected channel models, which are software models of shale micro-nanoscale pore structures containing interconnected fractures of different numbers and / or different positions; inject pre-constructed crude oil molecules into the shale interconnected channel model, and perform equilibrium molecular dynamics simulation on the shale interconnected channel model to obtain a crude oil stable adsorption model; wherein the crude oil stable adsorption model is a model when the crude oil in the shale interconnected channel model reaches a stable state; inject pre-constructed oil-displacing gas molecules into the crude oil stable adsorption model, and perform non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model; based on the non-equilibrium molecular dynamics simulation process, analyze the influence of shale pore connectivity on the gas drive oil recovery process. This technical solution can use the molecular dynamics simulation method to study the influence of shale pore connectivity on the gas drive oil effect from a microscopic perspective, so as to improve the shale oil recovery rate by optimizing the gas drive oil effect.

[0021] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 This is a flow chart of a gas drive oil recovery research method based on pore connectivity provided according to the first embodiment of the present invention;

[0024] Figure 2A is a schematic diagram of a shale interconnected channel model with a connected fracture provided according to Embodiment 1 of the present invention;

[0025] Figure 2B is a schematic diagram of a shale interconnected channel model with two interconnected fractures provided according to Embodiment 1 of the present invention;

[0026] Figure 3 is a schematic diagram of a change in the displacement of the center of mass of carbon dioxide provided according to Embodiment 1 of the present invention;

[0027] Figure 4 is a schematic diagram of the change of interaction energy in a single-notch connected pore provided in Example 1 of the present invention;

[0028] Figure 5is a schematic diagram of a radial distribution function provided according to Embodiment 1 of the present invention;

[0029] Figure 6 is a schematic diagram of a change in crude oil molecular recovery rate provided according to Example 1 of the present invention;

[0030] Figure 7 is a flow chart of a gas drive oil recovery research method based on pore connectivity provided according to the second embodiment of the present invention;

[0031] Figure 8 2 is a schematic structural diagram of a gas drive oil recovery research device based on pore connectivity provided according to Embodiment 3 of the present invention;

[0032] Fig. 9 It is a structural schematic diagram of an electronic device for implementing a gas drive oil production research method based on pore connectivity according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first", "second", "target", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0035] Embodiment 1

[0036] Figure 1The flowchart of a gas drive oil recovery research method based on pore connectivity provided in the first embodiment of the present invention is applicable to the situation where the molecular dynamics simulation method is used to study the influence of shale pore connectivity on gas drive oil recovery effect from a microscopic perspective. The method can be performed by a gas drive oil recovery research device based on pore connectivity. The gas drive oil recovery research device based on pore connectivity can be implemented in the form of hardware and / or software. The gas drive oil recovery research device based on pore connectivity can be configured in an electronic device with data processing capabilities. Figure 1 As shown, the method includes:

[0037] S110, constructing at least two shale interconnected pore models, where the shale interconnected pore model is a shale micro-nanoscale pore structure software model containing interconnected fractures of different numbers and / or different positions.

[0038] In this embodiment, at least two shale interconnected channel models are first constructed. The shale interconnected channel model is a software model of the micro-nanoscale pore structure of shale. Each constructed shale interconnected channel model contains interconnected fractures of different numbers and / or different positions, which can be set according to the simulation research requirements. For example, shale can be characterized by components such as cristobalite, calcite, kaolinite, and kerogen. Optionally, the process of constructing the shale connected channel model includes: obtaining a unit cell from a database, performing a first preprocessing on the unit cell to obtain an initial shale wall; wherein the first preprocessing includes a cutting process and a supercell process; deleting silicon atoms located on the outer surface of the initial shale wall, and adding a hydrogen atom to each oxygen atom exposed on the outer surface of the initial shale wall to obtain a reference shale wall; performing a second preprocessing on the reference shale wall to obtain a candidate shale wall; wherein the second preprocessing includes an amplification process and a movement process; cutting along the internal silicon atoms at a preset position of the candidate shale wall to form a connected fracture, and adding a hydrogen atom to each oxygen atom located near the connected fracture and exposed on the outer surface of the candidate shale wall to obtain a target shale wall; and determining the shale connected channel model according to the target shale wall.

[0039] For example, Materials Studio (MS) software can be used to construct a shale interconnected channel model. MS software can easily build a three-dimensional structure model and conduct in-depth research on the properties and related processes of various crystalline, amorphous and polymer materials. Specifically, first obtain the unit cell (a-quartz) from the database of MS software, and then The initial configuration is obtained by cutting a-quartz in the crystal direction, and the initial configuration forms the initial shale wall after supercell. In order to make the rock surface completely hydroxylated and make it conform to the hydrophilicity of the actual shale pores, it is necessary to delete the silicon atoms on the outer surface of the initial shale wall, expose the oxygen atoms, and add a hydrogen atom to each oxygen atom exposed on the outer surface of the initial shale wall to form a hydroxyl group, so as to obtain a reference shale wall, thereby achieving the hydrophilicity of the wall. Then, the reference shale wall is amplified using the Build layer method, and the amplified wall is moved to obtain a candidate shale wall, thereby forming multiple complete shale walls, and a pore is formed between every two shale walls. In this embodiment, the number of amplifications and the moving distance are not specifically limited, and can be set according to actual simulation requirements.

[0040] In order to simulate pore connectivity, one or more connected cracks are cut along the internal silicon atoms at the preset position of the candidate shale wall to expose the oxygen atoms, and a hydrogen atom is added to each oxygen atom located near the connected crack and exposed on the outer surface of the candidate shale wall, so that the connected part is also hydrophilic, thereby obtaining the target shale wall. Among them, the preset position is a pre-set wall cutting position, which can be set according to the actual simulation requirements, and this embodiment does not limit this. Finally, a shale micro-nanoscale pore structure software model (i.e., a shale connected pore model) containing connected cracks of different numbers and / or different positions can be determined according to the target shale wall.

[0041] Exemplarily, taking the shale micro-nanoscale pore structure software model containing different numbers of connected fractures as an example, two shale connected pore models are now constructed. Figure 2A and Figure 2B They are schematic diagrams of a shale interconnected channel model with one interconnected fracture and two interconnected fractures provided in Example 1 of the present invention, wherein the left part is the oil displacement gas molecule (such as carbon dioxide), the right part is the shale interconnected channel model, the horizontal strip on the right part is the shale wall, the space between the shale walls (i.e., the pores) is filled with crude oil molecules (such as alkane molecules), and the left and right parts can be separated by a partition formed by helium atoms.

[0042] like Figure 2A As shown in the figure, taking quartz as an example to represent shale, we first construct a shale interconnected channel model with a connected fracture. The specific construction process is as follows: Three quartz walls of different sizes are moved to form two channels with pore widths of 3nm and 6nm respectively, and then the middle wall is cut once, and the gap width of the middle wall is set to 3nm to form a heterogeneous shale connected channel model with connected fractures located at the front end of the middle wall. Figure 2BAs shown, a shale interconnected channel model with two interconnected fractures can be constructed by referring to the above method, the difference being that two cuts are made at different positions of the middle wall.

[0043] S120, injecting pre-constructed crude oil molecules into the shale interconnected pore model, and performing equilibrium molecular dynamics simulation on the shale interconnected pore model to obtain a crude oil stable adsorption model; wherein the crude oil stable adsorption model is a model when the crude oil in the shale interconnected pore model reaches a stable state.

[0044] In this embodiment, after the shale interconnected pore model is constructed, the pre-constructed crude oil molecules can be injected into the shale interconnected pore model, so as to perform equilibrium molecular dynamics simulation on the shale interconnected pore model to obtain a crude oil stable adsorption model. The crude oil molecules can be alkane molecules, such as octane. The crude oil stable adsorption model is a model when the crude oil in the shale interconnected pore model reaches a stable state. Specifically, the crude oil exists near the wall in an adsorbed state and exists in the pores in a free state.

[0045] For example, crude oil molecules can be pre-constructed using MS software, and crude oil molecules can be injected into the shale interconnected pore model to completely fill the pores. Then, LAMMPS software and the NVT ensemble are used to perform equilibrium molecular dynamics simulations on the shale interconnected pore model. The duration can be set to 3ns, and when the crude oil reaches a stable state, a stable adsorption model of crude oil can be obtained. Among them, LAMMPS (Large-scale Atomic / Molecular Massively Parallel Simulator) is a large-scale parallel open source molecular dynamics simulation calculation software that can simulate solids (metals, non-metals, semiconductors, etc.), liquids (water, solutions), soft matter (polymers, DNA, proteins) and coarse-grained materials, etc. Among them, NVT is one of the commonly used ensembles for molecular dynamics simulations, specifically referring to the canonical ensemble (a typical representative of Monte Carlo method simulation processing), which means having a certain number of particles, volume and temperature.

[0046] For example, Figure 2A and Figure 2B For example, when performing equilibrium molecular dynamics simulation on the shale interconnected pore model, the left and right sides are still kept separated. It is only necessary to inject crude oil molecules into the shale interconnected pore model so that the crude oil molecules completely fill the pores, and then use LAMMPS software to perform equilibrium molecular dynamics simulation.

[0047] S130, injecting pre-constructed oil displacement gas molecules into the crude oil stable adsorption model, and performing non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model.

[0048] In this embodiment, after obtaining the crude oil stable adsorption model, the pre-constructed oil-displacing gas molecules can be injected into the crude oil stable adsorption model to perform non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model. Among them, the oil-displacing gas molecules can be used to displace the crude oil molecules in the crude oil stable adsorption model from the pores. For example, the oil-displacing gas molecules can be gas molecules such as carbon dioxide, nitrogen, and methane. Exemplarily, the oil-displacing gas molecules can be pre-constructed using MS software, and the oil-displacing gas molecules can be injected into the crude oil stable adsorption model, and then the non-equilibrium molecular dynamics simulation of the crude oil stable adsorption model is performed using the pressure difference method based on the LAMMPS software and the NVT ensemble.

[0049] For example, Figure 2A and Figure 2B For example, when performing non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model, it is necessary to open the partition between the left and right sides so that the oil-displacing gas molecules on the left side can be injected into the crude oil stable adsorption model, and then use LAMMPS software to perform non-equilibrium molecular dynamics simulation.

[0050] S140, based on non-equilibrium molecular dynamics simulation process, analyzes the impact of shale pore connectivity on gas drive oil recovery process.

[0051] In this embodiment, during the non-equilibrium molecular dynamics simulation of the stable adsorption model of crude oil, the influence of shale pore connectivity on the gas drive oil recovery process can be analyzed based on the non-equilibrium molecular dynamics simulation process. Through the Tk Console module of the VMD software, a snapshot of the displacement process and a two-dimensional density map can be obtained, so that the displacement process can be intuitively displayed. Among them, VMD (Visual Molecular Dynamics) is a software specifically designed for modeling, visualization and analysis of biological macromolecules (such as proteins, nucleic acids, etc.), which can provide a variety of analysis, visualization options and rendering methods, and can also process and analyze the trajectory of molecular dynamics simulation.

[0052] In this embodiment, optionally, based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on the gas drive oil production process is analyzed, including: determining the density distribution change information of the target molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; wherein the target molecules include oil-driving gas molecules and crude oil molecules; based on the density distribution change information, the influence of shale pore connectivity on the gas drive oil production process is analyzed.

[0053] Specifically, the LAMMPS software can be used to determine the density distribution change information of the target molecules (oil-displacing gas molecules and crude oil molecules) during the displacement process, so as to analyze the changes in the crude oil structure and the flow of each phase of the fluid. The greater the density distribution change within the same time, the stronger the mobility of the target molecule, which further indicates that the gas drive oil recovery process is faster. Exemplarily, the Density Profile Tool module of the VMD software can be used to perform density calculations to obtain the density distribution information of the target molecule at each time, such as a density distribution diagram. The adsorption intensity of crude oil in the pores can be determined by the peak height of the density distribution diagram. Among them, the higher the peak value, the stronger the adsorption of crude oil on the wall, that is, the weaker the mobility. According to the density distribution information of the target molecule at each time, the density distribution change information of the target molecule can be obtained.

[0054] In this embodiment, optionally, based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on the gas drive oil production process is analyzed, including: determining the center of mass displacement change information of the target molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; wherein the target molecules include oil-driving gas molecules and crude oil molecules; based on the center of mass displacement change information, the influence of shale pore connectivity on the gas drive oil production process is analyzed.

[0055] Specifically, LAMMPS software can be used to determine the mass displacement change information of the target molecules (displacing gas molecules and crude oil molecules) during the displacement process, so as to analyze the changes in crude oil structure and the flow of each phase of fluid. The greater the mass displacement change within the same time, the stronger the mobility of the target molecule, and further indicates that the gas drive oil recovery process is faster. Figure 3 This is a schematic diagram of the displacement change of the center of mass of carbon dioxide (oil displacement gas molecules) provided in Example 1 of the present invention. The horizontal axis is time and the vertical axis is the displacement of the center of mass. Figure 3 As shown, the centroid displacement change of the 3nm pores in the double-notch connected pores is stronger than that of the single-notch connected pores, and the fluidity is stronger, while the difference of the 6nm pores is smaller.

[0056] In this embodiment, optionally, based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on the gas drive oil production process is analyzed, including: determining the interaction energy change information of two target objects in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; wherein the target objects include oil-driving gas molecules, crude oil molecules and target shale wall surfaces; based on the interaction energy change information, the influence of shale pore connectivity on the gas drive oil production process is analyzed.

[0057] Specifically, the LAMMPS software can be used to determine the interaction energy change information of the two target objects (oil-displacing gas molecules, crude oil molecules and target shale wall) during the displacement process. According to the change trend and value of the interaction energy change information, the strength of the interaction between the fluids in the connected pores can be determined, so as to evaluate the speed of gas drive oil production. The greater the change in interaction energy in the same time, the faster the gas drive oil production process. Figure 4 This is a schematic diagram of the change of interaction energy in a single-notch connected pore provided in Example 1 of the present invention. The horizontal axis is time, and the vertical axis is interaction energy (only the numerical value is concerned, not the positive or negative value). Figure 4 As shown in the figure, the oil-gas interaction energy increases first and then decreases, indicating that CO 2 After injection, the crude oil volume expands, reducing the viscosity and interfacial tension. 2 The interaction energy between oil / gas and the wall reflects the transformation of the adsorption layer molecules from oil molecules to CO 2 molecular.

[0058] In this embodiment, optionally, based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on the gas drive oil production process is analyzed, including: determining the radial distribution function information of the target molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; wherein the target molecules include oil-driving gas molecules and crude oil molecules; based on the radial distribution function information, analyzing the influence of shale pore connectivity on the gas drive oil production process.

[0059] Specifically, the radial distribution function of the displacement gas molecules and crude oil molecules can be calculated using the LAMMPS software and the Radial Pair Distribution Function g(r) module of the VMD software, so as to analyze the degree of destruction of the crude oil structure, the degree of mixing of the displacement gas molecules and crude oil molecules, and the degree of solubility of the crude oil molecules. The maximum value of the radial distribution function means that the distribution of the gas molecules reaches the highest level at the corresponding distance. Figure 5 Schematic diagram of a radial distribution function provided in Embodiment 1 of the present invention. The horizontal axis is the distance, and the vertical axis is the radial distribution function value. Figure 5 As shown in the figure, compared with the 3nm pore at the same time, the g(r) peak of the double-notch structure is higher than that of the single-notch structure, indicating that the crude oil and CO in the double-notch 3nm pore are 2 The miscibility is better and it dissolves in CO 2 There is more crude oil in it.

[0060] In this embodiment, optionally, based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on the gas drive oil production process is analyzed, including: determining the root mean square displacement information of crude oil molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; determining the diffusion coefficient of the crude oil molecules based on the root mean square displacement information; and analyzing the influence of shale pore connectivity on the gas drive oil production process based on the diffusion coefficient.

[0061] Specifically, the LAMMPS software can be used to calculate the root mean square displacement information of crude oil molecules, and then according to the formula Calculate the diffusion coefficient of crude oil molecules in each pore structure. Where D is the diffusion coefficient, t is the time, and MSD is the root mean square displacement. For example, the diffusion coefficient of a 3 nm pore is calculated to be: 0.618×10 -8 m 2 / s(double gap)>0.431×10 -8 m 2 / s (single gap), the diffusion coefficient of 6nm pore is: 1.365×10 -8 m 2 / s(double gap)<1.358×10 - 8 m 2 / s (single notch). This shows that the diffusion coefficient of 3nm pores in double-notch connected pores is higher than that of single-notch connected pores, and has little effect on the diffusion coefficient of crude oil in 6nm pores. Therefore, the improvement of pore connectivity is conducive to accelerating the gas drive oil recovery process.

[0062] In this embodiment, optionally, based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on the gas drive oil production process is analyzed, including: determining the recovery rate change information of crude oil molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; based on the recovery rate change information, analyzing the influence of shale pore connectivity on the gas drive oil production process.

[0063] Specifically, according to the formula Calculate the recovery rate of crude oil molecules at each time. Where R is the recovery rate, N O is the initial number of crude oil molecules, N N is the number of crude oil molecules remaining in the pores. According to the recovery rate of crude oil molecules at each time, the recovery rate change information of crude oil molecules can be determined, and then the impact of shale pore connectivity on gas drive oil production process can be analyzed based on the recovery rate change information. Figure 6 This is a schematic diagram of the change of crude oil molecular recovery rate provided by Example 1 of the present invention. The horizontal axis is time and the vertical axis is recovery rate. Figure 6As shown in the figure, the recovery rate of 3nm pores in the double-notch connected pores is higher than that of the single-notch connected pores, and it has little effect on the crude oil recovery effect in the 6nm pores. Therefore, the improvement of pore connectivity is conducive to accelerating the gas drive oil recovery process.

[0064] Furthermore, the LAMMPS software can also be used to determine the displacement rate of each connected pore in the crude oil stable adsorption model, and analyze the effect of shale pore connectivity on the gas drive oil recovery process based on the displacement rate. For example, the displacement rate of 3nm pores is calculated to be: 3.45m / s (double notch) > 2.99m / s (single notch), and the displacement rate of 6nm pores is: 4.03m / s (double notch) < 4.05m / s (single notch). This shows that the displacement rate of 3nm pores in double-notch connected pores is higher than that of single-notch connected pores, and has little effect on the displacement rate of crude oil in 6nm pores. Therefore, the improvement of pore connectivity is conducive to accelerating the gas drive oil recovery process.

[0065] The technical solution of the embodiment of the present invention is to construct at least two shale interconnected channel models, which are software models of shale micro-nanoscale pore structures containing interconnected fractures of different numbers and / or different positions; inject pre-constructed crude oil molecules into the shale interconnected channel model, and perform equilibrium molecular dynamics simulation on the shale interconnected channel model to obtain a crude oil stable adsorption model; wherein the crude oil stable adsorption model is a model when the crude oil in the shale interconnected channel model reaches a stable state; inject pre-constructed oil-displacing gas molecules into the crude oil stable adsorption model, and perform non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model; based on the non-equilibrium molecular dynamics simulation process, analyze the influence of shale pore connectivity on the gas drive oil recovery process. This technical solution can use the molecular dynamics simulation method to study the influence of shale pore connectivity on the gas drive oil effect from a microscopic perspective, so as to improve the shale oil recovery rate by optimizing the gas drive oil effect.

[0066] Embodiment 2

[0067] Figure 7 A flow chart of a gas-driven oil recovery research method based on pore connectivity provided in Example 2 of the present invention, this embodiment is optimized based on the above-mentioned embodiment. The specific optimization is: after obtaining the crude oil stable adsorption model, the method also includes: determining the density distribution information of free crude oil molecules in the crude oil stable adsorption model; determining the density error information based on the density distribution information and the reference density distribution information; if the density error information is less than the preset density threshold, injecting pre-constructed oil-driving gas molecules into the crude oil stable adsorption model, and performing non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model.

[0068] like Figure 7 As shown, the method of this embodiment specifically includes the following steps:

[0069] S210, construct at least two shale interconnected pore models, where the shale interconnected pore model is a shale micro-nanoscale pore structure software model containing interconnected fractures of different numbers and / or different positions.

[0070] S220, injecting pre-constructed crude oil molecules into the shale interconnected pore model, and performing equilibrium molecular dynamics simulation on the shale interconnected pore model to obtain a crude oil stable adsorption model; wherein the crude oil stable adsorption model is a model when the crude oil in the shale interconnected pore model reaches a stable state.

[0071] Among them, the specific implementation method of S210-S220 can refer to the detailed description of S110-S120, which will not be repeated here.

[0072] S230, determining density distribution information of free crude oil molecules in the crude oil stable adsorption model.

[0073] For example, the Density Profile Tool module of VMD software can be used to perform density calculation to obtain the density distribution information of free crude oil molecules.

[0074] S240, determining density error information according to the density distribution information and the reference density distribution information.

[0075] The reference density distribution information may be density distribution data in a standard database of the National Institute of Standards and Technology (NIST). In this embodiment, after determining the density distribution information of free crude oil molecules in the crude oil stable adsorption model, the density distribution information may be compared with the reference density distribution information to calculate density error information, so as to verify the rationality and applicability of the simulation according to the density error information.

[0076] S250: If the density error information is less than a preset density threshold, inject pre-constructed oil displacement gas molecules into the crude oil stable adsorption model to perform non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model.

[0077] Among them, the preset density threshold may refer to a preset density error reference value, which can be specifically set according to actual simulation requirements. For example, the preset density threshold may be set to 10%. Specifically, if the density error information is less than the preset density threshold, it may indicate that the density error is small, that is, the simulation is reasonable and applicable. At this time, the pre-constructed oil displacement gas molecules may be injected into the crude oil stable adsorption model to perform non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model. On the contrary, if the density error information is greater than or equal to the preset density threshold, it indicates that the density error is large, that is, the simulation is not reasonable and applicable. At this time, it is necessary to readjust the shale interconnected pore model, perform equilibrium molecular dynamics simulation on the shale interconnected pore model again, and perform density error judgment on the crude oil stable adsorption model obtained after the equilibrium molecular dynamics simulation until the density error information meets the requirements.

[0078] S260, based on non-equilibrium molecular dynamics simulation process, analyzes the impact of shale pore connectivity on gas drive oil recovery process.

[0079] The technical solution of the embodiment of the present invention, after obtaining the crude oil stable adsorption model, the method also includes: determining the density distribution information of the free crude oil molecules in the crude oil stable adsorption model; determining the density error information according to the density distribution information and the reference density distribution information; if the density error information is less than the preset density threshold, injecting the pre-constructed oil-displacing gas molecules into the crude oil stable adsorption model, and performing non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model. This technical solution, on the basis of using the molecular dynamics simulation method to study the influence of shale pore connectivity on the gas oil recovery effect from a microscopic perspective, so as to improve the shale oil recovery rate by optimizing the gas oil recovery effect, can also ensure the rationality and applicability of the simulation through density error judgment, thereby improving the accuracy of the simulation.

[0080] Embodiment 3

[0081] Figure 8 This is a schematic diagram of the structure of a gas drive oil recovery research device based on pore connectivity provided in the third embodiment of the present invention. The device can execute the gas drive oil recovery research method based on pore connectivity provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method. Figure 8 As shown, the device comprises:

[0082] A shale interconnected pore model construction module 310 is used to construct at least two shale interconnected pore models, wherein the shale interconnected pore models are software models of shale micro-nanoscale pore structures containing interconnected fractures of different numbers and / or different positions;

[0083] The equilibrium molecular dynamics simulation module 320 is used to inject pre-constructed crude oil molecules into the shale interconnected pore model, and perform equilibrium molecular dynamics simulation on the shale interconnected pore model to obtain a crude oil stable adsorption model; wherein the crude oil stable adsorption model is a model when the crude oil in the shale interconnected pore model reaches a stable state;

[0084] A non-equilibrium molecular dynamics simulation module 330 is used to inject pre-constructed oil displacement gas molecules into the crude oil stable adsorption model to perform a non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model;

[0085] The gas drive oil production process analysis module 340 is used to analyze the influence of shale pore connectivity on the gas drive oil production process based on the non-equilibrium molecular dynamics simulation process.

[0086] Optionally, the shale interconnected pore model building module 310 is specifically used to:

[0087] Acquire a unit cell from a database, and perform a first preprocessing on the unit cell to obtain an initial shale wall surface; wherein the first preprocessing includes a cutting process and a supercell process;

[0088] Deleting silicon atoms located on the outer surface of the initial shale wall and adding one hydrogen atom to each oxygen atom exposed on the outer surface of the initial shale wall to obtain a reference shale wall;

[0089] Performing a second preprocessing on the reference shale wall surface to obtain a candidate shale wall surface; wherein the second preprocessing includes an amplification process and a movement process;

[0090] Cutting along internal silicon atoms at a preset position of the candidate shale wall to form a connected fracture, and adding a hydrogen atom to each oxygen atom located near the connected fracture and exposed on the outer surface of the candidate shale wall to obtain a target shale wall;

[0091] A shale interconnected channel model is determined according to the target shale wall surface.

[0092] Optionally, the gas drive oil production process analysis module 340 is used to:

[0093] Determining density distribution change information of target molecules in the crude oil stable adsorption model during non-equilibrium molecular dynamics simulation; wherein the target molecules include oil displacement gas molecules and crude oil molecules;

[0094] Based on the density distribution change information, the effect of shale pore connectivity on the gas drive oil production process is analyzed.

[0095] Optionally, the gas drive oil production process analysis module 340 is further used to:

[0096] Determining the mass center displacement change information of the target molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; wherein the target molecules include oil displacement gas molecules and crude oil molecules;

[0097] According to the centroid displacement change information, the influence of shale pore connectivity on the gas drive oil production process is analyzed.

[0098] Optionally, the gas drive oil production process analysis module 340 is further used to:

[0099] Determine the interaction energy change information of two target objects in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; wherein the target objects include oil displacement gas molecules, crude oil molecules and target shale wall surfaces;

[0100] According to the interaction energy change information, the influence of shale pore connectivity on the gas drive oil production process is analyzed.

[0101] Optionally, the gas drive oil production process analysis module 340 is further used to:

[0102] Determining radial distribution function information of target molecules in the crude oil stable adsorption model during non-equilibrium molecular dynamics simulation; wherein the target molecules include oil displacement gas molecules and crude oil molecules;

[0103] Based on the radial distribution function information, the effect of shale pore connectivity on the gas drive oil production process is analyzed.

[0104] Optionally, the gas drive oil production process analysis module 340 is further used to:

[0105] Determining the root mean square displacement information of crude oil molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process;

[0106] determining a diffusion coefficient of the crude oil molecules according to the root mean square displacement information;

[0107] The influence of shale pore connectivity on the gas drive oil production process is analyzed based on the diffusion coefficient.

[0108] Optionally, the gas drive oil production process analysis module 340 is further used to:

[0109] Determining the recovery rate change information of crude oil molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process;

[0110] Based on the recovery factor change information, the effect of shale pore connectivity on the gas drive oil production process is analyzed.

[0111] Optionally, the device further comprises:

[0112] A density distribution information determination module, used to determine the density distribution information of free crude oil molecules in the crude oil stable adsorption model;

[0113] A density error information determination module, used to determine density error information according to the density distribution information and reference density distribution information;

[0114] The second non-equilibrium molecular dynamics simulation module is used to inject pre-constructed oil displacement gas molecules into the crude oil stable adsorption model if the density error information is less than a preset density threshold, and perform non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model.

[0115] A gas drive oil production research device based on pore connectivity provided in an embodiment of the present invention can execute a gas drive oil production research method based on pore connectivity provided in any embodiment of the present invention, and has functional modules and beneficial effects corresponding to the execution method.

[0116] Embodiment 4

[0117] Fig. 9 A schematic diagram of the structure of an electronic device 10 that can be used to implement an embodiment of the present invention is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0118] like Fig. 9 As shown, the electronic device 10 includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0119] A number of components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0120] The processor 11 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as a gas drive oil recovery research method based on pore connectivity.

[0121] In some embodiments, the gas drive oil recovery research method based on pore connectivity can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the gas drive oil recovery research method based on pore connectivity described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to execute the gas drive oil recovery research method based on pore connectivity in any other appropriate manner (for example, by means of firmware).

[0122] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0123] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0124] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0125] To provide interaction with a user, the systems and techniques described herein may be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0126] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0127] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0128] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0129] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A gas drive oil recovery research method based on pore connectivity, characterized in that: The method comprises: Constructing at least two shale interconnected pore models, wherein the shale interconnected pore models are software models of shale micro-nanoscale pore structures containing interconnected fractures of different numbers and / or different positions; Injecting pre-constructed crude oil molecules into the shale interconnected pore model, and performing equilibrium molecular dynamics simulation on the shale interconnected pore model to obtain a crude oil stable adsorption model; wherein the crude oil stable adsorption model is a model when the crude oil in the shale interconnected pore model reaches a stable state; Injecting pre-constructed oil displacement gas molecules into the crude oil stable adsorption model, and performing non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model; Based on the nonequilibrium molecular dynamics simulation process, the effect of shale pore connectivity on gas drive oil recovery process is analyzed.

2. The method according to claim 1, characterized in that The construction process of the shale interconnected pore model includes: Acquire a unit cell from a database, and perform a first preprocessing on the unit cell to obtain an initial shale wall surface; wherein the first preprocessing includes a cutting process and a supercell process; Deleting silicon atoms located on the outer surface of the initial shale wall and adding one hydrogen atom to each oxygen atom exposed on the outer surface of the initial shale wall to obtain a reference shale wall; Performing a second preprocessing on the reference shale wall surface to obtain a candidate shale wall surface; wherein the second preprocessing includes an amplification process and a movement process; Cutting along internal silicon atoms at a preset position of the candidate shale wall to form a connected fracture, and adding a hydrogen atom to each oxygen atom located near the connected fracture and exposed on the outer surface of the candidate shale wall to obtain a target shale wall; A shale interconnected channel model is determined according to the target shale wall surface.

3. The method according to claim 2, characterized in that Based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on gas drive oil recovery process is analyzed, including: Determining density distribution change information of target molecules in the crude oil stable adsorption model during non-equilibrium molecular dynamics simulation; wherein the target molecules include oil displacement gas molecules and crude oil molecules; Based on the density distribution change information, the effect of shale pore connectivity on the gas drive oil production process is analyzed.

4. The method according to claim 2, characterized in that: Based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on gas drive oil recovery process is analyzed, including: Determining the mass center displacement change information of the target molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; wherein the target molecules include oil displacement gas molecules and crude oil molecules; According to the centroid displacement change information, the influence of shale pore connectivity on the gas drive oil production process is analyzed.

5. The method according to claim 2, characterized in that: Based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on gas drive oil recovery process is analyzed, including: Determine the interaction energy change information of two target objects in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; wherein the target objects include oil displacement gas molecules, crude oil molecules and target shale wall surfaces; According to the interaction energy change information, the influence of shale pore connectivity on the gas drive oil production process is analyzed.

6. The method according to claim 2, characterized in that Based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on gas drive oil recovery process is analyzed, including: Determining radial distribution function information of target molecules in the crude oil stable adsorption model during non-equilibrium molecular dynamics simulation; wherein the target molecules include oil displacement gas molecules and crude oil molecules; Based on the radial distribution function information, the effect of shale pore connectivity on the gas drive oil production process is analyzed.

7. The method according to claim 2, characterized in that Based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on gas drive oil recovery process is analyzed, including: Determining the root mean square displacement information of crude oil molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; determining a diffusion coefficient of the crude oil molecules according to the root mean square displacement information; The influence of shale pore connectivity on the gas drive oil production process is analyzed based on the diffusion coefficient.

8. The method according to claim 2, characterized in that: Based on the non-equilibrium molecular dynamics simulation process, the influence of shale pore connectivity on gas drive oil recovery process is analyzed, including: Determining the recovery rate change information of crude oil molecules in the crude oil stable adsorption model during the non-equilibrium molecular dynamics simulation process; Based on the recovery factor change information, the effect of shale pore connectivity on the gas drive oil production process is analyzed.

9. The method according to claim 1, characterized in that: After obtaining the crude oil stable adsorption model, the method further comprises: Determining density distribution information of free crude oil molecules in the crude oil stable adsorption model; Determine density error information according to the density distribution information and reference density distribution information; If the density error information is less than a preset density threshold, pre-constructed oil displacement gas molecules are injected into the crude oil stable adsorption model to perform non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model.

10. A gas drive oil recovery research device based on pore connectivity, characterized in that: The device comprises: A shale interconnected pore model construction module, used to construct at least two shale interconnected pore models, wherein the shale interconnected pore models are shale micro-nanoscale pore structure software models containing interconnected fractures of different numbers and / or different positions; A balanced molecular dynamics simulation module is used to inject pre-constructed crude oil molecules into the shale interconnected pore model, and perform a balanced molecular dynamics simulation on the shale interconnected pore model to obtain a crude oil stable adsorption model; wherein the crude oil stable adsorption model is a model when the crude oil in the shale interconnected pore model reaches a stable state; A non-equilibrium molecular dynamics simulation module, used for injecting pre-constructed oil displacement gas molecules into the crude oil stable adsorption model to perform non-equilibrium molecular dynamics simulation on the crude oil stable adsorption model; The gas drive oil production process analysis module is used to analyze the impact of shale pore connectivity on the gas drive oil production process based on the non-equilibrium molecular dynamics simulation process.

11. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the gas drive oil recovery research method based on pore connectivity as described in any one of claims 1-9.

12. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the gas drive oil production research method based on pore connectivity according to any one of claims 1 to 9 when executed.

Images