A method for identifying water bridges in pores

Abstract

The present application provides a method for identifying water bridges in pores, wherein the method includes: constructing a microscopic pore model based on structural information of the microscopic pores, the microscopic pore model including multiple microscopic pores, and the microscopic pores refer to pores formed by setting a first medium surface and a second medium surface relative to each other; placing crude oil molecules and water molecules in the microscopic pore model and performing structural relaxation to obtain a mixed system model after structural relaxation; performing molecular dynamics simulation on the mixed system model to obtain a static model in a stable state; creating a van der Waals surface of water molecules for the static model; and determining whether the microscopic pore model forms a water bridge based on the continuity of the van der Waals surface.

Description

Technical Field

[0001] The present application relates to the field of microscopic pore simulation technology, and in particular to a method for identifying water bridges in pores. Background Art

[0002] Molecular dynamics simulations are widely used for characterizing microscopic fluid distribution and flow characteristics due to their intuitiveness, precision, and cost-effectiveness. Model building is the first step in molecular dynamics simulations. Existing techniques typically use the same solid material as the medium at either end of a pore to characterize the fluid distribution. However, molecular dynamics simulations based on this approach cannot fully reflect the actual underground conditions.

[0003] Water bridges are microscopic hydrogen-bonded networks formed by water molecules, connecting the pores between oil and rock. They play a crucial role in the storage and flow of porous fluids. Their presence influences the distribution of fluids at different locations within the pores. For example, their presence can cause water molecules to accumulate on the surface of the fluid's adsorption layer, thereby affecting the fluid's flow characteristics. Therefore, identifying the presence of water bridges within pores is crucial, providing a signature for studying fluid flow patterns. Summary of the Invention

[0004] In view of this, the purpose of the present application is to provide at least a method for identifying water bridges in pores, by constructing a microscopic pore model including multiple microscopic pores, and filling crude oil molecules and water molecules in the multiple microscopic pores, and obtaining a static model corresponding to the microscopic pore model in a stable state by performing structural relaxation and molecular dynamics simulation in sequence, and creating a van der Waals surface of water molecules under the static model, and determining the water bridge formation in the microscopic pore model by identifying the continuity of the van der Waals surface in multiple microscopic pores, thereby solving the technical problem in the prior art that it is impossible to determine whether a water bridge is formed in the pores and affecting fluid analysis, and achieving the technical effect of increasing the feature recognition capability for fluid analysis.

[0005] This application mainly includes:

[0006] An embodiment of the present application provides a method for identifying water bridges in pores, the method comprising: constructing a microscopic pore model based on structural information of the microscopic pores, the microscopic pore model comprising a plurality of microscopic pores, wherein the microscopic pores refer to pores formed by setting a first medium surface and a second medium surface relative to each other; placing crude oil molecules and water molecules in the microscopic pore model and performing structural relaxation to obtain a mixed system model after structural relaxation; performing molecular dynamics simulation on the mixed system model to obtain a static model in a stable state; creating a van der Waals surface of water molecules for the static model; and determining whether a water bridge is formed in the microscopic pore model based on the continuity of the van der Waals surface.

[0007] Optionally, the structural information of the micropores includes the boundary conditions, size levels, and material types corresponding to the first medium surface and the second medium surface, respectively, of the micropores, wherein the material types include minerals or kerogen, and the boundary conditions are used to control the number of micropores in the micropore model.

[0008] Optionally, the structural information further includes the material molecular layer structure of the mineral and the length and width corresponding to the material molecular layer structure.

[0009] Optionally, structural relaxation is performed in the following manner: geometric optimization is performed on the microscopic pore model, and annealing and molecular dynamics simulation are performed in sequence under a canonical ensemble to optimize the intermolecular structure in the microscopic pores.

[0010] Optionally, the molecular dynamics simulation of the mixed system model to obtain a static model in a stable state includes: performing molecular dynamics simulation on the mixed system model under an isothermal and isobaric ensemble, and obtaining a trajectory model corresponding to the simulation process, and taking the last frame of the trajectory model as the static model.

[0011] Optionally, creating the van der Waals surface for the water molecules in the static model includes: removing the crude oil molecules, the first medium surface and the second medium surface in the static model, retaining only the water molecules in the static model; creating a Connery surface for the water molecules in the static model, and configuring lattice parameters and Connery radius to obtain the van der Waals surface of the water molecules.

[0012] Optionally, before determining whether a water bridge is formed in the microscopic pore model according to the continuity of the van der Waals surface, the method further includes: restoring the first medium surface and the second medium surface in the static model.

[0013] Optionally, determining whether the micropore model forms a water bridge based on the continuity of the van der Waals surface includes: if the first medium surface and the second medium surface of at least one micropore are connected through the van der Waals surface, then the micropore model has a water bridge; if the first medium surface and the second medium surface of each micropore are not connected through the van der Waals surface, then the micropore model does not have a water bridge.

[0014] Optionally, before randomly distributing the crude oil molecules and water molecules into the multiple micropores of the micropore model, the method further includes: constructing a molecular model of the crude oil molecules and a molecular model of the water molecules, wherein the crude oil molecules include single hydrocarbon molecules or mixed hydrocarbon molecules, and the water molecules include pure water or formation water.

[0015] Optionally, the mixed system model after structural relaxation is obtained in the following manner: crude oil molecules and water molecules of a preset mass ratio are randomly placed in the micropore model in a random placement order, and the micropore model after placement is subjected to structural relaxation to obtain the mixed system model; or, a first molecule is randomly placed in the micropore model in a preset placement order, and the micropore model after the first molecule is placed is subjected to structural relaxation, and when part of the first molecule is adsorbed on the surface of the first medium surface and / or the second medium surface, a second molecule is randomly placed in the micropore model and the mixed system model is obtained by structural relaxation, wherein the preset placement order is used to improve the simulation ability of the mixed system model for the distribution of crude oil molecules and water molecules in an actual geological environment, the first molecule is one of the crude oil molecule and the water molecule, the second molecule is the other of the crude oil molecule and the water molecule, and the first molecule and the second molecule meet the preset mass ratio.

[0016] An embodiment of the present application provides a method for identifying water bridges in pores, the method comprising: constructing a microscopic pore model based on structural information of the microscopic pores, the microscopic pore model comprising a plurality of microscopic pores, wherein the microscopic pores refer to pores formed by setting a first medium surface and a second medium surface relative to each other; placing crude oil molecules and water molecules in the microscopic pore model and performing structural relaxation to obtain a mixed system model after structural relaxation; performing molecular dynamics simulation on the mixed system model to obtain a static model in a stable state; creating a van der Waals surface of water molecules for the static model; and determining whether a water bridge is formed in the microscopic pore model based on the continuity of the van der Waals surface. By constructing a micropore model including multiple micropores, and filling crude oil molecules and water molecules in the multiple micropores, a static model corresponding to the micropore model in a stable state is obtained by performing structural relaxation and molecular dynamics simulation in sequence, and the van der Waals surface of the water molecules under the static model is created. The water bridge formation in the micropore model is determined by identifying the continuity of the van der Waals surface in multiple micropores. This solves the technical problem in the existing technology that it is impossible to determine whether water bridges are formed in the pores, which affects fluid analysis, and achieves the technical effect of increasing the feature recognition capability for fluid analysis.

[0017] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A flow chart of a method for identifying water bridges in pores provided in an embodiment of the present application is shown.

[0020] Figure 2 A schematic diagram of a microscopic pore provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of illustration and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowcharts can be implemented out of sequence, and steps without logical context can be reversed or implemented simultaneously. In addition, those skilled in the art, under the guidance of the contents of this application, can add one or more other operations to the flowchart, or remove one or more operations from the flowchart.

[0022] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0023] In the existing technology, the media at both ends of the pore are set to the same solid position, and the solid materials on both sides are set to minerals or kerogen. However, under actual geological conditions, the minerals around some pores, such as the pores within mineral grains, may be the same, but there are also many pores, such as intergranular pores, where the minerals around them are different. At this time, if the same solid materials are still selected on both sides to build the pores, it is difficult to fully reflect the actual underground situation.

[0024] Current molecular dynamics simulations of fluid occurrence and characteristics at the microscale primarily analyze the density distribution of fluid molecules within pores, identifying their free, absorbed, or adsorbed states and calculating their relative proportions within the pores. Alternatively, they characterize parameters such as the rate of molecular migration under external forces, reflecting the slip effect experienced by nanoporous fluid flow. Overall, research on the connectivity of fluid distribution within pores is lacking, a key factor influencing the occurrence and flow characteristics of immiscible fluids within rock pores.

[0025] Water bridges play an important role in the storage and flow of pore fluids. The existence of water bridges will affect the distribution of fluids at different positions in the pores. For example, the existence of water bridges will cause water molecules to gather in large numbers on the surface of the fluid adsorption layer, thereby affecting the flow characteristics of the fluid.

[0026] Based on this, an embodiment of the present application provides a method for identifying water bridges in pores. By constructing a micropore model including multiple micropores and filling the multiple micropores with crude oil molecules and water molecules, a static model corresponding to the micropore model in a stable state is obtained by sequentially performing structural relaxation and molecular dynamics simulation. The van der Waals surface of the water molecules in the static model is created, and the continuity of the van der Waals surface in the multiple micropores is identified to determine the formation of water bridges in the micropore model. This solves the technical problem in the prior art of being unable to determine whether water bridges are formed in pores, which affects fluid analysis, and achieves the technical effect of increasing the feature recognition capability for fluid analysis, as follows:

[0027] See also Figure 1 , Figure 1 This is a flow chart of a method for identifying water bridges in pores provided in an embodiment of the present application. Figure 1 As shown, the method for identifying water bridges in pores provided in the embodiment of the present application can be implemented using Materials Studio software, and the method includes the following steps:

[0028] S101: Construct a microscopic pore model based on the structural information of the microscopic pores.

[0029] The microscopic pore model includes a plurality of microscopic pores, and the microscopic pores refer to pores formed by setting a first medium surface and a second medium surface opposite to each other.

[0030] That is to say, the space between the relative first medium surface and the second medium surface is used as a microscopic pore, and the relative first medium surface and the second medium surface are placed in parallel, and the projection is performed from the first medium surface to the second medium surface. The projection surface of the first medium surface can completely overlap with the second medium surface or partially overlap with the second medium surface.

[0031] For example, see Figure 2 , Figure 2 This is a schematic diagram of a microscopic pore provided in an embodiment of the present application. Figure 2 As shown, the microscopic pore can be understood as a hexahedral box. The edges intersecting at one corner of the hexahedral box are the first edge L1, the second edge L2, and the third edge L3. The plane containing the first dielectric surface S1 is parallel to the plane containing the second dielectric surface S2. The projection surface obtained by projecting the first dielectric surface vertically onto the plane containing the second dielectric surface partially overlaps with the second dielectric surface. The first and second dielectric surfaces facing each other in the hexahedral box serve as the media on both sides of the microscopic pore, and the space between the first and second dielectric surfaces serves as the microscopic pore. In this way, the hexahedral box is configured so that only the first and second dielectric surfaces exist, ignoring other surfaces. Furthermore, if the projection surface obtained by projecting the first dielectric surface vertically onto the plane containing the second dielectric surface completely overlaps with the second dielectric surface, then the hexahedral box corresponding to the microscopic pore is a cuboid.

[0032] The structural information of the microscopic pores includes the boundary conditions, size class, and material types corresponding to the first and second media surfaces, respectively, of the microscopic pores. The material types include minerals or kerogen. The boundary conditions are used to control the number of microscopic pores in the microscopic pore model. The structural information also includes the molecular layer structure of the mineral and the length and width corresponding to the molecular layer structure.

[0033] Specifically, the boundary conditions for the microscopic pores apply periodic boundary conditions along the first, second, and third sides L1, L2, and L3 of the hexahedral box, respectively, to set the number of microscopic pores in the microscopic pore model to multiple. The size of the microscopic pores is set to the nanoscale to meet microscopic requirements.

[0034] The structural information of the microscopic pores also includes unit cell parameters, namely, the lengths of the first side L1, the second side L2, and the third side L3 corresponding to the hexahedral box.

[0035] The material type of the microscopic pores is selected based on the subsurface material type of the study area. The material type of the first medium surface and the material type of the second medium surface can be the same or different. Material types include minerals or kerogen. In other words, the first medium surface is minerals or kerogen, and the second medium surface is minerals or kerogen. That is, the material type of the first medium surface and the second medium surface can be any of the following: the material type of the first medium surface and the second medium surface is minerals, the material type of the first medium surface and the second medium surface is kerogen, or the material type of the first medium surface is minerals and the material type of the second medium surface is kerogen.

[0036] If the material type is mineral, you also need to set the mineral's material molecular layer structure and the corresponding length and width of the material molecular layer structure. Among them, the mineral material molecular layer structure includes a monolayer structure and a multilayer structure. Then, set the mineral material molecular layer structure to a monolayer structure or a multilayer structure, and set the length of the monolayer structure or the multilayer structure according to an integer multiple of the length of the mineral unit cell, and set the width of the monolayer structure or the multilayer structure according to an integer multiple of the width of the mineral unit cell.

[0037] Exemplarily, minerals are selected for the first medium surface and the second medium surface, and illite is specifically selected, and a unit cell is established by cutting the (001) plane to increase structural stability, and the first medium surface and the second medium surface are set to a double-layer structure.

[0038] For example, if the length of a mineral unit cell is A and the width is B, regardless of whether the material molecular layer structure of the mineral is set to a single molecular layer structure or a multi-molecular layer structure, the length of the material molecular layer structure of the mineral needs to be set to n1 times A, and the width of the material molecular layer structure of the mineral needs to be set to n2 times B, where n1 and n2 are both integers.

[0039] Among them, the kerogen can select the corresponding pre-constructed kerogen molecular structure according to the type and maturity of the kerogen in the actual formation, and the kerogen molecular structure is irregular in shape.

[0040] S102: placing crude oil molecules and water molecules in the microscopic pore model and performing structural relaxation to obtain a mixed system model after structural relaxation.

[0041] Before randomly distributing crude oil molecules and water molecules into the multiple micropores of the micropore model, the method further includes: constructing a molecular model of the crude oil molecules and a molecular model of the water molecules, wherein the crude oil molecules include single hydrocarbon molecules or mixed hydrocarbon molecules, and the water molecules include pure water or formation water.

[0042] Crude oil samples are obtained from underground in the study area, separated, and analyzed to determine the relative content of each crude oil component and typical hydrocarbon molecules. This allows the molecular model of the crude oil molecule to be selected from the single hydrocarbon molecule with the highest relative content. Alternatively, a molecular model of a mixed hydrocarbon molecule can be constructed based on the ratios of the various crude oil components and their typical hydrocarbon molecules.

[0043] For example, the molecular model of crude oil molecules is selected from saturated hydrocarbons, with a specific molecular formula of C 21 H 44 , so that C 21 H 44 The molecular model of is used as the molecular model of crude oil molecule.

[0044] The molecular model of water molecules can be a molecular model of pure water, or a water molecular model of formation water can be established based on the mineralization characteristics of formation water in the study area.

[0045] The mixed system model after structural relaxation is obtained in the following manner: crude oil molecules and water molecules of a preset mass ratio are randomly placed in the microscopic pore model in a random placement order, and the mixed system model is obtained by structurally relaxing the microscopic pore model after placement; or first molecules are randomly placed in the microscopic pore model in a preset placement order, and the microscopic pore model after the placement of the first molecules is structurally relaxed, and when part of the first molecules is adsorbed on the surface of the first medium surface and / or the second medium surface, second molecules are randomly placed in the microscopic pore model and the mixed system model is obtained by structurally relaxing.

[0046] The preset injection sequence is used to improve the simulation capability of the mixed system model for the distribution of crude oil molecules and water molecules in an actual geological environment. The first molecule is one of the crude oil molecule and the water molecule, and the second molecule is the other of the crude oil molecule and the water molecule. The first molecule and the second molecule meet the preset mass ratio.

[0047] That is, the placement of crude oil molecules and water molecules in the microscopic pore model at a preset mass ratio includes a random placement method or a sequential placement method according to a preset placement order. In either case, the placement positions corresponding to the random placement method or the sequential placement method are random.

[0048] Furthermore, when placing crude oil and water molecules in a preset order, it is necessary to perform structural relaxation on the microscopic pore model following the first molecule. After a portion of the first molecule is adsorbed on the first and / or second medium surfaces of the microscopic pore model, the second molecule is placed in the microscopic pore model. After the second molecule is placed, the microscopic pore model is structurally relaxed to obtain a mixed system model. Furthermore, by sequentially placing the first and second molecules, the distribution of the first and second molecules in the actual geological environment corresponding to the microscopic pore model can be simulated, thereby obtaining a mixed system model that better conforms to the actual geological environment. Furthermore, the molecular types corresponding to the first and second molecules can be set according to the actual geological environment.

[0049] That is, the first molecule can be a crude oil molecule and the second molecule can be a water molecule; or the first molecule can be a water molecule and the second molecule can be a crude oil molecule.

[0050] For example, the preset mass ratio is set to 3:1 between the mass of crude oil molecules and the mass of water molecules, and the crude oil molecules and water molecules with set masses are randomly placed in the microscopic pore model in a random order.

[0051] Structural relaxation is performed in the following manner: geometric optimization of the microscopic pore model is performed in sequence, and annealing and molecular dynamics simulation are performed under a canonical ensemble to optimize the intermolecular structure in the microscopic pores.

[0052] In other words, the microscopic pore model after placing crude oil molecules and water molecules is first geometrically optimized, and then annealing treatment and molecular dynamics simulation are performed under the canonical ensemble to achieve structural relaxation, thereby obtaining a mixed system model with optimized intermolecular structure in the microscopic pores.

[0053] Among them, for geometry optimization, you can choose the Steepest descent algorithm (steepest descent method) or the Smart algorithm, set the maximum number of iterations of geometry optimization to 50,000, and choose not to optimize the cell parameters. In this way, perform geometry optimization at least once until the operation result shows normal (Termination status: Normal), indicating that the convergence curve (Convergence, unit log10) changes normally with the optimization step (Optimization Step). When the simulation reaches the convergence state, stop the geometry optimization.

[0054] The annealing process under the canonical ensemble (NVT) includes: setting the annealing cycle to 10, the initial temperature to 300K (Kelvin), the temperature rising to 1000K in each cycle, the total number of steps to 10000, the initial velocity to random, the time step to 1fs (femtosecond), and the thermostat selected as Nose.

[0055] Among them, molecular dynamics simulation under the canonical ensemble includes: setting the force field type according to the material type, setting the temperature to room temperature or formation temperature, setting the initial velocity to random, setting the time step to 1fs, and the total simulation time according to the size of the microscopic pore model. The minimum setting is 1ns (nanosecond), and the thermostat regulator uses Nose.

[0056] Furthermore, the structure of each molecule in the micropore model is optimized by performing structural relaxation on the micropore model, so that the organic molecular structure in the micropore model is more reasonable, and the intermolecular energy is reduced, thereby stabilizing the molecular structure of the micropore model.

[0057] S103: performing molecular dynamics simulation on the mixed system model to obtain a static model in a stable state.

[0058] The molecular dynamics simulation of the mixed system model to obtain a static model in a stable state includes: performing molecular dynamics simulation on the mixed system model under an isothermal and isobaric ensemble, and obtaining a trajectory model corresponding to the simulation process, and using the last frame of the trajectory model as the static model.

[0059] That is, molecular dynamics simulation was performed again under the isothermal and isobaric ensemble (constant-pressure constant-temperature, NPT), including: the pressure was set to the formation pressure, the temperature was set to the formation temperature, the time step was set to 1 fs, the total simulation time was set according to the size of the microscopic pore model, the minimum was set to 1 ns, the initial velocity was set to random, the constant temperature regulator was Nose, the constant pressure regulator was Berendsen, and one frame of results was output every 5000 time steps.

[0060] For example, the temperature is set to 77 degrees Celsius and the total simulation time is set to 5 ns.

[0061] Furthermore, by performing molecular dynamics simulation in an isothermal and isobaric ensemble, the trajectory of the microscopic pore model in each frame can be obtained, thereby obtaining the trajectory model of the entire process of molecular dynamics simulation in the isothermal and isobaric ensemble, and the trajectory model corresponding to the last frame is used as the static model.

[0062] Exemplarily, the static model is saved as a static format file.

[0063] S104: Creating a van der Waals surface of water molecules for the static model.

[0064] The creating of the van der Waals surface of the water molecules in the static model includes: removing the crude oil molecules, the first medium surface, and the second medium surface in the static model, retaining only the water molecules in the static model; creating a Connery surface for the water molecules in the static model, and configuring lattice parameters and Connery radius to obtain the van der Waals surface of the water molecules.

[0065] That is, the crude oil molecules other than water molecules and the medium on both sides of the microscopic pores in the static model are deleted, so that only the water molecules in the static model are retained, and Connery surfaces are created for the water molecules. The lattice resolution is set to medium or above, the default lattice spacing matches the lattice resolution, the Connery radius is set to 0 nm, and the probe is controlled to move along the water molecules in the static model to generate the Connery surface. Thus, the generated Connery surface is used as the van der Waals surface of the water molecules in the static model.

[0066] S105: Determine whether a water bridge is formed in the microscopic pore model according to the continuity of the van der Waals surface.

[0067] Before determining whether a water bridge is formed in the microscopic pore model according to the continuity of the van der Waals surface, the method further includes: restoring the first medium surface and the second medium surface in the static model.

[0068] That is, after the first medium surface and the second medium surface in the static model are restored, only the van der Waals surface, the first medium surface and the second medium surface remain in the static model, which is equivalent to removing the crude oil molecules in the static model.

[0069] The determining whether the microscopic pore model forms a water bridge based on the continuity of the van der Waals surface includes: if the first medium surface and the second medium surface of at least one microscopic pore are connected through the van der Waals surface, then the microscopic pore model has a water bridge; if the first medium surface and the second medium surface of each microscopic pore are not connected through the van der Waals surface, then the microscopic pore model does not have a water bridge.

[0070] Furthermore, among the multiple micropores in the micropore model, as long as there is a van der Waals surface in the gap between the first medium surface and the second medium surface of one micropore, and the van der Waals surface connects the first medium surface and the second medium surface, then the van der Waals surface is considered to be a water bridge between the two side medium surfaces of the target micropore, and thus, it is considered that a water bridge exists in the micropore model.

[0071] That is, in the connected space of any of the multiple micropores in the micropore model, several channels surrounded by van der Waals surfaces may be formed. If there is a channel with both ends connected to the first medium surface and the second medium surface respectively, it is determined that a water bridge is formed in the micropore; if the two ends of any channel cannot connect the first medium surface and the second medium surface, it is determined that no water bridge exists in the micropore.

[0072] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0073] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0074] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0075] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0076] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A method for identifying water bridges in pores, characterized in that: The method comprises: Constructing a microscopic pore model based on the structural information of the microscopic pores, wherein the microscopic pore model includes a plurality of microscopic pores, wherein the microscopic pores refer to pores formed by setting a first medium surface and a second medium surface opposite to each other; placing crude oil molecules and water molecules in the microscopic pore model and performing structural relaxation to obtain a mixed system model after structural relaxation; Performing molecular dynamics simulation on the mixed system model to obtain a static model in a stable state; creating a van der Waals surface of water molecules for the static model; determining whether a water bridge is formed in the microscopic pore model according to the continuity of the van der Waals surface; The creating of the van der Waals surface of the water molecules in the static model includes: removing the crude oil molecules, the first medium surface, and the second medium surface in the static model, and retaining only the water molecules in the static model; creating a Connolly surface for the water molecules in the static model, and configuring lattice parameters and Connolly radius to obtain the van der Waals surface of the water molecules; Before determining whether a water bridge is formed in the microscopic pore model based on the continuity of the van der Waals surface, the method further includes: restoring the first medium surface and the second medium surface in the static model so that only the van der Waals surface, the first medium surface, and the second medium surface remain in the static model, and removing the crude oil molecules in the static model; The determining whether the microscopic pore model forms a water bridge based on the continuity of the van der Waals surface includes: if the first medium surface and the second medium surface of at least one microscopic pore are connected through the van der Waals surface, then the microscopic pore model has a water bridge; if the first medium surface and the second medium surface of each microscopic pore are not connected through the van der Waals surface, then the microscopic pore model does not have a water bridge.

2. The method according to claim 1, characterized in that The structural information of the microscopic pores includes the boundary conditions, size levels, and material types corresponding to the first medium surface and the second medium surface, respectively. Wherein, the material type includes minerals or kerogen, and the boundary conditions are used to control the number of microscopic pores in the microscopic pore model.

3. The method according to claim 2, characterized in that The structural information also includes the material molecular layer structure of the mineral and the length and width corresponding to the material molecular layer structure.

4. The method according to claim 1, wherein Structural relaxation is performed by: The microscopic pore model is subjected to geometric optimization, annealing treatment and molecular dynamics simulation in a canonical ensemble in sequence to optimize the intermolecular structure in the microscopic pores.

5. The method according to claim 1, wherein The performing molecular dynamics simulation on the mixed system model to obtain a static model in a stable state includes: A molecular dynamics simulation is performed on the mixed system model under an isothermal and isobaric ensemble to obtain a trajectory model corresponding to the simulation process, and the last frame of the trajectory model is used as the static model.

6. The method according to any one of claims 1 to 5, characterized in that Before randomly distributing the crude oil molecules and water molecules into the plurality of microscopic pores of the microscopic pore model, the method further includes: Constructing a molecular model of the crude oil molecule and a molecular model of the water molecule, The crude oil molecules include single hydrocarbon molecules or mixed hydrocarbon molecules, and the water molecules include pure water or formation water.

7. The method according to any one of claims 1 to 5, characterized in that The mixed system model after structural relaxation is obtained by the following method: The mixed system model is obtained by randomly placing crude oil molecules and water molecules in a preset mass ratio in the microscopic pore model in a random order, and performing structural relaxation on the microscopic pore model after placement; Alternatively, the first molecules are randomly placed in the microscopic pore model in a preset placement order, and the microscopic pore model after the first molecules are placed is subjected to structural relaxation. When part of the first molecules is adsorbed on the surface of the first medium surface and / or the second medium surface, the second molecules are randomly placed in the microscopic pore model and the mixed system model is obtained by performing structural relaxation. The preset injection sequence is used to improve the simulation capability of the mixed system model for the distribution of crude oil molecules and water molecules in an actual geological environment. The first molecule is one of the crude oil molecule and the water molecule, and the second molecule is the other of the crude oil molecule and the water molecule. The first molecule and the second molecule meet the preset mass ratio.

Images