Oil reservoir numerical simulation method and system for shale oil compression oil production whole process

Abstract

The invention provides an oil reservoir numerical simulation method and system for a shale oil compression oil production whole process. The simulation method comprises the steps that a fine oil reservoir geologic model, a geomechanical model and a natural fracture model are established; establishing a ground stress model; establishing an artificial hydraulic fracture dynamic expansion model; establishing an oil reservoir pressure sensitive model for equivalently representing dynamic changes of oil reservoir scale porosity and permeability; establishing a capillary force model for equivalently representing the reservoir scale imbibition replacement efficiency; respectively establishing different lithofacies matrix partition models, different layer series partition models and different proppant type partition models; and respectively defining different capillary force models for the different lithofacies matrix partition models and the different proppant type partition models established in the step S6. And the influence of important physical phenomena such as rock stress sensitivity, fracture closure and shale imbibition and replacement on the oil reservoir can be accurately predicted.

Description

Technical Field

[0001] The present invention relates to the technical field of oil reservoir numerical simulation, and in particular to an oil reservoir numerical simulation method and system for the entire process of shale oil compression production. Background Art

[0002] The present invention relates to the technical field of reservoir numerical simulation, and in particular to a reservoir numerical simulation method for the entire process of shale oil fracturing, well blocking, and oil production that takes into account imbibition displacement and stress sensitivity. Reservoir numerical simulation refers to the simulation of fluid migration and thermodynamic processes inside the reservoir, as well as the technology of exploration, mining, production, and adjustment of oil and gas resources. Its main task is to provide technical support and decision-making basis for reservoir development.

[0003] In the process of the rise of new energy and the continuous exploitation of oil resources, shale oil reservoirs, as a potential oil and gas reservoir, have become a hot research direction for development and design. Unlike traditional homogeneous or micro-homogeneous oil and gas reservoirs, shale oil reservoirs have the characteristics of low porosity, low permeability, low adhesion, and low permeability, and it is a technical difficulty to carry out effective development and production. Traditional numerical simulation methods do not take into account the stress sensitivity and the influence of imbibition displacement during fracturing, and cannot accurately predict the stress sensitivity of rocks, the closure of cracks, and the influence of imbibition displacement on oil reservoirs. "A Simulation Method for Repeated Fracturing of Horizontal Wells in Tight Conglomerate Reservoirs" failed to consider the imbibition mechanism, "A Dual Porosity and Dual Permeability Model Construction and Pressure Dynamic Prediction Method for Shale Gas Reservoirs Based on Gas-Water Two-Phase Flow" uses analytical methods for simulation, which cannot support field applications well, and "Fracturing Fluid Imbibition Production Simulation Method and Device for Dual Porosity and Dual Permeability Reservoirs" failed to consider the differences in stress sensitivity and imbibition efficiency of different lithofacies, different strata, and different types of support fractures in actual oil reservoirs. Therefore, how to carry out more accurate numerical simulation of shale oil reservoirs has become an important technical difficulty in solving shale oil reservoir development problems. Summary of the invention

[0004] In view of the above problems, the present invention is proposed to provide a method and system for numerical simulation of the entire process of shale oil pressure production, which overcomes the above problems or at least partially solves the above problems.

[0005] According to one aspect of the present invention, a reservoir numerical simulation method for the entire process of shale oil pressure production is provided, the simulation method comprising:

[0006] Step S1: Establish a detailed reservoir geological model, a geomechanical model and a natural fracture model;

[0007] Step S2: Establishing a geostress model;

[0008] Step S3: establishing a dynamic expansion model of artificial hydraulic fractures;

[0009] Step S4: establishing a reservoir pressure sensitivity model that equivalently represents the dynamic changes of reservoir-scale porosity and permeability;

[0010] Step S5: establishing a capillary force model that is equivalent to characterizing the reservoir-scale imbibition displacement efficiency;

[0011] Step S6: establishing different lithofacies matrix partition models, different layer partition models and different proppant type partition models respectively according to the distribution ranges of different lithofacies matrixes, different layer systems and different proppant types;

[0012] Step S7: Based on the reservoir pressure sensitivity model established in step S4, different reservoir pressure sensitivity models are defined for the different stratum zoning models and the different proppant type zoning models established in step S6, and based on the capillary force model established in step S5, different capillary force models are defined for the different lithofacies matrix zoning models and the different proppant type zoning models established in step S6.

[0013] Optionally, the reservoir numerical simulation method further includes:

[0014] Step S8: Carry out reservoir numerical simulation on the basis of step S7, adopt injection method to realize the simulation of fracturing injection process, adopt well shut-in method to realize the simulation of well shut-in process, adopt production method to realize the simulation of production process, and simulate the reservoir numerical value of the whole process of fracturing and shut-in production considering the reservoir numerical simulation parameters.

[0015] Optionally, the reservoir numerical simulation parameters specifically include: rock stress sensitivity, fracture closure, and imbibition replacement mechanism.

[0016] Optionally, the step S1: establishing a fine reservoir geological model, a geomechanical model and a natural fracture model specifically includes: establishing a fine reservoir geological model, a geomechanical model and a natural fracture model based on actual block data.

[0017] Optionally, the step S2: establishing a geostress model specifically includes:

[0018] On the basis of step S1, a finite element simulation method is used to carry out a geostress simulation and establish a geostress model using a finite element simulator.

[0019] Optionally, the step S3: establishing a dynamic expansion model of artificial hydraulic fractures specifically includes:

[0020] On the basis of step S2, the fracturing process is fitted by using fracturing simulation software to establish a dynamic expansion model of artificial hydraulic fractures.

[0021] Optionally, the step S4: establishing a reservoir pressure sensitivity model that equivalently characterizes the dynamic changes of reservoir-scale porosity and permeability specifically includes:

[0022] With reference to the results of indoor stress sensitivity experiments, the core-scale stress sensitivity curve is upgraded, and a reservoir pressure sensitivity model that equivalently characterizes the dynamic changes of reservoir-scale porosity and permeability is established to guide the simulation of stress sensitivity mechanism in commercial numerical simulation software.

[0023] Optionally, the step S5: establishing a capillary force model that is equivalent to characterizing the reservoir-scale imbibition displacement efficiency specifically includes:

[0024] With reference to the results of indoor experimental imbibition replacement experiments, the imbibition replacement efficiency affected by multiple factors at the core scale was scaled up, and a capillary force model that equivalently characterizes the imbibition replacement efficiency at the reservoir scale was established to guide the simulation of the imbibition replacement mechanism in commercial numerical simulation software.

[0025] Optionally, in step S6 and step S7, based on step S1 and step S3, the models of different lithofacies matrices, different strata and different proppant types are partitioned according to the mine knowledge;

[0026] On the basis of step S4 and step S5, different equivalent imbibition displacement models and equivalent stress sensitivity models are defined for different partitions, and an overall equivalent imbibition displacement model and an equivalent stress sensitivity model are established.

[0027] The present invention also provides a reservoir numerical simulation system for the whole process of shale oil pressure-suppression oil production, which uses the above-mentioned reservoir numerical simulation method for the whole process of shale oil pressure-suppression oil production, and is characterized in that the simulation system comprises:

[0028] Model building module, used to build detailed reservoir geological model, geomechanical model and natural fracture model;

[0029] A geostress model building module is used to build a geostress model;

[0030] Dynamic expansion model building module, used to build a dynamic expansion model of artificial hydraulic fractures;

[0031] The reservoir pressure sensitivity model building module is used to establish a reservoir pressure sensitivity model that equivalently represents the dynamic changes of reservoir-scale porosity and permeability;

[0032] Capillary force model building module, used to establish a capillary force model that is equivalent to characterizing the reservoir-scale imbibition displacement efficiency;

[0033] Multiple model building modules, used to build different lithofacies matrix partition models, different layer partition models and different proppant type partition models according to the distribution range of different lithofacies matrix, different layer systems and different proppant types;

[0034] The model definition module is used to define different reservoir pressure sensitivity models for the different stratum partition models and the different proppant type partition models established in step S6 according to the reservoir pressure sensitivity model established in step S4, and to define different capillary force models for the different lithofacies matrix partition models and the different proppant type partition models established in step S6 according to the capillary force model established in step S5.

[0035] The present invention provides a reservoir numerical simulation method and system for the whole process of shale oil compression production. The simulation method comprises: step S1: establishing a fine reservoir geological model, a geomechanical model and a natural fracture model; step S2: establishing a geostress model; step S3: establishing a dynamic expansion model of artificial hydraulic fractures; step S4: establishing a reservoir pressure sensitivity model that equivalently represents the dynamic changes of reservoir-scale porosity and permeability; step S5: establishing a capillary force model that equivalently represents the imbibition replacement efficiency of the reservoir; step S6: establishing different lithofacies matrix partition models, different strata partition models and different proppant type partition models according to the distribution ranges of different lithofacies matrixes, different strata and different proppant types; step S7: according to the reservoir pressure sensitivity model established in step S4, defining different reservoir pressure sensitivity models for the different strata partition models and the different proppant type partition models established in step S6, and according to the capillary force model established in step S5, defining different capillary force models for the different lithofacies matrix partition models and the different proppant type partition models established in step S6. It can accurately predict the impact of important physical phenomena such as rock stress sensitivity, fracture closure, and shale imbibition and replacement on oil reservoirs, and can be used to formulate more accurate production plans, improve drilling, and complete the effectiveness of crude oil production and development.

[0036] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0038] Figure 1 A flow chart of a method for numerical simulation of a reservoir for the entire process of shale oil compression production provided by an embodiment of the present invention;

[0039] Figure 2The geomechanical model provided in the embodiment of the present invention - taking the Young's modulus attribute model as an example;

[0040] Figure 3 The geostress model provided in the embodiment of the present invention - taking the maximum horizontal principal stress model as an example;

[0041] Figure 4 An artificial hydraulic seam network model provided by an embodiment of the present invention;

[0042] Figure 5 A stress sensitivity model of matrix rocks of different strata provided in an embodiment of the present invention;

[0043] Figure 6 A stress sensitivity model of proppant joints of different proppant types provided in an embodiment of the present invention;

[0044] Figure 7 Capillary force models of different lithofacies matrices provided by embodiments of the present invention;

[0045] Figure 8 The partition model provided for the embodiment of the present invention - taking different proppant types as an example;

[0046] Fig. 9 The production fitting and prediction results provided by the embodiments of the present invention;

[0047] Fig.10 The embodiment of the present invention provides a method for predicting the production capacity of different well blocking solutions. DETAILED DESCRIPTION

[0048] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0049] The terms "comprises" and "having" and any variations thereof in the description embodiments, claims and drawings of the present invention are intended to cover non-exclusive inclusions, for example, including a series of steps or units.

[0050] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0051] Example 1

[0052] like Figure 1As shown, the present invention relates to a reservoir numerical simulation method, especially a reservoir numerical simulation method for the whole process of shale oil fracturing, well blocking and oil production. The present invention combines experiments and theoretical simulations to propose a new reservoir numerical simulation method, which can more accurately predict the migration process of fluids inside the reservoir and provide technical support for the development and adjustment of shale oil blocks.

[0053] Step S1: Establish a detailed reservoir geological model, geomechanical model and natural fracture model

[0054] This step is the basis of geostress simulation. Through basic geological research and reservoir numerical simulation needs, relevant software is used to establish reservoir geological models, geomechanical models and natural fracture models. Laboratory and field data are used to establish basic rock property analysis and determine rock physical and mechanical parameters (such as elastic modulus, Poisson's ratio and shear modulus, etc.), thereby obtaining the mechanical properties of the reservoir and establishing a detailed reservoir geomechanical model.

[0055] Step S2: Establishing the geostress model

[0056] Based on the experimental and field test data, the geostress model is established, and the model is reconstructed and restructured using computer simulation to obtain an accurate geostress field.

[0057] Step S3: Establishing an artificial hydraulic seam network model

[0058] Rock mechanics parameters and construction parameters are used to simulate the interaction between rock and drilling fluid, fracturing fluid and proppant, so as to obtain an artificial hydraulic fracture network model.

[0059] Step S4: Establish a rock stress sensitivity model for pressure sensitivity equivalent representation

[0060] Based on the basic properties of rocks, geomechanical effects and laboratory test data, a reservoir-scale matrix pressure sensitivity model for different layers and a proppant fracture pressure sensitivity model for different proppant types were established to equivalently characterize the differential stress sensitivity of the reservoir after fracturing and predict the changes in matrix porosity and permeability caused by stress and the possibility of fracture closure.

[0061] Step S5: Establishing an imbibition displacement model for equivalent characterization of capillary force

[0062] In view of the characteristics of shale oil such as high density, low porosity and permeability, low adhesion and low permeability, referring to the results of indoor core imbibition displacement test, the capillary force model is used to equivalently characterize the imbibition displacement efficiency, and a differential imbibition displacement model of different lithofacies matrices at the reservoir scale is established to predict the oil and water migration process caused by imbibition displacement in the reservoir.

[0063] Step S6: Establishing a zoning model for different lithofacies matrix, different layers and different proppant types

[0064] According to the distribution of different lithofacies, different strata and different types of proppants, the corresponding zoning model is established.

[0065] Step S7: Establish an imbibition displacement model and a stress sensitivity model for overall description of the work area and zoning control.

[0066] Corresponding imbibition replacement models are defined for fractures in different lithofacies matrices and different proppant types, and corresponding rock stress sensitivity models are defined for fractures in different strata and different proppant types.

[0067] Step S8: Implementing numerical simulation of the whole process of oil reservoir compression and recovery taking into account rock stress sensitivity, fracture closure, and imbibition replacement mechanism in the numerical simulation model.

[0068] By using various models and simulation tools, we comprehensively establish numerical simulation results that take into account rock stress sensitivity, fracture closure, and imbibition replacement mechanisms, complete field production fitting, and predict the fluid migration laws within the reservoir.

[0069] Example 2

[0070] The specific steps are as follows:

[0071] (1) Figure 2 Establish the reservoir geomechanical model (Young's modulus, Poisson's ratio, etc.) of the target block. The specific model parameters are as follows:

[0072] ① The grid step size is 25×25 meters,

[0073] ②The number of grid nodes is 296×144×74=3154176,

[0074] ③Complete attribute modeling and reserve calculation fitting;

[0075] (2) Figure 2 A three-dimensional geostress model is established based on the geomechanical model. The main model attributes include: three-dimensional triaxial stress magnitude and direction, three-dimensional pore pressure, etc.

[0076] (3) Figure 4 Establish an artificial hydraulic fracture network model through fracturing simulation;

[0077] (4) Figure 5 Establish a matrix stress sensitivity model for different strata based on laboratory tests and field knowledge;

[0078] (5) Figure 6 Based on laboratory tests and field knowledge, a stress sensitivity model of proppant joints with different proppant types was established;

[0079] (6) Figure 7Based on indoor tests and field knowledge, an equivalent imbibition displacement model for characterizing capillary forces in different lithofacies was established;

[0080] (7) Figure 8 Based on the artificial hydraulic fracture network model established in step (3), a zoning model of different lithofacies matrix, different strata and different proppant types is established;

[0081] (8) Fig. 9 Combined with steps (4), (5), (6), and (7), a reservoir numerical simulation model considering imbibition displacement and stress sensitivity is established to complete production history matching and production prediction;

[0082] (9) Fig.10 Based on the reliable model after fitting inversion, the production of different well blocking times is simulated and the well blocking scheme is optimized.

[0083] Beneficial effects: The reservoir numerical simulation method proposed in the present invention combines the geological characteristics of shale oil, engineering practice data and high-tech means, comprehensively considers the influencing factors such as stress sensitivity and imbibition displacement in the fracturing process, and obtains more accurate and reliable simulation results, including:

[0084] (1) Improve the efficiency of numerical simulation, accurately analyze the dynamic changes of oil reservoirs, and predict the development and production effects of oil reservoirs;

[0085] (2) Simulate rock stress sensitivity, fracture closure, imbibition and replacement processes to more accurately predict shale oil reserves and basic reservoir characteristics, and optimize the design and implementation of fracturing technology;

[0086] (3) Improve the accuracy and reliability of simulation results, achieve accurate simulation of fluid migration processes within reservoirs, and help decision makers make more scientific decisions.

[0087] The reservoir numerical simulation method of the present invention establishes a fine reservoir geological model and geomechanical model, combines laboratory data and theoretical analysis, and comprehensively applies factors such as geostress simulation, rock stress sensitivity, fracture closure, and imbibition displacement to numerical simulation, thereby obtaining more accurate simulation results. Therefore, the technical solution of the present invention is a very valuable method that can provide necessary technical support for shale oil geological engineering and engineering design. At the same time, the method of the present invention can accurately predict the impact of important physical phenomena such as rock stress sensitivity, fracture closure, and shale imbibition displacement on the reservoir, and can be used to formulate more accurate production plans, improve drilling, and complete the effectiveness of crude oil production and development.

[0088] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A reservoir numerical simulation method for the entire process of shale oil pressure production, characterized in that: The simulation method comprises: Step S1: Establish a detailed reservoir geological model, a geomechanical model and a natural fracture model; Step S2: Establishing a geostress model; Step S3: establishing a dynamic expansion model of artificial hydraulic fractures; Step S4: establishing a reservoir pressure sensitivity model that equivalently represents the dynamic changes of reservoir-scale porosity and permeability; Step S5: establishing a capillary force model that is equivalent to characterizing the reservoir-scale imbibition displacement efficiency; Step S6: establishing different lithofacies matrix partition models, different layer partition models and different proppant type partition models respectively according to the distribution ranges of different lithofacies matrixes, different layer systems and different proppant types; Step S7: Based on the reservoir pressure sensitivity model established in step S4, different reservoir pressure sensitivity models are defined for the different stratum zoning models and the different proppant type zoning models established in step S6, and based on the capillary force model established in step S5, different capillary force models are defined for the different lithofacies matrix zoning models and the different proppant type zoning models established in step S6.

2. The method for numerical simulation of the whole process of shale oil production by shale oil reservoir according to claim 1, characterized in that: The reservoir numerical simulation method further comprises: Step S8: Carry out reservoir numerical simulation on the basis of step S7, adopt injection method to realize the simulation of fracturing injection process, adopt well shut-in method to realize the simulation of well shut-in process, adopt production method to realize the simulation of production process, and simulate the reservoir numerical value of the whole process of fracturing and shut-in production considering the reservoir numerical simulation parameters.

3. The method for numerical simulation of the whole process of shale oil production by shale oil reservoir according to claim 2, characterized in that: The reservoir numerical simulation parameters specifically include: rock stress sensitivity, fracture closure, and imbibition replacement mechanism.

4. The method for numerical simulation of the whole process of shale oil production by shale oil reservoir according to claim 1, characterized in that: The step S1: establishing a fine reservoir geological model, a geomechanical model and a natural fracture model specifically includes: establishing a fine reservoir geological model, a geomechanical model and a natural fracture model based on actual block data.

5. The method for numerical simulation of the whole process of shale oil production by shale oil reservoir according to claim 1, characterized in that: The step S2: establishing the geostress model specifically includes: On the basis of step S1, a finite element simulation method is used to carry out a geostress simulation and establish a geostress model using a finite element simulator.

6. The method for numerical simulation of the whole process of shale oil production by pressure pumping according to claim 1 is characterized in that: The step S3: establishing a dynamic expansion model of artificial hydraulic fractures specifically includes: On the basis of step S2, the fracturing process is fitted by using fracturing simulation software to establish a dynamic expansion model of artificial hydraulic fractures.

7. The method for numerical simulation of the whole process of shale oil production by shale oil reservoir according to claim 1, characterized in that: The step S4: establishing a reservoir pressure sensitivity model that is equivalent to characterizing the dynamic changes of reservoir-scale porosity and permeability specifically includes: With reference to the results of indoor stress sensitivity experiments, the core-scale stress sensitivity curve is upgraded, and a reservoir pressure sensitivity model that equivalently characterizes the dynamic changes of reservoir-scale porosity and permeability is established to guide the simulation of stress sensitivity mechanism in commercial numerical simulation software.

8. The method for numerical simulation of the whole process of shale oil production by pressure pumping according to claim 1 is characterized in that: The step S5: establishing a capillary force model that is equivalent to characterizing the reservoir-scale imbibition displacement efficiency specifically includes: With reference to the results of indoor experimental imbibition replacement experiments, the imbibition replacement efficiency affected by multiple factors at the core scale was scaled up, and a capillary force model that equivalently characterizes the imbibition replacement efficiency at the reservoir scale was established to guide the simulation of the imbibition replacement mechanism in commercial numerical simulation software.

9. The method for numerical simulation of the whole process of shale oil production by compression according to claim 1, characterized in that: In the step S6 and step S7, based on the step S1 and step S3, the models of different lithofacies matrices, different strata and different proppant types are partitioned according to the mine field knowledge; On the basis of step S4 and step S5, different equivalent imbibition displacement models and equivalent stress sensitivity models are defined for different partitions, and an overall equivalent imbibition displacement model and an equivalent stress sensitivity model are established.

10. A reservoir numerical simulation system for the whole process of shale oil pressure production, using a reservoir numerical simulation method for the whole process of shale oil pressure production as described in any one of claims 1 to 9, characterized in that: The simulation system comprises: Model building module, used to build detailed reservoir geological model, geomechanical model and natural fracture model; A geostress model building module is used to build a geostress model; Dynamic expansion model building module, used to build a dynamic expansion model of artificial hydraulic fractures; The reservoir pressure sensitivity model building module is used to establish a reservoir pressure sensitivity model that equivalently represents the dynamic changes of reservoir-scale porosity and permeability; Capillary force model building module, used to establish a capillary force model that is equivalent to characterizing the reservoir-scale imbibition displacement efficiency; Multiple model building modules, used to build different lithofacies matrix partition models, different layer partition models and different proppant type partition models according to the distribution range of different lithofacies matrix, different layer systems and different proppant types; The model definition module is used to define different reservoir pressure sensitivity models for the different stratum partition models and the different proppant type partition models established in step S6 according to the reservoir pressure sensitivity model established in step S4, and to define different capillary force models for the different lithofacies matrix partition models and the different proppant type partition models established in step S6 according to the capillary force model established in step S5.

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