A method for optimizing the reuse of well patterns for tapping remaining oil after polymer flooding in an oil reservoir

Abstract

The application relates to the technical field of intelligent control, and proposes a remaining oil tapping well pattern reuse optimization method for a type of oil layer after polymer flooding, which comprises the following steps: acquiring basic data of all unit grids in all grid units of a well pattern in a block after polymer flooding of a type of oil layer; screening dead oil area grids in the grid units, calculating remaining oil tapping potential of the dead oil area grids; determining dead oil area clusters composed of the dead oil area grids, calculating comprehensive potential of the dead oil area clusters, and screening high-potential dead oil area clusters; calculating new well fitness of each dead oil area grid in the potential dead oil area clusters, acquiring new well positions determined by the potential dead oil area clusters, and re-siting the new well positions according to relative distribution of all the new well positions, so that the optimization of the tapping well pattern reuse is realized. The application aims to improve the optimization effect of the well pattern reuse.

Description

Technical Field

[0001] This application relates to the field of intelligent control technology, specifically to an optimization method for reusing residual oil well networks after polymer flooding of oil reservoirs. Background Technology

[0002] Type I oil-bearing reservoirs are the main oil-bearing reservoirs in oilfields, characterized by abundant reserves, high permeability, and good connectivity. Polymer flooding (PF) involves optimizing the well network for reuse. This optimization, without drilling new wells, involves adjusting the existing well network to allow for the efficient extraction of unrecovered crude oil from the reservoirs after PF. Optimizing the well network for reuse after PF in Type I oil-bearing reservoirs can improve crude oil recovery rates, achieve efficient resource utilization, reduce costs, increase efficiency, and enhance the economic benefits of oilfield development.

[0003] In the process of adjusting the existing polymer flooding well network, it is necessary to analyze the location of newly drilled and produced wells based on the remaining oil saturation distribution map, to accurately drill wells and reduce the well spacing and network. However, the analysis process often ignores the coupled influence of multiple factors such as reservoir heterogeneity, inter-well interference, and dynamic remaining oil distribution, which leads to the selection of some new well locations in areas with low remaining oil potential, resulting in a waste of investment. Summary of the Invention

[0004] This application provides a method for optimizing the reuse of residual well networks after polymer flooding in oil reservoirs, in order to solve the problem of resource waste caused by unreasonable selection of new well locations, resulting in poor optimization of well network reuse. The specific technical solution adopted is as follows:

[0005] One embodiment of this application provides an optimization method for reusing residual well networks after polymer flooding of oil reservoirs, the method comprising the following steps:

[0006] Collect basic data of all wells in all grid cells of the well network within the block after polymer flooding of a type of oil reservoir, and calculate the basic data of the cell grid.

[0007] Based on the total number and area of ​​all grid cells, and the spatial relationship between the centroid of the grid cell and the well, dead oil zone grids are selected from the grid cells. Combined with the basic data, the remaining oil tapping potential of the dead oil zone grids is calculated.

[0008] Based on the remaining oil tapping potential of dead oil zone grids and the distance between dead oil zone grids, dead oil zone clusters composed of some dead oil zone grids are determined. Based on the remaining oil tapping potential, area and basic data of all dead oil zone grids in the dead oil zone cluster, the comprehensive potential of the dead oil zone cluster is calculated. Based on the comprehensive potential, high-potential dead oil zone clusters are selected from the dead oil zone clusters.

[0009] Based on the remaining oil tapping potential and basic data of the dead oil zone grids within the potential dead oil zone cluster, as well as the distance between the dead oil zone grids and well points, the new well fitness of each dead oil zone grid within the potential dead oil zone cluster is calculated. Based on the new well fitness, the new well locations determined by the potential dead oil zone cluster are obtained. Based on the relative distribution of all new well locations, the new well locations are relocated to optimize the reuse of the tapping well network.

[0010] Furthermore, the specific method for filtering dead oil zone grids within the grid cells based on the total number and area of ​​all grid cells, and the spatial relationship between the centroid of the grid cell and the well, includes:

[0011] Calculate the effective displacement radius based on the total number and total area of ​​all grid cells;

[0012] The position of the centroid of the grid cell is taken as the position of the grid cell, and the Euclidean distance between the centroid of the grid cell and the position of the nearest well is denoted as the nearest neighbor distance of the grid cell.

[0013] Grid cells whose distance to neighboring wells is greater than the effective displacement radius are denoted as dead oil zone grids.

[0014] Furthermore, the method for determining the effective displacement radius is as follows:

[0015] The product of the total number of all grid cells and pi is denoted as the first product. The square root of the ratio of the total area of ​​all grid cells to the first product is taken as the effective displacement radius.

[0016] Furthermore, the specific calculation method for the remaining oil tapping potential of the dead oil zone grid is as follows:

[0017] The ratio of the difference between the nearest well distance and the effective displacement radius in the dead oil zone grid to the effective displacement radius is denoted as the relative distance of the dead oil zone grid.

[0018] The basic data includes remaining oil saturation, permeability, and effective thickness. The positive correlation between the relative distance of the dead oil zone grid and the remaining oil saturation, permeability, and effective thickness in the basic data is recorded as the remaining oil potential of the dead oil zone grid.

[0019] Furthermore, the specific method for determining the dead oil zone cluster is as follows:

[0020] The 60th percentile of the remaining oil potential of all dead oil zone grids is taken as the first screening threshold. Dead oil zone grids with remaining oil potential less than or equal to the first screening threshold are deleted.

[0021] When the Euclidean distance between the centroids of two dead oil zone grids is less than or equal to the preset spatial neighborhood radius, the two dead oil zone grids are assigned to the same dead oil zone cluster, and dead oil zone clusters containing fewer than or equal to the preset second screening threshold are deleted.

[0022] Furthermore, the specific calculation method for the comprehensive potential of the dead oil zone cluster is as follows:

[0023] The average remaining oil tapping potential of all dead oil grids within the same dead oil zone cluster is denoted as the average tapping potential of the dead oil zone cluster.

[0024] The total area of ​​all dead oil region grids within a dead oil region cluster is denoted as the total area of ​​the dead oil region cluster.

[0025] The average residual oil saturation of all dead oil grids within the same dead oil zone cluster is denoted as the average residual oil saturation of the dead oil zone cluster.

[0026] The average effective thickness of all dead oil zone grids within the same dead oil zone cluster is denoted as the effective average thickness of the dead oil zone cluster.

[0027] The average porosity of the dead oil zone cluster is denoted as the average porosity of the dead oil zone cluster, which is the average porosity of all dead oil zone grids within the same dead oil zone cluster.

[0028] The positive correlation between the average potential, total area, average remaining oil saturation, effective average thickness, and average porosity of dead oil clusters is denoted as the comprehensive potential of dead oil clusters.

[0029] Furthermore, the specific method for screening high-potential dead oil clusters from dead oil clusters based on comprehensive potential includes:

[0030] The dead oil clusters with the highest average potential at the third screening threshold are all recorded as high-potential dead oil clusters.

[0031] Furthermore, the formula for calculating the new well fitness of the dead oil zone grid is: ; in, Indicates the first high-potential dead oil cluster New well adaptability of dead oil zone grids; , and These are the first weighting coefficient, the second weighting coefficient, and the third weighting coefficient, respectively, and the sum of the first weighting coefficient, the second weighting coefficient, and the third weighting coefficient is 1. Indicates the first high-potential dead oil cluster The remaining oil potential of each dead oil zone grid; Indicates the first high-potential dead oil cluster The distance from the nearest well point to the grid of dead oil zones; This represents the minimum distance from all dead oil zone grids within a high-potential dead oil zone cluster to the nearest well point; Indicates the first high-potential dead oil cluster The remaining oil saturation in the base data of each dead oil zone grid.

[0032] Furthermore, the specific method for determining the location of new wells based on the new well adaptability and the potential dead oil zone cluster includes:

[0033] The centroid of the dead oil zone grid corresponding to the maximum new well fitness of all dead oil zone grids within the potential dead oil zone cluster is used as the location of the new well determined by the potential dead oil zone cluster.

[0034] Furthermore, the specific method for relocating new wells based on their relative distribution includes:

[0035] When the distance between the new well locations determined by two potential dead oil zone clusters is less than the well spacing threshold, the new well location corresponding to the maximum value of the new well fitness of the two new well locations is retained, and the new well location corresponding to the minimum value of the new well fitness of the two new well locations is relocated.

[0036] The relocation step includes: selecting all dead oil zone grids within the potential dead oil zone cluster corresponding to the new well location and whose distance from the retained new well location is greater than or equal to the well spacing threshold; and taking the centroid of the dead oil zone grid corresponding to the maximum value of the new well fitness in the selected dead oil zone grid as the new well location.

[0037] The beneficial effects of this application are:

[0038] This application first selects grid cells that are far from existing wells based on their location relative to the existing grid cells, thus obtaining dead oil zones within these grid cells. Then, based on the enrichment and reserves of remaining oil at the location of these dead oil zones, the relative permeability of the reservoir, and the distance between the grid cells and the wells, the development value of the remaining oil at the location of these dead oil zones is evaluated, thus obtaining the remaining oil tapping potential of these dead oil zones. Furthermore, considering the connectivity and scale effect of the dead oil zone grids, large-area continuous distribution of high-potential dead oil zone grids is selected to obtain dead oil zone clusters composed of these grid cells. Then, the reserves and development value of the remaining oil in the area where the dead oil zone clusters are located are evaluated to obtain the comprehensive potential of the dead oil zone clusters. The greater the comprehensive potential of a dead oil zone cluster, the more suitable it is for new wells to be drilled and produced. Based on the comprehensive potential, high-potential dead oil zone clusters are selected from among the dead oil zone clusters. Subsequently, the location of a new production well can be determined based on each high-potential dead oil cluster. To improve production efficiency, when determining the location of a new production well based on the location of a high-potential dead oil cluster, it is necessary to ensure that the location of the new production well is as close as possible to the location with high remaining oil saturation within the high-potential dead oil cluster, while also keeping it as far away as possible from the existing well network to avoid inter-well interference and reduce mutual impact on production capacity between different wells. Therefore, the location of the new well is determined based on the adaptability of the new well to the potential dead oil cluster. Finally, to avoid the problem of inter-well interference caused by the new well locations determined by different potential dead oil clusters being too close, the spatial distribution of all new well locations is used to determine whether there are any conflicts. Conflicting new well locations are then adjusted to form a well network layout scheme with reduced well spacing. This optimizes the reuse of the tapped well network and solves the problem of resource waste caused by unreasonable selection of new well locations, resulting in poor optimization of the well network reuse effect. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of a method for optimizing the reuse of residual oil well networks after polymer flooding in an oil reservoir, provided in one embodiment of this application. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] Please see Figure 1 The document illustrates a flowchart of an optimized method for reusing residual well networks after polymer flooding of oil reservoirs, according to an embodiment of this application. The method includes the following steps:

[0043] Step S001: Collect basic data of all wells in all grid cells of the well network within the block after polymer flooding of a type of oil reservoir, and calculate the basic data of the cell grid.

[0044] In the process of reducing the well spacing and well network, all polymer drive wells are converted into injection wells, all water drive wells are converted into production wells, and new well locations are selected, with all newly drilled wells being used as production wells. The objective of this application is to determine the locations of new wells and improve the optimization effect of well network reuse.

[0045] After polymer flooding of a certain type of oil reservoir, the well network within the block is divided into uniformly sized grid cells, and the basic data of all wells within all grid cells are obtained.

[0046] In this embodiment, the size of the grid cell is set to 10m×10m; the wells include polymer flooding wells and water flooding wells; the basic data includes the well number, spatial coordinates, geological parameters, production data and remaining oil saturation; the geological parameters include sandstone thickness, effective thickness, permeability and porosity; the production data includes the daily injection volume of the injection well, the daily production volume of the production well, the daily oil production and water cut.

[0047] Using the centroid of the cell grid as the cell grid's location, determine the two wells closest to the centroid of the cell grid, and perform linear interpolation calculations based on the basic data of the two wells to obtain the basic data of the cell grid.

[0048] Linear interpolation is a well-known technique and will not be elaborated further.

[0049] At this point, the basic data for all wells and cell grids within all grid cells have been obtained.

[0050] Step S002: Based on the total number and area of ​​all grid cells, and the spatial relationship between the centroid of the grid cell and the well, filter the dead oil zone grids in the grid cells, and calculate the remaining oil tapping potential of the dead oil zone grids in combination with the basic data.

[0051] The product of the total number of all grid cells and pi is denoted as the first product. The square root of the ratio of the total area of ​​all grid cells to the first product is taken as the effective displacement radius. The position of the centroid of the grid cell is taken as the position of the grid cell. The Euclidean distance between the centroid of the grid cell and the position of the nearest well is denoted as the nearest neighbor distance of the grid cell. Grid cells whose nearest neighbor distance is greater than the effective displacement radius are denoted as dead oil zone grids.

[0052] For ease of calculation, this embodiment uses 3.14 for pi.

[0053] Understandably, the effective displacement radius is the radius of the circular region corresponding to each well, determined by uniformly distributing the total area of ​​all grid cells to each well. If the distance to the nearest well of a grid cell is greater than the effective displacement radius, it means that the distance from the grid cell to any well is greater than the effective displacement radius, and such a grid cell is designated as a dead oil zone grid.

[0054] The ratio of the difference between the nearest well distance and the effective displacement radius of the dead oil zone grid to the effective displacement radius is denoted as the relative distance of the dead oil zone grid. The positive correlation between the relative distance of the dead oil zone grid and the remaining oil saturation, permeability and effective thickness in the basic data is denoted as the remaining oil potential of the dead oil zone grid.

[0055] It is understood that a positive correlation is applied to the relative distance with the remaining oil saturation, permeability, and effective thickness in the basic data, ensuring that the relative distance, remaining oil saturation, permeability, and effective thickness in the basic data are positively correlated with the remaining oil potential of the dead oil zone grid. It is understood that the positive correlation in this application refers to the relationship between the independent and dependent variables. The independent variables are the relative distance with the remaining oil saturation, permeability, and effective thickness in the basic data, and the dependent variable is the remaining oil potential of the dead oil zone grid. The positive correlation means that the dependent variable increases (decreases) as the independent variable increases (decreases), and can be an additive or multiplicative relationship.

[0056] Preferably, as an embodiment of this application, the normalized value of the product of the relative distance of the dead oil zone grid plus the number 1 and the normalized value of the remaining oil saturation, permeability and effective thickness in the basic data is recorded as the remaining oil potential of the dead oil zone grid.

[0057] It should be noted that this embodiment uses the Z-Score standard normalization method to calculate the normalized value. In practical applications, implementers may use other methods of existing technology, such as the maximum-minimum normalization method or the sigmoid function, to calculate the normalized value, and no limitation is made here.

[0058] Among them, residual oil saturation reflects the enrichment of residual oil at the location of the dead oil zone grid; the higher the residual oil saturation, the richer the residual oil at the location of the dead oil zone grid. Permeability reflects the relative seepage capacity of the reservoir at the location of the dead oil zone grid; the higher the permeability, the stronger the relative seepage capacity of the reservoir at the location of the dead oil zone grid, which is more conducive to the flow and exploitation of residual oil. Effective thickness reflects the relative thickness of the reservoir at the location of the dead oil zone grid; the greater the effective thickness, the richer the residual oil reserves at the location of the dead oil zone grid, and the higher the development value. When the relative distance of the dead oil zone grids is larger, the grid unit is farther away from the existing well network, the degree of impact of the existing well network on the location of the dead oil zone grid is lower, and the more intact the residual oil is. The greater the potential for tapping the residual oil in the dead oil zone grid, the greater the value and potential for developing the residual oil at the location of the dead oil zone grid.

[0059] This completes the extraction of remaining oil potential from the dead oil zone grid.

[0060] Step S003: Based on the remaining oil tapping potential of the dead oil zone grid and the distance between the dead oil zone grids, determine the dead oil zone clusters composed of some dead oil zone grids. Based on the remaining oil tapping potential, area and basic data of all dead oil zone grids in the dead oil zone cluster, calculate the comprehensive potential of the dead oil zone cluster. Based on the comprehensive potential, select the high-potential dead oil zone clusters among the dead oil zone clusters.

[0061] Furthermore, considering the connectivity and scale effect of dead oil zone grids, high-potential dead oil zone grids with large-area continuous distribution are screened.

[0062] The 60th percentile of the remaining oil potential of all dead oil zone grids is set as the first screening threshold. Dead oil zone grids with remaining oil potential less than or equal to the first screening threshold are deleted. The following process only analyzes the remaining dead oil zone grids.

[0063] If the Euclidean distance between the centroids of two dead oil region grids is less than or equal to a preset spatial neighborhood radius, the two dead oil region grids are assigned to the same dead oil region cluster. The number of dead oil region grids contained in each dead oil region cluster is counted. If the number of dead oil region grids contained in each cluster is less than or equal to a preset second screening threshold, the dead oil region cluster is deleted. The following process only analyzes the remaining dead oil region clusters.

[0064] In this embodiment, the second screening threshold is set to 30 meters. Dead oil clusters containing fewer than or equal to the preset second screening threshold are deleted. The purpose is to eliminate dead oil clusters corresponding to local anomalies with low noise and development value based on the connectivity and scale effect of the oil field grid, so as to avoid local isolated low-potential dead oil grids being selected as the location of new wells.

[0065] The average remaining oil tapping potential of all dead oil zone grids within the same dead oil zone cluster is denoted as the average tapping potential of the dead oil zone cluster; the total area of ​​all dead oil zone grids within the same dead oil zone cluster is denoted as the total area of ​​the dead oil zone cluster; the average remaining oil saturation in the basic data of all dead oil zone grids within the same dead oil zone cluster is denoted as the average remaining oil saturation of the dead oil zone cluster; the average effective thickness in the basic data of all dead oil zone grids within the same dead oil zone cluster is denoted as the effective average thickness of the dead oil zone cluster; the average porosity in the basic data of all dead oil zone grids within the same dead oil zone cluster is denoted as the average porosity of the dead oil zone cluster; and the positive correlation result of the average tapping potential, total area, average remaining oil saturation, effective average thickness, and average porosity of the dead oil zone cluster is denoted as the comprehensive potential of the dead oil zone cluster.

[0066] It is understood that a positive correlation is applied to the average potential, total area, average remaining oil saturation, effective average thickness, and average porosity of the dead oil cluster, ensuring that these factors are positively correlated with the overall potential of the dead oil cluster. It is also understood that the positive correlation in this application refers to the relationship between the independent and dependent variables. The independent variables are the average potential, total area, average remaining oil saturation, effective average thickness, and average porosity of the dead oil cluster, and the dependent variable is the overall potential of the dead oil cluster. The positive correlation means that the dependent variable increases (decreases) as the independent variable increases (decreases), and can be an additive or multiplicative relationship.

[0067] Preferably, as an embodiment of this application, the cumulative product of the average potential for tapping the dead oil cluster, the total area, the average remaining oil saturation, the effective average thickness, and the average porosity is denoted as the comprehensive potential of the dead oil cluster.

[0068] The average tapping potential of a dead oil cluster is used to evaluate the average enrichment and recoverability of the remaining oil within the cluster; the total area of ​​the dead oil cluster reflects its spatial scale; the average saturation of the remaining oil within the dead oil cluster is used to evaluate its average saturation; the effective average thickness of the dead oil cluster is used to evaluate its average effective reservoir thickness; the product of the total area, effective average thickness, and average porosity of the dead oil cluster is used to evaluate the void volume of the subsurface rock, i.e., the spatial volume of the remaining oil; the larger the product, the more remaining oil it can hold; the average porosity of the dead oil cluster is used to evaluate its reservoir capacity; the comprehensive potential of the dead oil cluster is used to evaluate the expected volume of the recoverable remaining oil, with dimensions of [missing information]. The greater the overall potential of a dead oil cluster, the greater the remaining oil reserves in the area where the dead oil cluster is located, and the greater the value and potential for development, making it more suitable for new wells to be drilled and produced.

[0069] The dead oil clusters with the highest average potential at the third screening threshold are all recorded as high-potential dead oil clusters.

[0070] It is understood that the value of the third screening threshold is determined by the preset number of newly drilled and produced wells. In this embodiment, 25 new wells need to be drilled and produced. Therefore, the value of the third screening threshold in this embodiment is 25, that is, the location of a new well is determined for each high-potential dead oil zone cluster.

[0071] Thus, a high-potential dead oil cluster was obtained.

[0072] Step S004: Based on the remaining oil tapping potential and basic data of the dead oil zone grids within the potential dead oil zone cluster, as well as the distance between the dead oil zone grids and well points, calculate the new well fitness of each dead oil zone grid within the potential dead oil zone cluster. Based on the new well fitness, obtain the new well locations determined by the potential dead oil zone cluster. Based on the relative distribution of all new well locations, relocate the new well locations to optimize the reuse of the tapping well network.

[0073] When determining the location of a new production well based on the location of a high-potential dead oil cluster, in order to improve production efficiency, the location of the new production well should be as close as possible to the location with high remaining oil saturation within the high-potential dead oil cluster. At the same time, it should be as far away as possible from the existing well network to avoid inter-well interference and reduce the mutual impact of production capacity between different wells.

[0074] Based on the remaining oil tapping potential of the dead oil zone grid within the potential dead oil zone cluster, the remaining oil saturation in the basic data, and the distance between the dead oil zone grid and the well point, the new well fitness of each dead oil zone grid within the potential dead oil zone cluster is calculated. Specifically, the new well fitness calculation formula is as follows: ; in, Indicates the first high-potential dead oil cluster New well adaptability of dead oil zone grids; , and The first, second, and third weighting coefficients are respectively, and the sum of the first, second, and third weighting coefficients is 1. In this embodiment, the values ​​of the first, second, and third weighting coefficients are 0.5, 0.3, and 0.2, respectively, to avoid interference from the distance between wells and to emphasize the influence of the remaining oil tapping potential and the remaining oil saturation. Indicates the first high-potential dead oil cluster The remaining oil potential of each dead oil zone grid; Indicates the first high-potential dead oil cluster The distance from the nearest well point to the grid of dead oil zones; This represents the minimum distance from all dead oil zone grids within a high-potential dead oil zone cluster to the nearest well point; Indicates the first high-potential dead oil cluster The remaining oil saturation in the base data of each dead oil zone grid.

[0075] The greater the adaptability of the dead oil zone grid to new wells, the more appropriate it is to select the area corresponding to the dead oil zone grid as the location for new wells to determine the potential dead oil zone cluster.

[0076] The centroid of the dead oil zone grid corresponding to the maximum new well fitness of all dead oil zone grids within the potential dead oil zone cluster is used as the location of the new well determined by the potential dead oil zone cluster.

[0077] To avoid interference between wells caused by the locations of new wells identified in clusters of dead oil with different potential, it is necessary to determine whether there are any conflicts based on the spatial distribution of all new well locations, and to adjust the locations of conflicting new wells to form a well network layout scheme with reduced well spacing.

[0078] Specifically, the preset well spacing threshold is 80 meters. When the distance between the new well locations determined by two potential dead oil zone clusters is less than the well spacing threshold, it is determined that there is a conflict between the new well locations determined by the two potential dead oil zone clusters. The new well location corresponding to the maximum value of the new well fitness of the two new well locations is retained, and the new well location corresponding to the minimum value of the new well fitness of the two new well locations is relocated.

[0079] Specifically, the relocation steps are as follows: Select all dead oil zone grids within the potential dead oil zone cluster corresponding to the new well location, whose distance from the retained new well location is greater than or equal to the well spacing threshold. Take the centroid of the dead oil zone grid corresponding to the maximum value of the new well fitness in the selected dead oil zone grid as the new well location.

[0080] Determine whether the distance between all new well locations after relocation is less than the well spacing threshold. If so, relocate the conflicting new well locations until the distance between all new well locations after relocation is greater than or equal to the well spacing threshold, thus achieving the selection of new well locations.

[0081] All polymer flooding wells in the well network are converted into injection wells, all water flooding wells are converted into production wells, all new wells are used as production wells, and all new wells are added to high-potential dead oil areas to form an injection-production well network, which constitutes an 80m well spacing five-point method well network.

[0082] Among them, new wells are set in high-potential dead oil areas where the remaining oil is rich and has not been effectively affected by the existing well network, which can maximize the degree of well network control and the efficiency of remaining oil production.

[0083] This achieves the optimization of the well network reuse.

[0084] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. An optimization method for reusing residual oil well networks after polymer flooding of oil reservoirs, characterized in that, The method includes the following steps: Collect basic data of all wells in all grid cells of the well network within the block after polymer flooding of a type of oil reservoir, and calculate the basic data of the cell grid. Based on the total number and area of ​​all grid cells, and the spatial relationship between the centroid of the grid cell and the well, dead oil zone grids are selected from the grid cells. Combined with the basic data, the remaining oil tapping potential of the dead oil zone grids is calculated. Based on the remaining oil tapping potential of dead oil zone grids and the distance between dead oil zone grids, dead oil zone clusters composed of some dead oil zone grids are determined. Based on the remaining oil tapping potential, area and basic data of all dead oil zone grids in the dead oil zone cluster, the comprehensive potential of the dead oil zone cluster is calculated. Based on the comprehensive potential, high-potential dead oil zone clusters are selected from the dead oil zone clusters. Based on the remaining oil tapping potential and basic data of the dead oil zone grids within the high-potential dead oil zone cluster, as well as the distance between the dead oil zone grids and well points, the new well fitness of each dead oil zone grid within the high-potential dead oil zone cluster is calculated. Based on the new well fitness, the new well locations determined for the high-potential dead oil zone cluster are obtained. Based on the relative distribution of all new well locations, the new well locations are relocated to optimize the reuse of the tapping well network. The specific calculation method for the remaining oil tapping potential of the dead oil zone grid is as follows: The ratio of the difference between the nearest well distance and the effective displacement radius in the dead oil zone grid to the effective displacement radius is denoted as the relative distance of the dead oil zone grid. The basic data includes remaining oil saturation, permeability, and effective thickness. The positive correlation between the relative distance of the dead oil zone grid and the remaining oil saturation, permeability, and effective thickness in the basic data is recorded as the remaining oil potential of the dead oil zone grid. The specific method for determining the dead oil zone cluster is as follows: The 60th percentile of the remaining oil potential of all dead oil zone grids is taken as the first screening threshold. Dead oil zone grids with remaining oil potential less than or equal to the first screening threshold are deleted. When the Euclidean distance between the centroids of two dead oil zone grids is less than or equal to the preset spatial neighborhood radius, the two dead oil zone grids are assigned to the same dead oil zone cluster, and dead oil zone clusters containing fewer than or equal to the preset second screening threshold are deleted.

2. The method for optimizing the reuse of residual well networks after polymer flooding of oil reservoirs according to claim 1, characterized in that, The method for filtering dead oil zone grids in the grid cells based on the total number and area of ​​all grid cells, as well as the spatial relationship between the centroid of the grid cell and the well, includes the following specific methods: Calculate the effective displacement radius based on the total number and total area of ​​all grid cells; The position of the centroid of the grid cell is taken as the position of the grid cell, and the Euclidean distance between the centroid of the grid cell and the position of the nearest well is denoted as the nearest neighbor distance of the grid cell. Grid cells whose distance to neighboring wells is greater than the effective displacement radius are denoted as dead oil zone grids.

3. The method for optimizing the reuse of residual well networks after polymer flooding of oil reservoirs according to claim 2, characterized in that, The method for determining the effective displacement radius is as follows: The product of the total number of all grid cells and pi is denoted as the first product. The square root of the ratio of the total area of ​​all grid cells to the first product is taken as the effective displacement radius.

4. The method for optimizing the reuse of residual well networks after polymer flooding of oil reservoirs according to claim 1, characterized in that, The specific calculation method for the comprehensive potential of the dead oil zone cluster is as follows: The average remaining oil tapping potential of all dead oil grids within the same dead oil zone cluster is denoted as the average tapping potential of the dead oil zone cluster. The total area of ​​all dead oil region grids within a dead oil region cluster is denoted as the total area of ​​the dead oil region cluster. The average residual oil saturation of all dead oil grids within the same dead oil zone cluster is denoted as the average residual oil saturation of the dead oil zone cluster. The average effective thickness of all dead oil zone grids within the same dead oil zone cluster is denoted as the effective average thickness of the dead oil zone cluster. The average porosity of the dead oil zone cluster is denoted as the average porosity of the dead oil zone cluster, which is the average porosity of all dead oil zone grids within the same dead oil zone cluster. The positive correlation between the average potential, total area, average remaining oil saturation, effective average thickness, and average porosity of dead oil clusters is denoted as the comprehensive potential of dead oil clusters.

5. The method for optimizing the reuse of residual well networks after polymer flooding of oil reservoirs according to claim 1, characterized in that, The specific method for screening high-potential dead oil clusters from dead oil clusters based on comprehensive potential is as follows: The dead oil clusters with the highest average potential at the third screening threshold are all recorded as high-potential dead oil clusters.

6. The method for optimizing the reuse of residual well networks after polymer flooding of oil reservoirs according to claim 1, characterized in that, The formula for calculating the new well fitness of the dead oil zone grid is: in, Indicates the first high-potential dead oil cluster. New well adaptability of grids in dead oil zones; , and These are the first weighting coefficient, the second weighting coefficient, and the third weighting coefficient, respectively, and the sum of the first weighting coefficient, the second weighting coefficient, and the third weighting coefficient is 1. Indicates the first high-potential dead oil cluster. The remaining oil potential of each dead oil zone grid; Indicates the first high-potential dead oil cluster. The distance from the nearest well point to the grid of dead oil zones; This represents the minimum distance from all dead oil zone grids within a high-potential dead oil zone cluster to the nearest well point; Indicates the first high-potential dead oil cluster. The remaining oil saturation in the base data of each dead oil zone grid.

7. The method for optimizing the reuse of residual well networks after polymer flooding of oil reservoirs according to claim 1, characterized in that, The specific method for determining the location of new wells based on new well adaptability and high-potential dead oil zone clusters includes: The centroid of the dead oil zone grid corresponding to the maximum new well fitness of all dead oil zone grids within the high-potential dead oil zone cluster is used as the location of the new well determined by the high-potential dead oil zone cluster.

8. The method for optimizing the reuse of residual well networks after polymer flooding of oil reservoirs according to claim 1, characterized in that, The specific method for relocating new wells based on their relative distribution includes: When the distance between the new well locations determined by two high-potential dead oil clusters is less than the well spacing threshold, the new well location corresponding to the maximum value of the new well fitness of the two new well locations is retained, and the new well location corresponding to the minimum value of the new well fitness of the two new well locations is relocated. The relocation step includes: selecting all dead oil zone grids within the high-potential dead oil zone cluster corresponding to the relocated new well location, whose distance from the retained new well location is greater than or equal to the well spacing threshold; and taking the centroid of the dead oil zone grid corresponding to the maximum value of the new well fitness in the selected dead oil zone grid as the relocated new well location.

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