A method, system and medium for characterizing remaining oil dynamics truncation in a fractured-vug reservoir

Abstract

The application discloses a method for characterizing remaining oil in a fracture-vug type reservoir, comprising the following steps: obtaining production data, physical property data and a geological model of the fracture-vug type reservoir; establishing a numerical model of the fracture-vug type reservoir; calculating the numerical model of the fracture-vug type reservoir to perform history matching; exporting a numerical simulation result report file; importing an extraction file of the numerical simulation result, and selecting a type of the numerical model; extracting a remaining oil calculation result, a reservoir type phase model, a grid volume model, a porosity model and an NTG model; calculating specific thickness movable remaining oil; extracting oil saturation and residual oil saturation at initial, water injection, gas injection and current time points of the fracture-vug type reservoir, calculating specific thickness movable remaining oil, and outputting a result. The method eliminates the influence of matrix, fractures and oil-water interfaces on the accuracy of remaining oil characterization.

Description

Technical Field

[0001] This invention relates to the field of residual oil characterization technology in fractured-vuggy reservoirs, specifically to a dynamic cutoff characterization method, system, and medium for residual oil in fractured-vuggy reservoirs. Background Technology

[0002] Fractured-vuggy reservoirs do not store residual oil within the matrix. However, the numerical simulation equilibrium initialization results in poor representation of the residual oil distribution morphology in the matrix and reservoir above the oil-water interface. The three-dimensional representation of the residual oil distribution location is unclear, and the accuracy of residual oil identification is low. Therefore, a method for characterizing residual oil that can remove the interference of equilibrium initialization is expected.

[0003] In fractured-vuggy reservoirs, the matrix refers to the basic rock component of the reservoir excluding fractures and caverns. It typically has low permeability, a relatively complex pore structure, and small pore size.

[0004] In reservoir numerical simulation, equilibrium initialization refers to setting the initial state of the simulation at the beginning based on the initial conditions of the reservoir (such as oil-water distribution, pressure, etc.). It assumes that the reservoir is in a certain equilibrium state in the initial state, for example, the oil-water interface is determined based on the equilibrium of gravity and capillary forces.

[0005] In fractured-vuggy reservoirs, due to the low matrix permeability, the distribution of remaining oil within the matrix is ​​primarily formed during production through complex mechanisms such as adsorption between fractures and the matrix. However, during the initial equilibrium phase of numerical simulations, the model may not adequately account for this complex adsorption process and the interaction between the matrix and the fracture-vuggy system. It is often based on a relatively idealized physical model, assuming that oil and water are distributed according to a simple gravity-capillary equilibrium, resulting in the matrix portion above the oil-water interface failing to accurately reflect the actual distribution morphology of the remaining oil.

[0006] Because the initialization process did not correctly consider the formation mechanism of residual oil in the matrix, the location of residual oil within the matrix could not be accurately determined during 3D visualization. Furthermore, this error resulted in a significant discrepancy between the calculated residual oil distribution and the actual situation, leading to low accuracy in residual oil location. In other words, the simulated location of residual oil did not match the actual location and quantity of residual oil in the reservoir, affecting the accurate assessment of residual oil in the reservoir and the formulation of subsequent exploitation strategies. Summary of the Invention

[0007] To achieve the above objectives, this invention provides a method, system, and medium for characterizing the dynamic cutoff of remaining oil in fractured-vuggy reservoirs. The specific technical solution is as follows:

[0008] A method for characterizing the dynamic cutoff of remaining oil in fractured-vuggy reservoirs includes the following steps:

[0009] Step S1: Obtain production data, physical property data, and geological models of fractured-vuggy reservoirs;

[0010] Step S2: Establish a numerical model of fractured-vuggy reservoir based on tNavigator and calculate the numerical simulation reserves;

[0011] Step S3: Calculate the numerical model of the fractured-vuggy reservoir, perform historical fitting, compare the actual geological reserves with the numerical simulation reserves, and compare the actual production data with the numerical simulation production data to determine that the error is within the allowable range;

[0012] Step S4: Export the numerical simulation results report file and save it as a binary file;

[0013] Step S5: Use Petrel to create the Cases module, import the extracted files of the numerical simulation results, and select the type of numerical model;

[0014] Step S6: Extract the remaining oil calculation results, reservoir type phase separation model, grid volume model, porosity model and NTG model for each time step;

[0015] Step S7: Define the specific thickness movable residual oil index, and calculate it using the following formula:

[0016] N_R=V×PORO×NTG×(SOIL-SOR);

[0017] Where V is the grid volume, PORO is the grid porosity, NTG is the net-to-gross ratio, SOIL is the oil saturation at each time point, and SOR is the residual oil saturation for different reservoir types.

[0018] Step S8: Extract the oil saturation and residual oil saturation at the initial time, water injection time, gas injection time and current time of the fractured-vuggy reservoir, calculate the movable remaining oil at the specific thickness, and output the results.

[0019] Preferably, the production data includes daily oil production, daily water production, daily gas production, daily gas injection, and daily water injection; the physical property data includes water and crude oil volume coefficients, rock compressibility coefficients, dissolved gas-oil ratio, relative permeability curve data, water and crude oil density, and water and crude oil viscosity; and the geological model includes a porosity model, a permeability model, well data, and reserve data.

[0020] Preferably, in step S2, the numerical simulation of reserves is completed by balancing and initializing the input oil-water interface parameters.

[0021] Preferably, in step S3, if the error is not within the allowable range, the model attributes and parameters are corrected by comparing the single well and unit errors, the corrected data file is re-exported, and the process returns to step S2.

[0022] Preferably, in step S4, the binary file includes a .egrid format network, an initial map, calculated attributes, and a report file, and the exported file format includes EGRID, h5, INIT, INSPEC, RSSPEC, SMSPEC, UNRST, and UNSMRY.

[0023] This invention also provides a dynamic cutoff characterization system for residual oil in fractured-vuggy reservoirs, comprising:

[0024] The acquisition module is used to acquire production data, physical property data, and geological models of fractured-vuggy reservoirs;

[0025] A module is established to build a numerical model of fractured-vuggy reservoirs based on tNavigator and calculate the numerical simulation reserves.

[0026] The history fitting module is used to calculate the numerical model of fractured-vuggy reservoirs, perform history fitting, compare the actual geological reserves with the numerical simulation reserves, and compare the actual production data with the numerical simulation production data to determine that the error is within the allowable range.

[0027] The data export module is used to export numerical simulation result report files and save them as binary files;

[0028] The data import module is used to create a Cases module using Petrel, import the extracted files of numerical simulation results, and select the type of numerical model.

[0029] The extraction module is used to extract the remaining oil calculation results, reservoir type phase separation model, grid volume model, porosity model and NTG model for each time step;

[0030] The dynamic truncation module is used to extract the oil saturation and residual oil saturation at the initial time, water injection time, gas injection time, and current time of fractured-vuggy reservoirs, calculate the movable remaining oil at specific thickness, and output the results. The calculation formula is as follows:

[0031] N_R=V×PORO×NTG×(SOIL-SOR);

[0032] Where V is the grid volume, PORO is the grid porosity, NTG is the net-to-gross ratio, SOIL is the oil saturation at each time point, and SOR is the residual oil saturation for different reservoir types.

[0033] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described method for dynamic truncation characterization of residual oil in fractured-vuggy reservoirs.

[0034] The provided method, system, and medium for dynamic cutoff characterization of remaining oil in fractured-vuggy reservoirs have the following technical advantages:

[0035] This invention addresses the shortcomings of residual oil characterization in fractured-vuggy reservoirs by processing numerical simulation results files to obtain residual oil results at different times and performing dynamic truncation calculations. This eliminates the influence of matrix, fractures, and oil-water interface on the accuracy of residual oil characterization, thereby improving the characterization effect and accuracy of residual oil in fractured-vuggy reservoirs. Attached Figure Description

[0036] Figure 1 A flowchart according to an embodiment of this disclosure;

[0037] Figure 2 A numerical model diagram of a fractured-vuggy reservoir according to an embodiment of this disclosure;

[0038] Figure 3 A historical fitting curve graph according to embodiments of this disclosure;

[0039] Figure 4 A diagram of the exported data file according to an embodiment of this disclosure;

[0040] Figure 5 To derive a format diagram according to embodiments of this disclosure;

[0041] Figure 6 This is a diagram illustrating the conversion of Petrel format files according to an embodiment of this disclosure;

[0042] Figure 7 This is a numerical simulation attribute extraction diagram according to an embodiment of the present disclosure;

[0043] Figure 8 This is a diagram of the computation module according to an embodiment of the present disclosure;

[0044] Figure 9 A specific thickness movable residual oil map according to an embodiment of this disclosure. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method, system, and medium for dynamic cutoff characterization of residual oil in fractured-vuggy reservoirs. The advantages and features of this invention will become clearer from the following description. It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions, used only to facilitate and clearly illustrate the purpose of the embodiments of this invention. Please refer to the accompanying drawings for a clearer understanding of the objectives, features, and advantages of this invention. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes and to enable those skilled in the art to understand and read them. They are not intended to limit the implementation conditions of this invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0046] This invention discloses a method for dynamic truncation characterization of residual oil in fractured-vuggy reservoirs, comprising the following steps:

[0047] Step S1: Obtain production data, physical property data, and geological models of fractured-vuggy reservoirs;

[0048] Step S2: Establish a numerical model of fractured-vuggy reservoir based on tNavigator and calculate the numerical simulation reserves;

[0049] Step S3: Calculate the numerical model of the fractured-vuggy reservoir, perform historical fitting, compare the actual geological reserves with the numerical simulation reserves, and compare the actual production data with the numerical simulation production data to determine that the error is within the allowable range;

[0050] Step S4: Export the numerical simulation results report file and save it as a binary file;

[0051] Step S5: Use Petrel to create the Cases module, import the extracted files of the numerical simulation results, and select the type of numerical model;

[0052] Step S6: Extract the remaining oil calculation results, reservoir type phase separation model, grid volume model, porosity model and NTG model for each time step;

[0053] Step S7: Define the specific thickness movable residual oil index, and calculate it using the following formula:

[0054] N_R=V×PORO×NTG×(SOIL-SOR);

[0055] Where V is the grid volume, PORO is the grid porosity, NTG is the net-to-gross ratio, SOIL is the oil saturation at each time point, and SOR is the residual oil saturation for different reservoir types.

[0056] Step S8: Extract the oil saturation and residual oil saturation at the initial time, water injection time, gas injection time and current time of the fractured-vuggy reservoir, calculate the movable remaining oil at the specific thickness, and output the results.

[0057] In step S1, the production data, physical property data, and geological model of the actual fractured-vuggy reservoir are compiled. The production data includes daily oil production, daily water production, daily gas production, daily gas injection, and daily water injection. The physical property data includes water and crude oil volume coefficients, rock compressibility coefficients, dissolved gas-oil ratio, relative permeability curve data, water and crude oil density, and water and crude oil viscosity data. The geological model includes a porosity model, a permeability model, well data, and reserve data, such as... Figure 1 As shown;

[0058] Next, proceed to step S2.

[0059] Figure 2 A numerical model diagram of a fractured-vuggy reservoir according to an embodiment of this disclosure.

[0060] In step S2, a numerical model of a fractured-vuggy reservoir is established using tNavigator, and the numerical simulation reserves are calculated.

[0061] The geological model, including the porosity model, permeability model, and well data, was imported into tNavigator in sequence. The relative permeability curve and fluid property data were also imported, as were the production data, including daily oil production, daily water production, daily gas production, daily gas injection, and daily water injection data. The oil-water interface parameters were input using equilibrium initialization, and the reserves were calculated through numerical simulation. The reserves were compared with those in the numerical model, which showed a value of 9.26 million tons.

[0062] Next, proceed to step S3.

[0063] Figure 3 This is a historical fitting curve graph according to an embodiment of the present disclosure.

[0064] In step S3, the numerical model of the fractured-vuggy reservoir is calculated, historical data is fitted, and the actual geological reserves are compared with the numerically simulated reserves. The actual production data is also compared with the numerically simulated production data to determine if the error is within the allowable range. (If the error is within the allowable range, proceed to steps S4-S8; if the error is not within the allowable range, compare the errors of single wells and units, correct the model attributes and parameters, re-export the corrected data file, and then return to step S2.)

[0065] Next, proceed to step S4.

[0066] Figure 4 This is a diagram of the exported data file according to an embodiment of the present disclosure. Figure 5 A format diagram is derived according to an embodiment of this disclosure.

[0067] In step S4, select tNavigator to export the numerical simulation results report file and save it as a binary file. The file includes a .egrid format network, initial map, calculated attributes and report files. The exported file formats include EGRID, h5, INIT, INSPEC, RSSPEC, SMSPEC, UNRST and UNSMRY.

[0068] Next, proceed to step S5.

[0069] Figure 6 This is a diagram illustrating the conversion of Petrel format files according to an embodiment of this disclosure.

[0070] In step S5, use Petrel to create the Cases module, import the extracted file of the numerical simulation results in INIT format, and select the E100 black oil model as the type of numerical model.

[0071] Next, proceed to step S6.

[0072] Figure 7 This is a numerical simulation attribute extraction diagram according to an embodiment of the present disclosure.

[0073] In step S6, the remaining oil calculation results, reservoir type phase separation model, grid volume model, porosity model, and NTG model are extracted for each time step; among them, static attributes include model porosity, grid volume, and NTG attributes.

[0074] Next, proceed to step S7.

[0075] Figure 8 This is a diagram of the computation module according to an embodiment of the present disclosure. Figure 9 A specific thickness movable residual oil map according to an embodiment of this disclosure.

[0076] In step S7, the Petrel calculation module is used to calculate the specific thickness movable remaining oil, and the calculation formula is as follows:

[0077] N_R=V×PORO×NTG×(SOIL-SOR);

[0078] Where V is the grid volume, PORO is the grid porosity, NTG is the net-to-gross ratio, SOIL is the oil saturation at each time point, and SOR is the residual oil saturation for different reservoir types.

[0079] In the field of oil exploration, the net-gross ratio refers to the ratio of the effective storage space (net thickness) in a reservoir to the total reservoir thickness (gross thickness). Simply put, it reflects the proportion of the reservoir that can effectively store and flow oil. For example, if a reservoir has a total thickness (gross thickness) of 10 meters, and the effective oil-bearing net thickness is 6 meters, then the net-gross ratio is 0.6 (or 60%).

[0080] Grid volume refers to the space occupied by each grid cell after an oil reservoir or formation has been divided into small grid cells in three-dimensional space. These grid cells can be regular cubes (structured grids) or irregularly shaped polyhedra (unstructured grids). For example, imagine an oil reservoir as a huge three-dimensional cube, and divide it into many small cubes (grid cells) using computer software or mathematical methods; the volume of each small cube is the grid volume.

[0081] Grid porosity refers to the proportion of rock pore volume to the total volume of each grid cell after dividing an oil reservoir into grids. It is a dimensionless physical quantity used to describe the distribution characteristics of pore space in oil reservoir rocks. For example, if the total volume of a grid cell is 1 cubic meter, and the pore volume is 0.3 cubic meters, then the porosity of that grid cell is 0.3 (or 30%).

[0082] Oil saturation refers to the ratio of the pore volume occupied by oil in an oil layer to the total pore volume.

[0083] Residual oil saturation refers to the ratio of the volume of oil remaining in the reservoir pores to the pore volume after a certain oil recovery method has been used. It is an important indicator for measuring the degree of reservoir recovery and the potential for remaining oil. For example, after water injection, even if most of the oil has been extracted, some oil will still remain in the rock pores; the proportion of this remaining oil to the pore volume is the residual oil saturation.

[0084] Next, proceed to step S8.

[0085] In step S8, extract the oil saturation and residual oil saturation at the initial time, water injection time, gas injection time and the current time of the fractured-vuggy reservoir, calculate the movable remaining oil at the specific thickness, and output the results.

[0086] The definition of dynamic truncation calculation is to extract the oil saturation and residual oil saturation at the initial time, water injection time, gas injection time and the current time of fractured-vuggy reservoirs, and calculate the movable residual oil at the specific thickness.

[0087] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for characterizing the dynamic cutoff of remaining oil in fractured-vuggy reservoirs, characterized in that, Includes the following steps: Step S1: Obtain production data, physical property data, and geological models of fractured-vuggy reservoirs; Step S2: Establish a numerical model of fractured-vuggy reservoir based on tNavigator and calculate the numerical simulation reserves; Step S3: Calculate the numerical model of the fractured-vuggy reservoir, perform historical fitting, compare the actual geological reserves with the numerical simulation reserves, and compare the actual production data with the numerical simulation production data to determine that the error is within the allowable range; Step S4: Export the numerical simulation results report file and save it as a binary file; Step S5: Use Petrel to create the Cases module, import the extracted files of the numerical simulation results, and select the type of numerical model; Step S6: Extract the remaining oil calculation results, reservoir type phase separation model, grid volume model, porosity model and NTG model for each time step; Step S7: Define the specific thickness movable residual oil index, and calculate it using the following formula: N_R=V×PORO×NTG×(SOIL-SOR); Where V is the grid volume, PORO is the grid porosity, NTG is the net-to-gross ratio, SOIL is the oil saturation at each time point, and SOR is the residual oil saturation for different reservoir types. Step S8: Extract the oil saturation and residual oil saturation at the initial time, water injection time, gas injection time and current time of the fractured-vuggy reservoir, calculate the movable remaining oil at the specific thickness, and output the results.

2. The method for characterizing the dynamic cutoff of remaining oil in fractured-vuggy reservoirs according to claim 1, characterized in that, The production data includes daily oil production, daily water production, daily gas production, daily gas injection, and daily water injection. The physical property data includes water and crude oil volume coefficients, rock compressibility coefficients, dissolved gas-oil ratio, relative permeability curve data, water and crude oil density, and water and crude oil viscosity. The geological model includes porosity model, permeability model, well data, and reserve data.

3. The method for characterizing the dynamic cutoff of remaining oil in fractured-vuggy reservoirs according to claim 2, characterized in that, In step S2, the numerical simulation of reserves is completed by balancing and initializing the input oil-water interface parameters.

4. The method for characterizing the dynamic cutoff of remaining oil in fractured-vuggy reservoirs according to claim 3, characterized in that, In step S3, if the error is not within the allowable range, compare the single well and unit errors, correct the model attributes and parameters, re-export the corrected data file, and return to step S2.

5. The method for characterizing the dynamic cutoff of remaining oil in fractured-vuggy reservoirs according to claim 4, characterized in that, In step S4, the binary file includes a .egrid format network, an initial map, calculated attributes, and a report file. The exported file formats include EGRID, h5, INIT, INSPEC, RSSPEC, SMSPEC, UNRST, and UNSMRY.

6. A dynamic cutoff characterization system for residual oil in fractured-vuggy reservoirs, characterized in that, include: The acquisition module is used to acquire production data, physical property data, and geological models of fractured-vuggy reservoirs; A module is established to build a numerical model of fractured-vuggy reservoirs based on tNavigator and calculate the numerical simulation reserves. The history fitting module is used to calculate the numerical model of fractured-vuggy reservoirs, perform history fitting, compare the actual geological reserves with the numerical simulation reserves, and compare the actual production data with the numerical simulation production data to determine that the error is within the allowable range. The data export module is used to export numerical simulation result report files and save them as binary files; The data import module is used to create a Cases module using Petrel, import the extracted files of numerical simulation results, and select the type of numerical model. The extraction module is used to extract the remaining oil calculation results, reservoir type phase separation model, grid volume model, porosity model and NTG model for each time step; The dynamic truncation module is used to extract the oil saturation and residual oil saturation at the initial time, water injection time, gas injection time, and current time of fractured-vuggy reservoirs, calculate the movable remaining oil at specific thickness, and output the results. The calculation formula is as follows: N_R=V×PORO×NTG×(SOIL-SOR); Where V is the grid volume, PORO is the grid porosity, NTG is the net-to-gross ratio, SOIL is the oil saturation at each time point, and SOR is the residual oil saturation for different reservoir types.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the dynamic truncation characterization method for residual oil in fractured-vuggy reservoirs as described in any one of claims 1 to 5.

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