Multi-layer heterogeneous oil reservoir water injection development balanced production well completion perforation optimization method

Abstract

The invention discloses a multilayer heterogeneous oil reservoir water injection development balanced production well completion perforation optimization method, and relates to the technical field of oil and gas field development engineering. The method comprises the steps that S1, basic parameters of a multilayer oil reservoir are collected, and engineering constraints are determined; s2, performing numerical simulation on perforation near-well flow of the multi-layer oil reservoir based on basic parameters of the multi-layer oil reservoir and the engineering constraint, and establishing a skin coefficient inversion library; s3, a preset skin coefficient of each layer in the multi-layer oil reservoir is set, and water injection rate distribution of each layer of the multi-layer oil reservoir under the general water injection condition is calculated based on the preset skin coefficient; s4, on the basis of the water injection amount distribution, calculating the water drive leading edge advancing speed of the oil phase and the water phase; s5, on the basis of the water drive front edge advancing speed of each layer, the water drive front edge advancing speed variance of each layer in the multi-layer oil reservoir is determined; and S6, the steps S3-S5 are repeated, the preset skin coefficient set when the advancing speed variance of the water drive front edge of each layer is minimum is obtained, and the optimal perforation parameter combination at the moment is obtained.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development engineering technology, specifically to an optimized method for balanced well completion perforation during water injection development in multi-layered heterogeneous oil reservoirs. Background Technology

[0002] Multilayered heterogeneous oil reservoirs are widely distributed in continental sedimentary basins and fault-block reservoirs in my country. Their significant characteristic lies in the substantial differences between different layers in terms of permeability, pore structure, thickness, and oil saturation. During water injection development, injected water, driven by pressure, often preferentially flows along high-permeability layers or highly connected channels, forming distinct dominant seepage paths. This leads to rapid water flooding of high-permeability layers, while the displacement pressure of medium- and low-permeability layers is insufficient, resulting in low utilization.

[0003] As water injection development continues, high-permeability layers often experience water breakthrough first, forming stable water channeling pathways. Injected water circulates along these existing channels, resulting in a large amount of ineffective water injection circulation and a significant decrease in formation energy utilization. Simultaneously, medium- and low-permeability layers still contain a large amount of recoverable residual oil, leading to significantly lower overall reservoir vertical sweep efficiency and final recovery rate. This type of inter-layer imbalance has become a key constraint on stable production and improved recovery rates in medium- to high-water-cut reservoirs.

[0004] To address the water injection imbalance problem in multi-layered heterogeneous reservoirs, two main technical approaches were employed on-site: mechanical stratified water injection and chemical profile control and water shut-off.

[0005] Mechanical stratified water injection relies on downhole tools such as packers and distributors to achieve segmented control of the wellbore, theoretically enabling independent water injection into different segments. However, in environments with high salinity, high temperature, or strong corrosion, the sealing performance of packers is easily degraded, downhole tools suffer from severe scaling and corrosion, resulting in high system maintenance costs and insufficient operational reliability. At the same time, the accuracy of stratified injection is limited, making it difficult to maintain stable control of the water injection ratio between segments over a long period.

[0006] Chemical profile control technology can improve the flow resistance of high-permeability layers and improve the water absorption profile in the short term by injecting plugging agents such as polymers, gels or foams into high-permeability channels. However, under high salinity and high temperature conditions, plugging agents are prone to degradation or erosion failure, the control cycle is short, and there are risks such as near-wellbore damage and perforation channel blockage.

[0007] Furthermore, in high-salinity reservoirs, salt ions have a significant destructive effect on tubing materials and formation structures, with common problems such as casing corrosion, scaling, and deformation, which further restricts the widespread application of complex downhole injection tools.

[0008] To overcome the limitations of mechanical injection and chemical profile control, differentiated perforation technology has gradually gained attention. This technology adjusts the seepage resistance in the near-wellbore zone of different formations by changing parameters such as perforation density, pore size, and penetration depth, achieving static stratified water injection control without complex downhole equipment. In high-permeability zones, reducing perforation density, pore size, or penetration depth increases flow resistance; conversely, in low-permeability zones, increasing pore density, pore size, or penetration depth reduces flow resistance, thus mitigating uneven water absorption between formations to some extent. This method is simple in structure, highly adaptable, and offers advantages such as long-term stability, convenient construction, and high economic efficiency.

[0009] Compared to mechanical water injection and chemical profile control, differentiated perforation technology has the following significant advantages: simple structure, convenient construction, and high economic efficiency; it does not rely on moving parts and has good long-term stability; it is unaffected by high-salt, high-temperature, and highly corrosive environments; and it can be implemented in one go during well completion, making it suitable for both new and old well stimulation. Therefore, differentiated perforation is considered a passive, structural water injection equalization control method suitable for complex, multi-layered, heterogeneous reservoirs.

[0010] Although differentiated perforation has been applied to some extent in engineering practice, the following prominent problems still exist at present: First, the design of perforation parameters mainly relies on experience: most engineering schemes are based on the empirical principle of "less perforation for high permeability and more perforation for low permeability" for qualitative design, lacking a unified and replicable quantitative method; second, the relationship between perforation parameters and flow resistance is unclear: existing designs often do not clearly define the quantitative relationship between perforation density, diameter, depth and skin coefficient, making it difficult to accurately control near-wellbore flow resistance; third, there is a lack of design objectives directly coupled with the water drive mechanism: existing methods mostly use water absorption or injection index as targets, without considering the interlayer equilibrium of water drive front advance velocity from the perspective of reservoir development essence; finally, multi-layer heterogeneous reservoirs lack a systematic optimization design process: a complete design and optimization method system from perforation parameters—skin effect—interlayer water injection distribution—water drive front advance velocity has not yet been formed.

[0011] Current technologies for improving water injection development in multi-layered heterogeneous reservoirs mainly focus on differentiated perforation and its associated water injection control methods. These technologies attempt to mitigate inter-layer water absorption differences and suppress water channeling in high-permeability layers by altering well completion structures or near-wellbore flow conditions, thereby increasing the vertical utilization of the reservoir.

[0012] Existing differentiated perforation technology is typically implemented under casing completion conditions. Its basic structure involves using different combinations of perforation parameters, including pore density, pore diameter, penetration depth, and phase angle, in different sections within the same injection well. By artificially adjusting these parameters, different levels of additional flow resistance are created in the near-wellbore zone of different sections. In terms of working principle, existing technologies generally rely on the perforation structure altering the flow boundary conditions between the wellbore and the formation; this effect can be equivalently characterized by the "skin coefficient." By introducing the skin coefficient term generated by perforation into the classical radial flow equation, the injection capacity or productivity change of a perforated well relative to an open-hole well can be estimated. Based on this, some studies attempt to establish the correspondence between perforation parameters and the skin coefficient through empirical formulas, experimental data fitting, or simplified analytical models, and design perforation schemes accordingly.

[0013] In engineering applications, existing differentiated perforation methods mainly increase near-wellbore flow resistance by reducing the number of perforations or decreasing the diameter in high-permeability layers, and reduce flow resistance by increasing the number of perforations or increasing the penetration depth in low-permeability layers. This, to some extent, achieves a redistribution of injected water between layers, improving the injection profile.

[0014] However, existing technologies struggle to achieve quantitative equilibrium of the water-drive front advance velocity during water injection development of multi-layer reservoirs; they also struggle to coordinate and optimize perforation parameters with key reservoir parameters such as reservoir permeability and initial water saturation; and they struggle to develop a complete perforation optimization design process for engineering implementation, providing directly executable design basis for the field.

[0015] In summary, considering both overall technological maturity and applicability, existing technologies still exhibit the following significant shortcomings:

[0016] The design of perforation parameters is mainly based on experience, lacking a systematic quantitative optimization method. Furthermore, the skin coefficient model has limited applicability and is difficult to reflect the real perforation effect. At the same time, it ignores the influence of the oil-water two-phase displacement process on the perforation effect and lacks a design concept with "equalization of water-drive front advance speed" as the core objective. Summary of the Invention

[0017] To address the technical problems existing in the prior art, this invention provides an optimized method for balanced well completion perforation during water injection development in multi-layered heterogeneous oil reservoirs. The technical solution is as follows:

[0018] On the one hand, a method for optimizing well completion and perforation in balanced water injection development of multi-layer heterogeneous reservoirs is provided. The optimization method includes the following steps: S1, collecting basic parameters of the multi-layer reservoir and determining engineering constraints; S2, performing numerical simulation of near-well flow through perforation in the multi-layer reservoir based on the basic parameters and engineering constraints, and establishing a skin coefficient inversion library, which includes the mapping relationship or response surface from perforation parameters to skin coefficients; S3, setting a preset skin coefficient for each layer in the multi-layer reservoir as a set of parameter values ​​in a preset parameter set, and calculating the perforation flow under generalized water injection conditions based on the preset skin coefficients. S4. Based on the water injection distribution, calculate the water-drive front advance velocity of the oil-water two-phase system in each layer; S5. Based on the water-drive front advance velocity of each layer, determine the variance of the water-drive front advance velocity of each layer in the multi-layer reservoir; S6. Modify the preset skin coefficient to different values ​​in the preset parameter set, repeat steps S3 to S5, obtain the variance of the water-drive front advance velocity of each layer corresponding to different preset skin coefficients, and determine the perforation parameter combination corresponding to the skin coefficient corresponding to the minimum value of the variance of the water-drive front advance velocity of each layer in the skin coefficient inversion library.

[0019] Optionally, the establishment of the skin coefficient inversion library in S2 includes: S21, establishing a database for near-wellbore numerical simulation of single-layer perforation in a single well; S22, calculating the production capacity of single-layer steady-state radial flow based on the open-hole well benchmark production capacity model; S23, calculating the perforation well production ratio based on the production capacity of the single-layer steady-state radial flow and the perforation well flow rate obtained from the database simulation, and calculating the skin coefficient based on the perforation well production ratio; S24, establishing a skin coefficient inversion library based on obtaining different skin coefficients by repeatedly executing S21 to S23 under different perforation parameter combinations.

[0020] Optionally, the database establishment in S21 includes: S211, constructing a three-dimensional numerical model of a single well and a single layer near the wellbore; S212, assigning formation properties and mechanical parameters to the three-dimensional numerical model; S213, setting a pore fluid seepage field and a rock skeleton mechanical field in the three-dimensional numerical model, and achieving coupling between the two through Biot's effective stress principle; S214, setting the boundary and initial conditions of the three-dimensional numerical model; S215, setting a locally refined mesh in the perforation channels and the area near the wellbore in the three-dimensional numerical model, and using a steady-state or quasi-steady-state fully coupled solver for solving; S216, after the three-dimensional numerical model converges, obtaining the steady-state total flow rate at the wellbore.

[0021] Optionally, S213 includes: setting the pore fluid seepage field based on Darcy's law and the mass conservation equation; establishing the coupling relationship between pore pressure and rock stress based on Biot's effective stress principle, and setting the rock skeleton mechanical field so that changes in pore pressure can cause formation stress and deformation response.

[0022] Optionally, the formula for calculating the perforated well production ratio (PRI) in step S23 is:

[0023]

[0024] in The production rate of the perforated well, in meters (m³). 3 / s; where The production rate of open-hole wells, in meters (m³). 3 / s, its formula is:

[0025]

[0026] in, This refers to the production rate after open-hole completion, expressed in meters (m³). 3 / s; k is the formation permeability, in meters. 2 h is the reservoir thickness in meters; pe is the boundary pore pressure in Pa; pw is the bottom hole flowing pressure in Pa; μ is the formation fluid viscosity in Pa·s; re is the supply boundary radius in meters; rw is the wellbore radius in meters.

[0027] The formula for the epidermal coefficient S is:

[0028]

[0029] in, The reservoir radius is in meters. The diameter is measured in meters (m).

[0030] Optionally, the formula for the water-driven leading edge propulsion velocity in S4 is:

[0031]

[0032] in, denoted as the propulsion velocity of the i-th water-drive leading edge, in m / s; The volume of water injected into the i-th layer, in meters. 3 / s; The effective seepage cross-sectional area of ​​the i-th layer, in meters. 2 ; The initial water saturation is dimensionless. The water saturation at the leading edge is dimensionless. At initial water saturation Under certain conditions, the flow fraction of the aqueous phase in the oil-water two-phase flow (i.e., the initial aqueous phase splitting rate).

[0033] Let be the aqueous phase flow function, and its formula is:

[0034]

[0035] in, The water saturation level is The relative permeability of the aqueous phase, dimensionless; The water saturation level is Relative permeability of the oil phase, dimensionless; The viscosity of the aqueous phase is expressed in Pa·s. The viscosity is the oil phase viscosity, in Pa·s.

[0036] Water saturation at the leading edge Determined by the following formula:

[0037]

[0038] in, The first derivative of the water phase splitting function at the leading edge saturation represents the instantaneous rate of change of the splitting at that point.

[0039] Optionally, the minimum variance of the propulsion velocity of each water-driven leading edge in S6 is calculated using the following formula:

[0040]

[0041] in, The propulsion speed of the water-driven leading edge.

[0042] Optionally, the optimization method employs a particle swarm optimization algorithm, which includes: firstly, modeling the problem and optimizing variables, determining the objective function, and determining constraints; secondly, the algorithm sequentially performs initialization, fitness evaluation, individual and global optimum updates, iterative updates, constraint handling, and termination judgment steps.

[0043] On the other hand, a device for optimizing the well completion and perforation of water injection development in multi-layer heterogeneous oil reservoirs is provided. This device is used to implement the optimization method for optimizing the well completion and perforation of water injection development in multi-layer heterogeneous oil reservoirs. The device includes: a processor; a memory, on which computer-readable instructions are stored. When the computer-readable instructions are executed by the processor, the optimization method for optimizing the well completion and perforation of water injection development in multi-layer heterogeneous oil reservoirs is implemented.

[0044] On the other hand, a computer-readable storage medium is provided, wherein at least one instruction is stored in the storage medium, the at least one instruction being loaded and executed by a processor to implement any of the above-described methods for optimizing well completion and perforation in multi-layer heterogeneous reservoir water injection development.

[0045] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0046] This study quantitatively characterizes and establishes the functional / graphical relationship between perforation structural parameters (including but not limited to perforation density, diameter, penetration depth, and phase angle) and near-wellbore skin coefficient, eliminating the arbitrariness and uncertainty of current empirical design and providing a reproducible physical and quantitative basis for perforation design. Simultaneously, it introduces perforation parameters into a multi-layer water injection conduction model, establishing a quantitative mapping relationship between perforation, skin, inter-layer conduction capacity, and water injection volume distribution. This enables accurate calculation of water injection volume distribution in each layer under a given total injection volume, reflecting the direct impact of different perforation schemes on the inter-layer water injection profile. Furthermore, it uses oil-water two-phase displacement dynamics as a design evaluation objective, proposing and using the equalization of water drive front advance velocity as the core objective of perforation optimization. This guides perforation parameter adjustments based on the displacement mechanism, ensuring the synchronous advancement of water injection across multiple layers and maximizing reservoir sweep efficiency. Based on the established coupled model, it proposes and implements an engineering-oriented differentiated perforation optimization program, supporting the rapid generation of workable perforation schemes under field constraints. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used 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 those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a flowchart of the optimized method for balanced well completion and perforation utilization in water injection development of multi-layer heterogeneous oil reservoirs provided in this embodiment of the invention;

[0049] Figure 2 These are the perforation model diagram and mesh diagram provided in the embodiments of the present invention;

[0050] Figure 3 This is a graph showing the relationship between yield ratio and perforation density provided in an embodiment of the present invention;

[0051] Figure 4 This is a graph showing the relationship between the skin coefficient and perforation density provided in an embodiment of the present invention;

[0052] Figure 5 This is a graph showing the relationship between the yield ratio and the perforation depth provided in an embodiment of the present invention;

[0053] Figure 6 This is a graph showing the relationship between the skin coefficient and the perforation depth provided in an embodiment of the present invention;

[0054] Figure 7 This is a graph showing the relationship between the yield ratio and the perforation diameter provided in an embodiment of the present invention;

[0055] Figure 8 This is a graph showing the relationship between the epidermal coefficient and the perforation diameter provided in an embodiment of the present invention;

[0056] Figure 9 This is an optimized diagram of the perforation density, skin coefficient, water absorption, and water-driven leading edge propulsion speed of each layer provided in the embodiments of the present invention. Detailed Implementation

[0057] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0058] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0059] In the embodiments of this invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, their intended meanings are consistent. Similarly, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, their intended meanings are consistent.

[0060] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0061] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0062] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0063] To address the problems existing in the prior art, this invention provides an optimized method for balanced well completion and perforation during water injection development in multi-layered heterogeneous oil reservoirs. The invention will be described in detail below with reference to the accompanying drawings.

[0064] The technical route of the proposed method for optimizing perforation in multi-layer heterogeneous reservoirs with balanced water injection development is as follows: Perforation-near-well fluid-structure interaction simulation is conducted using numerical platforms such as COMSOL to invert the skin coefficient, establishing a perforation parameter-skin coefficient inversion library; inter-layer water injection distribution is calculated using this database and a water injection conduction model; the advance velocity of the water drive front in each layer is calculated using the Buckley-Leverett theory; a particle swarm optimization algorithm is used to solve for the perforation parameter combination that balances the advance velocity of the water drive front in each layer under the premise of satisfying engineering constraints; and the optimization results are converted into an engineering-executable perforation construction plan and monitoring feedback process, realizing a closed loop from design to construction to production feedback.

[0065] This invention aims to provide a differentiated perforation equalization method that has both theoretical depth and can directly guide field implementation, overcoming the main defects of existing technologies such as qualitative nature, strong reliance on experience, disconnect from displacement mechanisms, and poor engineering adaptability, thereby significantly improving the water injection development effect of multi-layer heterogeneous reservoirs.

[0066] Figure 1 This is a flowchart of an optimized method for balanced well completion and perforation utilization in water injection development of multi-layered heterogeneous oil reservoirs according to an embodiment of the present invention. Figure 1 As shown, it includes the following steps:

[0067] S1. Acquisition of basic parameters and determination of engineering constraints for multi-layered reservoirs: Before implementing perforation optimization design, parameter acquisition and engineering constraint determination are first performed on the target injection well and the multi-layered reservoirs within its control range. The input parameters include: 1. Layered geological and physical property parameters (layer i): permeability Effective thickness Porosity Initial water saturation Initial formation pressure 2. Fluid parameters: Injected water viscosity Crude oil viscosity 3. Wellbore and well pattern parameters: wellbore radius, oil-water relative permeability model parameters (residual saturation, Corey index, etc.). Supply boundary radius Injection well type and well network pattern (e.g., five-point well network), designed total injection volume 4. Perforation construction constraint parameters: selectable perforation gun model, perforation diameter range, perforation depth range, minimum / maximum allowable perforation density per layer, construction cost, time and safety constraints;

[0068] S2. Numerical simulation of near-wellbore flow in perforation and establishment of a skin coefficient inversion library. The purpose of this step is to quantitatively establish the correspondence between perforation parameters and equivalent skin coefficients, providing a callable basic database or function model for perforation parameter optimization.

[0069] S3. Calculate the water injection volume distribution of the multi-layer reservoir under general water injection conditions; specifically, set the preset skin coefficient of each layer in the multi-layer reservoir as a set of parameter values ​​in the preset parameter set, and calculate the water injection volume distribution of each layer in the multi-layer reservoir under general water injection conditions based on the preset skin coefficient.

[0070] S4. Based on the water injection volume distribution, calculate the water-drive leading edge propulsion speed of the oil-water two-phase system to evaluate the multi-layer dynamic balance.

[0071] S5. Based on the advance velocity of the water drive front of each layer, determine the variance of the advance velocity of the water drive front of each layer in the multi-layer reservoir;

[0072] S6. Repeat steps S3 to S5 to obtain the preset skin coefficient set in step S3 when the variance of the propulsion velocity of each water-drive leading edge is minimized, and obtain the optimal perforation parameter combination at this time based on the skin coefficient inversion library.

[0073] Wherein, S2 in the optimization method includes the following steps:

[0074] S21. Establish a near-well numerical simulation library for single-well single-layer perforation (i.e., COMSOL library construction). This is to quantitatively obtain the mapping relationship or response surface (database / fitting function) from perforation parameters (pore density, pore diameter, pore depth, etc.) to skin coefficients in subsequent steps.

[0075] S22. Establish a baseline productivity model for open-hole wells. Under open-hole completion conditions, the productivity expression for a single-layer steady-state radial flow is:

[0076]

[0077] in For open-hole completion production, m 3 / s; k is the formation permeability, m 2 h is the reservoir thickness, m; pe is the boundary pore pressure, Pa; pw is the bottom hole flowing pressure, Pa; μ is the formation fluid viscosity, Pa·s; re is the supply boundary radius, m; Let be the wellbore radius, in meters (m).

[0078] S23. Obtain the perforated well flow rate through near-wellbore numerical simulation of single-well single-layer perforation in S1. The yield ratio is calculated as follows:

[0079]

[0080] in The production rate of the perforated well is expressed in m³ / s. For the production of open-hole wells, m 3 / s.

[0081] The skin coefficient can be calculated from the yield ratio:

[0082]

[0083] in, The radius of the reservoir is in meters. The figure represents the well diameter, in meters (m). This skin factor is used to equivalently characterize the near-wellbore flow resistance introduced by the perforation structure.

[0084] S24. Establish a mapping library between perforation parameters and skin coefficients. That is, by repeating steps S21 to S23 for different combinations of perforation parameters, calculate the corresponding skin coefficients and form a mapping library between perforation parameters and skin coefficients. The specific forms include, but are not limited to: discrete tables; fitting functions; response surface models.

[0085] This mapping database unifies the complex influence of perforation geometry on near-wellbore seepage into skin coefficient parameters that can be directly used for multi-layer water injection balance design and perforation parameter optimization calculation. It is the core foundation for the present invention to achieve quantitative optimization design.

[0086] Step S21 above also includes the following steps:

[0087] S211. Construct a numerical model of the near-wellbore area for a single well and a single layer. Specifically, for any wellbore and its corresponding single reservoir in the target reservoir, construct a three-dimensional numerical model including the wellbore, perforation channels, and the near-wellbore formation area. The near-wellbore formation area is modeled as a cylinder with a radius equal to the supply radius and a thickness equal to the corresponding reservoir thickness. A wellbore model with a radius equal to the wellbore radius is placed at the center of the cylinder. Several perforation channels are arranged on the wellbore wall, and the structural parameters of the perforation channels include at least perforation density, perforation diameter, and perforation depth.

[0088] S212. Assign formation physical and mechanical parameters to the three-dimensional numerical model; assign seepage parameters such as formation permeability, porosity and fluid viscosity to the formation region in the three-dimensional numerical model, and assign mechanical parameters such as elastic modulus, Poisson's ratio and Biot coefficient, so that the formation region can simultaneously characterize seepage behavior and mechanical response behavior.

[0089] S213. In the three-dimensional numerical model, both the pore fluid seepage field and the rock skeleton mechanical field are simultaneously set, and the coupling between the two is achieved through Biot's effective stress principle. The specific settings are as follows:

[0090] First, the pore fluid seepage field is described using Darcy's law:

[0091]

[0092] Where q is the fluid flow rate, u is the fluid viscosity, and k is the permeability. It is a pressure gradient.

[0093] The fluid flow simultaneously satisfies the governing equations of the seepage field:

[0094]

[0095] For source and sink terms, ρ is the fluid density. Reservoir porosity, where u is the fluid viscosity and k is the permeability. It is a pressure gradient.

[0096] Considering fluid compressibility, the seepage field equation becomes:

[0097]

[0098] is the fluid compressibility coefficient; other parameters are the same as above.

[0099] Secondly, the mechanical field of the rock skeleton is considered. The coupling relationship between pore pressure and rock stress is established using Biot's effective stress principle, enabling changes in pore pressure to induce formation stress and deformation responses. Assuming the formation rock mass is an isotropic, homogeneous, elastic porous medium with small deformations, its strain-displacement relationship is as follows:

[0100]

[0101] in These are the components of the strain tensor. and These are displacement components. Ignoring inertial forces, the equilibrium equations can be expressed as:

[0102]

[0103] in These are the stress tensor components. This represents the volume force component.

[0104] The strain-stress relationship of the rock skeleton is as follows:

[0105]

[0106] in, The invariant in stress is K, the bulk modulus of the reservoir rock mass is G, the shear modulus is ν, Poisson's ratio is α, and Biot coefficient is α. , It is the bulk modulus of the rock mass framework, and P is the fluid pressure. It is the Kronecker notation, when i=j =1; when i≠j =0. From the above formula, we can obtain:

[0107]

[0108] The effects of pore pressure variations on formation stress and deformation are realized through the above coupling equations.

[0109] S214. Boundary and Initial Condition Settings: Apply constant pore pressure to the outer boundary of the formation. A constant bottom hole pressure is applied to the inner wall of the wellbore. Alternatively, a constant injection flow boundary can be applied; displacement constraints can be applied to the outer boundary of the formation in the mechanical field to prevent overall rigid body displacement.

[0110] S215. Mesh generation and solution control: Locally finer meshes are set in the areas near the perforation channels and wellbore; relatively coarser meshes are used in areas far from the wellbore; mesh independence is checked to ensure that the calculation results are not sensitive to mesh size; a steady-state or quasi-steady-state fully coupled solver is used to ensure that the flow field and the mechanical field converge synchronously.

[0111] S215. Calculation of steady-state flow rate in perforated wells: After the numerical model converges, the total steady-state flow rate at the wellbore is extracted and denoted as the perforated well production rate. .

[0112] S3 in the optimization method includes calculating the water injection distribution of multi-layer reservoirs under general water injection conditions, based on the introduction of the perforation skin coefficient. Under a five-point well network with a fixed total injection volume and one injection well and four production wells, assuming no crossflow between layers and approximate linear flow, the equivalent transmission coefficient between injection and production wells is:

[0113]

[0114] The water absorption of each layer is distributed proportionally according to the conductivity coefficient:

[0115]

[0116] S4 in the optimization method includes converting the water injection volume allocation result into the water-drive front propulsion velocity, which serves as an evaluation index for multi-layer mobilization equilibrium. The displacement process is described using Buckley–Leverett theory, and the water phase splitting function is:

[0117]

[0118] in, The water saturation level is The relative permeability of the aqueous phase, dimensionless; The water saturation level is Relative permeability of the oil phase, dimensionless; The viscosity of the aqueous phase is expressed in Pa·s. The viscosity is the oil phase viscosity, in Pa·s.

[0119] Leading edge saturation The Rankine–Hugoniot condition must be met:

[0120]

[0121] in, The first derivative of the aqueous phase split function at the leading-edge saturation represents the instantaneous rate of change of the split at that point;

[0122] The propulsion velocity of the water-drive leading edge is:

[0123]

[0124] in, denoted as the propulsion velocity of the i-th water-drive leading edge, in m / s; The water injection volume for the i-th layer is expressed in m³ / s. The effective seepage cross-sectional area of ​​the i-th layer, in meters. 2 ; i represents the initial water saturation, which is dimensionless; The water saturation at the leading edge is dimensionless. To achieve the initial water saturation Under certain conditions, the flow fraction of the aqueous phase in the oil-water two-phase flow (i.e., the initial aqueous phase splitting rate).

[0125] The optimization objective is to minimize the variance of the propulsion velocity at the water-driven front between multiple layers and achieve balanced propulsion. This step elevates the perforation design objective from "water injection balance" to "displacement process balance," which is the core idea that distinguishes this invention from existing technologies.

[0126] In step S5 of the optimization method, the optimal combination of perforation parameters is determined to make the advance velocity of the multi-layer water-drive leading edge as consistent as possible:

[0127]

[0128] Considering the mechanical strength of the tubing, the perforation density falls within a reasonable range:

[0129]

[0130] Optimization of perforation parameters in multi-layered reservoirs is a global optimization problem characterized by multiple variables, strong nonlinearity, and multiple constraints.

[0131] To achieve balanced propulsion at the leading edge of multi-layer water-drive systems, this invention can also model the perforation parameter optimization as a multivariable constrained optimization problem and solve it using a particle swarm optimization algorithm. The specific steps are as follows:

[0132] The first step is to model the optimization problem, which requires optimizing the variable, namely the n-dimensional vector composed of the perforation densities of each layer. It is also necessary to determine the objective function, namely, minimizing the variance of the propulsion velocity at the leading edge of each water-drive layer. We also need to define constraints, that is... ;

[0133] Secondly, the algorithm flow needs to be established, which requires initialization, i.e., randomly generating M particle positions (perforation density combinations) within the feasible region, with the initial velocity set to zero; fitness evaluation is also required, i.e., for each particle, steps S2 to S4 are executed sequentially (calculating the skin coefficient, conduction coefficient, water injection volume, and leading edge velocity) to calculate the objective function value; individual and global optimum updates are also required, i.e., recording the historical best position and the global optimum position of each particle; iterative updates are also required, i.e., adjusting the perforation density vector of each particle according to the velocity and position update formula of the particle swarm optimization algorithm; constraint handling is also required, i.e., using a reflection boundary strategy to handle variables outside the feasible region; finally, a termination judgment is made, i.e., the algorithm terminates when the maximum number of iterations is reached or the optimal solution shows no significant improvement for several consecutive times.

[0134] This invention makes the following improvements to the standard particle swarm optimization algorithm, specifically addressing the characteristics of the perforation optimization problem:

[0135] Fitness function design: The leading-edge velocity variance is directly used as the optimization objective, achieving precise control of the "displacement process equilibrium"; Adaptive parameter adjustment: Linearly decreasing inertia weights and dynamically adjusted acceleration coefficients improve convergence efficiency; Engineering constraint handling: A reflection boundary strategy ensures that the perforation density remains within the engineering feasible range. The algorithm outputs the optimal perforation density vector. The corresponding skin coefficient, water injection volume distribution, and water-driven leading edge propulsion speed provide a direct basis for differentiated perforation design.

[0136] By implementing differentiated perforation schemes, we can achieve clear improvements in engineering indicators, including but not limited to: reducing the advance velocity of the water-driven water injection front in high-permeability layers, increasing the advance velocity of the water-driven water injection front in low-permeability layers, significantly reducing the velocity variance of multi-layer fronts, improving the liquid absorption intensity per unit thickness in low-permeability layers, delaying the overall water breakthrough time, and improving long-term recovery rate. At the same time, we can verify the feasibility and effectiveness of the schemes through numerical simulation and field monitoring.

[0137] Optionally, in a more specific embodiment, to study the impact of perforation parameters on reservoir productivity and reservoir physical properties, such as... Figure 1 As shown, a numerical simulation model of single-phase radial flow in a single well was constructed based on the COMSOL multi-field coupling software platform. The reservoir radius is 150 m, the thickness is 1 m, the wellbore radius is set to 0.07 m, and the thickness of the cement sheath around the wellbore is 30 mm. The model considers fluid-structure interaction effects and fluid compressibility. Under different perforation parameters (perforation density, depth, and diameter), the distribution of reservoir pressure with well spacing was simulated and calculated. Based on the production rate, the production ratio and skin factor were determined, thereby obtaining a complete perforation production chart.

[0138] The model's physical properties are as follows: crude oil density =885.1 kg / m³, viscosity =24.5 mPa·s, compressibility coefficient =1.0×10−9 Pa⁻¹; initial porosity =0.20, initial permeability =100 mD, effective stress coefficient α=0.7, elastic modulus G=20 GPa, Poisson's ratio ν=0.20, rock density =2500 kg / m³; initial formation pressure =18.9 MPa, bottom hole flowing pressure =11 MPa.

[0139] like Figure 2 and Figure 3 As shown, when the perforation depth is set to 0.6 m and the perforation diameter is 0.1 m, the production rate under different perforation densities is simulated, and the relationship between the yield ratio and the skin coefficient is calculated according to the formula. Figure 2 As shown, as the perforation density increases from 4 holes / m to 32 holes / m, the yield ratio exhibits a non-linear upward trend, increasing from 0.61 to 1.093. When the perforation density exceeds 16 holes / m, the yield ratio growth slows down, indicating that the production increase effect exhibits diminishing marginal returns. Meanwhile, as... Figure 3 As shown, the skin factor decreased significantly from 3.778 to -0.653, indicating that increasing the perforation density can effectively reduce the additional pressure drop in the wellbore and improve near-well flow conditions. Overall, increasing the perforation density can significantly improve productivity, but when the density exceeds a certain threshold (approximately 16 perforations / m), the productivity improvement effect gradually weakens.

[0140] Using the same COMSOL modeling steps described above, the yield ratio and skin coefficient values ​​at different perforation depths can be simulated. For example... Figure 4 As shown, when the perforation depth increases from 0.4 m to 2.0 m, the yield ratio increases from 0.855 to 1.285. The skin coefficient at different perforation depths is calculated using the formula, as follows: Figure 5As shown, the skin coefficient decreased from 1.301 to -1.701, indicating that deep-penetrating perforations can significantly enhance reservoir conductivity, reduce additional pressure drop, and even achieve flow capacity superior to open-hole completions. For low-permeability reservoirs, deep-penetrating perforation technology can effectively improve flow channels and increase productivity.

[0141] Using the same COMSOL modeling steps described above, the yield ratio and skin coefficient values ​​under different perforation diameters can be simulated. For example... Figure 6 As shown, as the aperture increases from 5 mm to 30 mm, the yield ratio increases from 0.802 to 1.331.

[0142] The skin coefficient for different perforation diameters is calculated using the formula, such as... Figure 7 As shown, the skin factor decreased from 1.894 to -1.907, and the trend gradually slowed down. The larger the orifice diameter, the stronger the fluid flow into the wellbore, and the smaller the skin factor. When the orifice diameter exceeds 12 mm, the production ratio approaches 1, and further increasing the orifice diameter will cause the skin factor to turn negative, indicating that large-diameter perforation can significantly improve near-wellbore flow performance.

[0143] To address the issues of uneven interlayer utilization, insufficient injection of low-permeability layers, and severe crossflow in high-permeability layers during the injection and production process of multi-layer heterogeneous reservoirs, a differentiated perforation optimization model for multi-layer parallel systems was constructed based on the aforementioned perforation skin coefficient calculation model. By adjusting the perforation parameters (mainly perforation density and perforation depth) of different permeability zones, the near-wellbore resistance distribution is controlled, thereby achieving balanced displacement and coordinated utilization of multi-layer reservoirs.

[0144] Assuming the reservoir consists of multiple layers, the physical properties (permeability) of each layer are as follows: ,thickness Porosity Initial water saturation Given that the perforation diameter and depth are the same, select the perforation density. As an optimization variable, the relationship between the skin coefficient and the perforation density function can be established based on the skin effect calculation results. .

[0145] Under a five-point well network with a fixed total injection volume and one injection well and four production wells, assuming no crossflow between layers and approximate linear flow, the equivalent transmission coefficient between injection and production wells is:

[0146]

[0147] The water absorption of each layer is distributed proportionally according to the conductivity coefficient:

[0148]

[0149] The displacement process is described using the Buckley–Leverett theory, and the aqueous phase splitting function is:

[0150]

[0151] Leading edge saturation Satisfying the Rankine–Hugoniot condition:

[0152]

[0153] The propulsion velocity of the water-drive leading edge is:

[0154]

[0155] The optimization objective is to minimize the variance of the leading-edge velocities across multiple layers to achieve balanced propulsion.

[0156] Considering the mechanical strength of the tubing, the perforation density falls within a reasonable range:

[0157]

[0158] Optimization of perforation parameters in multi-layered reservoirs is a multivariable, highly nonlinear, and multi-constrained global optimization problem. Complex nonlinear relationships exist between perforation density, skin factor, and flow capacity. Conventional gradient-based optimization algorithms are prone to getting trapped in local optima during the solution process, making it difficult to obtain the global optimum.

[0159] Particle Swarm Optimization (PSO) is inspired by the cooperative behavior of flocks of birds and schools of fish, and is an optimization method based on swarm intelligence. The algorithm treats each candidate solution as a particle, and through information sharing and dynamic adjustments of position and velocity among particles, it achieves self-organized evolution of the swarm in the search space. Particles continuously update their states based on their historical best position and the global best position of the swarm, thus gradually approaching the optimal solution. It has a simple structure, few parameters, and is easy to implement, and exhibits a relatively fast convergence speed in continuous variable optimization. Its drawback is that it may experience premature convergence in later stages, resulting in slightly weaker global search capabilities compared to genetic algorithms or differential evolution algorithms.

[0160] To compare the performance of different algorithms in perforation parameter optimization, a typical five-point well pattern with one injection and four production points was selected as a case study. The well spacing was 150 m, the water injection rate was 50 m³ / d, and the well diameter was 0.1 m. The reservoir was vertically divided into four layers, and the permeability, thickness, porosity, and initial water saturation of each layer are shown in Table 1.

[0161] Table 1. Physical property parameters of multi-layer reservoirs

[0162]

[0163] Before optimization, the perforation density of each layer was 16 holes / m. Under these conditions, due to the significant difference in permeability between layers, the water injection propulsion velocity in high-permeability layers was much higher than that in low-permeability layers, which easily led to the formation of upper crossflow channels and insufficient utilization of low-permeability layers. To improve the flow distribution between layers and the balance of water-drive front propulsion velocity, four intelligent algorithms were used to optimize the perforation density of each layer.

[0164] Calculations showed that the optimal perforation densities for each layer obtained by the particle swarm optimization algorithm were: 4 perforations / m for high-permeability layers, 5.4 perforations / m for medium-permeability layers, 22.5 perforations / m for low-permeability layers, and 40 perforations / m for ultra-low-permeability layers. The optimization results indicate that the perforation density of high-permeability layers should be appropriately reduced to increase near-wellbore resistance and suppress water flow-induced breakthrough; simultaneously, the perforation density of low-permeability and ultra-low-permeability layers should be increased to reduce surface resistance and enhance conductivity, thereby promoting coordinated propulsion of multiple reservoir layers. The changes in the main parameters of each layer before and after optimization are shown in Table 2.

[0165] Table 2 Optimization results for non-uniform perforation:

[0166]

[0167] As can be seen from the results in the table, after optimization, the proportion of water absorption in the low-permeability layer and the ultra-low-permeability layer is significantly increased, and the liquid absorption intensity per unit thickness and the advance speed of the water-drive front are significantly increased; while the proportion of water absorption in the high-permeability layer and the medium-permeability layer decreases and the advance speed slows down, indicating that the fluid distribution in the longitudinal direction is more reasonable. Figure 8 The optimized perforation density, skin coefficient, and leading edge velocity changes in each layer further validate this trend.

[0168] Optimization results show that the multi-layer kinetic equilibrium achieved through differentiated perforation design mainly relies on a "high-resistance, low-promotion" flow control mechanism. Increasing the perforation density in low-permeability layers significantly reduces their skin resistance, improves the near-wellbore flow field, and enhances conductivity; conversely, reducing the number of perforations in high-permeability layers effectively increases the near-wellbore pressure gradient and delays the formation of water channeling channels. After optimization, the advance velocity of the water drive front in each layer tends to be consistent from the significantly dispersed state before optimization, indicating that differentiated perforation can achieve effective inter-layer flow coupling and synergistic displacement. From the perspective of algorithm performance, the particle swarm optimization algorithm has high computational efficiency while ensuring global search capability, making it suitable for continuous parameter optimization problems, especially in perforation density optimization design, where it exhibits good adaptability and stability. Overall, the particle swarm optimization algorithm shows the best comprehensive performance in perforation optimization for multi-layer heterogeneous reservoirs. Differentiated perforation optimization design based on intelligent optimization algorithms can effectively improve inter-layer flow distribution, achieve synergistic displacement and kinetic equilibrium in multi-layer reservoirs, and provide reliable theoretical support and technical means for refined injection-production control in complex heterogeneous reservoirs.

[0169] Compared with existing water injection well completion design methods based on empirical coefficients or qualitative stratified adjustments, this invention introduces a fine numerical simulation of near-wellbore perforation and a skin coefficient inversion mechanism to establish a quantitative control relationship between "perforation parameters, flow resistance, and water injection propulsion speed," achieving at least the following technical effects:

[0170] 1. Achieving quantitative and balanced control of water injection propulsion velocity in multi-layered heterogeneous reservoirs: This invention no longer relies solely on reservoir permeability or inter-layer correlation coefficients for qualitative stratified water injection. Instead, it introduces controllable near-wellbore additional flow resistance by adjusting the perforation parameters of each layer, thereby making the equivalent flow capacity of reservoirs with different permeabilities tend to be consistent under water injection conditions. This achieves quantitative balance of the propulsion velocity at the multi-layered oil-water front. This method effectively avoids the problems of excessively rapid water injection in high-permeability layers and insufficient water injection in low-permeability layers.

[0171] 2. Suppressing early water channeling in high-permeability layers and delaying water injection breakthrough time: By specifically reducing the perforation density or perforation equivalent flow area in high-permeability layers and increasing the skin coefficient in the near-wellbore area of ​​the layer, this invention can significantly increase the water injection resistance of high-permeability layers, thereby delaying the breakthrough time of the water drive front in high-permeability layers and reducing the amount of ineffective circulating water.

[0172] 3. Improve the water injection utilization of low-permeability and medium-low permeability layers: This invention improves the water injection capacity of low-permeability layers by increasing the perforation density or depth in the perforation layer and reducing the skin coefficient of the near-wellbore area of ​​the layer. This allows the water injection volume to be effectively distributed to the medium-low permeability reservoir, thereby improving the overall vertical utilization of the reservoir.

[0173] 4. Achieving a shift from experience-based to mechanism-based quantitative perforation parameter design: This invention constructs a near-wellbore numerical model of single-well, single-layer perforation, and combines production ratio calculation with skin coefficient inversion to establish a quantitative mapping relationship between perforation parameters and skin coefficient. This avoids the problem of perforation design in existing technologies being highly dependent on field experience or analog parameters, and improves the scientificity and repeatability of perforation scheme design.

[0174] 5. Applicable to reservoirs with different degrees of heterogeneity and different reservoir conditions: Since the present invention explicitly introduces formation permeability, porosity, mechanical parameters and perforation geometry parameters into the model, its method can be applied to reservoirs with different degrees of heterogeneity, different layer thickness combinations and different stress sensitivity characteristics, and has good engineering applicability and promotion value.

[0175] 6. Provides a unified parameter basis for subsequent multi-layer water injection allocation and dynamic optimization: By establishing a skin coefficient inversion library, this invention provides a unified and callable basic parameter system for multi-layer water injection volume allocation calculation, multi-layer water injection balance mobilization model and subsequent dynamic optimization adjustment, which is convenient for connection with water injection development scheme design and on-site implementation.

[0176] In a specific implementation, as one example, a multi-layer heterogeneous reservoir water injection development balanced mobilization completion perforation optimization device may also include multiple processors, each of which may be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). Here, a processor may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0177] Optionally, a memory may also be included for storing software programs that execute the present invention, and the execution of such programs is controlled by a processor. For specific implementation details, please refer to the above method embodiments, which will not be repeated here.

[0178] Optionally, the memory may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. The memory may be integrated with the first processor or may exist independently and be coupled to the processor through optimized device interface circuitry; this embodiment of the invention does not specifically limit this.

[0179] It may also include transceivers for communicating with network devices or with terminal devices.

[0180] Optionally, the transceiver may include a receiver and a transmitter. The receiver is used to implement the receiving function, and the transmitter is used to implement the sending function.

[0181] Optionally, the transceiver can be integrated with the processor or exist independently, and can be coupled to the processor by optimizing the interface circuit of the device. This embodiment of the invention does not specifically limit this.

[0182] Furthermore, the technical effects of the well completion and perforation optimization equipment for balanced water injection development in multi-layer heterogeneous reservoirs can be referred to the technical effects of the well completion and perforation optimization method for balanced water injection development in multi-layer heterogeneous reservoirs described in the above method embodiments, and will not be repeated here.

[0183] It should be understood that the processor in the embodiments of the present invention can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor, or it can be any conventional processor.

[0184] It should also be understood that the memory in the embodiments of the present invention can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDR SDRAM), enhanced synchronous DRAM (ESDRAM), synchronous linked DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0185] The above embodiments can be implemented, in whole or in part, by software, hardware (such as circuits), firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0186] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0187] It should be understood that, in various embodiments of the present invention, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0188] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0189] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0190] In the several embodiments provided by this invention, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0191] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0192] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0193] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0194] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for optimizing well completion and perforation in the balanced development of water injection in multi-layered heterogeneous oil reservoirs, characterized in that... The optimization method includes the following steps: S1. Collect basic parameters of multi-layered reservoirs and determine engineering constraints; S2. Based on the basic parameters of the multi-layer reservoir and the engineering constraints, numerical simulation of the perforated near-well flow in the multi-layer reservoir is performed, and a skin coefficient inversion library is established. The skin coefficient inversion library includes the mapping relationship or response surface from perforation parameters to skin coefficients; S3. Set the preset skin coefficient of each layer in the multi-layer reservoir as a set of parameter values ​​in the preset parameter set, and calculate the water injection volume distribution of each layer in the multi-layer reservoir under the general water injection condition based on the preset skin coefficient. S4. Based on the water injection volume distribution, calculate the water-driven leading edge propulsion velocity of each layer; S5. Based on the advance velocity of the water drive front of each layer, determine the variance of the advance velocity of the water drive front of each layer in the multi-layer reservoir; S6. Modify the preset skin coefficient to different values ​​in the preset parameter set, repeat steps S3 to S5, obtain the variance of the water-drive leading edge propulsion velocity of each layer corresponding to different preset skin coefficients, and determine the perforation parameter corresponding to the skin coefficient of the minimum value of the variance of the water-drive leading edge propulsion velocity of each layer in the skin coefficient inversion library as the optimal perforation parameter combination.

2. The optimized method for balanced well completion and perforation utilization in water injection development of multi-layer heterogeneous oil reservoirs according to claim 1, characterized in that, The establishment of the epidermal coefficient inversion library in S2 includes: S21. Establish a database for near-wellbore numerical simulation of single-well single-layer perforation; S22. Based on the open-hole well benchmark production model, calculate the production capacity of a single layer of steady-state radial flow; S23. Based on the production capacity of the single-layer steady-state radial flow and the perforation flow rate obtained from the database simulation, calculate the perforation production ratio, and calculate the skin coefficient based on the perforation production ratio; S24. Based on different perforation parameter combinations, repeat S21 to S23 to obtain different skin coefficients and establish a skin coefficient inversion library.

3. The optimized method for balanced well completion and perforation utilization in water injection development of multi-layer heterogeneous oil reservoirs according to claim 2, characterized in that, The database establishment in S21 includes: S211. Construct a three-dimensional numerical model of a single-well, single-layer near-well zone; S212. Assign values ​​to the formation properties and mechanical parameters of the three-dimensional numerical model; S213. In the three-dimensional numerical model, a pore fluid seepage field and a rock skeleton mechanical field are set up, and the coupling between the two is achieved through Biot's effective stress principle. S214. Set the boundary and initial conditions of the three-dimensional numerical model; S215. Set up a locally refined mesh in the area near the perforation channels and wellbore of the three-dimensional numerical model, and use a steady-state or quasi-steady-state fully coupled solver for solving; S216. After the three-dimensional numerical model converges, the steady-state total flow rate at the wellbore is obtained.

4. The optimized method for balanced well completion and perforation utilization in multi-layer heterogeneous reservoir water injection development according to claim 3, characterized in that, S213 includes: The pore fluid seepage field is set based on Darcy's law and the mass conservation equation; Based on the Biot effective stress principle, a coupling relationship between pore pressure and rock stress is established, and the mechanical field of the rock skeleton is set so that changes in pore pressure can cause formation stress and deformation response.

5. The optimized method for balanced well completion and perforation utilization in water injection development of multi-layer heterogeneous oil reservoirs according to claim 2, characterized in that, The formula for calculating the perforated well productivity ratio (PRI) in S23 is as follows: in The production rate of the perforated well, in meters (m³). 3 / s; in The production rate of open-hole wells, in meters (m³). 3 / s, its formula is: Where q0 is the open-hole completion production, in m³. 3 / s; k is the formation permeability, in meters. 2 h is the reservoir thickness in meters; pe is the boundary pore pressure in Pa; pw is the bottom hole flowing pressure in Pa; μ is the formation fluid viscosity in Pa·s; re is the supply boundary radius in meters; rw is the wellbore radius in meters. The formula for the epidermal coefficient S is: in, The radius of the reservoir is in meters. The diameter is in meters (m).

6. The optimized method for balanced well completion and perforation utilization in water injection development of multi-layer heterogeneous oil reservoirs according to claim 1, characterized in that, The formula for the water-drive leading-edge propulsion velocity in S4 is: in, denoted as the propulsion velocity of the i-th water-drive leading edge, in m / s; The volume of water injected into the i-th layer, in meters. 3 / s; The effective seepage cross-sectional area of ​​the i-th layer, in meters. 2 ; The initial water saturation is dimensionless. The water saturation at the leading edge is dimensionless. To achieve the initial water saturation Under certain conditions, the flow fraction of the aqueous phase in the oil-water two-phase flow (i.e., the initial aqueous phase splitting rate). in, Let be the aqueous phase flow function, and its formula is: in, The water saturation level is The relative permeability of the aqueous phase, dimensionless; The water saturation level is Relative permeability of the oil phase, dimensionless; The viscosity of the aqueous phase is expressed in Pa·s. The viscosity is the oil phase viscosity, in Pa·s. Water saturation at the leading edge Determined by the following formula: in, Let be the first derivative of the water phase split function at the leading edge saturation, and represent the instantaneous split rate at that point.

7. The optimized method for balanced well completion and perforation utilization in multi-layer heterogeneous reservoir water injection development according to claim 1, characterized in that, The minimum variance of the propulsion velocity of each layer of the water-driven leading edge in S6 is calculated using the following formula: in, The propulsion speed of the water-driven leading edge.

8. The optimized method for balanced well completion and perforation utilization in multi-layer heterogeneous reservoir water injection development according to claim 1, characterized in that, The optimization method employs a particle swarm optimization algorithm for solution, which includes: First, the problem is modeled by optimizing variables, determining the objective function, and defining constraints. Then, the algorithm sequentially performs initialization, fitness evaluation, individual and global optimum updates, iterative updates, constraint handling, and termination judgment steps.

9. A well completion and perforation optimization device for balanced water injection development in multi-layer heterogeneous oil reservoirs, characterized in that, The optimized well completion and perforation equipment for balanced water injection development in multi-layer heterogeneous reservoirs includes: processor; A memory storing computer-readable instructions that, when executed by the processor, implement the method as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium contains program code that can be invoked by a processor to execute the method as described in any one of claims 1 to 8.

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