Four-phase hydrate digital core reconstruction method with time-coupled constraint field

Abstract

The application provides a four-phase hydrate digital core reconstruction method of a time sequence coupling constraint field, and belongs to the field of digital rock physics and pore-scale multiphase medium reconstruction. Hydrate is incorporated into an equivalent solid boundary set and a constraint field is reconstructed on an effective pore to realize that gas phase generation can reflect the pore topology change caused by hydrate occupation, and a four-phase distribution result with stronger physical consistency is obtained. First, a hydrate phase is generated in an initial pore domain, and the hydrate phase is incorporated into an equivalent solid boundary set to reflect the occupation and binding effect of hydrate growth on pore topology; then, a constraint field is reinitialized on the effective pore domain after hydrate generation, and a secondary distance potential field is obtained which is jointly constrained by the rock skeleton and the hydrate boundary; secondly, the gas phase distribution is generated on the secondary distance potential field according to a preset gas occurrence mode; finally, the remaining pores are automatically defined as the water phase, and a four-phase digital core satisfying the mutual exclusion complete rule is obtained.

Description

Technical Field

[0001] This application proposes a digital core reconstruction method for four-phase hydrates that achieves temporal coupling through equivalent solid updates and constraint field re-initialization, belonging to the field of digital rock physics and pore-scale multiphase media reconstruction. Background Technology

[0002] Current applications such as natural gas hydrate reservoirs and their exploitation, carbon dioxide hydrate storage, and the coexistence of free gas and water-bearing systems in unconventional oil and gas reservoirs all involve multiphase coupling distribution at the pore scale. The microscopic spatial structure of the solid skeleton, hydrate solid phase, free gas phase, and liquid water phase in the pores directly affects the seepage channels, relative permeability, capillary pressure, and acoustic and electrical physical properties.

[0003] In existing digital core reconstruction studies, each phase is typically generated separately according to preset rules and then statically superimposed. For example, the rock skeleton and pores are first obtained from CT threshold segmentation, then hydrate voxels are generated in the pores according to certain rules, and gas phase voxels are generated independently in the same pore. Finally, the remaining voxels are used as the water phase. This type of "static superposition" process has a key drawback: hydrate generation changes the pore topology (e.g., blocking pore throats, reducing the effective radius of pore throats, changing connectivity paths), while the generation of the gas phase in the static superposition process is often still based on the "pore geometry before hydrate generation" or based only on the distance field of the rock skeleton, resulting in a mismatch between the gas phase distribution and hydrate occupation.

[0004] Specifically, when hydrates form bridges at the pore throat or coat the pore walls, the original high-distance field region shrinks or disappears. If the gas phase still forms in the original high-distance field region, non-physical phenomena such as the gas phase "passing through the blocked pore throat," "occupying the narrow region bound by hydrates," and "overestimating connectivity" may occur, causing subsequent numerical simulation results to deviate from the actual reservoir behavior. On the other hand, existing literature or patents may involve hydrate formation or gas formation, but lack a clear and operable temporal coupling mechanism: that is, to use the changes in pore geometry caused by the first-formed hydrates as a constraint input for the distribution of the later-formed gas phase, and to explicitly transmit it in the form of a potential field or constraint field, thereby ensuring that the multiphase distribution is consistent with the pore topological evolution.

[0005] Therefore, there is an urgent need for a four-phase hydrate-bearing digital core reconstruction method that can realize a temporally coupled framework of "hydrate generation - pore domain redefinition - constrained field reconstruction - constrained gas phase generation" without relying on specific generation details, in order to solve the distribution inconsistency problem caused by static superposition. In view of this, this application is hereby proposed. Summary of the Invention

[0006] This application proposes a digital core reconstruction method for four-phase hydrates using a time-coupled constraint field. The aim is to solve the problems existing in the prior art by incorporating hydrates into an equivalent solid boundary set and reconstructing the constraint field on the effective pores. The goal is to achieve a design objective where gas phase generation can reflect the pore topological changes caused by hydrate occupation, thereby obtaining a four-phase distribution result with stronger physical consistency.

[0007] Therefore, the four-phase hydrate-bearing digital core reconstruction method with temporally coupled constraint fields described in this application firstly generates a hydrate phase in the initial pore domain using a binarized three-dimensional voxel digital core as input, and incorporates the hydrate phase into the equivalent solid boundary set to reflect the occupation and binding effect of hydrate growth on the pore topology; then, the constraint field is reinitialized on the effective pore domain after hydrate generation to obtain a secondary distance potential field that is simultaneously constrained by the rock skeleton and hydrate boundaries; secondly, a gas phase distribution is generated on the secondary distance potential field according to a preset gas phase occurrence mode, so that the spatial morphology of the gas phase can self-consistently evolve with the pore throat blockage, pore throat diameter changes and connectivity changes caused by hydrate occupation; finally, the remaining pores are automatically defined as the water phase, and a four-phase digital core satisfying the mutual exclusion completeness rule is synthesized.

[0008] The method includes the following implementation steps:

[0009] Step (1): Input and pore domain determination;

[0010] Acquire binarized three-dimensional voxel digital core data;

[0011] Identify the rock framework voxel set and the initial pore voxel set, where the rock framework voxel set is denoted as... Let be the set of voxel coordinates of all elements labeled as rocks; the initial set of pore voxels is denoted as . , is the set of voxel coordinates labeled as pores, and and Mutual exclusion and overwriting of the input voxel domain;

[0012] In the initial porosity voxel set The distance field of the constructed rock skeleton is denoted as The Euclidean distance is used to characterize the distance from any pore voxel to the nearest rock skeleton boundary; the rock skeleton distance field. satisfy:

[0013]

[0014] in, This is the 2-norm operator, representing Euclidean distance; when implemented using Euclidean distance transformation (EDT), For the pore domain All voxels on the surface are assembled with a rock skeleton. The distance field calculated for the set of nearest neighbor targets;

[0015] Step (2): hydrate phase formation;

[0016] Based on the preset hydrate saturation With respect to hydrate occurrence type, in the initial pore voxel set The set of elements that generate hydrated matter internally is denoted as ,satisfy ;

[0017] The number of hydrated voxels satisfies the target voxel number constraint corresponding to the target saturation, whereby the hydrate saturation is denoted as... and defined by voxel measurement method ,in, Indicates the number of voxels in the set;

[0018] Step (3): Equivalent solid update and effective porosity redefinition;

[0019] hydrated object element set Incorporate into the equivalent solid boundary set, where the equivalent solid boundary set is denoted as... Defined as ,in, It represents the set of equivalent solid boundaries that are unoccupiable and impenetrable, making the surface of a hydrate equivalent to a rock surface in a geometrically constrained sense;

[0020] The set of pore voxels after deducting hydrates is defined as the effective set of pore voxels, denoted as . Defined as ;in, This represents the set of available porous voxels after hydrate formation, used for subsequent constraint field reinitialization and constrained gas phase formation.

[0021] Step (4): Reinitialize the constraint field;

[0022] In the effective pore voxel set Above, calculate the equivalent solid boundary set. Let be the secondary range potential field under the boundary conditions; where the secondary range potential field is denoted as . The Euclidean distance used to characterize any effective pore voxel to the nearest equivalent solid boundary (rock skeleton or hydrate) is as follows:

[0023]

[0024] When implemented using Euclidean distance transformation (EDT) To define the effective pore size domain All voxels on the equivalent solid boundary set The range potential field recalculated for the nearest neighbor target set;

[0025] Step (5): Constrained gas phase generation;

[0026] Based on the preset gas saturation Compared with the gas phase occurrence mode, in the effective pore voxel set Internal based on secondary distance potential field Or by The constructed composite potential field selects the target voxel to generate a gas voxel set, and satisfies the gas saturation. Corresponding target voxel count constraints;

[0027] The set of gas voxels is denoted as and satisfy , ;

[0028] gas saturation Defined in voxel measurement method Or defined as per project agreement ;

[0029] The constrained gas phase is generated by a secondary distance potential field. Or by Voxel selection is based on the composite potential field of the structure, rather than on the distance field of the rock skeleton before the update. Alternatively, the original pore geometry can be directly selected;

[0030] Step (6): Aqueous phase determination and four-phase synthesis;

[0031] Initial pore voxel set The set of elements excluding hydrated matter With gas voxel set The remaining set of voxels other than the water phase voxels is defined as the water phase voxel set, denoted as ,satisfy This ensures that the four phases are mutually exclusive and complete within the voxel domain;

[0032] Aqueous Voxel Collection With rock skeleton voxel set , collection of gaseous voxels Hydrated object set A four-phase digital core was synthesized together, denoted as .

[0033] In step (2), the hydrate generation algorithm uses morphological expansion / corrosion, potential field growth, pore core point growth or closing operation. After the hydrate is generated, its boundary can be obtained and it can participate in the subsequent equivalent solid update. The hydrate occurrence type is pore filling, particle encapsulation or bridging cementation.

[0034] Step (4), re-initialization, refers to the process of updating the equivalent solid and redefining the effective porosity after completing step (3), based on the new set of equivalent solid boundaries. With a new set of effective pore voxels Recalculate the secondary distance potential field .

[0035] In step (5), the gas phase is generated based on the secondary distance potential field. Or a composite potential field constructed therefrom.

[0036] In step (5), the gas phase occurrence mode is pore center type, wall adsorption type, dispersed bubble type or cluster patch type.

[0037] Step (5) defines the effective pore size domain. Connectivity constraints or pore-throat constraints are applied to suppress gas phase crossings of channels blocked by equivalent solid boundaries; these constraints are based on a set of equivalent solid boundaries. With the effective pore domain Geometric relationships or based on secondary distance potential fields The threshold partitioning results are achieved.

[0038] When generating the hydrated voxel aggregate in step (2) or the gaseous voxel aggregate in step (5), the pore-filling hydrate and the dispersed bubble gas are confined within a safe pore region to prevent the generated voxels from penetrating the solid boundary or generating non-physical wall-attachment noise. The safe pore region is denoted as […]. ;

[0039] definition or Inside,

[0040] in, and This is a preset safety distance threshold for the generation of hydrates or gases, expressed as a positive integer in units of voxel side length, used to ensure the selected voxel's boundary with the equivalent solid. Maintaining a minimum geometric gap between them allows for the creation of a potential field based on the secondary distance. The constraint generation results are consistent with the topological constraints after the pore throat is blocked.

[0041] This application also proposes a novel electronic device, which includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the program, it implements the above-mentioned method for reconstructing four-phase hydrate digital cores with time-coupled constraint fields.

[0042] This application also proposes a novel computer-readable storage medium storing a computer program that, when executed, enables the implementation of the aforementioned method for digital core reconstruction of four-phase hydrates using a time-coupled constraint field.

[0043] In summary, this application has the following advantages and beneficial effects compared with the prior art:

[0044] 1. This application effectively solves the problem in the prior art where the static superposition of hydrates and gas phases causes the gas phase to still be distributed according to the pore distribution before blockage. It realizes the temporal coupling reconstruction framework of "hydrate generation - pore domain redefinition - constraint field reconstruction - constrained gas phase generation", which significantly improves the physical consistency and comparability of the four-phase micro-distribution.

[0045] 2. Regarding the self-consistency of the distribution, the gas phase generation in this application is based on the updated secondary distance potential field. Its spatial position, connectivity, and pore throat occupancy will automatically adjust as hydrate blockage occurs, thereby effectively avoiding non-physical crossing and overestimation of connectivity.

[0046] 3. In terms of temporal expressibility, this application can explicitly transmit the "change of pore geometry by the first-generation phase" to the subsequent-generation phase in the form of boundary sets and constraint fields, thereby expressing the temporal effects in the geological evolution / reservoir formation / mining process;

[0047] 4. In terms of pattern scalability, this application can form multiple types of gas phase occurrence patterns by coupling high-value / low-value / partition / random field or using random field alone as the priority field, without limiting the specific generation details.

[0048] 5. This application features a user-friendly interface, and its output of four-phase voxel label results is easy to integrate with numerical simulation preprocessing, sample library comparison, and machine learning dataset construction, resulting in good overall performance;

[0049] 6. In terms of decoupling from the details of hydrate generation, the proposed hydrate generation algorithm can adopt a variety of morphological or potential field methods to truly realize "boundary update and constraint field reconstruction after generation", thus having wider engineering applicability. Attached Figure Description

[0050] The implementation process of the present application will now be further explained and illustrated with reference to the following figures.

[0051] Figure 1 This is a flowchart of the digital core reconstruction method for four-phase hydrates using a time-coupled constraint field as described in this application;

[0052] Figure 2 Existing technology only considers the rock boundary. A schematic diagram of constraint field reinitialization;

[0053] Figure 3 This application considers the rock + hydrate boundary. A schematic diagram of re-initialization of the constraint field with the contraction of the high-value region due to pore throat blockage;

[0054] Figure 4 This is a schematic diagram of a four-phase digital core containing hydrates based on CT scan results; Figure 4 The hydrates in the mixture are encapsulated particles, while the gas is dispersed bubble-like. Detailed Implementation

[0055] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be further described below in conjunction with the accompanying drawings and embodiments. Many specific details are set forth in the following description to provide a thorough understanding of this application; however, this application may be implemented in other ways than those described herein, and therefore, this application is not limited to the specific embodiments disclosed below.

[0056] Example 1, such as Figures 1 to 4 As shown, this application proposes a four-phase hydrate-bearing digital core reconstruction method with temporally coupled constraint field. First, a hydrate phase is generated in the initial pore domain using a binarized three-dimensional voxel digital core as input. The hydrate phase is then incorporated into the equivalent solid boundary set to reflect the occupation and confinement effect of hydrate growth on the pore topology.

[0057] Then, the constraint field is reinitialized on the effective pore domain after hydrate formation to obtain the secondary distance potential field that is simultaneously constrained by the rock skeleton and the hydrate boundary.

[0058] Secondly, a gas phase distribution is generated on the secondary distance potential field according to the preset gas phase occurrence mode, so that the gas phase spatial morphology can evolve self-consistently with the pore throat blockage, pore throat diameter change and connectivity change caused by hydrate occupation.

[0059] Finally, the remaining pores were automatically defined as the aqueous phase, and a four-phase digital core satisfying the mutual exclusion completeness rule was synthesized.

[0060] The method includes the following implementation steps:

[0061] Step (1): Input and pore domain determination;

[0062] Acquire binarized three-dimensional voxel digital core data;

[0063] Identify the rock framework voxel set and the initial pore voxel set, where the rock framework voxel set is denoted as... Let be the set of voxel coordinates of all elements labeled as rocks; the initial set of pore voxels is denoted as . , is the set of voxel coordinates labeled as pores, and and Mutual exclusion and overwriting of the input voxel domain;

[0064] To facilitate multi-phase output, a unified labeling system can be established. ;

[0065] In the initial porosity voxel set The distance field of the constructed rock skeleton is denoted as , used to characterize the Euclidean distance from any pore voxel to the nearest rock skeleton boundary;

[0066] Rock skeleton distance field satisfy:

[0067]

[0068] in, This is the 2-norm operator, representing Euclidean distance; when implemented using Euclidean distance transformation (EDT), For the pore domain All voxels on the surface are assembled with a rock skeleton. The distance field calculated for the set of nearest neighbor targets;

[0069] The input data can come from:

[0070] 1) Binary rock-pore voxels obtained from micro-CT scan data after thresholding and morphological cleaning;

[0071] 2) Rock-pore voxels obtained by artificially generating digital cores (such as particle packing, program-generated porous media, etc.);

[0072] Step (2): hydrate phase formation;

[0073] Based on the preset hydrate saturation With respect to hydrate occurrence type, in the initial pore voxel set The set of elements that generate hydrated matter internally is denoted as ,satisfy ;

[0074] The number of hydrated voxels satisfies the target voxel number constraint corresponding to the target saturation, whereby the hydrate saturation is denoted as... and defined by voxel measurement method ,in, Indicates the number of voxels in the set;

[0075] In this application, the formation of hydrate phase is a preliminary step. The specific generation algorithm can be adopted by various methods such as morphological expansion / corrosion, potential field growth, pore core point growth, and closing operation. The specific implementation is not limited. After the hydrate is generated, its boundary can be obtained and participate in the subsequent equivalent solid update.

[0076] The hydrate occurrence types mentioned include pore filling, particle encapsulation, and bridging cementation;

[0077] Furthermore, when generating voxel assemblies of hydrated hydrates, the pore-filling hydrates are confined within a safe pore region to avoid voxels penetrating solid boundaries or generating non-physical adhesion noise.

[0078] The safe porosity region is denoted as ,

[0079] And defined as or Inside, among them, and A preset safety distance threshold (a positive integer in units of voxel side length) is used to ensure that the selected voxel is within the boundary of the equivalent solid. Maintaining a minimum geometric gap between them allows for the creation of a potential field based on the secondary distance. The constraint generation results are consistent with the topological constraints after the pore throat is blocked;

[0080] Step (3): Equivalent solid update and effective porosity redefinition;

[0081] After hydrates are formed, the pore topology changes;

[0082] hydrated object element set Incorporate into the equivalent solid boundary set, where the equivalent solid boundary set is denoted as... Defined as ,in, It represents the set of equivalent solid boundaries that are unoccupiable and impenetrable, making the surface of hydrates geometrically equivalent to the surface of rock.

[0083] The set of pore voxels after deducting hydrates is defined as the effective set of pore voxels, denoted as . Defined as This ensures that subsequent phases are selected only from voxels within the available pore space after hydrate formation;

[0084] in, This represents the set of available pore voxels after hydrate formation, used for subsequent constraint field reinitialization and constrained gas phase formation. Through the above definition, the occupancy effect of hydrate on available pore space is strictly incorporated into subsequent steps to avoid sampling of the subsequent generated phase in the region already occupied by hydrate.

[0085] Step (4): Reinitialize the constraint field;

[0086] In the effective pore voxel set Above, calculate the equivalent solid boundary set. Let be the secondary range potential field under the boundary conditions; where the secondary range potential field is denoted as . The Euclidean distance used to characterize any effective pore voxel to the nearest equivalent solid boundary (rock skeleton or hydrate) is as follows:

[0087]

[0088] When implemented using Euclidean distance transformation (EDT), To define the effective pore size domain All voxels on the equivalent solid boundary set The range potential field recalculated for the nearest neighbor target set;

[0089] The reinitialization refers to the process after completing the equivalent solid update and effective pore redefinition in step (3), based on the new equivalent solid boundary set. With a new set of effective pore voxels Recalculate the secondary distance potential field Instead of using the result obtained in step (1) This allows the secondary distance potential field to simultaneously reflect the geometric constraints of the rock skeleton boundary and the hydrate boundary on the effective pore space.

[0090] like Figure 2 and Figure 3 As shown, the distance field from the rock skeleton In comparison, the secondary distance potential field The boundary is no longer merely the rock skeleton, but a union of the rock skeleton and hydrates. Its physical significance lies in the fact that the hydrate surface becomes an impenetrable, unoccupiable boundary, equivalent to the rock surface, causing the surrounding voxels to become more susceptible to damage after the pore throat is occupied by the hydrate. The value decreases significantly, and the high-value region shrinks or breaks towards the pore center; therefore, the secondary potential field... Mapping the effect of hydrates on pore topology into a continuous potential field can serve as a constraint input for subsequent gas phase generation.

[0091] Step (5): Constrained gas phase generation;

[0092] Based on the preset gas saturation Compared with the gas phase occurrence mode, in the effective pore voxel set Internal based on secondary distance potential field Or by The constructed composite potential field selects the target voxel to generate a gas voxel set, and satisfies the gas saturation. Corresponding target voxel count constraints;

[0093] The set of gas voxels is denoted as and satisfy , ;

[0094] gas saturation Defined in voxel measurement method Or defined as per project agreement ;

[0095] The constrained gas phase is generated by a secondary distance potential field. Or by Voxel selection is based on the composite potential field of the structure, rather than on the distance field of the rock skeleton before the update. Alternatively, the original pore geometry can be directly selected;

[0096] In this application, gas generation must be based on a secondary distance potential field. Or the composite potential field constructed therefrom, rather than the distance field based on the unupdated rock skeleton. Or the original pore geometry can be directly generated;

[0097] The aforementioned gas-phase occurrence modes include pore center type, wall adsorption type, dispersed bubble type, and cluster patch type, etc.

[0098] Furthermore, the effective pore size domain can be defined. Connectivity constraints or pore-throat constraints are applied to suppress gas phase crossings of channels blocked by equivalent solid boundaries; these constraints are based on a set of equivalent solid boundaries. With the effective pore domain Geometric relationships or based on secondary distance potential fields The threshold partitioning results are achieved;

[0099] Furthermore, during the generation of gaseous voxel assemblies, dispersed bubble-type gases are confined within a safe porosity region to prevent the generated voxels from penetrating the solid boundary or generating non-physical adhesion noise; wherein, the safe porosity region is denoted as... and defined as or Inside;

[0100] in, and A preset safety distance threshold (a positive integer in units of voxel side length) is used to ensure that the selected voxel is within the boundary of the equivalent solid. Maintaining a minimum geometric gap between them allows for the creation of a potential field based on the secondary distance. The constraint generation results are consistent with the topological constraints after the pore throat is blocked;

[0101] Step (6): Aqueous phase determination and four-phase synthesis;

[0102] Initial pore voxel set The set of elements excluding hydrated matter With gas voxel set The remaining set of voxels other than the water phase voxels is defined as the water phase voxel set, denoted as ,satisfy This ensures that the four phases are mutually exclusive and complete within the voxel domain;

[0103] Aqueous Voxel Collection With rock skeleton voxel set , collection of gaseous voxels Hydrated object set A four-phase digital core was synthesized together, denoted as ;

[0104] When outputting, a unified tag code can be used, for example: rock skeleton=1, water phase=2, gas phase=3, hydrate=4; other equivalent tag systems can also be used.

[0105] Therefore, the four-phase hydrate digital core reconstruction method with temporal coupling constraint field proposed in this application realizes the temporal coupling constraint field reconstruction link in the above steps (3) and (4), thereby enabling the gas phase distribution generated in step (5) to self-consistently adjust with the pore topology change caused by hydrate occupation.

[0106] This application may also be directed to and Multiple sets of values ​​and various hydrate occurrence forms, along with different gas microscopic distribution patterns, are generated in batches. It is recommended to record the following information in the output directory or metadata: resolution, input source, porosity, etc. , The occurrence forms of hydrates and the microscopic distribution patterns of different gases are studied to ensure that the samples are traceable and reproducible.

[0107] This application can also output four-phase digital cores as three-dimensional images or voxel mesh files according to a unified labeling system. The labeling system includes at least four types of label values: rock skeleton, liquid water, gas, and hydrate. The output format includes, but is not limited to, tif, raw, bdf, or other formats that can be used for numerical simulation preprocessing.

[0108] This application also proposes a novel electronic device, which includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the program, it implements the above-mentioned method for digital core reconstruction of four-phase hydrates with temporally coupled constraint fields.

[0109] This application also proposes a novel computer-readable storage medium storing a computer program that, when executed, enables the implementation of the aforementioned method for digital core reconstruction of four-phase hydrates using a time-coupled constraint field.

[0110] As described above, similar technical solutions can be derived from the solutions presented in the accompanying drawings and description, and all of them still fall within the scope of the claims of this application.

Claims

1. A method for digital core reconstruction of four-phase hydrates using a time-coupled constrained field, characterized in that: First, using a binarized three-dimensional voxel digital core as input, a hydrate phase is generated in the initial pore domain. The hydrate phase is then incorporated into the equivalent solid boundary set to reflect the occupation and confinement effect of hydrate growth on the pore topology. Then, the constraint field is reinitialized on the effective pore domain after hydrate formation to obtain the secondary distance potential field that is simultaneously constrained by the rock skeleton and the hydrate boundary. Secondly, a gas phase distribution is generated on the secondary distance potential field according to the preset gas phase occurrence mode, so that the gas phase spatial morphology can evolve self-consistently with the pore throat blockage, pore throat diameter change and connectivity change caused by hydrate occupation. Finally, the remaining pores were automatically defined as the aqueous phase, and a four-phase digital core satisfying the mutual exclusion completeness rule was synthesized. The implementation steps include the following: Step (1): Input and pore domain determination; Acquire binarized three-dimensional voxel digital core data; Identify the rock framework voxel set and the initial pore voxel set, where the rock framework voxel set is denoted as... Let be the set of voxel coordinates of all elements labeled as rocks; the initial set of pore voxels is denoted as . , is the set of voxel coordinates labeled as pores, and and Mutual exclusion and overwriting of the input voxel domain; In the initial porosity voxel set The distance field of the constructed rock skeleton is denoted as , used to characterize the Euclidean distance from any pore voxel to the nearest rock skeleton boundary; rock skeleton distance field satisfy: in, This is the 2-norm operator, representing Euclidean distance; when implemented using Euclidean distance transformation (EDT), In the pore domain All voxels on the surface are assembled with a rock skeleton. The distance field calculated for the set of nearest neighbor targets; Step (2): hydrate phase formation; Based on the preset hydrate saturation With respect to hydrate occurrence type, in the initial pore voxel set The set of elements that generate hydrated matter internally is denoted as ,satisfy ; The number of hydrated voxels satisfies the target voxel number constraint corresponding to the target saturation, whereby the hydrate saturation is denoted as... and defined by voxel measurement method ,in, Indicates the number of voxels in the set; Step (3): Equivalent solid update and effective porosity redefinition; hydrated object element set Incorporate into the equivalent solid boundary set, where the equivalent solid boundary set is denoted as... Defined as ,in, It represents the set of equivalent solid boundaries that are unoccupiable and impenetrable, making the surface of a hydrate equivalent to a rock surface in a geometrically constrained sense; The set of pore voxels after deducting hydrates is defined as the effective set of pore voxels, denoted as . Defined as ;in, This represents the set of available porous voxels after hydrate formation, used for subsequent constraint field reinitialization and constrained gas phase formation. Step (4): Reinitialize the constraint field; In the effective pore voxel set Above, calculate the equivalent solid boundary set. Let be the secondary range potential field under the boundary conditions; where the secondary range potential field is denoted as . The Euclidean distance used to characterize any effective porosity voxel to the nearest equivalent solid boundary is as follows: When implemented using Euclidean distance transformation (EDT) To define the effective pore size domain All voxels on the equivalent solid boundary set The distance potential field recalculated for the nearest neighbor target set; Step (5): Constrained gas phase generation; Based on the preset gas saturation Compared with the gas phase occurrence mode, in the effective pore voxel set Internal based on secondary distance potential field Or by The constructed composite potential field selects the target voxel to generate a gas voxel set, and satisfies the gas saturation. Corresponding target voxel count constraints; The set of gas voxels is denoted as and satisfy , ; gas saturation Defined in voxel measurement method Or defined as per project agreement ; The constrained gas phase is generated by a secondary distance potential field. Or by Voxel selection is based on the composite potential field of the structure, rather than on the distance field of the rock skeleton before the update. Alternatively, the original pore geometry can be directly selected; Step (6): Aqueous phase determination and four-phase synthesis; Initial pore voxel set The set of elements excluding hydrated matter With gas voxel set The remaining set of voxels other than the water phase voxels is defined as the water phase voxel set, denoted as ,satisfy This ensures that the four phases are mutually exclusive and complete within the voxel domain; Aqueous Voxel Collection With rock skeleton voxel set Gaseous voxel collection Hydrated object set A four-phase digital core was synthesized together, denoted as .

2. The method for reconstructing four-phase hydrate digital cores using a time-coupled constrained field according to claim 1, characterized in that: In step (2), the hydrate generation algorithm employs morphological expansion / corrosion, potential field growth, pore core point growth, or closure operation. After the hydrate is generated, its boundary can be obtained and it can participate in subsequent equivalent solid updates. The hydrate occurrence type is pore filling, particle encapsulation, or bridging cementation.

3. The method for reconstructing four-phase hydrate digital cores using a time-coupled constrained field according to claim 1, characterized in that: Step (4), re-initialization, refers to the process of updating the equivalent solid and redefining the effective porosity after completing step (3), based on the new set of equivalent solid boundaries. With a new set of effective pore voxels Recalculate the secondary distance potential field .

4. The method for reconstructing four-phase hydrate digital cores using a time-coupled constrained field according to claim 1, characterized in that: In step (5), the gas phase is generated based on the secondary distance potential field. Or a composite potential field constructed therefrom.

5. The method for reconstructing four-phase hydrate digital cores using a time-coupled constrained field according to claim 1, characterized in that: In step (5), the gas phase occurrence mode is pore center type, wall adsorption type, dispersed bubble type or cluster patch type.

6. The method for reconstructing four-phase hydrate digital cores using a time-coupled constrained field according to claim 1, characterized in that: Step (5) defines the effective pore size domain. Connectivity constraints or pore-throat constraints are applied to suppress gas phase crossings of channels blocked by equivalent solid boundaries; these constraints are based on a set of equivalent solid boundaries. With the effective pore domain Geometric relationships or based on secondary distance potential fields The threshold partitioning results are achieved.

7. The method for reconstructing four-phase hydrate digital cores using a time-coupled constrained field according to claim 1, characterized in that: When generating the hydrated voxel aggregate in step (2) or the gaseous voxel aggregate in step (5), the pore-filling hydrate and the dispersed bubble gas are confined within a safe pore region to prevent the generated voxels from penetrating the solid boundary or generating non-physical wall-attachment noise. The safe pore region is denoted as […]. ; definition or Inside, in, and This is a preset safety distance threshold for the generation of hydrates or gases, expressed as a positive integer in units of voxel side length, used to ensure the selected voxel's boundary with the equivalent solid. Maintaining a minimum geometric gap between them allows for the creation of a potential field based on the secondary distance. The constraint generation results are consistent with the topological constraints after the pore throat is blocked.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, it implements the four-phase hydrate digital core reconstruction method of the temporally coupled constraint field as described in any one of claims 1 to 7.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed, it can realize the four-phase hydrate digital core reconstruction method of the temporally coupled constraint field as described in any one of claims 1 to 7.

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