Low-permeability gas reservoir type gas storage site screening method

Abstract

The invention belongs to the technical field of geological exploration, and particularly discloses a low-permeability gas reservoir type gas storage site screening method. The method comprises the following steps: acquiring original data, cleaning and screening the original data, performing parameter correlation analysis and parameter isolation analysis on cleaned and screened parameters to obtain an independent parameter set, determining a relation equation according to the independent parameter set, and calculating library address comprehensive values of all well points according to the relation equation. Carrying out plane aggregation analysis on the library address comprehensive value of each well point, and selecting a library address according to a plane aggregation analysis result; the objective and accurate low-permeability gas reservoir type gas storage site screening method is provided, the method is simple and practical, the method is not repeated with other types of gas storage site screening methods, good innovativeness is achieved, the technical blank is filled, and the market application prospect is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of geological exploration, and in particular relates to a method for screening a low-permeability gas reservoir type gas storage site. Background Art

[0002] Underground natural gas storage has played a huge role in solving the imbalance between natural gas supply and consumption. It has long been an important facility for storing, collecting and allocating natural gas in major natural gas consuming countries. Therefore, gas storage is a key facility for the effective utilization of pipeline natural gas. How to select the site of the gas storage is a crucial link in its construction.

[0003] At present, regarding the methods of gas storage site screening, the research on gas storage related technologies at home and abroad is mainly focused on salt cavern type gas storage, followed by fault development and depleted gas reservoir type gas storage. There are few studies on the screening methods of low-permeability gas reservoir type gas storage, and there are almost no other scientific methods that can be used for reference.

[0004] The site selection for low-permeability gas reservoirs mainly relies on the experience of geologists, which is too subjective and unscientific. How to find an area suitable for natural gas storage in a large-scale, multi-layer gas zone has become a difficult problem. At present, the site selection of gas storage is still mainly based on the geological experience of geologists in each block at home and abroad; this method lacks logic, is not replicable, and is too subjective. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for screening low-permeability gas reservoir type gas storage sites to solve the problem of excessive subjectivity and lack of logic when using geologists' geological experience to screen low-permeability gas reservoir type gas storage sites.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for screening a low-permeability gas reservoir type gas storage site, comprising:

[0008] Obtaining raw data, cleaning and screening the raw data, and obtaining parameters after cleaning and screening;

[0009] According to the parameters after cleaning and screening, parameter correlation analysis is performed to obtain a parameter set after correlation analysis; according to the parameter set after correlation analysis, parameter isolation analysis is performed to obtain an independent parameter set;

[0010] Perform equation analysis on independent parameter sets to establish relationship equations;

[0011] According to the relationship equation, the comprehensive value of the reservoir site of all well points in the area is calculated to obtain the comprehensive value of the reservoir site of each well point; the plane aggregation analysis is carried out according to the comprehensive value of the reservoir site of each well point;

[0012] The reservoir site is selected based on the results of planar clustering analysis.

[0013] Furthermore, the obtaining of raw data, cleaning and screening the raw data, and obtaining the parameters after cleaning and screening specifically include:

[0014] Number all single wells in the area, obtain the original data of each single well, clean the original data, and obtain the cleaned data;

[0015] The cleaned data is sorted into tables according to small layers, and the unobstructed flow of each well in a small layer in each table is sorted from large to small;

[0016] Set the minimum threshold for unimpeded traffic flow and delete data below the minimum threshold;

[0017] Set the maximum threshold of daily water production, select single wells with daily water production greater than the maximum threshold, and assign the matrix permeability of all layers of the single well point to its opposite number;

[0018] Get the parameters after cleaning and screening.

[0019] Furthermore, the original data include: layer position, top depth, bottom depth, thickness, total porosity, gas saturation, matrix permeability and daily water production.

[0020] Furthermore, the parameters after cleaning and screening include: effective thickness, porosity, matrix permeability, gas saturation, daily water production and open flow rate.

[0021] Furthermore, the parameter correlation analysis is performed to obtain a parameter set after the correlation analysis, which specifically includes:

[0022] A certain parameter except the unobstructed flow after cleaning and screening is correlated with the unobstructed flow to obtain the correlation coefficient of the parameter. When the correlation coefficient of the parameter is greater than 0.5, the parameter is output as the parameter after correlation analysis; all parameters except the unobstructed flow after cleaning and screening are analyzed in turn to obtain the parameter set after correlation analysis.

[0023] Furthermore, the parameter isolation analysis is performed on the parameter set after the correlation analysis to obtain the independent parameter set, which specifically includes:

[0024] A parameter in the parameter set after correlation analysis is subjected to parameter isolation analysis with other parameters in turn to determine the correlation index. When the correlation index of the parameter is greater than 0.5, the parameter is output as an independent parameter. The parameters in the parameter set after correlation analysis are analyzed in turn to obtain an independent parameter set.

[0025] Furthermore, the independent parameter set is subjected to equation group analysis to establish the relationship equation as follows:

[0026] After the analysis, each independent parameter is tabulated, the data of the three adjacent wells are listed in equations respectively, and the three equations are grouped together and analyzed, and then the three equation groups are combined and solved to obtain the relationship equation.

[0027] Furthermore, the planar aggregation analysis based on the comprehensive value of the reservoir site of each well point specifically includes:

[0028] Project the comprehensive value of the reservoir site of each well point onto the plane map to make a contour map of the comprehensive value of the reservoir site;

[0029] When the difference between the adjacent well data within 8 km and the current well data exceeds 4 times, they are considered to be in different areas.

[0030] Furthermore, according to the planar aggregation analysis results, the selected storage sites are specifically:

[0031] For areas with negative comprehensive values ​​of the reservoir site, the area with a radius of 9 km is regarded as a non-selected area;

[0032] The criteria for delineating the selected storage sites are: balance coefficient>150, comprehensive value of storage sites>100, and aggregation coefficient>4;

[0033] Output the selected library address range.

[0034] Furthermore, the calculation method of the said balance coefficient is: taking the average value of the comprehensive values ​​of the storage sites in the area that are greater than 100;

[0035] The calculation formula of the clustering coefficient is: balance coefficient / area of ​​the selected storage site.

[0036] The present invention has at least the following beneficial effects:

[0037] The present invention obtains original data, cleans and screens the original data, performs parameter correlation analysis and parameter isolation analysis on the parameters after cleaning and screening, obtains an independent parameter set, establishes a relationship equation according to the independent parameter set, calculates the comprehensive values ​​of the storage sites of all well points according to the relationship equation, performs a planar aggregation analysis on the comprehensive values ​​of the storage sites of each well point, and selects a storage site according to the planar aggregation analysis results; provides an objective and accurate method for screening the storage sites of low-permeability gas reservoir-type gas storage reservoirs, the method is simple and practical, does not overlap with other types of gas storage reservoir site screening methods, has good innovation, fills a technical gap, and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0039] In the attached picture:

[0040] Figure 1 The schematic diagram of the process of selecting the site for low-permeability gas reservoir-type gas storage is shown in FIG.

[0041] Figure 2 Schematic diagram of the correlation between effective thickness and unimpeded flow in Example 2;

[0042] Figure 3 Schematic diagram of the correlation between porosity and open flow rate in Example 2;

[0043] Figure 4 Schematic diagram of the correlation between matrix permeability and open flow rate in Example 2;

[0044] Figure 5 Schematic diagram of the correlation between gas saturation and open flow rate in Example 2;

[0045] Figure 6 Schematic diagram of the correlation between porosity and permeability in Example 2;

[0046] Figure 7 It is the contour map of comprehensive value of reservoir site;

[0047] Figure 8 Schematic diagram for demarcating the scope of the library site. DETAILED DESCRIPTION

[0048] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0049] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0050] Example 1

[0051] like Figure 1 As shown, a method for screening a low-permeability gas reservoir type gas storage site comprises:

[0052] S1: Get the original data, clean and filter the original data, and get the parameters after cleaning and filtering; ensure that all data are valid and usable data.

[0053] All single wells in the area are numbered and the original data of each single well is obtained; the original data include: layer position, top depth, bottom depth, thickness, total porosity, gas saturation, matrix permeability and daily water production;

[0054] Clean the original data, including the following: delete duplicate values, singular values, and supplement missing values; obtain the cleaned data;

[0055] Each single well includes multiple layers. The cleaned data is sorted according to the small layer table. The unobstructed flow of each single well in a small layer in each table is sorted from large to small.

[0056] Set the minimum threshold of unimpeded traffic flow to 200,000 cubic meters, and delete data below the minimum threshold;

[0057] The maximum threshold of daily water production is set to 5 cubic meters per day. The single wells with daily water production greater than the maximum threshold are screened, and the matrix permeability of all layers of the single well point is uniformly assigned to its opposite number; the opposite number is assigned to be a negative number, which can intuitively screen out unusable data, and the first step of attribute identification of the data is performed using positive and negative signs, which negates some data;

[0058] The parameters after cleaning and screening are obtained; the parameters after cleaning and screening include: effective thickness, porosity, matrix permeability, gas saturation, daily water production and open flow rate.

[0059] S2: Perform parameter correlation analysis based on the parameters after cleaning and screening to obtain a parameter set after correlation analysis; perform parameter isolation analysis based on the parameter set after correlation analysis to obtain independent parameters;

[0060] A certain parameter other than the open flow rate after cleaning and screening is correlated with the open flow rate to obtain the correlation coefficient of the parameter. When the correlation coefficient of the parameter is greater than 0.5, the parameter is output as the parameter after correlation analysis; all parameters (effective thickness, porosity, matrix permeability, gas saturation and daily water production) other than the open flow rate after cleaning and screening are analyzed in turn to obtain a parameter set after correlation analysis;

[0061] A parameter in the parameter set after correlation analysis is subjected to parameter isolation analysis with other parameters in turn to determine the correlation index. When the correlation index of the parameter is greater than 0.5, the parameter is output as an independent parameter. The parameters in the parameter set after correlation analysis are analyzed in turn to obtain an independent parameter set.

[0062] S3: Perform equation analysis on independent parameter sets and establish relationship equations.

[0063] After analysis, each independent parameter (data with unimpeded flow greater than the minimum threshold value) is tabulated, and a group of equations is formed according to the geological blocks and the distance between neighbors. That is, the data of the three adjacent wells are listed in equations separately, and the three equations are grouped together and analyzed. The three equation groups are then combined and solved to obtain the relationship equation.

[0064] Specifically, equations are listed for the three wells that are adjacent to each other according to the relationship between independent parameters and open-flow capacity, and the three equations are combined and solved to obtain a first solution result. The three equation groups are combined and solved in turn, and the solution results are averaged to obtain a final solution result and establish a relationship equation.

[0065] S4: According to the relationship equation, the comprehensive value of the reservoir site of all well points in the area is calculated to obtain the comprehensive value of the reservoir site of each well point; and the plane aggregation analysis is performed based on the comprehensive value of the reservoir site of each well point.

[0066] According to the relationship equation, all well points in the area before data deletion are calculated to obtain the comprehensive value W of the reservoir site at the well point.

[0067] Project the comprehensive value W of the reservoir site of each well point onto the plane map to make a contour map of the comprehensive value W of the reservoir site;

[0068] When the difference between the adjacent well data within 8 km and the current well data exceeds 4 times, they can be considered to be in different blocks.

[0069] S5: Select the storage site based on the results of the planar aggregation analysis.

[0070] For areas where the comprehensive value W of the reservoir site is negative, the area within a radius of 9 km is regarded as a non-selected area.

[0071] The criteria for selecting the storage sites are: balance coefficient>150, comprehensive value of storage site W>100, and aggregation coefficient>4;

[0072] The calculation method of the balance coefficient is as follows: take the average value of the comprehensive value W of the storage sites in the area that is greater than 100;

[0073] The calculation formula of the aggregation coefficient is: equilibrium coefficient / area of ​​the selected storage site;

[0074] Output the selected library address range.

[0075] Example 2

[0076] S1: Get the original data, as shown in the following table:

[0077] Table 1. Raw data

[0078]

[0079]

[0080]

[0081] The data is cleaned and sorted into tables according to small layers. The unimpeded flow of each well in a small layer in each table is sorted from large to small. The following table shows a table of single wells in a small layer sorted by unimpeded flow:

[0082] Table 2 Sorting of single wells in a certain layer by unimpeded flow rate

[0083]

[0084]

[0085] Delete data with unimpeded traffic below 200,000 cubic meters;

[0086] Wells with a daily water production of more than 5 cubic meters per day are selected, and the permeability of all layers of the well point is uniformly assigned to its opposite number; the table after selection is:

[0087] Table 3 Parameters after cleaning and screening

[0088]

[0089] S2: Perform correlation analysis on effective thickness and unimpeded flow to determine whether it is an influencing factor and obtain the first correlation coefficient R h ,like Figure 2 As shown; if the first correlation coefficient R h If it is greater than 0.5, the effective thickness is used as the parameter after correlation analysis;

[0090] Conduct correlation analysis on porosity and open flow to determine whether it is an influencing factor and obtain the second correlation coefficient R Φ ,like Figure 3 As shown; if the second correlation coefficient RΦ is greater than 0.5, the porosity is used as the parameter after the correlation analysis; when the porosity is greater than the first preset value, the first preset value is 20, and the original value Φ is assigned to -Φ;

[0091] The matrix permeability and open flow rate were correlated to determine whether it was an influencing factor and the third correlation coefficient R was obtained. k ,like Figure 4 As shown; if the third correlation coefficient R k When the matrix permeability is greater than 0.5, the matrix permeability is used as the parameter after correlation analysis; when the matrix permeability is greater than the second preset value, the second preset value is 14, and the original value k is assigned to -k;

[0092] The gas saturation and open flow rate were correlated to determine whether they were influencing factors and the fourth correlation coefficient R was obtained. s ,like Figure 5 As shown, if the fourth correlation coefficient R sIf it is greater than 0.5, gas saturation is used as the parameter after correlation analysis.

[0093] A correlation analysis is performed between porosity and matrix permeability to determine the correlation index between the two, such as Figure 6 As shown, if it reaches above 0.5, only the matrix permeability is used as the independent parameter;

[0094] Conduct correlation analysis between matrix permeability and gas saturation to determine the correlation index between the two. If it reaches above 0.5, only matrix permeability is used as an independent parameter.

[0095] Output independent parameters after isolation analysis;

[0096] In this embodiment, effective thickness, matrix permeability and gas saturation are independent parameters.

[0097] S3: List the independent parameters (data with unimpeded flow greater than 200,000 cubic meters), as shown in the following table. Perform equation analysis on each group of three rows of data. Combine and solve the three equation groups to obtain the relationship equation.

[0098] Table 4 Independent parameter table

[0099]

[0100]

[0101] The first set of equations: 20a+1b+80c=154

[0102] 17a+11b+70c=109

[0103] 13a+10b+86c=103

[0104] The solution is: a = 9, b = 15.4, c = 1

[0105] The second set of equations: 11a+5b+82c=60

[0106] 4a+6b+80c=37

[0107] 14a+5b+75c=36

[0108] The solution is: a = 4.8, b = 12.6, c = 0.6

[0109] The third set of equations: 9a+6b+75c=31

[0110] 9a+2b+61c=30

[0111] 10a+13b+87c=28

[0112] The solution is: a = 5.1, b = 25.2, c = 0.2

[0113] Then we get the average values ​​of a, b, and c, which are 6.3, 17.7, and 0.6 respectively.

[0114] Finally, we get the relationship equation Z=6.3H+17.7K+0.6Sg.

[0115] S4: According to the relationship equation, the comprehensive value of the reservoir site of all well points in the area is calculated to obtain the comprehensive value of the reservoir site W of each well point, W = 0.4Q + 0.6Z, which is calculated by solving the determinant calculation rule of the coefficient of the equation group. This is the general calculation process for solving the linear equation group in mathematics, so it is not elaborated here;

[0116] Table 5 Comprehensive values ​​of each well point reservoir site

[0117]

[0118] Project the comprehensive value of the reservoir site of each well point onto the plane map, and then make a contour map of the comprehensive value of the reservoir site.

[0119] When the difference between the adjacent well data within 8 km and the current well data exceeds 4 times, it can be considered that they are not in the same block, such as Figure 7 shown.

[0120] S5: Select the library site

[0121] (1) For areas with negative comprehensive values, the area with a radius of 9 km is regarded as a non-selected area.

[0122] (2) Site delineation criteria: areas with a balance coefficient > 150, a comprehensive value > 100, and a clustering coefficient greater than 4 are selected as reservoir areas.

[0123] (3) Calculate the comprehensive value balance coefficient of each area: take the average value of W greater than 100, which is 170.

[0124] (4) Calculation of the clustering coefficient: W mean 170 / area of ​​the selected reservoir site 40 km 2 , which is 4.25.

[0125] (5) Draw the selected storage site range, such as Figure 8 shown.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for screening a low-permeability gas reservoir type gas storage site, characterized in that: include: Obtaining raw data, cleaning and screening the raw data, and obtaining parameters after cleaning and screening; According to the parameters after cleaning and screening, parameter correlation analysis is performed to obtain a parameter set after correlation analysis; according to the parameter set after correlation analysis, parameter isolation analysis is performed to obtain an independent parameter set; Perform equation analysis on independent parameter sets to establish relationship equations; According to the relationship equation, the comprehensive value of the reservoir site is calculated for all the well points in the area to obtain the comprehensive value of the reservoir site of each well point; Planar aggregation analysis is conducted based on the comprehensive value of the reservoir site of each well point; The reservoir site is selected based on the results of planar clustering analysis.

2. A method for selecting a low-permeability gas reservoir site according to claim 1, characterized in that: The obtaining of raw data, cleaning and screening the raw data, and obtaining parameters after cleaning and screening specifically include: Number all single wells in the area, obtain the original data of each single well, clean the original data, and obtain the cleaned data; The cleaned data is sorted into tables according to small layers, and the unobstructed flow of each well in a small layer in each table is sorted from large to small; Set the minimum threshold for unimpeded traffic flow and delete data below the minimum threshold; Set the maximum threshold of daily water production, select single wells with daily water production greater than the maximum threshold, and assign the matrix permeability of all layers of the single well point to its opposite number; Get the parameters after cleaning and screening.

3. A method for selecting a low-permeability gas reservoir type gas storage site according to claim 1, characterized in that: The original data include: horizon, top depth, bottom depth, thickness, total porosity, gas saturation, matrix permeability and daily water production.

4. A method for selecting a low-permeability gas reservoir site according to claim 1, characterized in that: The parameters after cleaning and screening include: effective thickness, porosity, matrix permeability, gas saturation, daily water production and open flow rate.

5. A method for selecting a low-permeability gas reservoir type gas storage site according to claim 4, characterized in that: The parameter correlation analysis is performed to obtain a parameter set after the correlation analysis, which specifically includes: A certain parameter except the unobstructed flow after cleaning and screening is correlated with the unobstructed flow to obtain the correlation coefficient of the parameter. When the correlation coefficient of the parameter is greater than 0.5, the parameter is output as the parameter after correlation analysis; all parameters except the unobstructed flow after cleaning and screening are analyzed in turn to obtain the parameter set after correlation analysis.

6. A method for selecting a low-permeability gas reservoir site according to claim 5, characterized in that: The parameter isolation analysis is performed on the parameter set after the correlation analysis to obtain the independent parameter set, which specifically includes: A parameter in the parameter set after correlation analysis is subjected to parameter isolation analysis with other parameters in turn to determine the correlation index. When the correlation index of the parameter is greater than 0.5, the parameter is output as an independent parameter. The parameters in the parameter set after correlation analysis are analyzed in turn to obtain an independent parameter set.

7. A method for selecting a low-permeability gas reservoir type gas storage site according to claim 6, characterized in that: The equation group analysis is performed on the independent parameter set to establish the relationship equation as follows: After the analysis, each independent parameter is tabulated, the data of the three adjacent wells are listed in equations respectively, and the three equations are grouped together and analyzed, and then the three equation groups are combined and solved to obtain the relationship equation.

8. The method for selecting a low-permeability gas reservoir site according to claim 1, characterized in that: The planar aggregation analysis based on the comprehensive value of the reservoir site of each well point specifically includes: Project the comprehensive value of the reservoir site of each well point onto the plane map to make a contour map of the comprehensive value of the reservoir site; When the difference between the adjacent well data within 8 km and the current well data exceeds 4 times, they are considered to be in different areas.

9. The method for selecting a low-permeability gas reservoir site according to claim 1, characterized in that: According to the results of the planar aggregation analysis, the selected storage sites are specifically: For areas with negative comprehensive values ​​of the reservoir site, the area with a radius of 9 km is regarded as a non-selected area; The criteria for delineating the selected storage sites are: balance coefficient>150, comprehensive value of storage sites>100, and aggregation coefficient>4; Output the selected library address range.

10. A method for selecting a low-permeability gas reservoir site according to claim 9, characterized in that: The calculation method of the said balance coefficient is: taking the average value of the comprehensive values ​​of the storage sites in the area that are greater than 100; The calculation formula of the clustering coefficient is: balance coefficient / area of ​​the selected storage site.

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