Method and device for evaluating remaining geological reserves in middle and late development of gas reservoirs

Abstract

The application discloses a method and device for evaluating remaining geological reserves in the middle and late stages of gas reservoir development, and belongs to the technical field of gas reservoir exploitation. The method comprises the following steps: dividing a region where a target gas reservoir is located into a plurality of grids, wherein the grids in a gas-bearing area are effective grids; obtaining original effective thickness, original effective porosity and original gas saturation of each effective grid; obtaining current formation pressure of each effective grid; calculating current natural gas volume coefficient of each effective grid according to the current formation pressure of each effective grid; inputting the original effective thickness, the original effective porosity, the original gas saturation and the current natural gas volume coefficient of each effective grid into a gas reservoir geological reserve calculation model to obtain remaining natural gas geological reserves of the target gas reservoir. The method can ensure the accuracy of the result and accelerate the speed of evaluating the remaining geological reserves in the middle and late stages of gas reservoir development.

Description

Technical Field

[0001] This invention relates to the field of gas reservoir development technology, and in particular to a method and apparatus for evaluating the remaining geological reserves in the middle and late stages of gas reservoir development. Background Technology

[0002] The assessment of remaining geological reserves in a gas reservoir is an extremely important part of gas reservoir development, especially in the later stages of gas reservoir development. Accurate assessment of remaining geological reserves can provide a reliable basis for gas reservoir development and also allow for reasonable adjustment of development technology strategies based on the assessment results. Therefore, rapid and accurate assessment of remaining geological reserves in the later stages of gas reservoir development is of great significance for the continuous and efficient development of natural gas.

[0003] Among related technologies, one method for evaluating the remaining geological reserves of a gas reservoir is the single-well control method, which estimates the controlled reserves of a single well using single-well geological parameters and well test data. Another method for evaluating the remaining geological reserves of a gas reservoir is the numerical simulation method, which establishes a mathematical model of the fluid seepage law in the gas reservoir, uses a computer to input relevant data into the mathematical model, and derives the fluid seepage change law based on the output values, thereby predicting the dynamics of actual gas reservoir development.

[0004] In the process of realizing this invention, the inventors discovered that the related technology has at least the following problems:

[0005] When calculating the remaining geological reserves of a gas reservoir using the single-well control method, not only is the accuracy of the division of the single-well control area relatively low, but also, due to the large well spacing between gas wells in the middle and late stages of gas reservoir development, the single-well control method takes into account less reservoir heterogeneity, resulting in low accuracy of the calculation results. When calculating the remaining geological reserves of a gas reservoir using the numerical simulation method, due to the large amount of data, slow calculation speed, and long working cycle, it is difficult to conduct reserve analysis in a timely manner, resulting in low timeliness. Summary of the Invention

[0006] In view of this, the embodiments of this application provide a method and apparatus for evaluating the remaining geological reserves in the middle and late stages of gas reservoir development, which accelerates the evaluation of the remaining geological reserves in the middle and late stages of gas reservoir development while ensuring the accuracy of the results.

[0007] On the one hand, a method for evaluating the remaining geological reserves in the middle and late stages of gas reservoir development is provided, the method comprising:

[0008] The area where the target gas reservoir is located is divided into several grids, among which the grids within the gas-bearing area are the effective grids;

[0009] Obtain the original effective thickness, original effective porosity, and original gas saturation of each effective grid.

[0010] Obtain the current formation pressure for each of the effective grids;

[0011] The current natural gas volume factor for each of the effective grids is calculated based on the current formation pressure for each effective grid.

[0012] By inputting the original effective thickness, original effective porosity, original gas saturation, and current natural gas volume factor of each effective grid into the gas reservoir geological reserve calculation model, the remaining natural gas geological reserves of the target gas reservoir are obtained.

[0013] Optionally, the gas reservoir geological reserve calculation model is the following first formula:

[0014]

[0015] Where n is the number of effective grids, which is a positive integer; s is the area of ​​a single grid, in meters. 2 G r The remaining geological reserves of natural gas in the target gas reservoir are expressed in units of 10. 8 m 3 h x The original effective thickness of the x-th effective grid is expressed in meters. S represents the original effective porosity of the x-th effective grid, dimensionless; gx B represents the original gas saturation of the x-th effective grid, dimensionless; gxr Let be the current natural gas volume factor for the x-th valid grid, which is dimensionless.

[0016] Optionally, calculating the current natural gas volume factor for each effective grid based on the current formation pressure of each effective grid includes:

[0017] The current natural gas volume factor B for each effective grid is calculated based on the following second formula. gxr :

[0018]

[0019] Among them, T SC The surface standard temperature is given by K; T is the average formation temperature of the target gas reservoir, also given by K; P SC This refers to the standard ground pressure, expressed in MPa; P x Z represents the current formation pressure of the xth effective grid, in MPa. x is the current gas deviation coefficient for the x-th effective grid, dimensionless.

[0020] Optionally, the current natural gas volume factor B for each effective grid is calculated based on the second formula. gxr This includes the current formation pressure P based on the xth effective grid.x The current gas deviation coefficient Z of the xth effective grid is calculated. x .

[0021] Optionally, the method further includes: drawing a map of the remaining natural gas geological reserves of the target gas reservoir based on the remaining natural gas geological reserves of each effective grid.

[0022] On the other hand, embodiments of this application provide an apparatus for evaluating the remaining geological reserves in the middle and late stages of gas reservoir development, the apparatus comprising:

[0023] The partitioning module is used to divide the area where the target gas reservoir is located into several grids, among which the grids within the gas-bearing area are effective grids;

[0024] The first acquisition module is used to acquire the original effective thickness, original effective porosity, and original gas saturation of each effective grid.

[0025] The second acquisition module is used to acquire the current formation pressure of each of the effective grids;

[0026] The calculation module is used to calculate the current natural gas volume factor of each of the effective grids based on the current formation pressure of each effective grid.

[0027] The input module is used to input the original effective thickness, original effective porosity, original gas saturation and current natural gas volume factor of each effective grid in the gas reservoir geological reserve calculation model;

[0028] The output module is used to output the remaining geological reserves of the target gas reservoir.

[0029] Optionally, the gas reservoir geological reserve calculation model is the following first formula:

[0030]

[0031] Where n is the number of effective grids, which is a positive integer; s is the area of ​​a single grid, in meters. 2 G r The remaining geological reserves of natural gas in the target gas reservoir are expressed in units of 10. 8 m 3 h x The original effective thickness of the x-th effective grid is expressed in meters. S represents the original effective porosity of the x-th effective grid, dimensionless; gx B represents the original gas saturation of the x-th effective grid, dimensionless; gxr Let be the current natural gas volume factor for the x-th valid grid, which is dimensionless.

[0032] Optionally, the calculation module includes a calculation submodule, which is used to calculate the current natural gas volume factor B of the xth effective grid according to the following second formula. gxr :

[0033]

[0034] Among them, T SC The surface standard temperature is given by K; T is the average formation temperature of the target gas reservoir, also given by K; P SC This refers to the standard ground pressure, expressed in MPa; P x Z represents the current formation pressure of the xth effective grid, in MPa. x is the current gas deviation coefficient for the x-th effective grid, dimensionless.

[0035] Optionally, the calculation submodule includes a calculation subunit, which is used to calculate the current formation pressure P of the xth effective grid. x Calculate the current gas deviation coefficient Z of the xth effective grid. x .

[0036] On the other hand, embodiments of this application provide a computer-readable storage medium storing instructions that, when executed by a processor, implement any step of the method described in the first aspect.

[0037] The beneficial effects of the technical solutions provided in this application include at least the following:

[0038] This application divides the gas reservoir in the study area into grids, calculates the current natural gas volume factor for each grid using the changing formation pressure, and inputs the obtained current natural gas volume factor for each grid, along with other original, unchanging parameters, into the gas reservoir geological reserve calculation model to calculate the current remaining geological reserves of the gas reservoir. This method for evaluating the remaining geological reserves in the mid-to-late stages of gas reservoir development not only ensures the accuracy of the results but also accelerates the evaluation process due to its ease of operation, thus demonstrating high timeliness. Attached Figure Description

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

[0040] Figure 1 A flowchart illustrating a method for evaluating the remaining geological reserves in the mid-to-late stages of gas reservoir development, provided in an embodiment of this application;

[0041] Figure 2 A flowchart illustrating an application example of the method for evaluating the remaining geological reserves in the mid-to-late stages of gas reservoir development provided in this application;

[0042] Figure 3 A block diagram of a device for evaluating the remaining geological reserves in the later stages of gas reservoir development, provided in an embodiment of this application.

[0043] The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0044] 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, 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.

[0045] Unless otherwise defined, all technical terms used in the embodiments of this application have the same meaning as commonly understood by those skilled in the art. Before further describing the embodiments of the application in detail, some terms for understanding the embodiments of this application are explained.

[0046] To make the technical solutions and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0047] Figure 1 This is a flowchart of a method for evaluating the remaining geological reserves in the mid-to-late stages of gas reservoir development, provided in an embodiment of this application. The method includes:

[0048] S101: Divide the area where the target gas reservoir is located into several grids, among which the grids within the gas-bearing area are effective grids;

[0049] S102: Obtain the original effective thickness, original effective porosity, and original gas saturation for each effective grid.

[0050] S103: Obtain the current formation pressure for each valid grid;

[0051] S104: Calculate the current natural gas volume factor for each effective grid based on the current formation pressure of each effective grid;

[0052] S105: Input the original effective thickness, original effective porosity, original gas saturation and current natural gas volume factor of each effective grid into the gas reservoir geological reserve calculation model to obtain the remaining natural gas geological reserves of the target gas reservoir.

[0053] The following provides a more detailed explanation of each step in the method for evaluating the remaining geological reserves in the middle and late stages of gas reservoir development provided in this embodiment.

[0054] The gas reservoir geological reserve calculation model used in step S105 is the following first formula:

[0055]

[0056] Where n is the number of valid grid cells, which is a positive integer; s is the area of ​​a single grid cell, in meters. 2 G r The remaining geological reserves of natural gas in the target gas reservoir are expressed in units of 10. 8 m 3 h x The original effective thickness of the x-th effective grid is expressed in meters. S represents the original effective porosity of the x-th effective grid, dimensionless; gx B represents the original gas saturation of the x-th effective grid, dimensionless; gxr Let be the current natural gas volume factor for the x-th valid grid, which is dimensionless.

[0057] Optionally, in step S104, the current natural gas volume factor for each effective grid is calculated based on the current formation pressure of each effective grid, including:

[0058] The current natural gas volume factor B for each effective grid is calculated based on the following second formula. gxr :

[0059]

[0060] Among them, T SC ρ is the surface standard temperature, in K; T is the average formation temperature of the target gas reservoir, in K; P SC This refers to the standard ground pressure, expressed in MPa; P x Z represents the current formation pressure of the xth effective grid, in MPa. x is the current gas deviation coefficient for the x-th effective grid, dimensionless.

[0061] Based on the first formula above, the remaining natural gas geological reserves of each effective grid can be obtained, and the remaining natural gas geological reserve abundance map of the target gas reservoir can be drawn based on the obtained remaining natural gas geological reserves of each effective grid.

[0062] Understandably, using the remaining natural gas geological reserve abundance map of the target gas reservoir allows for a more intuitive observation of the remaining geological reserves at various locations within the target gas reservoir, and also facilitates rapid adjustments to subsequent gas reservoir exploitation operations.

[0063] In summary, this application divides the gas reservoir in the study area into grids, calculates the current natural gas volume factor for each grid using the changing formation pressure, and inputs the obtained current natural gas volume factor for each grid, along with other original, unchanging parameters, into the gas reservoir geological reserve calculation model to calculate the current remaining geological reserves of the gas reservoir. This method for evaluating the remaining geological reserves in the mid-to-late stages of gas reservoir development not only ensures the accuracy of the results but also accelerates the evaluation process due to its ease of operation, thus demonstrating high timeliness.

[0064] To better illustrate the method of this application, the following explanation is based on practical applications:

[0065] Taking a homogeneous edge-water gas reservoir as an example, the original geological reserves of the reservoir are calculated according to the following third formula:

[0066]

[0067] Where G represents the original geological reserves of natural gas in the reservoir, in units of 10. 8 m 3 A represents the original gas-bearing area, in km². 2 h represents the original average effective thickness, in meters (m). S represents the original average effective porosity, which is dimensionless. gi B represents the original average gas saturation, dimensionless. gi This is the original volume coefficient of natural gas, dimensionless.

[0068] It should be noted that the original gas-bearing area A can be obtained from geological data; the original average effective thickness h and the original average effective porosity... It can be obtained from detailed description studies of gas reservoirs.

[0069] It should be noted that, since static data does not change when a gas reservoir enters the mid-to-late stages of development without the addition of new wells, the original gas-bearing area A, the original average effective thickness h, and the original average effective porosity remain unchanged. The original average gas saturation S will not change if the gas reservoir is not flooded or the flooding is within a preset range. gi The change is negligible, meaning it can be considered constant.

[0070] As gas reservoir development progresses, the reservoir will eventually deplete, and formation energy will continuously decrease, primarily manifested as a drop in formation pressure. The original volume factor of natural gas changes with variations in formation pressure; therefore, the original volume factor B of natural gas... gi This will result in significant changes. The relationship between formation pressure and the natural gas volume factor can be expressed by the following fourth formula:

[0071]

[0072] Among them, T SC The surface standard temperature is given by K; T is the average formation temperature of the gas reservoir, also given by K; P... SC ρ is the standard ground pressure, in MPa; P is the current formation pressure, in MPa; Z is the current gas deviation coefficient, dimensionless.

[0073] It should be noted that in actual gas reservoir development, the main factors that change significantly in the above formula are the current formation pressure P and the current gas deviation coefficient Z. Furthermore, the current gas deviation coefficient Z is calculated based on the current formation pressure P. Therefore, when evaluating the remaining geological reserves in the later stages of gas reservoir development, the remaining geological reserves of the target gas reservoir can be calculated solely based on the changed current formation pressure P.

[0074] It should be noted that, in order to make the method for evaluating the remaining geological reserves in the mid-to-late stages of gas reservoir development more convenient and accurate, the method for evaluating the remaining geological reserves in the mid-to-late stages of gas reservoir development provided in this application embodiment can adopt the micro-element method, dividing the target gas reservoir area into several grids, which can be 100m×100m grids or 50m×50m grids, wherein the grids within the gas-bearing area are effective grids. For example, Surfer software can be used to evaluate the original average effective thickness h and the original average effective porosity. and the original average gas saturation S gi Using contour lines for gridding, the formula for calculating the original geological reserves of the gas reservoir is then transformed into the following fifth formula:

[0075]

[0076] Where n is the number of valid grid cells, which is a positive integer; and s is the area of ​​a single grid cell, in meters. 2 G i The original geological reserves of natural gas in the target gas reservoir are expressed in units of 10. 8 m 3 h x The original effective thickness of the x-th effective grid is expressed in meters. S represents the original effective porosity of the x-th effective grid, dimensionless; gxB represents the original gas saturation of the x-th effective grid, dimensionless; gxi Let be the original natural gas volume factor for the x-th effective grid, which is dimensionless.

[0077] like Figure 2 As shown, when evaluating the remaining geological reserves of a target gas reservoir, the calculation is performed according to the following steps:

[0078] S201: Obtain the current formation pressure for each valid grid, which can be achieved, for example, in the following way:

[0079] After the well is shut in and pressure is restored, the current formation pressure of each well in the target gas reservoir area is measured using a high-temperature and high-pressure resistant pressure gauge; or the current formation pressure of each well is calculated based on the wellhead pressure of each well in the target gas reservoir area. Based on the current formation pressure of each well, the current formation pressure of each effective grid is assigned using the Kriging interpolation method, and then the current formation pressure of each effective grid is obtained.

[0080] S202: Calculate the current gas deviation coefficient of each effective grid based on the current formation pressure of each effective grid using empirical formulas or state equations.

[0081] S203: Calculate the current natural gas volume factor for each effective grid based on the current formation pressure and current gas deviation coefficient. This can be achieved, for example, in the following manner:

[0082] Using data analysis software such as Excel, WPS, or SPSS, input the current formation pressure and the current gas deviation coefficient for each effective grid in the second formula below to obtain the current natural gas volume factor for each effective grid:

[0083]

[0084] Among them, B gxr T represents the current natural gas volume factor for the x-th effective grid, dimensionless; SC ρ is the surface standard temperature, in K; T is the average formation temperature of the target gas reservoir, in K; P SC This refers to the standard ground pressure, expressed in MPa; P x Z represents the current formation pressure of the xth effective grid, in MPa. x is the current gas deviation coefficient for the x-th effective grid, dimensionless.

[0085] S204: Obtain the original effective thickness, original effective porosity, and original gas saturation of each effective grid after meshing, as well as the current natural gas volume factor B corresponding to each effective grid obtained in step S203. gxr .

[0086] S205: Based on the parameters obtained in step S204, calculate the remaining natural gas geological reserves of the target gas reservoir. For example, this can be achieved in the following way:

[0087] Input the parameters obtained in step S204 into the following first formula to obtain the remaining natural gas geological reserves of the target gas reservoir:

[0088]

[0089] Where n is the number of valid grid cells, which is a positive integer; s is the area of ​​a single grid cell, in meters. 2 G r The remaining geological reserves of natural gas in the target gas reservoir are expressed in units of 10. 8 m 3 h x The original effective thickness of the x-th effective grid is expressed in meters. S represents the original effective porosity of the x-th effective grid, dimensionless; gx B represents the original gas saturation of the x-th effective grid, dimensionless; gxr Let be the current natural gas volume factor for the x-th valid grid, which is dimensionless.

[0090] S206: Based on the remaining natural gas geological reserves of each effective grid, draw a map of the remaining natural gas geological reserves abundance of the target gas reservoir. For example, this can be achieved in the following way:

[0091] Divide the remaining natural gas geological reserves of each effective grid before summation in the first formula by the area of ​​each grid, in units of 100 million cubic meters per square kilometer, and then input it into the Surfer software to draw the remaining natural gas geological reserve abundance map of the target gas reservoir.

[0092] Understandably, by using a map of the remaining natural gas geological reserves of the target gas reservoir, the observation of the target gas reservoir becomes more intuitive and clear, and this map can serve as a basis for the implementation and adjustment of subsequent gas reservoir development plans.

[0093] In summary, the embodiments of this application, by gridding the gas reservoir in the study area and calculating the current natural gas volume factor for each grid using the changing formation pressure, input the obtained current natural gas volume factor for each grid, along with other original, unchanging parameters, into the gas reservoir geological reserve calculation model to calculate the current remaining geological reserves of the gas reservoir. This method for evaluating the remaining geological reserves in the mid-to-late stages of gas reservoir development not only ensures the accuracy of the results but also accelerates the evaluation process due to its ease of operation, thus achieving high timeliness. Furthermore, the method of drawing a remaining natural gas geological reserve abundance map of the target gas reservoir based on the remaining natural gas geological reserves of each effective grid makes the observation of the target gas reservoir more intuitive and clear, and this map can serve as a basis for the implementation and adjustment of subsequent gas reservoir development plans.

[0094] To better illustrate and verify the method of this application, a gas reservoir will be used as an example below.

[0095] The development of this gas reservoir has now entered the middle to late stages. Using Surfer software for grid-based calculations, the original geological reserves of this gas reservoir are estimated to be 255.16 × 10⁻⁶. 8 m 3 At this point, the original effective thickness, original effective porosity, and original gas saturation of each effective grid in the gas reservoir can be obtained.

[0096] By the end of December 2019, the gas reservoir had accumulated a gas production of 112 × 10⁻⁶. 8 m 3 .

[0097] Single-well pressure data, i.e., the current formation pressure of each effective grid, is obtained through methods such as well shut-in and calculation. Then, using data analysis software such as Excel, WPS, or SPSS, the current natural gas volume factor for each effective grid is calculated based on an empirical formula, namely the second formula mentioned above.

[0098] In the first formula above, the original effective thickness, original effective porosity, original gas saturation, and current natural gas volume factor of each effective grid are input. That is, the remaining natural gas geological reserves of each effective grid are first calculated, and then summed to obtain the remaining natural gas geological reserves of the entire gas reservoir, which is 140.68 × 10⁻⁶. 8 m 3 .

[0099] The above data indicates that the remaining geological reserves of natural gas in the entire gas reservoir are 140.68 × 10⁻⁶. 8 m 3 With a cumulative gas production of 112×10 8 m 3 The sum is 252.68 × 10 8 m 3The original geological reserves of this gas reservoir are 255.16 × 10⁻⁶. 8 m 3 The error is within the normal range. This verifies that the method provided by the embodiments of this application can more conveniently and accurately calculate the remaining natural gas geological reserves in the later stages of target gas reservoir development.

[0100] On the other hand, such as Figure 3 As shown in the embodiment of this application, an apparatus for evaluating the remaining geological reserves in the middle and late stages of gas reservoir development is also provided. The apparatus includes:

[0101] The partitioning module 301 is used to divide the area where the target gas reservoir is located into several grids, wherein the grids within the gas-bearing area are effective grids;

[0102] The first acquisition module 302 is used to acquire the original effective thickness, original effective porosity, and original gas saturation of each effective grid.

[0103] The second acquisition module 303 is used to acquire the current formation pressure for each valid grid.

[0104] Calculation module 304 is used to calculate the current natural gas volume factor for each effective grid based on the current formation pressure of each effective grid.

[0105] Input module 305 is used to input the original effective thickness, original effective porosity, original gas saturation and current natural gas volume factor of each effective grid in the gas reservoir geological reserve calculation model;

[0106] Output module 306 is used to output the remaining geological reserves of the target gas reservoir.

[0107] The following provides a more detailed description of each module of the apparatus provided in this embodiment for evaluating the remaining geological reserves in the mid-to-late stages of gas reservoir development.

[0108] The gas reservoir geological reserve calculation model in input module 305 is the following first formula:

[0109]

[0110] Where n is the number of valid grid cells, which is a positive integer; s is the area of ​​a single grid cell, in meters. 2 G r The remaining geological reserves of natural gas in the target gas reservoir are expressed in units of 10. 8 m 3 h x The original effective thickness of the x-th effective grid is expressed in meters. S represents the original effective porosity of the x-th effective grid, dimensionless; gx B represents the original gas saturation of the x-th effective grid, dimensionless;gxr Let be the current natural gas volume factor for the x-th valid grid, which is dimensionless.

[0111] Calculation module 304 includes a calculation submodule, which is used to calculate the current natural gas volume factor B of the x-th effective grid according to the following second formula. gxr :

[0112]

[0113] Among them, T SC ρ is the surface standard temperature, in K; T is the average formation temperature of the target gas reservoir, in K; P SC This refers to the standard ground pressure, expressed in MPa; P x Z represents the current formation pressure of the xth effective grid, in MPa. x is the current gas deviation coefficient for the x-th effective grid, dimensionless.

[0114] The calculation submodule includes calculation sub-units, which are used to calculate the current formation pressure P of the xth effective grid. x Calculate the current gas deviation coefficient Z for the x-th effective grid. x .

[0115] In summary, the embodiments of this application, by gridding the gas reservoir in the study area and calculating the current natural gas volume factor for each grid using the changing formation pressure, input the obtained current natural gas volume factor for each grid, along with other original, unchanging parameters, into the gas reservoir geological reserve calculation model to calculate the current remaining geological reserves of the gas reservoir. This method for evaluating the remaining geological reserves in the mid-to-late stages of gas reservoir development not only ensures the accuracy of the results but also accelerates the evaluation process due to its ease of operation, thus demonstrating high timeliness.

[0116] On the other hand, embodiments of this application also provide a computer-readable storage medium storing instructions that, when executed by a processor, implement any step of the method provided in the first aspect.

[0117] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0118] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only.

[0119] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for evaluating remaining geologic reserves in the middle and late stages of gas reservoir development, characterized in that, The method comprises: dividing a region where a target gas reservoir is located into a plurality of grids, wherein a grid within a gas-bearing area is an effective grid; obtaining original effective thickness, original effective porosity and original gas saturation of each effective grid; obtaining current formation pressure of each effective grid; calculating current natural gas volume factor of each effective grid according to the current formation pressure of each effective grid; inputting the original effective thickness, the original effective porosity, the original gas saturation and the current natural gas volume factor of each effective grid into a gas reservoir geological reserve calculation model to obtain remaining natural gas geological reserve of the target gas reservoir; the gas reservoir geological reserve calculation model is the following first formula: wherein n is the number of the effective grids, being a positive integer; is the single grid area, unit is m2; ; is the remaining natural gas geological reserves of the target gas reservoir, unit is 108m3; ; is the original effective thickness of the xth effective grid, unit is m; ; is the original effective porosity of the xth effective grid, dimensionless; is the original gas saturation of the xth effective grid, dimensionless; is the current natural gas volume coefficient of the xth effective grid, dimensionless; the calculating current natural gas volume factor of each effective grid according to the current formation pressure of each effective grid comprises: The current gas volume factor of each effective grid is calculated based on the following second formula : × wherein, is the surface standard temperature, in °F; ; is the average formation temperature of the target gas reservoir, in °F; ; is the surface standard pressure, in psia; ; is the current formation pressure of the xth active grid, in psia; ; is the current gas deviation factor of the xth active grid, dimensionless.

2. The method of claim 1, wherein, The current gas volume factor of each effective grid is calculated based on the second formula , including the current formation pressure of the xth effective grid The current gas deviation factor of the xth effective grid is calculated .

3. The method of claim 1, wherein, the method further comprises: drawing a remaining natural gas geological reserve abundance map of the target gas reservoir based on the remaining natural gas geological reserve of each effective grid.

4. An apparatus for evaluating remaining geologic reserves in a middle-late stage of gas reservoir development, characterized in that, The device comprises: a dividing module configured to divide a region where a target gas reservoir is located into a plurality of grids, wherein a grid within a gas-bearing area is an effective grid; a first obtaining module configured to obtain original effective thickness, original effective porosity and original gas saturation of each effective grid; a second obtaining module configured to obtain current formation pressure of each effective grid; a calculating module configured to calculate current natural gas volume factor of each effective grid according to the current formation pressure of each effective grid; an inputting module configured to input the original effective thickness, the original effective porosity, the original gas saturation and the current natural gas volume factor of each effective grid into a gas reservoir geological reserve calculation model; an outputting module configured to output remaining geological reserve of the target gas reservoir; the gas reservoir geological reserve calculation model is the following first formula: Where n is the number of effective grids, which is a positive integer; Area of ​​a single grid cell, in units of ; The remaining geological reserves of natural gas in the target gas reservoir are expressed in units of... ; The original effective thickness of the x-th effective grid, in units of ; Let be the original effective porosity of the x-th effective grid, which is dimensionless; Let x be the original gas saturation of the x-th effective grid, which is dimensionless; Let be the current natural gas volume factor for the x-th effective grid, which is dimensionless; The computing module comprises a computing submodule, which is configured to calculate the current natural gas volume coefficient of the xth effective grid according to a second formula : × wherein, is the surface standard temperature, in °F; ; is the average formation temperature of the target gas reservoir, in °F; ; is the surface standard pressure, in psia; ; is the current formation pressure of the xth active grid, in psia; ; is the current gas deviation factor of the xth active grid, dimensionless.

5. The apparatus of claim 4, wherein, The calculating sub-module comprises a calculating subunit, which is configured to calculate a current formation pressure of the xth effective grid according to the current formation pressure of the xth effective grid calculate a current gas deviation factor of the xth effective grid .

6. A computer-readable storage medium, characterized in that, the computer readable storage medium has instructions stored thereon, and the instructions are executed by a processor to implement the method of any one of claims 1-3.

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