Well group control reserve chemical flooding sweep efficiency calculation method

Abstract

The application discloses a kind of well group control reserves chemical flooding sweep efficiency calculation method, comprising the following steps: (1), three-dimensional fine porosity and permeability model is established;(2), well group control reserves chemical flooding sweep efficiency calculation.This method can improve the accuracy of well group control reserves chemical flooding sweep efficiency calculation, so as to provide accurate basis for chemical flooding reservoir engineering design, numerical simulation accuracy, tracking adjustment and post-evaluation of implementation effect of scheme.Compared with the traditional chemical flooding sweep efficiency calculation, the method is more scientific, the concept is clearer, the index is more quantitative, and the chemical flooding sweep efficiency calculation result is more accurate and reliable, which has important significance for guiding oilfield production and development.

Description

Technical Field

[0001] This invention relates to the technical field of quantifying the spatial sweep efficiency of chemical flooding for controlled reserves in well groups based on three-dimensional geological models, and in particular to a method for improving the calculation accuracy of the spatial sweep efficiency of chemical flooding for controlled reserves in well groups of three types of oil formations. Background Technology

[0002] The spatial sweep efficiency of chemical flooding for controlled reserves refers to the extent to which the chemical agent sweeps through the reservoir. It is the ratio of the volume of the reservoir washed by the chemical agent to the total volume of the reservoir. It directly affects the development effectiveness of chemical flooding and is of great significance for the design of chemical flooding reservoir engineering schemes, the accuracy of numerical simulations, follow-up adjustments, and post-implementation evaluation of the scheme's effectiveness. Currently, the commonly used method in oilfields is to calculate the sweep efficiency by dividing the volume of the sand body connected to the total volume of the controlled reserves by the well group. This method does not consider the inaccessible porosity of chemical flooding and the connectivity quality between injection and production units, leading to an overestimation of the calculated sweep efficiency of chemical flooding for controlled reserves. This directly affects the results of chemical flooding reservoir engineering scheme design, numerical simulations, follow-up adjustments, and post-implementation evaluation of the scheme's effectiveness. Summary of the Invention

[0003] To address the problems existing in the background art, this invention provides a method for calculating the sweep efficiency of chemical flooding for controlled reserves in well groups. This application takes water wells as the center and considers the effects of microscopic accessible porosity, interlayer heterogeneity, and phase transition in chemical flooding to determine the method for calculating the sweep efficiency of chemical flooding for controlled reserves in well groups.

[0004] The technical solution provided by this invention is: a method for calculating the sweep efficiency coefficient of chemical flooding for well group controlled reserves, comprising the following steps:

[0005] (1) Establishment of a three-dimensional fine porosity and permeability model:

[0006] ④ Resample at 0.125m to construct a fine interpretation model for porosity and permeability logging, complete the secondary interpretation of logging, and further characterize the heterogeneity within a single well layer;

[0007] ⑤ The spatial distribution of sedimentary units is controlled by both marker layers and thickness surfaces to ensure the rationality of the spatial structural framework. At the same time, the thickness of oil layers and interlayers and their contact relationship with oil layers are considered. The thickness of vertical sedimentary units is subdivided by "equal scale subdivision" to characterize the vertical heterogeneity and establish a three-dimensional fine structural model.

[0008] ⑥ Based on the three-dimensional fine structural model, and using the results of secondary interpretation of well logging, a porosity and permeability geological model is established through phase control stochastic modeling technology;

[0009] (2) Calculation of sweep efficiency of chemical flooding for controlled reserves in well groups:

[0010] ①Based on the three-dimensional fine-structure model, a mesh volume model is established through the Geometrical Modeling module, and then the total pore volume model is finally obtained by multiplying the mesh volume model and the porosity model.

[0011] ②Based on the relationship between the microscopic sweep pore volume correction coefficient and permeability of the chemical agent obtained from the experiment, a layered accessible pore volume coefficient field is established. The porosity correction model is established by multiplying the accessibility coefficient field with the porosity. The sweep pore volume model without considering the layer combination and planar phase transition is obtained by multiplying the porosity correction model with the grid volume model.

[0012] ③ Implement the sand body combination mode between different injection and production units of typical well groups. Multiply the chemical flooding accessible pore volume model without considering phase change in a certain direction by the corresponding experimentally determined macroscopic sweep pore volume correction coefficient of the chemical agent between injection and production units to obtain the accessible pore volume considering phase change in a certain direction. Accumulate the sweep pore volume of the controlled reserves in all directions of the well group to obtain the chemical flooding accessible pore volume considering phase change in a single layer of the well group.

[0013] ④ The ratio of the accumulated swept pore volume to the total pore volume is the chemical sweep efficiency coefficient of the well group's controlled reserves.

[0014] In step (1) above, step ③, firstly, a three-dimensional sedimentary facies model is established: using the existing fine reservoir description area, sedimentary facies data points are derived according to sedimentary units, including three columns of data: horizontal axis, vertical axis, and facies value. The sedimentary facies data points of each sedimentary unit are added to the three-dimensional fine structural model area. According to the nearest point method, the sedimentary facies data points of each sedimentary unit are quantified. Through the grid assignment method, the quantified sedimentary facies data of each unit are sampled into the grid, and finally, a three-dimensional sedimentary facies model is established; then, a porosity geological model and a permeability geological model are established: using 0.1 The results of the 25m reservoir physical property parameter densification were interpreted. According to the physical property parameter sampling interval of 0.125m, the porosity and permeability data of all single wells in the study area were split, and a physical property parameter file was formed for each single well. The split single well physical property parameter files were loaded into the three-dimensional model. Through data discretization processing, the single well physical property parameter files were sampled into the grid frame. Then, based on the theory of random function interpolation, the random simulation technology controlled by the sedimentary facies model was adopted. Through variogram analysis, the sequential Gaussian interpolation method was applied to generate a three-dimensional geological model of porosity and permeability physical property parameters.

[0015] In step (1) above, step ④ involves implementing the sand body combination model between different injection and production units in a typical well group. The accessible pore volume model of chemical flooding without considering phase change in a certain direction is multiplied by the corresponding experimentally determined macroscopic sweep pore volume correction coefficient of the chemical agent between injection and production units to obtain the accessible pore volume considering phase change in a certain direction. The cumulative sweep pore volume of the controlled reserves in all directions of the well group is then added to obtain the chemical flooding accessible pore volume of a single layer of the well group considering phase change. The ratio of the cumulative sweep pore volume to the total pore volume is the chemical flooding sweep efficiency coefficient of the controlled reserves of the well group.

[0016] The beneficial effects of this invention are as follows: This method can improve the accuracy of calculating the sweep efficiency coefficient of chemical flooding in well groups, thereby providing an accurate basis for the design of chemical flooding reservoir engineering schemes, the accuracy of numerical simulation, tracking and adjustment, and the post-implementation evaluation of the scheme's effectiveness. Compared with traditional chemical flooding sweep efficiency coefficient calculations, this method is more scientific, with clearer concepts and more quantifiable indicators, resulting in more accurate and reliable calculation results, which is of great significance for guiding oilfield production and development. Attached Figure Description

[0017] Figure 1 It is a three-dimensional detailed structural model diagram;

[0018] Figure 2 It is a three-dimensional sedimentary facies model diagram;

[0019] Figure 3 It is a geological model diagram of porosity;

[0020] Figure 4 It is a geological model diagram of permeability;

[0021] Figure 5 This is a graph showing the relationship between the microscopic pore volume correction factor of chemical agents and permeability;

[0022] Figure 6 This is a distribution diagram of the accessibility coefficient model for sedimentary units;

[0023] Figure 7 This is a diagram showing the porosity of the well group and its corrected porosity.

[0024] Figure 8 This is a porosity model diagram of well group correction (single well group example);

[0025] Figure 9 This is a well profile diagram showing the accessible pore volume of the well group without considering phase change.

[0026] Figure 10 This is a chemical flooding accessible pore volume model diagram (without considering phase transition);

[0027] Figure 11 This is an experimentally determined graph showing the macroscopic sweep pore volume correction coefficient of the phase change agent between injection and production units;

[0028] Figure 12 This is a distribution map of phase change types of well group controlled reserves;

[0029] Figure 13 This is a diagram of the total pore volume model;

[0030] Figure 14 This is a diagram of the accessible pore volume model. Detailed Implementation

[0031] The following is a method for calculating the sweep efficiency of chemical flooding for controlled reserves in well groups. However, it should be noted that this method is not limited to these embodiments. In the detailed description of this method below, some specific details are described in detail. However, those skilled in the art will fully understand the parts not described in detail.

[0032] This application focuses on the calculation of the sweep efficiency of chemical flooding for controlled reserves in well groups. It clarifies methods to improve the accuracy of the calculation of the sweep efficiency of chemical flooding for controlled reserves in well groups from three aspects: the establishment of a fine geological model, the determination of the microscopic accessible porosity correction coefficient and the phase change porosity volume correction coefficient.

[0033] The specific process is as follows:

[0034] (1) Establishment of a three-dimensional fine porosity and permeability model:

[0035] ① The porosity and permeability fine interpretation model was reconstructed based on 0.125m sampling, and the secondary interpretation of single-well logging was completed. Through the intensified interpretation of reservoir physical property parameters at 0.125m, the heterogeneity within the layer can be finely characterized, providing a reliable basis for the fine calculation of the degree of chemical flooding control.

[0036] Table 1. Comparison of interpretation results from original boreholes and seepage with those from 0.125m reinforced drilling.

[0037]

[0038] ② Create a new simulated work area, import wellhead data, well strata data, well logging interpretation breakpoints, seismic interpretation fault files (sticks format), and seismic tracing stratigraphic files. Apply seismic interpretation stratigraphic data as constraints, and establish a stratified bedding model based on the well strata files using convergence interpolation. Define a new geological model and determine the boundaries of the simulated work area. Perform Pillar gridding (establish a spatial grid body) to create an empty grid geological body. Activate the fault module (Faultmodeling), and directly convert the seismic interpretation faults (sticks) into a preliminary fault model. Apply well logging interpretation breakpoint constraints to correct the strike and morphology of the preliminary fault model, ultimately establishing a fault model with accurate location and reasonable morphology. Grid the bedding model and faults, considering the thickness of interlayers and their contact relationships with different sedimentary units. Use the "equal thickness subdivision" (Laying) method to subdivide the thickness of vertical sedimentary units, thereby characterizing the vertical heterogeneity within the layers and establishing a three-dimensional fine structural model containing fault and structural information. Simultaneously, four checks are conducted on the construction model: consistency checks between bedding planes and strata points, contact relationships between bedding planes and faults, cross-mesh checks between upper and lower bedding planes, and negative volume checks of the mesh. This completes the quality control of the 3D fine construction model. The 3D fine construction model, such as... Figure 1 As shown.

[0039] ③ Utilizing existing detailed reservoir description areas, gridded sedimentary facies data points are exported for each sedimentary unit, including three columns of data: x-axis, y-axis, and facies point. The sedimentary facies data points of each unit are imported into the 3D detailed structural model area. Make / edit the surface for each sedimentary unit's sedimentary facies data points, using the closest point method to quantify the data. Under the Facies modeling module conditions, the direct grid assignment method is applied to sample the quantified sedimentary facies data of each sedimentary unit into the grid, ultimately establishing a 3D sedimentary facies model as follows: Figure 2 As shown;

[0040] ④ Using the in-depth interpretation results of the 0.125m reservoir physical property parameters, the porosity and permeability attribute data of all single wells in the study area were split according to the 0.125m sampling interval, and a separate physical property parameter log file was formed for each single well; the splitting results of the physical property parameter data of wells G124-S345 are shown in Table 2.

[0041] Table 2 shows the splitting results of physical property parameter data for wells G124-S345 (physical property parameter log file).

[0042]

[0043] ⑤ Load the split single-well physical property parameter log files into the wellhead file. Apply the Scale up well logs module to sample the single-well physical property parameter log files into the grid frame. Then, based on the theory of random function interpolation, apply the Petrophysical modeling module and use stochastic simulation technology controlled by sedimentary facies models. Through data analysis, apply the sequential Gaussian interpolation method to establish the porosity (Ф) and permeability (stl) geological models for each sedimentary unit. The porosity (Ф) geological model is as follows: Figure 3 As shown, the permeability (STL) geological model is as follows: Figure 4 As shown.

[0044] (2) Calculation of sweep efficiency of chemical flooding for controlled reserves in well groups:

[0045] ① Based on the 3D refined structural model, the Geometrical Modeling module is applied, and the Cellvolume method is selected to establish a mesh volume model. Then, using the Propertycalculator, a new property model is defined. The new property model is equal to the product of the mesh volume model and the porosity model (Ф). The template selected during the calculation is Pore volume. This new property model is the total pore volume model. Figure 13 As shown;

[0046] ② Based on the experimentally determined limit that pores with permeability less than 20 mD are difficult for chemical agents to penetrate, the property calculator was used. During the calculation, the Poro volume template was selected to filter out pores with permeability less than 20 mD from the total pore volume model, resulting in a macroscopically accessible pore volume model. The macroscopically accessible pore volume model is shown below. Figure 14 As shown;

[0047] ③ Based on the relationship between the microscopic accessible pore volume correction factor and permeability determined by the block experiment, the curve of the relationship between the accessible pore volume correction factor and permeability is shown in the figure below. Figure 5 As shown; based on the geological model of physical parameters, a new property model is defined using the property calculator. The new property model is equal to 0.2304ln(stl)-0.5589. The template selected during the calculation is General. This new property model is the accessible pore volume correction coefficient model. The accessible pore volume correction coefficient model for each sedimentary unit is as follows. Figure 6As shown; using the property calculator again, a new property model is defined. This new property model is equal to the product of the accessible pore volume correction factor model and the porosity model. The template selected during the calculation is Porosity. This new property model is the corrected accessible porosity model, as shown below. Figure 8 As shown; in the data input module, right-click the settings button of the wellhead file, apply the Make logs function key to sample the corrected accessible porosity attribute model into the logs file of a single well, open the profile window, and display the original porosity and corrected porosity of the five wells in the Gao 229-Xiong 345 well group in the profile window, and compare the changes in porosity before and after correction. The changes in porosity before and after correction of the well group are compared as follows: Figure 7 As shown.

[0048] ④ Using the property calculator, define a new property model. This new model is equal to the product of the macroscopically accessible pore volume model and the modified accessible porosity model. The template selected during the calculation is Pore volume. The new property model does not consider the accessible pore volume model for phase transitions; the accessible pore volume model for chemical flooding (without considering phase transitions) is as follows: Figure 10 As shown. The well profile diagram of the accessible pore volume without considering phase change is shown below. Figure 9 As shown.

[0049] ⑤ The accessible pore volumes (without considering phase change) of four injection-production units were read from the chemical flooding accessible pore volume model (without considering phase change). The sand body combination modes among the four injection-production units in a typical well group were determined to be non-matrix and non-matrix combination, non-matrix and channel combination, non-matrix and non-matrix combination, and non-matrix and non-matrix combination. The macroscopic sweep efficiency correction factor of the chemical agent for the non-matrix and non-matrix combination was experimentally determined to be 0.68, and that for the non-matrix and channel combination was 0.863. Thus, the macroscopic sweep efficiency correction factors of the chemical agent for the four injection-production units were 0.68, 0.863, 0.68, and 0.68, respectively. The product of the accessible pore volume (without considering phase change) read from each injection-production unit and the corresponding macroscopic sweep efficiency correction factor of the chemical agent yields the accessible pore volume considering phase change in each direction, which is 16128 m³. 3 28122m 3 18622m 3 16133m 3 The accumulated accessible pore volume of the four injection-production units controlling the reserves in the well group, considering phase change, yields a single layer of the well group with a chemical flooding accessible pore volume of 79005 m³. 3 The total pore volume of the well group was read as 107414 m³ from the total pore volume model. 3The reachable pore volume of chemical flooding in a single layer of the well group, considering phase change, is 79005 m³. 3 Divided by the total pore volume of the well group, it is 107414 m³. 3 The chemical sweep efficiency of the controlled reserves in the well group was thus obtained as 0.4713. The experimental measurement diagram of the macroscopic sweep efficiency and pore volume correction factor for the phase change chemical agent between the injection and production units is shown below. Figure 11 As shown in the figure. Distribution map of phase change types of well group controlled reserves. Figure 12 As shown.

[0050] This application is highly comprehensive and targeted, with simple and efficient operation methods, and can guide the calculation of sweep efficiency coefficients for chemical flooding of well groups to control reserves.

Claims

1. A method for calculating the sweep efficiency coefficient of chemical flooding for controlled reserves in a well group, comprising the following steps: (1) Establishment of a three-dimensional fine porosity and permeability model: ① Resample at 0.125m to construct a fine interpretation model for porosity and permeability logging, complete the secondary interpretation of logging, and thus finely characterize the heterogeneity within a single well layer; ② The spatial distribution of sedimentary units is controlled by both marker layers and thickness surfaces to ensure the rationality of the spatial structural framework. At the same time, the thickness of oil layers and interlayers and their contact relationship with oil layers are considered. The thickness of vertical sedimentary units is subdivided by "equal scale subdivision" to characterize the vertical heterogeneity and establish a three-dimensional fine structural model. ③Based on the three-dimensional fine structural model, and using the results of secondary interpretation of well logging, a porosity and permeability geological model is established through phase control stochastic modeling technology; (2) Calculation of sweep efficiency of chemical flooding for controlled reserves in well groups: ①Based on the three-dimensional fine-structure model, a mesh volume model is established through the Geometrical Modeling module, and then the total pore volume model is finally obtained by multiplying the mesh volume model and the porosity model. ②Based on the relationship between the microscopic sweep pore volume correction coefficient and permeability of the chemical agent obtained from the experiment, a layered accessible pore volume coefficient field is established. The porosity correction model is established by multiplying the accessibility coefficient field with the porosity. The sweep pore volume model without considering the layer combination and planar phase transition is obtained by multiplying the porosity correction model with the grid volume model. ③ Implement the sand body combination mode between different injection and production units of typical well groups. Multiply the chemical flooding accessible pore volume model in a certain direction without considering phase change by the corresponding experimentally determined macroscopic sweep pore volume correction coefficient of the chemical agent between injection and production units to obtain the accessible pore volume in a certain direction considering phase change. Accumulate the sweep pore volume in all directions of the controlled reserves of the well group to obtain the chemical flooding accessible pore volume of a single layer of the well group considering phase change. ④ The ratio of the accumulated swept pore volume to the total pore volume is the chemical sweep efficiency coefficient of the well group's controlled reserves.

2. The method for calculating the sweep efficiency coefficient of chemical flooding for controlled reserves in well groups according to claim 1, characterized in that: In step (1), step ③, firstly, a three-dimensional sedimentary facies model is established: using the existing fine reservoir description area, sedimentary facies data points are derived according to sedimentary units, including three columns of data: horizontal axis, vertical axis, and facies value. The sedimentary facies data points of each sedimentary unit are added to the three-dimensional fine structural model area. The sedimentary facies data points of each sedimentary unit are quantified according to the nearest point method. The quantified sedimentary facies data of each unit are sampled into the grid through the grid assignment method, and finally, a three-dimensional sedimentary facies model is established; then, a porosity geological model and a permeability geological model are established: using 0.12 The results of the 5m reservoir physical property parameter densification were used to split the porosity and permeability data of all single wells in the study area according to the sampling interval of 0.125m physical property parameters, and a physical property parameter file was formed for each single well. The split single well physical property parameter files were loaded into the three-dimensional model. Through data discretization processing, the single well physical property parameter files were sampled into the grid frame. Then, based on the theory of random function interpolation, the random simulation technology controlled by the sedimentary facies model was adopted. Through variogram analysis, the sequential Gaussian interpolation method was applied to generate a three-dimensional geological model of porosity and permeability physical property parameters.

3. The method for calculating the sweep efficiency coefficient of chemical flooding for controlled reserves in well groups according to claim 1, characterized in that: In step (1), step ④ involves implementing the sand body combination model between different injection and production units in a typical well group. The accessible pore volume model of chemical flooding without considering phase change in a certain direction is multiplied by the corresponding experimentally determined macroscopic sweep pore volume correction coefficient of the chemical agent between injection and production units to obtain the accessible pore volume considering phase change in a certain direction. The cumulative sweep pore volume of the controlled reserves in all directions of the well group is then added to obtain the chemical flooding accessible pore volume of a single layer of the well group considering phase change. The ratio of the cumulative sweep pore volume to the total pore volume is the chemical flooding sweep efficiency coefficient of the controlled reserves of the well group.

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