Method, medium and equipment for improving numerical simulation efficiency of large heavy oil reservoir

Abstract

The invention belongs to the technical field of oil and gas field development, and discloses a method, medium and equipment for improving numerical simulation efficiency of a large heavy oil reservoir. According to the method, a target oil reservoir root is divided into a first stage and a second stage according to different development modes of an oil field, the first stage is a cold production stage, and the second stage is a regional cold and hot mixed production stage of mixed development of a cold production region and a hot production region; and cold production simulation is conducted on the first stage, and cold production simulation and thermal production simulation are conducted on the second stage in different areas. According to different development modes of an oil field, the target oil reservoir is divided into the development stages and the development areas, the black oil model / thermal recovery model is constructed in stages and areas, the heavy oil number simulation combination time can be remarkably shortened, the heavy oil number simulation combination efficiency can be improved, the fitting precision can be improved, and therefore the purpose of saving cost is achieved.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field development technology, specifically relating to a method, medium, and equipment for improving the efficiency of numerical simulation of large heavy oil reservoirs. Background Technology

[0002] Numerical simulation is an indispensable part of reservoir development scheme research. It enables dynamic tracking of the reservoir, study of remaining oil distribution, and prediction of development plans. Reservoir numerical models can be divided into black oil models, thermal recovery models, and component models. The development principle of heavy oil reservoirs mainly focuses on heating crude oil to reduce viscosity and improve its fluidity, often employing thermal recovery development methods, including steam huff and puff, steam drive, and steam-assisted gravity drainage (SAGD). Therefore, numerical simulation of heavy oil reservoirs generally uses thermal recovery models.

[0003] However, thermal recovery models involve temperature changes, heat exchange, and fluid phase changes during calculation, resulting in computation time that is more than ten times longer than that of similar black oil models. In conventional heavy oil numerical simulations, if thermal recovery development is implemented in any area within any given time period, the entire model for that time period needs to be established, which significantly increases the time required for full reservoir numerical simulation.

[0004] Therefore, conventional numerical simulation methods for heavy oil typically employ small well groups for mechanistic studies. However, these small well groups cannot represent the entire reservoir and are only effective for studying certain policy-imposed limitations. In practice, however, tasks sometimes require full-reservoir numerical simulation, such as studying the distribution of remaining oil across the entire reservoir, analyzing overall reservoir pressure changes, and predicting comprehensive reservoir indicators. In these cases, conventional full-reservoir numerical simulation methods result in extremely long computation times. Therefore, reducing computation time necessitates upgrading both hardware and software, which increases investment costs and, to some extent, hinders the development of full-reservoir heavy oil numerical simulation research. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a method, medium, and equipment for improving the efficiency of numerical simulation of large heavy oil reservoirs. By establishing a full reservoir model based on the development mode and development area of ​​the oilfield, the simulation time for heavy oil can be significantly shortened, the simulation efficiency can be improved, and the fitting accuracy can be increased, thereby achieving the goal of saving costs.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] A method for improving the efficiency of numerical simulation of large heavy oil reservoirs, the method comprising:

[0008] Based on different development methods, the target reservoir is divided into a first stage and a second stage. The first stage is the cold production stage, and the second stage is the regional cold and hot mixed production stage, which involves the mixed development of cold and hot production areas.

[0009] The first stage is simulated by cold mining, and the second stage is simulated by cold mining and hot mining in different regions.

[0010] Furthermore, the method specifically includes the following steps:

[0011] Step S1: Conduct a development history analysis of the target reservoir. Based on different development methods, divide the development stages of the target reservoir into the first stage and the second stage in chronological order.

[0012] The first stage is the cold extraction stage;

[0013] The second stage is a regional cold and hot mixed mining stage, which involves the mixed development of cold mining areas and hot mining areas.

[0014] Step S2: Establish the first-stage full reservoir black oil model and conduct the first-stage cold production simulation;

[0015] Step S3: Based on different development methods, divide the target reservoir into cold production areas and hot production areas; based on the principle of material balance, and according to the attribute field of the last time step of the first stage of cold production, establish the full reservoir model for the second stage, and conduct the second stage of regional cold and hot mixed production simulation.

[0016] Furthermore, step S3 specifically includes:

[0017] Step S31. Divide into regions:

[0018] Based on different development methods, the target reservoir is divided into cold recovery areas and hot recovery areas.

[0019] Step S32. Splitting Model:

[0020] The second-stage whole reservoir model is divided into multiple partition models. The partition model corresponding to the cold production area adopts the black oil model, and the partition model corresponding to the hot production area adopts the hot production model.

[0021] Step S33. Construct the model:

[0022] Based on the principle of material balance, and according to the attribute field of the last time step of the first stage of cold production, we establish the corresponding partition models for each region of the target reservoir.

[0023] Step S34. Attribute cases and:

[0024] Each partition model is fitted separately, and the properties of the fitted partition models are combined to form the full reservoir model for the second stage.

[0025] Furthermore, in step S32, the flow boundary model is used to split the second stage of the full reservoir model.

[0026] Furthermore, in step S32, the second-stage full reservoir model is divided using a flow boundary model. The specific method is as follows:

[0027] A. Characterize the flow field intensity distribution inside the reservoir through streamline simulation;

[0028] B. Analyze the direction and magnitude of fluid transport;

[0029] C. Determine the inter-well connectivity based on the direction and magnitude of fluid transport.

[0030] Furthermore, in step S32, the minimum flow boundary model is used to divide the second stage of the whole reservoir model, that is: the second stage of the whole reservoir model is divided in the region with the sparsest streamlines.

[0031] In addition, the present invention also provides a computer-readable storage medium storing a computer program, the computer program including program instructions, which, when executed by a computer, cause the computer to perform the method described in any of the preceding claims.

[0032] In addition, the present invention provides an electronic device comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements the method described in any of the preceding claims.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) According to the different development methods of oilfields, the present invention divides the target oil reservoir into the first stage (cold production stage) and the second stage (regional cold and hot mixed production stage) according to the development stage. The cold production simulation of the first stage is carried out first, and then the cold and hot production simulation of the second stage is carried out in different regions. The fitting rate of each region reaches more than 95%, and the fitting accuracy is good. Through the above method, the present invention divides the numerical model of large heavy oil reservoirs in time and space, which can significantly shorten the time of heavy oil numerical simulation and improve the efficiency of heavy oil numerical simulation, thereby achieving the purpose of saving costs.

[0035] (1) In the second stage of this invention, based on the principle of material balance, according to the attribute field of the corresponding partition in the last time step of the first stage of cold extraction, a black oil model / thermal extraction model of the corresponding partition is established, which can ensure the conservation of material energy and ensure the accuracy of the final simulation results.

[0036] (2) In actual production, fluid migration will pass through the boundary. In order to simulate this phenomenon, this invention abandons the closed boundary model and adopts the flow boundary model when splitting the whole reservoir model. At this time, streamlines can pass through the boundary, making the simulation of reservoir fluid flow more in line with reality. At the same time, in order to reduce the influence of the flow boundary, the minimum flow boundary is selected through streamline analysis, which can effectively improve the fitting accuracy. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the phased and regional numerical simulation method according to an embodiment of the present invention;

[0038] Figure 2 The diagrams show a comparison of streamline numerical simulations under closed boundary conditions and flow boundary conditions in an embodiment of the present invention. (a) is a schematic diagram of streamline numerical simulation under closed boundary conditions, and (b) is a schematic diagram of streamline numerical simulation under flow boundary conditions.

[0039] Figure 3 A schematic diagram illustrating the selection of the minimum flow boundary in the streamline simulation method of this invention;

[0040] Figure 4 This is a schematic diagram illustrating the phased implementation of an embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram of the fitting results of the production history during the cold mining stage in an embodiment of the present invention.

[0042] Figure 6 This is a schematic diagram of the region division according to an embodiment of the present invention;

[0043] Figure 7 This is a schematic diagram of the partition model of each partition in an embodiment of the present invention;

[0044] Figure 8 This is a schematic diagram of the fitting results of each partition model in an embodiment of the present invention;

[0045] Figure 9 This is a schematic diagram of the distribution of remaining oil in the entire reservoir after merging the various partition models in this embodiment of the invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] To address the technical problems existing in the prior art, this invention provides a method for improving the efficiency of numerical simulation of large heavy oil reservoirs. Based on different development methods of the oilfield, the target reservoir is divided into development stages and development areas. Then, a full reservoir numerical simulation model is established in stages and areas, which can significantly improve the efficiency of heavy oil numerical simulation, shorten the time of heavy oil numerical simulation, and improve the fitting accuracy.

[0048] The method specifically includes the following steps:

[0049] Step S1: First, conduct a development history analysis of the target reservoir. Based on different development methods, divide the development stages of the target reservoir into the first stage and the second stage in chronological order.

[0050] The first stage is the cold production stage, that is: the target reservoir in the first stage is produced entirely by cold production;

[0051] The second stage is a regional cold and hot mixed mining stage, which involves the mixed development of cold mining areas and hot mining areas.

[0052] Cold recovery refers to the extraction method without heating. For example, shallow reservoirs are extracted using open-pit mining, and reservoirs with viscosity less than 1000 mPa·s are extracted using water-drive mining. Thermal recovery involves injecting high-temperature and high-pressure steam into the reservoir, or heating the reservoir by means of fire, so that the heavy oil is heated, its viscosity is reduced, and its flowability is improved.

[0053] Step S2: Establish the first-stage full reservoir black oil model and conduct the first-stage cold production simulation;

[0054] Step S3: Based on different development methods, divide the target reservoir into cold production areas and hot production areas; based on the principle of material balance, and according to the attribute field of the last time step of the first stage of cold production, establish the full reservoir model for the second stage, and conduct the second stage of regional cold and hot mixed production simulation.

[0055] In step S3, based on the principle of material balance, a black oil model / thermal recovery model for the corresponding partition is established according to the attribute field of the corresponding partition in the last time step of the first stage of cold recovery. This ensures the conservation of material and energy and guarantees the accuracy of the final simulation results.

[0056] Step S3 specifically includes the following steps:

[0057] Step S31. Divide into regions:

[0058] Based on different development methods, the target reservoir is divided into cold recovery areas and hot recovery areas.

[0059] Step S32. Splitting Model:

[0060] The second-stage whole reservoir model is divided into multiple partition models. The partition model corresponding to the cold production area adopts the black oil model, and the partition model corresponding to the hot production area adopts the hot production model.

[0061] Step S33. Construct the model:

[0062] Based on the principle of material balance, and according to the attribute field of the last time step of the first stage of cold production, we establish the corresponding partition models for each region of the target reservoir.

[0063] Step S34. Attribute cases and:

[0064] Each partition model is fitted separately, and the properties of the fitted partition models are combined to form the full reservoir model for the second stage.

[0065] In actual production processes, fluid transport crosses boundaries. To simulate this phenomenon, see [reference needed]. Figure 2 As shown, in step S32, the flow boundary model is used to split the second stage of the full reservoir model. Compared with the closed boundary conditions and streamline flow around the flow in Figure (a), the flow boundary conditions in Figure (b) allow streamlines to pass through the boundary, making the simulation of reservoir fluid flow more realistic.

[0066] In step S32, the second stage of the full reservoir model is split using a flow boundary model. The specific method is as follows:

[0067] A. Characterize the flow field intensity distribution inside the reservoir through streamline simulation;

[0068] B. Analyze the direction and magnitude of fluid transport;

[0069] C. Determine the inter-well connectivity based on the direction and magnitude of fluid transport.

[0070] Preferably, such as Figure 3 As shown, the minimum flow boundary model is selected to split the second stage of the full reservoir model, that is, to split the second stage of the full reservoir model in the region with the sparsest streamlines. This has the least impact on the fitting accuracy and can further improve the fitting accuracy.

[0071] Based on different development methods in oilfields, this paper divides the target reservoir into two stages: a first stage (cold production stage) and a second stage (regional cold and hot mixed production stage). First, cold production simulations are conducted for the first stage, followed by regional cold and hot production simulations for the second stage. This approach divides the numerical model of large heavy oil reservoirs both temporally and spatially, constructing black oil / hot production models in stages and regions. This significantly shortens the time required for heavy oil numerical simulation, improves the efficiency of heavy oil numerical simulation, and enhances fitting accuracy, thereby achieving cost savings.

[0072] Example 1

[0073] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0074] This embodiment takes a heavy oil reservoir A in a certain region as an example. The maximum oil-bearing area of ​​heavy oil reservoir A is 23.35 km². 2 It is a shallow heavy oil reservoir. Development began in 1966, and as of September 2018, there were 1,451 wells drilled.

[0075] Step S1: Conduct a development history analysis of heavy oil reservoir A, and divide it into development stages, such as... Figure 4 As shown, where:

[0076] Prior to 2003, the target oil reservoir was developed using natural energy and water injection, which was the cold production stage and belonged to the first stage.

[0077] After 2003, the target reservoir adopted a mixed development approach of cold and hot production areas, which is the second stage of regional cold and hot mixed production.

[0078] Therefore, in this embodiment of the invention, 2003 is used as the dividing point for the development phase.

[0079] Step S2: Establish the first-stage full reservoir black oil model and conduct the first-stage cold production simulation;

[0080] like Figure 5 As shown, the whole reservoir black oil model fits the production history of the cold production phase from 1966 to September 2003, with a fitting rate of 95%.

[0081] Step S3: Based on different development methods, divide the target reservoir into cold production areas and hot production areas; based on the principle of material balance, and according to the attribute field of the last time step of the first stage of cold production, establish the full reservoir model for the second stage, and conduct the second stage of regional cold and hot mixed production simulation.

[0082] Specifically, such as Figure 6 As shown, in this embodiment of the invention, the target reservoir is divided into five areas: Zone I, Zone II, Zone III, Zone IV, and Zone V. In the second stage, that is, after 2003, steam injection and steam drive development began in Zones I, II, and V. Zone III was developed using natural energy and water injection. The production area of ​​Zone IV was mainly concentrated in the west, and the western part of Zone IV was developed using hot water injection.

[0083] To address the different development methods for each zone model, the second-stage full reservoir model was divided into multiple zone models for fitting, such as... Figure 7As shown, thermal recovery models were established for zones I, II, and V, while black oil models were established for zones III and IV, and fitting was performed on each model.

[0084] The fitting results of the model for each partition are as follows: Figure 8 As shown, Figure 8 The bar charts for each section, from left to right, represent: calculated cumulative liquid production, actual cumulative liquid production, calculated cumulative output, and actual cumulative output. According to... Figure 8 The fitting results show that the fitting rate of each partition reaches over 95%, indicating good fitting accuracy.

[0085] Finally, the properties of the five fitted partition models are combined to form the second-stage full reservoir model, such as... Figure 9 The diagram shows the distribution of remaining oil in the entire reservoir after merging the models of each zone.

[0086] Example 2

[0087] This invention provides a computer-readable storage medium storing a computer program, the computer program including program instructions, which, when executed by a computer, cause the computer to perform the method described in Embodiment 1.

[0088] Example 3

[0089] This invention provides an electronic device, which includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the method described in Embodiment 1.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for improving the efficiency of numerical simulation of large heavy oil reservoirs, characterized in that, The method includes: Based on different development methods, the target reservoir is divided into a first stage and a second stage. The first stage is the cold production stage, and the second stage is the regional cold and hot mixed production stage, which involves the mixed development of cold and hot production areas. The first stage is simulated by cold mining, and the second stage is simulated by cold mining and hot mining in different regions.

2. The method according to claim 1, characterized in that, The method specifically includes the following steps: Step S1: Conduct a development history analysis of the target reservoir. Based on different development methods, divide the development stages of the target reservoir into the first stage and the second stage in chronological order. The first stage is the cold extraction stage; The second stage is a regional cold and hot mixed mining stage, which involves the mixed development of cold mining areas and hot mining areas. Step S2: Establish the first-stage full reservoir black oil model and conduct the first-stage cold production simulation; Step S3: Based on different development methods, divide the target reservoir into cold production areas and hot production areas; based on the principle of material balance, and according to the attribute field of the last time step of the first stage of cold production, establish the full reservoir model for the second stage, and conduct the second stage of regional cold and hot mixed production simulation.

3. The method according to claim 2, characterized in that, Step S3 specifically includes: Step S31. Divide into regions: Based on different development methods, the target reservoir is divided into cold recovery areas and hot recovery areas. Step S32. Splitting Model: The second-stage whole reservoir model is divided into multiple partition models. The partition model corresponding to the cold production area adopts the black oil model, and the partition model corresponding to the hot production area adopts the hot production model. Step S33. Construct the model: Based on the principle of material balance, and according to the attribute field of the last time step of the first stage of cold production, we establish the corresponding partition models for each region of the target reservoir. Step S34. Attribute cases and: Each partition model is fitted separately, and the properties of the fitted partition models are combined to form the full reservoir model for the second stage.

4. The method according to claim 3, characterized in that, In step S32, the flow boundary model is used to split the second stage of the full reservoir model.

5. The method according to claim 4, characterized in that, In step S32, the second stage of the full reservoir model is split using a flow boundary model. The specific method is as follows: A. Characterize the flow field intensity distribution inside the reservoir through streamline simulation; B. Analyze the direction and magnitude of fluid transport; C. Determine the inter-well connectivity based on the direction and magnitude of fluid transport.

6. The method according to claim 4, characterized in that, In step S32, the second stage of the full reservoir model is split using the minimum flow boundary model, that is, the second stage of the full reservoir model is split in the region with the sparsest streamlines.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, the computer program including program instructions that, when executed by a computer, cause the computer to perform the method as described in any one of claims 1-6.

8. An electronic device comprising a processor, a memory, 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 method as described in any one of claims 1-7.

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