Shale reservoir classification evaluation method and system based on pore-crack

Abstract

The invention provides a pore-fracture-based shale reservoir classification evaluation method and system, and relates to the technical field of oil and gas geology, and the method comprises the steps: S1, scanning an electron microscope image of a shale reservoir to be classified and evaluated, and recognizing different types of reservoir spaces of the shale reservoir; s2, reservoir space parameters of the shale reservoir are extracted according to the recognition result of the reservoir space; s3, calculating evaluation parameters of the shale reservoir based on the reservoir space parameters and a pre-obtained view field area of the shale reservoir; s4, inputting the evaluation parameters and the pre-calculated weight value of each evaluation parameter into a pre-constructed classification evaluation model, and calculating to obtain an evaluation coefficient of the shale reservoir; and S5, based on the evaluation coefficient, performing classification evaluation on the shale reservoir. According to the method, quantitative evaluation can be carried out on the shale reservoir on the microcosmic aspect, and compared with a traditional shale reservoir evaluation method, the shale reservoir evaluation is more visual and accurate on the basis of the microcosmic characteristics of the pore fractures.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas geology, and in particular to a shale reservoir classification evaluation method and system based on pores and fractures. Background Art

[0002] Porosity refers to the percentage of the volume of the reservoir space in the reservoir to the total volume of the rock, and is an important parameter for studying reservoir physical properties. In microscopic two-dimensional images, the porosity is mainly quantitatively characterized by the surface area ratio, which refers to the percentage of the pore area of ​​the rock under the microscope to the total area of ​​the observation field. Exploration and development practice has shown that the better the connectivity between pores and fractures, the better the reservoir properties, and the easier it is to extract oil and gas. At present, the evaluation methods of shale reservoirs mostly regard microscopic pores and fractures as a whole evaluation, without considering the contribution of pores and fractures to the reservoir and fluid seepage, so it is impossible to accurately evaluate the quality of shale reservoirs at the microscopic level. Summary of the invention

[0003] The present invention provides a shale reservoir classification and evaluation method and system based on pores and fractures, which is used to solve the defect that the quality of shale reservoirs cannot be accurately evaluated at the microscopic level in the prior art, and quantitatively evaluates shale reservoirs at the microscopic level. Based on the microscopic characteristics of pores and fractures, the evaluation of shale reservoirs is more intuitive and accurate.

[0004] The present invention provides a shale reservoir classification and evaluation method based on pores and fractures, comprising the following steps: S1. Scanning an electron microscope image of a shale reservoir to be classified and evaluated to identify different types of reservoir spaces in the shale reservoir, wherein the reservoir spaces include pores and fractures; S2. extracting reservoir space parameters of the shale reservoir according to the reservoir space identification result; S3, calculating evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore diameter of the shale reservoir and the surface porosity of different types of reservoir spaces; S4, inputting the evaluation parameters and the pre-calculated weight values ​​of the evaluation parameters into a pre-built classification evaluation model to calculate the evaluation coefficient of the shale reservoir; S5. Based on the evaluation coefficient, classify and evaluate the shale reservoir.

[0005] According to the pore-fracture based shale reservoir classification and evaluation method provided by the present invention, S1, scanning the electron microscope image of the shale reservoir to be classified and evaluated to identify different types of reservoir spaces of the shale reservoir, specifically including: Analyzing the electron microscope image to obtain the ratio of the major axis to the minor axis of different types of reservoir spaces in the shale reservoir; Based on the ratio, the reservoir space is determined to be a pore or a fracture.

[0006] According to the pore-fracture based shale reservoir classification and evaluation method provided by the present invention, the step of determining whether the reservoir space is a pore or a fracture based on the ratio specifically includes: When the ratio is greater than or equal to a preset ratio threshold, the reservoir space is a fracture; When the ratio is less than the preset ratio threshold, the reservoir space is a pore; The ratio threshold is obtained through geological statistical analysis.

[0007] According to the pore-fracture based shale reservoir classification and evaluation method provided by the present invention, the reservoir space parameters include the pore size of each pore, the total field area, the total area of ​​pores and fractures, the pore area, the fracture area, and the connected area of ​​connected pores and fractures.

[0008] According to the pore-fracture based shale reservoir classification and evaluation method provided by the present invention, the surface ratios of different types of reservoir spaces include pore surface ratios , crack surface rate , connected pores and fracture surface ratio ; The calculation formula of the evaluation parameter is as follows: ; ; ; ; Wherein, R is the average pore size of the shale reservoir, is the pore size of the i-th pore, i=(0, 1, ... n), n is the total number of pores; A is the total viewing area of ​​the shale reservoir; A p is the pore area; A f is the crack area; A fp is the connected area of ​​voids and cracks.

[0009] According to the pore-fracture based shale reservoir classification and evaluation method provided by the present invention, the classification and evaluation model is specifically: ; Wherein, S is the evaluation coefficient, C1, C2, C3, and C4 are the weight values ​​of the average pore diameter, pore surface ratio, fracture surface ratio, and connected pore and fracture surface ratio of the shale reservoir, respectively. .

[0010] According to the pore-fracture based shale reservoir classification and evaluation method provided by the present invention, the step of classifying and evaluating the shale reservoir based on the evaluation coefficient specifically includes: When the evaluation coefficient is within the first threshold range, it is determined to be a Class I reservoir, and the Class I reservoir is used to characterize that the development and distribution characteristics of the pore-fracture system meet the preset oil and gas development conditions; When the evaluation coefficient is within the second threshold range, it is determined to be a Class II reservoir. The Class II reservoir is used to characterize the development and distribution characteristics of the pore-fracture system and needs to be combined with additional industrial means to meet the preset oil and gas development conditions; When the evaluation coefficient is within the third threshold range, it is determined to be a Class III reservoir, and the Class III reservoir is used to characterize that the development and distribution characteristics of the pore-fracture system do not meet the preset oil and gas development conditions; The values ​​of the evaluation coefficients represented by the first threshold range, the second threshold range, and the third threshold range decrease step by step.

[0011] According to the pore-fracture based shale reservoir classification and evaluation method provided by the present invention, the first threshold range is: evaluation coefficient>0.3; the second threshold range is: evaluation coefficient≥0.15 and≤0.3; the third threshold range is: evaluation coefficient≥0 and<0.15.

[0012] The present invention also provides a shale reservoir classification and evaluation system based on pores and fractures, comprising the following modules: An identification module is used to scan the electron microscope image of the shale reservoir to be classified and evaluated, and identify different types of reservoir spaces of the shale reservoir, wherein the reservoir spaces include pores and fractures; A reservoir space parameter extraction module, used for extracting the reservoir space parameters of the shale reservoir according to the reservoir space identification result; An evaluation parameter calculation module, used to calculate the evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore diameter of the shale reservoir and the surface porosity of different types of reservoir spaces; An evaluation coefficient calculation module, used for inputting the evaluation parameters and the pre-calculated weight values ​​of the evaluation parameters into a pre-built classification evaluation model to calculate the evaluation coefficient of the shale reservoir; A classification evaluation module is used to classify and evaluate the shale reservoir based on the evaluation coefficient.

[0013] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the program, a pore-fracture based shale reservoir classification and evaluation method as described above is implemented.

[0014] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the pore-fracture-based shale reservoir classification and evaluation method as described in any one of the above is implemented.

[0015] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the computer program implements any of the above-mentioned pore-fracture based shale reservoir classification and evaluation methods.

[0016] The pore-fracture based shale reservoir classification and evaluation method and system provided by the present invention identify different types of reservoir spaces of the shale reservoir by scanning the electron microscope image of the shale reservoir to be classified and evaluated, wherein the reservoir space includes pores and fractures; extract the reservoir space parameters of the shale reservoir according to the identification result of the reservoir space; calculate the evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore diameter of the pores of the shale reservoir and the surface ratio of different types of reservoir spaces; input the evaluation parameters and the weight values ​​of each evaluation parameter calculated in advance into a pre-constructed classification and evaluation model to calculate the evaluation coefficient of the shale reservoir; classify and evaluate the shale reservoir based on the evaluation coefficient, and quantitatively evaluate the shale reservoir at the microscopic level. Compared with the traditional shale reservoir evaluation method, the present invention is based on the microscopic characteristics of pores and fractures, and the evaluation of shale reservoirs is more intuitive and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic flow chart of the pore-fracture based shale reservoir classification and evaluation method provided by the present invention.

[0019] Figure 2 This is the original scanning electron microscope image of sample No. 1 provided in an embodiment of the present invention.

[0020] Figure 3This is the pore and crack extraction image of sample No. 1 provided in an embodiment of the present invention.

[0021] Figure 4 This is the original scanning electron microscope image of sample No. 2 provided in an embodiment of the present invention.

[0022] Figure 5 This is the pore and crack extraction image of sample No. 2 provided in an embodiment of the present invention.

[0023] Figure 6 This is the original scanning electron microscope image of sample No. 3 provided in an embodiment of the present invention.

[0024] Figure 7 This is the pore and crack extraction image of sample No. 3 provided in an embodiment of the present invention.

[0025] Figure 8 It is a structural schematic diagram of the pore-fracture based shale reservoir classification and evaluation system provided by the present invention.

[0026] Fig. 9 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Shale reservoirs are one of the important targets for oil and gas production and are of great significance to the exploitation of unconventional oil and gas resources. In some areas, such as the Wufeng-Longmaxi shale in the Sichuan Basin, the Yanchang shale in the Ordos Basin, the Gulong shale in the Songliao Basin, and the Fengcheng shale in the Junggar Basin, the microscopic pores and fractures are well developed, with strong heterogeneity, forming a relatively complex pore-fracture network system, which plays an important role in the storage and seepage of oil and gas in shale reservoirs.

[0029] At present, most evaluation methods for shale reservoirs consider microscopic pores and fractures as a whole, without considering the contribution of pores and fractures to the reservoir and fluid seepage. The shale reservoir classification and evaluation results based on this are difficult to truly, accurately and intuitively reflect the microscopic characteristics of shale reservoirs.

[0030] To solve the above problems, the present invention analyzes pores and fractures separately and studies their contributions to shale reservoirs respectively. This method can evaluate the quality of shale reservoirs more intuitively and accurately from a microscopic perspective.

[0031] Combine the following Figure 1-Figure 7 The pore-fracture based shale reservoir classification and evaluation method of the present invention is described.

[0032] Figure 1 is a schematic flow chart of the shale reservoir classification and evaluation method based on pores and fractures provided by the present invention, such as Figure 1 As shown, the method comprises the following steps: S1. Scanning an electron microscope image of a shale reservoir to be classified and evaluated to identify different types of reservoir spaces in the shale reservoir, wherein the reservoir spaces include pores and fractures; S2. extracting reservoir space parameters of the shale reservoir according to the reservoir space identification result; S3, calculating evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore diameter of the shale reservoir and the surface porosity of different types of reservoir spaces; S4, inputting the evaluation parameters and the pre-calculated weight values ​​of the evaluation parameters into a pre-built classification evaluation model to calculate the evaluation coefficient of the shale reservoir; S5. Based on the evaluation coefficient, classify and evaluate the shale reservoir.

[0033] It should be noted that existing shale reservoir evaluation schemes usually regard microscopic pores and fractures as a whole evaluation, without considering the contribution of each pore and fracture to the reservoir and fluid seepage. It is difficult to extract the microscopic characteristics of pores and fractures, and it is impossible to accurately identify the changes in reservoir quality caused by the differential contributions of microscopic pores and fractures and their connectivity to the reservoir.

[0034] Therefore, the present invention classifies and evaluates shale reservoirs by quantitatively characterizing the pore-fracture system of shale reservoirs, and clarifies the contribution of the pore-fracture system and its connectivity to the reservoir space. This invention provides a method for quantitatively evaluating the quality of shale reservoirs.

[0035] The above steps are described in detail below through specific embodiments.

[0036] S1. Scanning an electron microscope image of a shale reservoir to be classified and evaluated to identify different types of reservoir spaces in the shale reservoir, wherein the reservoir spaces include pores and fractures.

[0037] In some possible implementations of the present invention, S1, scanning an electron microscope image of a shale reservoir to be classified and evaluated to identify different types of reservoir spaces of the shale reservoir, specifically comprising: Analyzing the electron microscope image to obtain the ratio of the major axis to the minor axis of different types of reservoir spaces in the shale reservoir; Based on the ratio, the reservoir space is determined to be a pore or a fracture.

[0038] Specifically, this embodiment provides an implementation method for identifying different types of reservoir spaces in shale reservoirs, by analyzing the electron microscope image and determining whether the reservoir space is a pore or a fracture according to the ratio of the major axis to the minor axis of the different types of reservoir spaces.

[0039] In a possible embodiment, Image J software can be used to analyze electron microscope images, that is, reservoir scanning electron microscope images with obvious differences in pore and fracture development can be selected, and Image J software can be used to analyze the images to effectively identify pores and fractures, and measure the storage space area of ​​shale reservoirs, the sizes of major and minor axes of different types of storage spaces, and the field of view area of ​​shale reservoirs.

[0040] On this basis, the ratio of the major axis to the minor axis of different types of reservoir spaces is calculated, and based on the ratio, the reservoir space is determined to be a void or a fracture.

[0041] In some possible implementations of the present invention, based on the ratio, the step of determining that the reservoir space is a pore or a fracture specifically includes: When the ratio is greater than or equal to a preset ratio threshold, the reservoir space is a fracture; When the ratio is less than the preset ratio threshold, the reservoir space is a pore; Wherein, the ratio threshold is obtained according to geological statistical analysis.

[0042] In a possible embodiment, according to existing geological statistical analysis, the ratio threshold can be set to 10, that is, a reservoir body having a ratio of the major axis to the minor axis greater than or equal to 10 is defined as a fracture, and a reservoir body having a ratio less than 10 is defined as a pore.

[0043] Specifically, this embodiment provides an implementation method for determining whether a reservoir space is a pore or a fracture, by comparing the ratio of the major axis to the minor axis of the reservoir space with a preset ratio threshold, thereby determining whether the reservoir space is a fracture or a gap.

[0044] S2. Extracting reservoir space parameters of the shale reservoir according to the reservoir space identification result.

[0045] In some possible embodiments of the present invention, the reservoir space parameters include the pore size of each pore, the total field area, the total area of ​​pores and fractures, the pore area, the fracture area, and the connected area of ​​connected pores and fractures.

[0046] In a possible embodiment, pores and fractures are classified by different reservoir aspect ratios, and the pore size R of each pore in the total n pores is calculated by pore size and area data. i, where i=(0, 1, ... n), total face rate , pore surface ratio , crack surface rate and the surface ratio of connected pores and fractures , the parameters of such pores and cracks can be used as evaluation parameters for calculating the evaluation coefficient. The following are the evaluation parameters extracted from the SEM image: The pore size R of each pore among the total n pores i , unit: micrometer (μm); Total viewing area A, unit: square micrometer (μm 2 ); Total area of ​​pores and cracks A s , unit: square micrometer (μm 2 ); Pore ​​area A p , unit: square micrometer (μm 2 ); Crack area A f , unit: square micrometer (μm 2 ); Connected pore fracture area A fp , unit: square micrometer (μm 2 ).

[0047] Specifically, this embodiment provides an implementation method for using some parameters related to pores and cracks as evaluation parameters, by extracting the average pore diameter, total field of view area, total area of ​​pores and cracks, pore area, crack area, and connected area of ​​connected pores and cracks, to prepare for further calculation of evaluation parameters.

[0048] S3, calculating evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore diameter of the shale reservoir and the surface porosity of different types of reservoir spaces; In some possible embodiments of the present invention, different types of reservoir space surface ratios include pore surface ratios. , crack surface rate , connected pores and fracture surface ratio .

[0049] In other words, the evaluation parameters specifically include the average pore diameter, pore surface ratio, fracture surface ratio, connected pore and fracture surface ratio, etc. of the shale reservoir.

[0050] The evaluation parameters also include the total porosity and crack surface ratio. , which is used to understand the reservoir properties of a sample as a whole, that is, the porosity, Total porosity of pores and fractures By pore surface ratio and crack face ratio The process of participating in the classification evaluation model to calculate the evaluation coefficient of the shale reservoir to be classified and evaluated.

[0051] In a possible embodiment, the calculation formula of the above evaluation parameters can be expressed as: (1); (2); (3); (4); (5); Wherein, R is the average pore size of the shale reservoir, is the pore size of the i-th pore, i=(0, 1, ... n), n is the total number of pores; A is the total viewing area of ​​the shale reservoir; A s is the total area of ​​pores and cracks; A p is the pore area; A f is the crack area; A fp is the connected area of ​​voids and cracks.

[0052] Specifically, based on the extracted SEM image parameters, the average pore size of the reservoir and the surface porosity of different reservoir spaces were calculated as follows: Average pore size ; Total face rate = Total area of ​​pores and cracks A s / Total viewing area A × 100%; Porosity = Pore area A p / Total viewing area A × 100%; Fracture face rate = Crack area A f / Total viewing area A × 100%; Connected pores and fracture surface ratio = Area of ​​connected pore fractures A fp / Total viewing area A ×100%.

[0053] Through the above calculations, the calculation results of the evaluation parameters are obtained, preparing for further calculation of the evaluation coefficients.

[0054] S4, inputting the evaluation parameters and the pre-calculated weight values ​​of the evaluation parameters into a pre-built classification evaluation model to calculate the evaluation coefficient of the shale reservoir; In some possible implementations of the present invention, the classification evaluation model is specifically: (6); Wherein, S is the evaluation coefficient, C1, C2, C3, and C4 are weight values ​​of the average pore diameter, pore surface ratio, fracture surface ratio, and connected pore and fracture surface ratio of the shale reservoir, respectively, and: (7).

[0055] It is understandable that in shale reservoirs, pores are the main storage space for oil and gas, fractures are the main seepage channels for oil and gas, and the connectivity between pores and fractures is of great significance for oil and gas production. The data of pore size, pore surface ratio, fracture surface ratio, connected pores and fracture surface ratio are normalized, and fitting analysis is performed based on the test oil production at the corresponding sampling location. According to the sensitivity of different parameters to production, the weight coefficient is determined, the reservoir evaluation coefficient S is calculated, and different reservoirs are classified and evaluated. The calculation formula is as follows: ; .

[0056] Specifically, this embodiment provides an implementation method of a classification evaluation model, which constructs a classification evaluation model by weightedly summing the average pore diameter and total surface area of ​​pores and fractures, pore surface area, fracture surface area, and connected pore and fracture surface area of ​​the shale reservoir in the evaluation parameters, and quantitatively evaluates the shale reservoir at the microscopic level. Compared with traditional shale reservoir evaluation methods, this method is based on the microscopic characteristics of pores and fractures, and is more intuitive and accurate in evaluating shale reservoirs.

[0057] S5. Based on the evaluation coefficient, classify and evaluate the shale reservoir.

[0058] In some possible implementations of the present invention, the step of classifying and evaluating the shale reservoir based on the evaluation coefficient specifically includes: When the evaluation coefficient is within the first threshold range, it is determined to be a Class I reservoir, and the Class I reservoir is used to characterize that the development and distribution characteristics of the pore-fracture system meet the preset oil and gas development conditions; When the evaluation coefficient is within the second threshold range, it is determined to be a Class II reservoir. The Class II reservoir is used to characterize the development and distribution characteristics of the pore-fracture system and needs to be combined with additional industrial means to meet the preset oil and gas development conditions; When the evaluation coefficient is within the third threshold range, it is determined to be a Class III reservoir, and the Class III reservoir is used to characterize that the development and distribution characteristics of the pore-fracture system do not meet the preset oil and gas development conditions; The values ​​of the evaluation coefficients represented by the first threshold range, the second threshold range, and the third threshold range decrease step by step.

[0059] In a possible embodiment, the first threshold range can be set to a range of evaluation coefficient > 0.3; the second threshold range can be set to a range of evaluation coefficient ≥ 0.15 and ≤ 0.3; the third threshold range can be set to a range of evaluation coefficient ≥ 0 and < 0.15.

[0060] Specifically, this embodiment provides an implementation method for classifying and evaluating shale reservoirs based on an evaluation coefficient. By setting a threshold range for the evaluation coefficient, the value of the evaluation coefficient of the shale reservoir calculated by the above embodiment is compared with the preset threshold range to determine the classification level of the shale reservoir. By quantitatively characterizing the reservoir pore-fracture system, the shale reservoir is classified and evaluated, and the contribution of the pore-fracture system and its connectivity to the reservoir space is clarified, which provides a new idea for quantitative evaluation of shale reservoir quality.

[0061] It is understandable that the problem to be solved by the present invention is that the differential contribution of microscopic pores and fractures and their connectivity to the reservoir causes changes in reservoir quality. To solve the above problems, the present invention mainly quantitatively characterizes pores, fractures, and connected pores and fractures, clarifies the weight ratio of each factor, establishes a shale reservoir evaluation system, and comprehensively evaluates shale reservoirs. The technical solution of the present invention specifically includes the following steps: (1) identification of pores and fractures in scanning electron microscope images; (2) calculation of average pore diameter, pore surface ratio, fracture surface ratio, and connected pore and fracture surface ratio; (3) calculation of the comprehensive coefficient of shale reservoirs, and evaluation, sorting and classification of reservoirs.

[0062] The specific process of solving the above technical problems by the pore-fracture based shale reservoir classification and evaluation method provided by the present invention is further verified through specific examples below.

[0063] In this example, three samples of pore and fracture development in a continental shale oil layer in a block in western my country were selected for scanning electron microscope data. Sample 1 is a shale reservoir with mainly large pores. Its original electron microscope image and pore and fracture extraction image are shown in Figure 2. Figure 2 , 3 As shown in Figure 2, sample 2 is a shale reservoir with one main fracture and pores. Its original electron microscope image and pore fracture extraction image are shown in Figure 2. Figure 4 , 5 As shown in Figure 2; Sample No. 3 is a shale reservoir with dense fractures and pores. Its original electron microscope image and pore fracture extraction image are shown in Figure 2. Figure 6 , 7 The pore cracks of the above three samples were identified, and the evaluation parameters of each sample were obtained, such as the pore diameter Ri , viewing area A, total area of ​​pores and cracks A s , pore area A p , crack area A f and the area of ​​connected pore fractures A fp , as shown in Table 1, which is the extraction results of the evaluation parameters of the three samples provided in the embodiment of the present invention.

[0064] Table 1

[0065] Furthermore, the average pore diameter R and pore surface ratio are calculated according to formulas (1)-(5). , crack surface rate and the surface ratio of connected pore fractures , and then fit the test oil production at different sampling locations to determine the average pore size R and pore surface ratio , crack surface rate and the surface ratio of connected pore fractures The weight coefficients are approximately 0.2, 0.2, 0.2, and 0.4, respectively. Finally, the reservoir evaluation coefficient is calculated by normalizing the parameters, as shown in Table 2. Table 2 is the calculation results of the evaluation coefficients of the three samples provided in the embodiment of the present invention.

[0066] Table 2

[0067] Combined with the above calculation results, by analyzing the evaluation coefficient of shale reservoirs, the larger the evaluation coefficient S is, the better the reservoir is.

[0068] In a possible embodiment, shale reservoirs can be divided into three categories according to reservoir evaluation coefficients: The evaluation coefficient of Class I reservoir is greater than 0.3. The pore-fracture system of this type of reservoir is very developed, and the pore-fracture connectivity is good. Most of them are laminated shales, or shales with very developed fractures, such as reservoir sample No. 3.

[0069] The evaluation coefficient of Class II reservoir is 0.15~0.3. The pore-fracture system of this type of reservoir is relatively developed, and the connectivity of pores and fractures is general. This reservoir is usually layered shale or shale with relatively developed fractures, such as reservoir sample No. 2. Some of them may be reservoirs with undeveloped fractures but extremely developed pores.

[0070] The evaluation coefficient of Class III reservoirs is 0~0.15. The pore-fracture system of this type of reservoir is less developed, the pore-fracture connectivity is poor, and there are usually isolated pores and isolated fractures, such as reservoir sample No. 1.

[0071] The pore-fracture based shale reservoir classification and evaluation method provided by the present invention extracts scanning electron microscope images, calculates the pore and fracture surface ratios, and then comprehensively evaluates the shale reservoir. It can quantitatively characterize the pores and fractures in the shale reservoir, quantitatively evaluate the quality of the shale reservoir, and clarify the contribution of pores, fractures and the connectivity between the two to the shale reservoir, which has positive significance for the microscopic evaluation of the shale reservoir.

[0072] In some specific embodiments of the present invention, the present scheme also provides a shale reservoir classification and evaluation system based on pores and fractures. The shale reservoir classification and evaluation system based on pores and fractures provided by the present invention is described below. The shale reservoir classification and evaluation system based on pores and fractures described below and the shale reservoir classification and evaluation method based on pores and fractures described above can be referenced to each other.

[0073] Figure 8 Schematic diagram of the structure of the shale reservoir classification and evaluation system based on pores and fractures provided by the present invention. Figure 8 As shown, the shale reservoir classification and evaluation system based on pores and fractures provided by the present invention specifically includes the following modules: An identification module 81 is used to scan the electron microscope image of the shale reservoir to be classified and evaluated, and identify different types of reservoir spaces of the shale reservoir, wherein the reservoir spaces include pores and fractures; A reservoir space parameter extraction module 82, used to extract the reservoir space parameters of the shale reservoir according to the reservoir space identification result; An evaluation parameter calculation module 83 is used to calculate the evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore diameter of the shale reservoir and the surface porosity of different types of reservoir spaces; An evaluation coefficient calculation module 84 is used to input the evaluation parameters and the pre-calculated weight values ​​of the evaluation parameters into a pre-built classification evaluation model to calculate the evaluation coefficient of the shale reservoir; The classification evaluation module 85 is used to classify and evaluate the shale reservoir based on the evaluation coefficient.

[0074] In a possible embodiment, scanning the electron microscope image of the shale reservoir to be classified and evaluated to identify different types of reservoir spaces of the shale reservoir specifically includes: Analyzing the electron microscope image to obtain the ratio of the major axis to the minor axis of different types of reservoir spaces in the shale reservoir; Based on the ratio, the reservoir space is determined to be a pore or a fracture.

[0075] Specifically, this embodiment provides an implementation method for identifying different types of reservoir spaces in a shale reservoir.

[0076] In a possible embodiment, based on the ratio, the step of determining that the reservoir space is a pore or a fracture specifically includes: When the ratio is greater than or equal to a preset ratio threshold, the reservoir space is a fracture; When the ratio is less than the preset ratio threshold, the reservoir space is a pore; The ratio threshold is obtained through geological statistical analysis.

[0077] Specifically, this embodiment provides another implementation method for identifying different types of reservoir spaces in a shale reservoir.

[0078] In a possible embodiment, the reservoir space parameters include the pore size of each pore, the total field area, the total area of ​​pores and fractures, the pore area, the fracture area, and the connected area of ​​connected pores and fractures.

[0079] Specifically, this embodiment provides an implementation method of a reservoir space parameter.

[0080] In a possible embodiment, the surface ratios of different types of reservoir spaces include the total surface ratios of pores and fractures. , pore surface ratio , crack surface rate , connected pores and fracture surface ratio The evaluation parameters include the average pore size, total porosity of pores and fractures in the shale reservoir. , pore surface ratio , crack surface rate , connected pores and fracture surface ratio wait.

[0081] Specifically, this embodiment provides an implementation method for evaluating parameters.

[0082] In a possible embodiment, the step of classifying and evaluating the shale reservoir based on the evaluation coefficient specifically includes: When the evaluation coefficient is within the first threshold range, it is determined to be a Class I reservoir, and the Class I reservoir is used to characterize that the development and distribution characteristics of the pore-fracture system meet the preset oil and gas development conditions; When the evaluation coefficient is within the second threshold range, it is determined to be a Class II reservoir. The Class II reservoir is used to characterize the development and distribution characteristics of the pore-fracture system and needs to be combined with additional industrial means to meet the preset oil and gas development conditions; When the evaluation coefficient is within the third threshold range, it is determined to be a Class III reservoir, and the Class III reservoir is used to characterize that the development and distribution characteristics of the pore-fracture system do not meet the preset oil and gas development conditions; The values ​​of the evaluation coefficients represented by the first threshold range, the second threshold range, and the third threshold range decrease step by step.

[0083] Specifically, this embodiment provides an implementation method for classifying and evaluating shale reservoirs based on evaluation coefficients.

[0084] The implementation principle and beneficial effects of the pore-fracture-based shale reservoir classification and evaluation system provided in the embodiment of the present invention are similar to the implementation principle and beneficial effects of the pore-fracture-based shale reservoir classification and evaluation method shown in the above embodiment. Please refer to the implementation principle and beneficial effects of the pore-fracture-based shale reservoir classification and evaluation method shown in the above embodiment, and no further details will be given here.

[0085] Fig. 9 An example of a physical structure diagram of an electronic device is shown in FIG. Fig. 9 As shown, the electronic device may include: a processor (processor) 910 , a communication interface (Communications Interface) 920 , a memory (memory) 930 and a communication bus 940 , wherein the processor 910 , the communication interface 920 , and the memory 930 communicate with each other through the communication bus 940 . The processor 910 can call the logic instructions in the memory 930 to execute the pore-fracture based classification and evaluation method of shale reservoirs, which method includes: S1, scanning the electron microscope image of the shale reservoir to be classified and evaluated, and identifying different types of reservoir spaces of the shale reservoir, wherein the reservoir space includes pores and fractures; S2, extracting the reservoir space parameters of the shale reservoir according to the identification result of the reservoir space; S3, calculating the evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore diameter of the pores of the shale reservoir and the surface ratio of different types of reservoir spaces; S4, inputting the evaluation parameters and the pre-calculated weight values ​​of each evaluation parameter into a pre-constructed classification and evaluation model, and calculating the evaluation coefficient of the shale reservoir; S5, classifying and evaluating the shale reservoir based on the evaluation coefficient.

[0086] In addition, the logic instructions in the above-mentioned memory 930 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0087] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the pore-fracture-based shale reservoir classification and evaluation method provided by the above methods, which includes: S1, scanning the electron microscope image of the shale reservoir to be classified and evaluated, and identifying different types of reservoir spaces of the shale reservoir, wherein the reservoir space includes pores and fractures; S2, extracting the reservoir space parameters of the shale reservoir according to the identification result of the reservoir space; S3, calculating the evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore size of the pores of the shale reservoir and the surface area of ​​different types of reservoir spaces; S4, inputting the evaluation parameters and the pre-calculated weight values ​​of each evaluation parameter into a pre-constructed classification and evaluation model, and calculating the evaluation coefficient of the shale reservoir; S5, classifying and evaluating the shale reservoir based on the evaluation coefficient.

[0088] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the processor executes the pore-fracture based shale reservoir classification and evaluation method provided by the above methods, the method comprising: S1, scanning the electron microscope image of the shale reservoir to be classified and evaluated, and identifying different types of reservoir spaces of the shale reservoir, wherein the reservoir space includes pores and fractures; S2, extracting the reservoir space parameters of the shale reservoir according to the identification result of the reservoir space; S3, calculating the evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore size of the pores of the shale reservoir and the surface area ratio of different types of reservoir spaces; S4, inputting the evaluation parameters and the pre-calculated weight values ​​of each evaluation parameter into a pre-constructed classification and evaluation model, and calculating the evaluation coefficient of the shale reservoir; S5, classifying and evaluating the shale reservoir based on the evaluation coefficient.

[0089] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0090] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0091] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A shale reservoir classification and evaluation method based on pores and fractures, characterized in that: include: S1. Scanning an electron microscope image of a shale reservoir to be classified and evaluated to identify different types of reservoir spaces in the shale reservoir, wherein the reservoir spaces include pores and fractures; S2. extracting reservoir space parameters of the shale reservoir according to the reservoir space identification result; S3, calculating evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore diameter of the shale reservoir and the surface porosity of different types of reservoir spaces; S4, inputting the evaluation parameters and the pre-calculated weight values ​​of the evaluation parameters into a pre-built classification evaluation model to calculate the evaluation coefficient of the shale reservoir; S5. Based on the evaluation coefficient, classify and evaluate the shale reservoir.

2. The shale reservoir classification and evaluation method based on pores and fractures according to claim 1 is characterized in that: S1. Scanning the electron microscope image of the shale reservoir to be classified and evaluated to identify different types of reservoir spaces of the shale reservoir, specifically including: Analyzing the electron microscope image to obtain the ratio of the major axis to the minor axis of different types of reservoir spaces in the shale reservoir; Based on the ratio, the reservoir space is determined to be a pore or a fracture.

3. The shale reservoir classification and evaluation method based on pores and fractures according to claim 2 is characterized in that: Based on the ratio, the step of determining that the reservoir space is a pore or a fracture specifically comprises: When the ratio is greater than or equal to a preset ratio threshold, the reservoir space is a fracture; When the ratio is less than the preset ratio threshold, the reservoir space is a pore; The ratio threshold is obtained through geological statistical analysis.

4. The pore-fracture based shale reservoir classification and evaluation method according to claim 3, characterized in that: The reservoir space parameters include the pore size of each pore, the total field area, the total area of ​​pores and fractures, the pore area, the fracture area, and the connected area of ​​connected pores and fractures.

5. The pore-fracture based shale reservoir classification and evaluation method according to claim 4, characterized in that: The different types of reservoir space surface ratios include pore surface ratios , crack surface rate , connected pores and fracture surface ratio ; The calculation formula of the evaluation parameter is as follows: ； ； ； ； Wherein, R is the average pore size of the shale reservoir, is the pore size of the i-th pore, i=(0, 1, ... n), n is the total number of pores; A is the total viewing area of ​​the shale reservoir; A p is the pore area; A f is the crack area; A fp is the connected area of ​​voids and cracks.

6. The pore-fracture based shale reservoir classification and evaluation method according to claim 5, characterized in that: The classification evaluation model is specifically: ； Wherein, S is the evaluation coefficient, C1, C2, C3, and C4 are the weight values ​​of the average pore diameter, pore surface ratio, fracture surface ratio, and connected pore and fracture surface ratio of the shale reservoir, respectively. .

7. The pore-fracture based shale reservoir classification and evaluation method according to any one of claims 1 to 6, characterized in that: The step of classifying and evaluating the shale reservoir based on the evaluation coefficient specifically includes: When the evaluation coefficient is within the first threshold range, it is determined to be a Class I reservoir, and the Class I reservoir is used to characterize that the development and distribution characteristics of the pore-fracture system meet the preset oil and gas development conditions; When the evaluation coefficient is within the second threshold range, it is determined to be a Class II reservoir. The Class II reservoir is used to characterize the development and distribution characteristics of the pore-fracture system and needs to be combined with additional industrial means to meet the preset oil and gas development conditions; When the evaluation coefficient is within the third threshold range, it is determined to be a Class III reservoir, and the Class III reservoir is used to characterize that the development and distribution characteristics of the pore-fracture system do not meet the preset oil and gas development conditions; The values ​​of the evaluation coefficients represented by the first threshold range, the second threshold range, and the third threshold range decrease step by step.

8. The pore-fracture based shale reservoir classification and evaluation method according to claim 7, characterized in that: The first threshold range is: evaluation coefficient>0.3; The second threshold range is: evaluation coefficient ≥ 0.15 and ≤ 0.3; The third threshold range is: evaluation coefficient ≥ 0 and < 0.

15.

9. A shale reservoir classification and evaluation system based on pores and fractures, characterized in that: include: An identification module is used to scan the electron microscope image of the shale reservoir to be classified and evaluated, and identify different types of reservoir spaces of the shale reservoir, wherein the reservoir spaces include pores and fractures; A reservoir space parameter extraction module, used for extracting the reservoir space parameters of the shale reservoir according to the reservoir space identification result; An evaluation parameter calculation module, used to calculate the evaluation parameters of the shale reservoir based on the reservoir space parameters and the pre-acquired field area of ​​the shale reservoir, wherein the evaluation parameters include the average pore diameter of the shale reservoir and the surface porosity of different types of reservoir spaces; An evaluation coefficient calculation module, used for inputting the evaluation parameters and the pre-calculated weight values ​​of the evaluation parameters into a pre-built classification evaluation model, and calculating the evaluation coefficient of the shale reservoir to be classified and evaluated; A classification evaluation module is used to classify and evaluate the shale reservoir based on the evaluation coefficient.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the program, the pore-fracture based shale reservoir classification and evaluation method as described in any one of claims 1 to 8 is implemented.

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