Ultra-high water cut stage sandstone reservoir water drive development numerical simulation method based on saturation-physical relationship
By establishing a quantitative relationship between saturation and reservoir physical properties, dynamically adjusting the reservoir physical properties parameters, and coupling them into the traditional black oil numerical model, the problem of insufficient accuracy of traditional simulation methods is solved, and a higher precision reservoir water-drive simulation is achieved.
Patent Information
- Application Number
- CN202510214558.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-26
- Publication Date
- 2025-05-23
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Traditional reservoir development theory and numerical simulation methods cannot deeply reflect the law of local reservoir physical properties changing with saturation, resulting in low accuracy of simulation results and cannot meet the needs of refined injection and regulation.
By establishing a quantitative relationship between saturation and reservoir physical properties (such as permeability, viscosity, phase permeability, etc.), the reservoir physical properties parameters are dynamically adjusted so that they are dynamically adjusted with the change of reservoir saturation and coupled into the traditional black oil numerical model.
The numerical simulation accuracy during the water flood development process of sandstone reservoirs during ultra-high water-bearing period is improved, and the law of changes in physical properties parameters in the reservoir can be more accurately described, which improves the accuracy of water flooding process simulation, and reduces the calculation amount and cost.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of petroleum engineering, and specifically to a numerical simulation method for water flooding development of sandstone reservoirs in the ultra-high water cut period based on the saturation-physical property relationship. The method improves the accuracy and efficiency of numerical simulation by accurately coupling saturation with reservoir physical property changes. Background Art
[0002] As my country's old oil fields enter the ultra-high water-cut period, water flooding development faces increasingly greater technical challenges. Ultra-high water-cut sandstone reservoirs usually refer to reservoirs with a water cut of more than 90% after long-term water flooding development. The difficulty of reservoir development at this stage increases significantly, mainly manifested in the intensification of reservoir heterogeneity, changes in fluid properties (such as permeability, viscosity and relative permeability), and the distribution of remaining oil becomes more complex. Traditional reservoir development theory and numerical simulation methods are mainly based on macroscopic parameters such as water cut, water injection flux and development time to describe reservoir changes. However, these methods fail to deeply reflect the law of change of local reservoir properties with saturation, resulting in low accuracy of simulation results and unable to meet the needs of refined injection and production control. The current mainstream numerical simulation methods usually use fixed physical property parameters, or consider the change of a certain physical property (such as permeability or viscosity) alone, ignoring the synergistic effect between various physical property parameters. During the period of extremely high water content, the flow characteristics of the reservoir are affected by the complex water flooding process, and physical parameters such as permeability, crude oil viscosity and relative permeability will be dynamically adjusted with the change of oil and water saturation. Therefore, traditional methods cannot accurately reflect these physical property changes, resulting in low water flooding efficiency during reservoir development and difficulty in improving recovery.
[0003] In order to overcome this technical bottleneck, researchers gradually realized that the water flooding process of sandstone reservoirs in the ultra-high water-cut period can be simulated more accurately through the relationship between saturation and reservoir physical properties. Saturation, as a parameter of grid scale, can directly reflect the oil and water distribution of local reservoirs, and can dynamically adjust various parameters related to physical properties to significantly improve the simulation accuracy. Therefore, the numerical simulation method based on the saturation-physical property relationship is expected to better capture the complex changes of reservoirs in the ultra-high water-cut period and provide more accurate theoretical basis and technical support for refined water flooding development. Summary of the invention
[0004] The present application provides a numerical simulation method for water flooding development of sandstone reservoirs in the ultra-high water-cut period based on the saturation-physical property relationship, aiming to improve the problem of insufficient accuracy of traditional reservoir numerical simulation methods in the prior art when simulating the water flooding process of sandstone reservoirs in the ultra-high water-cut period. Existing methods usually only rely on parameters such as water cut, development time or displacement flux to describe reservoir changes, which cannot fully reflect the dynamic changes of reservoir physical properties during water flooding, resulting in limited simulation accuracy and failure to meet the needs of refined injection and production management. By introducing the relationship between saturation and reservoir physical property parameters (such as permeability, viscosity, relative permeability, etc.) in this application, the water flooding development process of sandstone reservoirs in the ultra-high water-cut period can be simulated with higher accuracy.
[0005] The technical solution of this application is: A numerical simulation method for water flooding development of sandstone reservoirs in the ultra-high water cut period based on saturation-physical property relationship, characterized by comprising the following steps: S1. Establish a quantitative relationship between the saturation and reservoir physical properties (such as permeability, viscosity, oil-water relative permeability, etc.) of sandstone reservoirs in the ultra-high water cut period through experimental data. The saturation-physical property relationship should be based on the actual development characteristics of the reservoir, combined with experimental data, to establish a functional relationship between saturation and reservoir physical property parameters (such as permeability, oil-water relative permeability curve, oil-water viscosity, etc.). This relationship should be able to dynamically reflect the changing characteristics of the reservoir during water flooding development and adapt to the development needs of the ultra-high water cut period; S2. Couple the saturation-physical property relationship established above into the traditional black oil numerical model. In the numerical simulation process, the saturation-physical property relationship is applied to the black oil model, and the physical property parameters such as permeability, oil-water relative permeability curve, and oil-water viscosity are adjusted dynamically with the change of reservoir saturation. This coupling process can ensure that the changes of reservoir physical properties with saturation are reflected in real time in the simulation, thereby improving the simulation accuracy and realism; S3. During the numerical simulation, the physical parameters of the reservoir are dynamically adjusted according to the change in saturation, and a complete basic geological model is established to simulate the changes in reservoirs and fluids during water flooding. Based on the established saturation-physical property relationship, a basic geological model of the reservoir is constructed, including rock physical parameters such as initial oil and gas saturation, porosity, and permeability. Combined with the dynamic changes of the reservoir during water flooding, physical parameters such as permeability, oil-water relative permeability curve, and oil-water viscosity are adjusted in real time to accurately simulate the heterogeneity of the reservoir and the fluid migration characteristics during water flooding; S4. Through step-by-step iterative calculations, the pressure, saturation, oil-water distribution and other information of each grid point are obtained, and the remaining oil distribution of the reservoir is analyzed. In the numerical simulation process, the pressure, oil-water saturation and oil-water distribution information of each grid point are iteratively updated to accurately simulate the fluid migration and reservoir state changes during the water flooding process. Finally, through multiple iterations, the dynamic development information of the reservoir is obtained to provide a basis for subsequent development optimization, especially to analyze the distribution of the remaining oil and optimize the injection and production plan.
[0006] As a technical solution, in step S1, when establishing the basic geological model, this application uses high-resolution geological data, combined with core experiments and development history data, to build a three-dimensional geological model of the reservoir, and obtains the quantitative relationship between saturation and reservoir properties (such as permeability, viscosity, relative permeability, etc.) through regression analysis or machine learning methods. These relationships provide an accurate basis for physical property changes for subsequent numerical simulations.
[0007] As a technical solution, in the process of coupling the saturation-physical property relationship to the traditional black oil numerical model in step S2, the physical property change function of the reservoir is embedded in the input module of the model to ensure that as the saturation changes during the simulation process, the relevant physical property parameters (such as permeability, oil-water phase permeability, etc.) can be dynamically updated, thereby improving the accuracy of the simulation.
[0008] As a technical solution, in step S3, the local iterative calculation is used to dynamically adjust the reservoir physical parameters according to the real-time saturation changes. Specifically, as the water flooding process proceeds, the reservoir permeability, oil-water phase permeability, oil viscosity and other physical parameters change according to the current saturation. Real-time correction is updated through the following relationship: , in, and is the base permeability and viscosity, and is the empirical fitting coefficient.
[0009] As a technical solution, this application solves the pressure field, saturation field and spatial distribution of oil and water distribution by step-by-step iterative calculation and numerical methods (such as finite difference method or finite element method) in step S4. In each iteration, the simulation model optimizes the calculation results according to the updated saturation and physical property parameters to obtain more accurate reservoir development process information and ultimately provide dynamic development plan optimization data.
[0010] Beneficial effects of this application: This application improves the accuracy of numerical simulation in the water flooding development process of sandstone reservoirs in the ultra-high water-cut period by introducing the saturation-physical property relationship and dynamically adjusting the reservoir physical property parameters. Compared with existing methods, this application can more accurately describe the law of changes in physical property parameters such as permeability, oil-water phase permeability, and oil-water viscosity in the reservoir with saturation, thereby improving the accuracy of water flooding process simulation; Using saturation as a control variable can reduce the amount of calculation, improve calculation efficiency, and reduce the calculation cost during the simulation process; This innovative numerical simulation method has important application value for the development of complex reservoirs, especially low permeability and high water cut reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 This is a flow chart of the numerical simulation method for water flooding development of sandstone reservoirs in the ultra-high water-cut period based on the saturation-physical property relationship provided in this application. This figure shows in detail the key steps of the relevant method of this application and their interrelationships.
[0012] Figure 1 The process of the method is clearly presented, making it easy to understand the role of each step in the simulation process and their interrelationships. DETAILED DESCRIPTION
[0013] The purpose of this embodiment is to provide a numerical simulation method for water flooding development of sandstone reservoirs in the ultra-high water-cut period based on the saturation-physical property relationship, aiming to solve the problem of inaccurate description of reservoir physical property changes in the prior art. Traditional numerical simulation methods mostly rely on simplified processing of the overall physical property parameters of the reservoir, such as permeability, viscosity, etc., while ignoring the impact of saturation changes on reservoir physical properties, especially local physical properties. Through the numerical simulation method of the present application, the evolution process of the reservoir and fluid during water flooding can be accurately simulated, especially the detailed characterization of the reservoir and fluid changes in the ultra-high water-cut period during water flooding, thereby improving the accuracy of the simulation and optimizing the development effect of the oil field.
[0014] To this end, this application introduces saturation as a core parameter into the numerical simulation process, and uses the saturation-physical property relationship to dynamically adjust the key physical property parameters such as reservoir permeability, oil-water relative permeability, and oil phase viscosity, thereby reflecting the dynamic changes of the reservoir fluid during the water flooding process. This method not only reduces the computational complexity, but also can more accurately reflect the impact of physical property changes on reservoir flow characteristics and development effects during actual reservoir development, especially in sandstone reservoirs with extremely high water content, and can accurately simulate the physical property change laws and water flooding effects at different water flooding stages.
[0015] The improvement of this embodiment is that a numerical simulation method based on the saturation-physical property relationship is proposed. By introducing the dynamic relationship between saturation and physical property parameters in the traditional black oil model, the deficiency of the prior art that the influence of physical property changes on reservoir development is not accurately considered. Specifically, the traditional method usually uses fixed physical property parameters to describe the permeability, relative permeability, oil phase viscosity, etc. of the reservoir, but these parameters change dynamically with the change of saturation, especially in the development process of the reservoir in the ultra-high water content period, the change of saturation significantly affects the fluid behavior and water flooding effect of the reservoir. Therefore, considering the influence of saturation on physical property parameters, the simulation process more accurately reflects the dynamic evolution of the reservoir during the water flooding process.
[0016] This application introduces the saturation-physical property relationship to dynamically adjust the reservoir physical properties during the simulation process. In particular, in the high water shear stage, the law of changes in physical parameters such as permeability, oil-water relative permeability and oil phase viscosity with water phase saturation is more precisely reflected. This method can better simulate the changes in reservoirs and fluids in ultra-high water-cut reservoirs, provide more accurate simulation data and theoretical basis for the optimized development of oil fields, and improve the overall efficiency and accuracy of water drive development. Example
[0017] In this embodiment, for a typical sandstone reservoir in the extra-high water content period, a basic geological model of the reservoir was established through the following steps, and the combination with the numerical simulation method was realized. First, based on the geological exploration data of the reservoir, a basic three-dimensional geological model of the reservoir was constructed, including basic data such as reservoir thickness, porosity, permeability, initial oil and gas saturation, and distribution of water injection areas and production areas. In order to ensure the accuracy of the model, the physical parameters measured by core experiments and actual development history data (such as water injection volume, oil production, water content, etc.) were used.
[0018] Next, based on the basic geological model, the relationship between saturation and reservoir physical parameters is defined. For example, the nonlinear functional relationship between permeability, oil-water relative permeability, oil phase viscosity and saturation is fitted using experimental data. Specifically, permeability It shows a downward trend with the increase of water saturation, and the relationship can be expressed as: in, is the initial permeability, is water saturation, a is an exponential parameter obtained by experimental fitting; oil-water relative permeability The change can be expressed by the following formula: in, is the initial oil phase relative permeability, and b is the fitting parameter, which indicates the sensitivity of relative permeability to water saturation. As the saturation changes, its changing rule can be described by the following formula: in, is the initial oil phase viscosity, and r is a fitting parameter, which indicates the variation of viscosity with water saturation. Through these functional relationships, reservoir permeability, fluid properties and other physical parameters can be dynamically adjusted with the change of water saturation, so that the model can more accurately reflect the reservoir characteristics in the actual development process.
[0019] Then, the saturation-physical property relationship is coupled to the traditional black oil numerical model. Specifically, in the numerical simulation, the conventional black oil model is used to calculate the pressure field, fluid saturation field, and oil-water distribution in the reservoir. Different from the traditional model's approach of fixing physical property parameters, the present application dynamically adjusts physical property parameters such as permeability, relative permeability, and oil phase viscosity according to the current saturation value within each time step, thereby accurately reflecting the changing pattern of the reservoir during the water flooding process. The realization of this dynamic adjustment process relies on the physical property relationship given above, which can update the physical property characteristics of the reservoir in real time according to the changes in water saturation.
[0020] For example, during the numerical simulation process, when the water flooding front moves, the water saturation in the local area continues to increase. Through the real-time adjustment of the saturation-physical property relationship, the permeability and relative permeability will gradually decrease. This change can be effectively reflected in the simulation, thereby affecting the production capacity and development effect of the reservoir.
[0021] Through step-by-step iterative calculations, the pressure field, saturation distribution, and oil-water distribution information of each grid point are finally obtained. This calculation process uses the finite difference method (FDM) and pressure-saturation coupling solution strategy to ensure the accuracy and stability of the simulation results. In each time step, based on the physical property update of the reservoir and the current injection and production conditions, the reservoir status at each time point is iteratively solved to provide a basis for subsequent development decisions.
[0022] It should be noted that the numerical simulation method used in this embodiment overcomes the limitation of fixed physical parameters in traditional numerical simulation methods by updating physical parameters in real time. In traditional black oil models, physical parameters such as permeability, relative permeability and viscosity are usually set according to the initial state, and it is assumed that these parameters remain unchanged throughout the simulation process. This simplified assumption is not applicable to ultra-high water-cut reservoirs. Ultra-high water-cut reservoirs usually have lower residual oil saturation, and the physical property changes of the reservoir and fluid during water flooding are more complex and drastic. Simply relying on static physical parameters cannot accurately describe the true evolution of the reservoir.
[0023] By introducing a dynamic relationship between saturation and physical properties, this application can achieve real-time adjustment of the physical properties of each grid point and accurately reflect the reservoir changes during the water flooding process. For example, in the high water content stage, as water is injected, the water saturation gradually increases, and physical parameters such as permeability, oil-water phase permeability, and oil phase viscosity change accordingly. In this way, the oil-water distribution, pressure field, and reservoir performance in the simulation process can be more accurately consistent with the actual development situation, effectively avoiding simulation errors caused by inaccurate physical property assumptions.
[0024] In addition, the numerical simulation method of this embodiment can handle the complexity of large-scale oil reservoirs, and can obtain more detailed and accurate simulation results by updating the real-time physical properties of each time step. This provides a scientific basis for the development of sandstone oil reservoirs in the ultra-high water cut period, and has important application value in injection and production optimization, well pattern design and production scheduling.
[0025] This embodiment also specifically considers the mutual influence and relative change law between various physical parameters in the sandstone reservoir in the ultra-high water content period. In practical applications, the physical parameters of the reservoir, such as permeability, oil phase viscosity, phase permeability, etc., change dynamically as the water flooding process proceeds. These changes are not only closely related to the saturation, but also affected by the internal heterogeneity of the reservoir. For example, in different water saturation intervals, the change characteristics of oil phase viscosity and permeability are different. Therefore, through dynamic adjustment based on the saturation-physical property relationship, not only the accuracy of numerical simulation can be improved, but also the actual production situation of the reservoir can be better reflected.
[0026] Specifically, during the numerical simulation, the saturation of the reservoir will be continuously adjusted as time goes by and the amount of water injected changes, and as the saturation changes, the reservoir physical properties (such as permeability, viscosity, relative permeability, etc.) will be updated in real time according to the predetermined mathematical relationship. This dynamic adjustment ensures that the simulation results can accurately reflect the reservoir evolution during the water flooding process, while avoiding the accumulation of errors caused by ignoring the changes in physical properties. This method can be widely applied to various types of sandstone reservoirs in the ultra-high water-cut period, especially those complex reservoirs with low residual oil saturation, and can obtain more realistic water flooding simulation effects without increasing the amount of calculation.
[0027] Therefore, this application can effectively reduce the computing cost while achieving high-precision numerical simulation, especially in the actual production process, and can provide a more reliable basis for injection and production optimization, production scheduling and the selection of future production increase measures in reservoir development.
[0028] In summary, the working principle of this application is: by establishing a basic geological model of sandstone reservoirs in the ultra-high water content period, combined with experimental data, the relationship between saturation and physical parameters such as permeability, viscosity, and phase permeability is determined. In the numerical simulation process, changes in saturation directly affect the dynamic adjustment of physical parameters, ensuring that reservoir and fluid changes during water flooding can accurately reflect the actual situation. Through this method, the simulation results are more in line with actual development, and because saturation itself is a numerical simulation output variable, the amount of calculation is reduced, and the simulation accuracy and efficiency are improved.
[0029] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present application and are not intended to limit the present application. Without departing from the spirit and scope of the present application, the present application may have various changes and improvements, which fall within the scope of the present application to be protected. The scope of protection claimed in the present application is defined by the attached claims and their equivalents.
Claims
1. A numerical simulation method for water flooding development of sandstone reservoirs in the ultra-high water cut period based on the saturation-physical property relationship, characterized in that: The following steps are involved: S1. Establish a quantitative relationship between the saturation and reservoir physical properties (such as permeability, viscosity, oil-water relative permeability, etc.) of sandstone reservoirs in the ultra-high water cut period through experimental data. The saturation-physical property relationship should be based on the actual development characteristics of the reservoir, combined with experimental data, to establish a functional relationship between saturation and reservoir physical property parameters (such as permeability, oil-water relative permeability curve, oil-water viscosity, etc.). This relationship should be able to dynamically reflect the changing characteristics of the reservoir during water flooding development and adapt to the development needs of the ultra-high water cut period; S2. Couple the saturation-physical property relationship established above into the traditional black oil numerical model. In the numerical simulation process, the saturation-physical property relationship is applied to the black oil model, and the physical property parameters such as permeability, oil-water relative permeability curve, and oil-water viscosity are adjusted dynamically with the change of reservoir saturation. This coupling process can ensure that the changes of reservoir physical properties with saturation are reflected in real time in the simulation, thereby improving the simulation accuracy and realism; S3. During the numerical simulation, the physical parameters of the reservoir are dynamically adjusted according to the change in saturation, and a complete basic geological model is established to simulate the changes in reservoirs and fluids during water flooding. Based on the established saturation-physical property relationship, a basic geological model of the reservoir is constructed, including rock physical parameters such as initial oil and gas saturation, porosity, and permeability. Combined with the dynamic changes of the reservoir during water flooding, physical parameters such as permeability, oil-water relative permeability curve, and oil-water viscosity are adjusted in real time to accurately simulate the heterogeneity of the reservoir and the fluid migration characteristics during water flooding; S4. Through step-by-step iterative calculations, the pressure, saturation, oil-water distribution and other information of each grid point are obtained, and the remaining oil distribution of the reservoir is analyzed. In the numerical simulation process, the pressure, oil-water saturation and oil-water distribution information of each grid point are iteratively updated to accurately simulate the fluid migration and reservoir state changes during water flooding. Finally, through multiple iterations, the dynamic development information of the reservoir is obtained to provide a basis for subsequent development optimization, especially to analyze the distribution of remaining oil and optimize the injection and production plan.
2. The method for numerical simulation of water flooding development of sandstone reservoirs in the ultra-high water cut period based on saturation-physical property relationship according to claim 1 is characterized by: In step S1, the basic geological model is established by using high-resolution geological data, combined with core experiments and development history data, to construct a three-dimensional geological model of the reservoir, and obtain the quantitative relationship between saturation and reservoir physical properties (such as permeability, viscosity, relative permeability, etc.) through regression analysis or machine learning methods. These relationships provide an accurate basis for physical property changes for subsequent numerical simulations.
3. The method for numerical simulation of water flooding development of sandstone reservoirs in the ultra-high water cut period based on saturation-physical property relationship according to claim 1 is characterized by: In step S2, the saturation-physical property relationship is coupled to the traditional black oil numerical model by using the reservoir physical property change function The input module embedded in the model ensures that relevant physical parameters (such as permeability) are updated as the saturation changes during the simulation process. , oil-water phase permeability , etc.) can be updated dynamically, thus improving the accuracy of the simulation.
4. The method for numerical simulation of water flooding development of sandstone reservoirs in the ultra-high water cut period based on saturation-physical property relationship according to claim 1 is characterized by: In step S3, local iterative calculation is used to dynamically adjust reservoir physical parameters according to the real-time saturation changes. Specifically, as the water flooding process proceeds, reservoir permeability, oil-water phase permeability, oil viscosity and other physical parameters change according to the current saturation. Real-time correction is updated through the following relationship: ， in, and is the base permeability and viscosity, and is the empirical fitting coefficient.
5. The numerical simulation method for water flooding development of sandstone reservoirs in the ultra-high water cut period based on saturation-physical property relationship according to claim 1 is characterized by: In step S4, numerical methods (such as finite difference method or finite element method) are used to solve the pressure field, saturation field and spatial distribution of oil and water through step-by-step iterative calculation. In each iteration, the simulation model will optimize the calculation results according to the updated saturation and physical property parameters to obtain more accurate reservoir development process information and ultimately provide dynamic development plan optimization data.