Method and system for evaluating compressibility of continental facies shale reservoir

Abstract

The invention relates to a continental facies shale reservoir compressibility evaluation method and system, and belongs to the field of unconventional oil and gas exploration and development. The evaluation method comprises the steps of obtaining a compressibility index of a to-be-evaluated well based on a calculation model of compressibility of a continental facies shale reservoir and plane fracture network parameters, crossing expansion parameters and equilibrium expansion parameters of the to-be-evaluated well; and based on the compressibility index of the well to be evaluated, completing the compressibility evaluation of the continental facies shale reservoir. The plane fracture network parameters comprise natural fracture density, horizontal stress difference and mechanical brittleness index Young modulus. According to the method, the defect that the compressibility of the continental facies shale reservoir is difficult to accurately characterize due to the fact that an existing compressibility evaluation model only takes the complexity degree of a hydraulic fracture network as an evaluation standard is overcome. The evaluation method is reliable in principle, high in operability, high in accuracy and good in engineering application and popularization value.

Description

Technical Field

[0001] The present invention belongs to the field of unconventional oil and gas exploration and development, and in particular relates to a method and system for evaluating the compressibility of continental shale reservoirs. Background Art

[0002] Unconventional oil and gas resources such as shale oil and gas generally have low porosity and ultra-low permeability reservoir physical properties. Conventional single-wing and double-wing fracture fracturing modes can no longer meet the needs of such reservoir fracturing transformation. At present, fracture network fracturing technology is the main means of transforming such reservoirs. However, fracture network fracturing technology requires a lot of financial and material resources. Blind implementation of fracturing will not only damage the reservoir, but also cause serious environmental problems. Therefore, in order to reasonably utilize fracture network fracturing production enhancement transformation technology and ensure the economic and efficient development of unconventional oil and gas reservoirs, it is necessary to first scientifically evaluate the fracture network fracturing compressibility of the reservoir.

[0003] The existing compressibility evaluation methods are basically established for marine shale reservoirs, and usually use the complexity of the hydraulic fracture network as the evaluation standard. Compared with marine shale reservoirs, continental shale reservoirs have high clay content, poor matrix brittleness, and are difficult to fracturing to create complex fracture networks. The reservoir has strong vertical heterogeneity, large differences in lithology and stress between layers, and interlayers such as marl and siltstone are developed. It is difficult for hydraulic fractures to penetrate the layers and expand, and it is difficult to obtain a large reservoir transformation volume, resulting in poor fracturing transformation effects. Therefore, in addition to the complexity of the hydraulic fracture network, the size of the reservoir transformation volume also needs to be considered in the compressibility evaluation model. In addition, horizontal well dense cutting fracturing technology is the most effective technical means to achieve fracture network fracturing transformation in continental shale oil and gas reservoirs. By reducing the spacing between perforation clusters and increasing the density of hydraulic fractures in the fracturing section, the problem of poor matrix brittleness in continental shale reservoirs that is difficult to form a complex fracture network is solved. However, the reduction in cluster spacing increases the stress interference between fractures, making it difficult for multiple clusters of hydraulic fractures in the fracturing section to expand evenly. Obviously, the balanced expansion capacity of multiple clusters of hydraulic fractures should also be considered in the compressibility evaluation model.

[0004] In summary, the existing compressibility evaluation model is difficult to accurately characterize the compressibility of continental shale reservoirs due to its overly single evaluation criteria. It is urgent to establish a compressibility evaluation model that comprehensively considers the complexity of the hydraulic fracture network, the size of the reservoir transformation volume, and the balanced expansion capacity of multiple clusters of hydraulic fractures. Summary of the invention

[0005] In view of the above problems, the present invention provides a method and system for evaluating the compressibility of continental shale reservoirs. According to the expansion law of hydraulic fractures in continental shale reservoirs, from the perspective of evaluating the complexity of hydraulic fracture networks, the size of reservoir transformation volume and the balanced expansion potential of multiple clusters of hydraulic fractures, compressibility evaluation parameters are optimized, and the weight coefficient of each evaluation parameter is determined by a multivariate linear regression analysis method. Then, a continental shale reservoir compressibility evaluation model is constructed to evaluate the reservoir quality of continental shale fracturing wells. The method has reliable principle, strong operability and high accuracy, and provides a new decision-making method for well and layer selection for fracturing of continental shale oil and gas reservoirs.

[0006] The first object of the present invention is to provide a method for evaluating the compressibility of a shale reservoir, the method comprising:

[0007] Based on the calculation model of the compressibility of continental shale reservoirs, as well as the plane fracture network parameters, layer penetration expansion parameters and equilibrium expansion parameters of the well to be evaluated, the compressibility index of the well to be evaluated is obtained;

[0008] Based on the compressibility index of the well to be evaluated, the compressibility evaluation of the continental shale reservoir is completed.

[0009] In an embodiment of the present invention, the plane fracture network parameters include natural fracture density, horizontal stress difference and mechanical brittleness index Young's modulus; the through-layer expansion parameters include interlayer interface friction coefficient, interlayer stress difference, interlayer tensile strength difference and vertical stress difference; the balanced expansion parameters include the horizontal minimum ground stress difference and fracture toughness difference within the fracturing section.

[0010] In the embodiment of the present invention, the calculation model based on the compressibility of the continental shale reservoir, and the plane fracture network parameters, the layer penetration expansion parameters and the equilibrium expansion parameters of the well to be evaluated are used to obtain the compressibility index of the well to be evaluated, including:

[0011] Establish a computational model for the compressibility of continental shale reservoirs;

[0012] Normalize the plane fracture network parameters, layer penetration expansion parameters and balanced expansion parameters of the well to be evaluated;

[0013] The normalized plane fracture network parameters, layer penetration expansion parameters and equilibrium expansion parameters of the well to be evaluated are substituted into the calculation model of the compressibility of continental shale reservoirs to obtain the compressibility index of the well to be evaluated.

[0014] In an embodiment of the present invention, the method of establishing a calculation model for the compressibility of continental shale reservoirs includes:

[0015] Based on the plane fracture network parameters of any well, a calculation model for the plane fracture network construction capability index is obtained;

[0016] Based on the penetration expansion parameters of any well, a calculation model for the penetration expansion capacity index of hydraulic fractures is obtained;

[0017] Based on the balanced expansion parameters of any well, a calculation model for the balanced expansion capacity index of multiple cluster hydraulic fractures can be obtained;

[0018] Based on the density of microseismic event points, microseismic monitoring fracture height, multi-cluster fracture balanced development index and output contribution rate, the weight coefficients corresponding to the plane fracture network construction capability index, hydraulic fracture penetration expansion capability index and multi-cluster hydraulic fracture balanced expansion capability index are obtained.

[0019] Based on the plane fracture network construction capability index, hydraulic fracture penetration expansion capability index and multi-cluster hydraulic fracture balanced expansion capability index and their corresponding weight coefficients, the calculation model of the compressibility index is obtained.

[0020] In the embodiment of the present invention, the calculation model for obtaining the plane fracture network construction capability index based on the plane fracture network parameters of any well includes:

[0021] Normalize the plane fracture network parameters of any well;

[0022] Based on the plane fracture network parameters of any well after normalization and the density of microseismic event points, a weight coefficient corresponding to the plane fracture network parameters of any well after normalization is determined;

[0023] Based on the normalized plane fracture network parameters of any well and the corresponding weight coefficients, a calculation model for the plane fracture network construction capability index is obtained.

[0024] In the embodiment of the present invention, the calculation model for obtaining the hydraulic fracture penetration expansion capability index based on the penetration expansion parameters of any well includes:

[0025] Normalize the layer-crossing expansion parameters;

[0026] Based on the normalized penetration extension parameter and the microseismic monitoring fracture height, the weight coefficient of the normalized penetration extension parameter is determined;

[0027] Based on the normalized penetration expansion parameters and the corresponding weight coefficients, the calculation model of the hydraulic fracture penetration expansion capacity index is obtained.

[0028] In an embodiment of the present invention, based on the balanced expansion parameters of any well, a multi-cluster hydraulic fracture balanced expansion capability index calculation model may be provided, including:

[0029] Normalize the equalization expansion parameters;

[0030] Based on the normalized balanced expansion parameters and the multi-cluster fracture balanced development index, the weight coefficient corresponding to the normalized balanced expansion parameters is determined;

[0031] Based on the normalized balanced expansion parameters and the corresponding weight coefficients, a calculation model for the balanced expansion capacity index of multi-cluster hydraulic fractures is obtained.

[0032] In the embodiment of the present invention, the compressibility of the continental shale reservoir is positively correlated with the compressibility index of the well to be evaluated.

[0033] The second object of the present invention is to provide a system for evaluating the compressibility of continental shale reservoirs, the system comprising a calculation module and an evaluation module;

[0034] The calculation module is used to obtain the compressibility index of the well to be evaluated based on the calculation model of the compressibility of the continental shale reservoir, as well as the plane fracture network parameters, the layer penetration expansion parameters and the equilibrium expansion parameters of the well to be evaluated;

[0035] The evaluation module is used to complete the evaluation of the compressibility of the continental shale reservoir based on the compressibility index of the well to be evaluated.

[0036] The third object of the present invention is to provide a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method for evaluating the compressibility of continental shale reservoirs as described above.

[0037] Beneficial effects of the present invention:

[0038] According to the expansion law of hydraulic fractures in continental shale reservoirs, the present invention optimizes the compressibility evaluation parameters from the perspective of evaluating the complexity of the hydraulic fracture network, the size of the reservoir transformation volume, and the balanced expansion potential of multiple clusters of hydraulic fractures, and adopts a multivariate linear regression analysis method to determine the weight coefficient of each evaluation parameter, thereby constructing a continental shale reservoir compressibility evaluation model, overcoming the deficiency that the existing compressibility evaluation model only uses the complexity of the hydraulic fracture network as the evaluation standard and is difficult to accurately characterize the compressibility of the continental shale reservoir. The evaluation method of the present invention has a reliable principle, strong operability, high accuracy, and good engineering application and promotion value.

[0039] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in 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.

[0041] Figure 1 A flow chart showing a method for evaluating the compressibility of a continental shale reservoir according to an embodiment of the present invention is shown;

[0042] Figure 2 A multivariate regression analysis diagram of the microseismic event point density of Well X according to an embodiment of the present invention is shown;

[0043] Figure 3 A multivariate regression analysis diagram of fracture height of microseismic monitoring of X well according to an embodiment of the present invention is shown;

[0044] Figure 4 A multivariate regression analysis diagram of the balanced development index of multiple cluster fractures in Well X according to an embodiment of the present invention is shown;

[0045] Figure 5 A multivariate regression analysis diagram of the production profile test results of Well X according to an embodiment of the present invention is shown;

[0046] Figure 6 A comparison diagram of the compressibility index and the production profile test results of Well Y according to an embodiment of the present invention is shown;

[0047] Figure 7 A framework diagram of a system for evaluating the compressibility of continental shale reservoirs according to an embodiment of the present invention is shown;

[0048] In the figure:

[0049] 1. Calculation module; 2. Evaluation module. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments 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.

[0051] like Figure 1 As shown, a method for evaluating the compressibility of a continental shale reservoir according to an embodiment of the present invention includes:

[0052] Step S1, based on the calculation model of the compressibility of the continental shale reservoir, and the plane fracture network parameters, the interlayer extension parameters and the balanced extension parameters of the well to be evaluated, the compressibility index of the well to be evaluated is obtained, wherein the plane fracture network parameters include natural fracture density, horizontal stress difference and mechanical brittleness index Young's modulus; the interlayer extension parameters include interlayer interface friction coefficient, interlayer stress difference, interlayer tensile strength difference and vertical stress difference; the balanced extension parameters include the horizontal minimum ground stress difference and fracture toughness difference in the fracturing section;

[0053] Step S2: Based on the compressibility index of the well to be evaluated, the compressibility of the continental shale reservoir is evaluated.

[0054] In the embodiment of the present invention, in step S1, the calculation model based on the compressibility of the continental shale reservoir, and the plane fracture network parameters, the layer penetration expansion parameters and the equilibrium expansion parameters of the well to be evaluated are used to obtain the compressibility index of the well to be evaluated, including:

[0055] Step A1, establishing a calculation model for the compressibility of continental shale reservoirs;

[0056] Step A2, normalizing the plane fracture network parameters, layer penetration expansion parameters and balanced expansion parameters of the well to be evaluated;

[0057] Step A3: Substitute the normalized plane fracture network parameters, layer penetration expansion parameters and equilibrium expansion parameters of the well to be evaluated into the calculation model of the compressibility of the continental shale reservoir to obtain the compressibility index of the well to be evaluated.

[0058] Specifically, in step A1, the establishment of a calculation model for the compressibility of continental shale reservoirs includes:

[0059] Step B1, based on the plane fracture network parameters of any well, a calculation model for the plane fracture network construction capability index is obtained;

[0060] Step B2, based on the penetration expansion parameters of any well, a hydraulic fracture penetration expansion capacity index calculation model is obtained;

[0061] Step B3, based on the balanced expansion parameters of any well, a calculation model for the balanced expansion capability index of multiple cluster hydraulic fractures is obtained;

[0062] Step B4, based on the density of microseismic event points, microseismic monitoring fracture height, multi-cluster fracture balanced development index and output contribution rate, obtain the weight coefficients corresponding to the plane fracture network construction capability index, the hydraulic fracture penetration expansion capability index and the multi-cluster hydraulic fracture balanced expansion capability index;

[0063] Step B5: Based on the plane fracture network construction capability index, the hydraulic fracture penetration expansion capability index and the multi-cluster hydraulic fracture balanced expansion capability index and their corresponding weight coefficients, a calculation model for the compressibility index is obtained.

[0064] Specifically, in step B1, the calculation model of the plane fracture network construction capability index based on the plane fracture network parameters of any well includes:

[0065] Step B11, normalizing the plane fracture network parameters of any well;

[0066] Step B12: based on the normalized plane fracture network parameters of any well and the microseismic event point density, determine the weight coefficient corresponding to the normalized plane fracture network parameters of any well;

[0067] Step B13: Based on the normalized plane fracture network parameters of any well and the corresponding weight coefficients, a plane fracture network construction capability index calculation model is obtained.

[0068] Specifically, any well is selected as well X, and the plane fracture network parameters in step B11 are natural fracture density, horizontal stress difference and mechanical brittleness index, and the plane fracture network parameters are normalized according to formulas (1) to (3):

[0069]

[0070]

[0071]

[0072] In formulas (1)-(3), ρ nf is the normalized natural fracture density, dimensionless; ρ NF is the natural fracture density before normalization, dimensionless; Δσ is the horizontal stress difference after normalization, dimensionless; B rit is the normalized mechanical brittleness index, dimensionless; ρ NF is the linear density of natural fractures, lines / m; Δσ H-h is the horizontal stress difference, MPa; YM is Young's modulus, GPa; YM cmax With YM cmin is the maximum and minimum static Young's modulus of the region, GPa; YM BRIT is the normalized Young's modulus, 0-1; PR is Poisson's ratio, dimensionless; PR cmax With PR cmin PR is the maximum and minimum static Poisson's ratio in the region, dimensionless; BRIT is the normalized Poisson's ratio, 0 to 1;

[0073] Substituting the data of each fracturing stage of Well X into equations (1)-(3), the normalized natural fracture density, horizontal stress difference and mechanical brittleness index are obtained, as shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] In step B12, based on the normalized plane fracture network parameters of any well and the microseismic event point density, the weight coefficient corresponding to the plane fracture network parameters of any well after normalization is determined. Specifically, the natural fracture density, horizontal stress difference and mechanical brittleness index after normalization obtained in step B11 are used as independent variables, and the microseismic event point density (actual values ​​are shown in Table 1) is used as the dependent variable. The multivariate linear regression analysis method is used to calculate the multivariate regression analysis diagram of the microseismic event point density of well X, as shown in FIG. Figure 2 As shown, in this process, the weight coefficients of the normalized natural crack density, horizontal stress difference and mechanical brittleness index are 0.49, 0.29 and 0.22 respectively;

[0078] In step B13, the plane fracture network parameters of any well after normalization and the corresponding weight coefficient are used to obtain a calculation model for the plane fracture network construction capability index. Specifically, the plane fracture network construction capability index is calculated according to formula (4) through multiple linear regression analysis:

[0079] F net =aρ nf +bΔσ+cB rit (4)

[0080] In formula (4), F net is the plane fracture network construction capability index, a is the weight coefficient corresponding to the normalized natural fracture density, b is the weight coefficient corresponding to the normalized horizontal stress difference, and c is the weight coefficient corresponding to the normalized mechanical brittleness index;

[0081] From step B12, it can be seen that a=0.49, b=0.29, c=0.22. Substituting a, b, and c into Table (4), the plane seam network construction capability index F can be obtained. net The calculation model formula (4)':

[0082] F net =0.49ρ nf +0.29Δσ+0.22B rit (4)'.

[0083] In the embodiment of the present invention, in step B2, the calculation model of the hydraulic fracture penetration expansion capability index based on the penetration expansion parameters of any well includes:

[0084] Step B21, normalizing the layer-crossing extension parameters;

[0085] Step B22, based on the normalized penetration extension parameter and the microseismic monitoring fracture height, determining the weight coefficient of the normalized penetration extension parameter;

[0086] Step B23: Based on the normalized penetration expansion parameters and the corresponding weight coefficients, a hydraulic fracture penetration expansion capability index calculation model is obtained.

[0087] Specifically, in step B21, the interlayer expansion parameters are interlayer interface shear strength, interlayer stress difference, tensile strength difference and vertical stress, and the interlayer interface shear strength, interlayer stress difference, tensile strength difference and vertical stress difference are normalized according to formulas (5)-(8):

[0088]

[0089]

[0090]

[0091]

[0092] In formulas (5)-(8), μ is the normalized interlayer interface friction coefficient, which is dimensionless; I is the interlayer friction coefficient, GPa; Δσ in is the normalized interlaminar interface shear strength, dimensionless; Δσ G-C is the interlaminar stress difference, MPa; ΔT in is the normalized interlaminar tensile strength difference, dimensionless; ΔT G-C is the difference in tensile strength between layers, GPa; Δσ v is the normalized vertical stress difference, dimensionless; Δσ v-h is the vertical stress difference, MPa;

[0093] Substituting the data of each fracturing stage of Well X into equations (5)-(6), the normalized interlayer interface shear strength, interlayer stress difference, tensile strength difference and vertical stress difference are obtained, as shown in Table 2.

[0094] Table 2

[0095] Segment number μ <![CDATA[Δσ in ]]> <![CDATA[ΔT in ]]> <![CDATA[Δσ v ]]> Microseismic monitoring crack height / m 1 0.64 0.24 0.28 0.31 23.46 2 0.86 0.38 0.39 0.72 27.68 3 0.83 0.34 0.36 0.55 26.16 4 0.87 0.38 0.41 0.72 27.99 5 1 0.71 0.69 0.92 33.46 6 0.85 0.38 0.39 0.69 27.56 7 0.91 0.52 0.52 0.79 30.64 8 0.91 0.52 0.59 0.8 30.12 9 0.86 0.49 0.43 0.75 28.59 10 0.931 0.59 0.59 0.83 30.61 11 0.91 0.57 0.59 0.81 30.15 12 0.95 0.62 0.61 0.89 31.54 13 0.88 0.51 0.49 0.78 29.32 14 0.88 0.43 0.43 0.75 28.49 15 0.89 0.51 0.52 0.79 29.46 16 0.91 0.59 0.58 0.81 30.25 17 0.84 0.34 0.36 0.61 26.94 18 0.95 0.64 0.61 0.89 31.69 19 0.932 0.59 0.59 0.83 30.68 20 0.72 0.31 0.33 0.39 24.64

[0096] In step B22, based on the normalized penetration expansion parameters and the microseismic monitoring fracture height, the weight coefficient of the normalized penetration expansion parameters is determined. Specifically, the normalized interlayer interface shear strength, interlayer stress difference, tensile strength difference and vertical stress difference obtained in step B21 are used as independent variables, and the microseismic monitoring fracture height (actual value specific value is shown in Table 2) is used as the dependent variable. The multivariate linear regression analysis method is used to calculate the multivariate regression analysis diagram of the microseismic monitoring fracture height of Well X (as shown in Figure 2). Figure 3 As shown in the figure, in this process, the weight coefficients corresponding to the normalized interlaminar interface shear strength, interlaminar stress difference, tensile strength difference and vertical stress difference are 0.40, 0.30, 0.17 and 0.13 respectively;

[0097] In step B23, based on the normalized penetration expansion parameters and the corresponding weight coefficients, a hydraulic fracture penetration expansion capacity index calculation model is obtained. Specifically, the hydraulic fracture penetration expansion capacity index is calculated according to formula (9) through multiple linear regression analysis:

[0098] F cc =dμ+eΔσ+fΔT in +gΔσ v (9)

[0099] In formula (9), F cc is the hydraulic fracture penetration capacity index, d is the weight coefficient corresponding to the normalized interlayer interface shear strength, e is the weight coefficient corresponding to the normalized interlayer stress difference, f is the weight coefficient corresponding to the normalized tensile strength difference, and g is the weight coefficient corresponding to the normalized vertical stress difference;

[0100] From step B22, we know that d = 0.40, e = 0.30, f = 0.17, g = 13. Substituting d, e, f, and g into Table (9), we can get the hydraulic fracture penetration capability index F. cc The calculation model formula (9)':

[0101] F cc =0.40μ+0.30Δσ+0.17ΔT in +0.13Δσ v (9)'.

[0102] In the embodiment of the present invention, in step B3, based on the balanced expansion parameters of any well, a multi-cluster hydraulic fracture balanced expansion capability index calculation model may be provided, including:

[0103] Step B31, normalizing the equalization extension parameters;

[0104] Step B32: determining a weight coefficient corresponding to the normalized balanced expansion parameter based on the normalized balanced expansion parameter and the multi-cluster fracture balanced development index;

[0105] Step B33: Based on the normalized balanced expansion parameters and the corresponding weight coefficients, a calculation model for the balanced expansion capability index of multiple cluster hydraulic fractures is obtained.

[0106] Specifically, in step B31, the equilibrium expansion parameters include the horizontal minimum in-situ stress difference and the fracture toughness difference in the fracturing section, and the horizontal minimum in-situ stress difference and the fracture toughness difference in the fracturing section are normalized according to formulas (10)-(11):

[0107]

[0108]

[0109] In formulas (10) and (11), Δσ h is the normalized minimum horizontal stress difference in the fracturing section, dimensionless; ΔK is the normalized fracture toughness difference in the fracturing section, dimensionless; Δσ h-h The difference between the maximum value of the horizontal minimum ground stress in the fracturing section where the point to be evaluated is located and the horizontal minimum ground stress at the point to be evaluated, MPa; ΔK IC It is the difference between the maximum value of the fracture toughness in the fracturing section where the point to be evaluated is located and the fracture toughness of the point to be evaluated, MPa;

[0110] Substituting the data of each fracturing section of Well X into equations (10)-(11), the normalized minimum horizontal in-situ stress difference and fracture toughness difference within the fracturing section are obtained, as shown in Table 3.

[0111] Table 3

[0112]

[0113]

[0114] In step B32, based on the normalized balanced expansion parameters and the balanced development index of multiple clusters of fractures, the weight coefficient corresponding to the normalized balanced expansion parameters is determined. Specifically, the horizontal minimum ground stress difference and the fracture toughness difference in the fracturing section after normalization obtained in step B31 are used as independent variables, and the balanced development index of multiple clusters of fractures (the ratio of the microseismic monitoring fracture length of the evaluation point to the longest fracture in the fracturing section, the actual value is shown in Table 3) is used as the dependent variable. The multiple linear regression analysis method is used to calculate the multiple regression analysis diagram of the balanced development index of multiple clusters of fractures in Well X, as shown in FIG. Figure 4 As shown in the figure, in this process, the weight coefficients corresponding to the normalized horizontal minimum ground stress difference and fracture toughness difference in the fracturing section are 0.66 and 0.34 respectively;

[0115] In step B33, based on the normalized balanced expansion parameters and the corresponding weight coefficients, a calculation model for the balanced expansion capacity index of multiple clusters of hydraulic fractures is obtained. Specifically, through the multivariate linear regression analysis method, the balanced expansion capacity index of multiple clusters of hydraulic fractures is calculated according to formula (12):

[0116] F jh =iΔσ h +jΔK (12)

[0117] In formula (12), F jh is the balanced expansion capacity index of multiple cluster hydraulic fractures, i is the weight coefficient corresponding to the normalized minimum horizontal stress difference in the fracturing section, and j is the weight coefficient corresponding to the normalized fracture toughness difference;

[0118] From step B32, we know that i=0.66, j=0.34. Substituting i and j into formula (12), we can obtain the calculation model formula (12)' of the balanced expansion capacity index of multi-cluster hydraulic fractures:

[0119] F jh =0.66Δσ h +0.37ΔK (12)'

[0120] In the embodiment of the present invention, in step B4, based on the microseismic event point density, microseismic monitoring fracture height, multi-cluster fracture balanced development index and output contribution rate, the weight coefficients corresponding to the plane fracture network construction capability index, the hydraulic fracture penetration expansion capability index and the multi-cluster hydraulic fracture balanced expansion capability index are obtained. Specifically, the microseismic event point density (see Table 1), the microseismic monitoring fracture height (see Table 2), and the multi-cluster fracture balanced development index (see Table 3) are used as independent variables, and the output contribution rate (that is, the specific value of the production profile test result is shown in Table 4) is used as the dependent variable. The multivariate linear regression analysis method is used to obtain the multivariate regression analysis diagram of the production profile test result, as shown in FIG. Figure 5 As shown in the figure, in this process, the corresponding weight coefficients of the plane fracture network construction capability index, hydraulic fracture penetration expansion capability index and multi-cluster hydraulic fracture balanced expansion capability index are 0.41, 0.31 and 0.28 respectively;

[0121] Table 4

[0122] Segment number Output contribution rate (%) 1 3.19 2 4.16 3 3.62 4 4.59 5 6.24 6 4.03 7 5.60 8 5.45 9 5.20 10 5.42 11 5.60 12 6.00 13 5.39 14 5.27 15 5.41 16 5.82 17 3.66 18 6.04 19 5.83 20 3.37

[0123] It can be obtained that in step B5, the calculation model of the compressibility index is obtained based on the plane fracture network construction capability index, the hydraulic fracture penetration expansion capability index and the multi-cluster hydraulic fracture balanced expansion capability index and their corresponding weight coefficients, that is, the compressibility index is calculated according to formula (13):

[0124] FI=1F net +mF cc +nF jh (13)

[0125] In formula (13), FI is the compressibility index, F net is the plane seam network construction capability index, F cc F is the hydraulic fracture penetration capacity index, jh is the balanced expansion capability index of multiple clusters of hydraulic fractures, l is the weight number corresponding to the plane fracture network construction capability index, m is the weight number corresponding to the hydraulic fracture penetration expansion capability index, and n is the weight number corresponding to the balanced expansion capability index of multiple clusters of hydraulic fractures. It can be seen that l = 0.41, m = 0.31, n = 0.28. Substituting l, m, and n into formula (13), the calculation model formula of the compressibility index FI can be obtained (13)':

[0126] FI=0.41F net +0.31F cc +0.28F jh (13)'.

[0127] Specifically, in step A2, the plane fracture network parameters, layer penetration expansion parameters and balanced expansion parameters of the well to be evaluated are normalized, that is, the plane fracture network parameters, layer penetration expansion parameters and balanced expansion parameters in the full well section data of well Y are normalized, wherein:

[0128] The natural fracture density, horizontal stress difference and mechanical brittleness index (i.e., plane fracture network parameters) of Well Y are normalized according to equations (1)-(3) to obtain the normalized natural fracture density, horizontal stress difference and mechanical brittleness index;

[0129] The interlayer interface friction coefficient, interlayer stress difference, interlayer tensile strength difference and vertical stress difference (i.e., penetration expansion parameters) of Well Y are normalized according to equations (5)-(8) to obtain the normalized interlayer interface friction coefficient, interlayer stress difference, interlayer tensile strength difference and vertical stress difference;

[0130] The horizontal minimum in-situ stress difference and the fracture toughness difference (i.e., the equilibrium expansion parameter) in the fracturing section of Well Y are normalized according to equations (10)-(12) to obtain the normalized horizontal minimum in-situ stress difference and the fracture toughness difference in the fracturing section;

[0131] Specifically, in step A3, the plane fracture network parameters, the layer penetration expansion parameters and the equilibrium expansion parameters of the well to be evaluated after normalization are substituted into the calculation model of the compressibility of the continental shale reservoir to obtain the compressibility index of the well to be evaluated.

[0132] That is, the plane fracture network parameters, penetration expansion parameters and balanced expansion parameters of Well Y obtained in step A2 after normalization are substituted into formulas (4)', (9)' and (12)' to obtain the plane fracture network construction capability index, hydraulic fracture penetration expansion capability index and multi-cluster hydraulic fracture balanced expansion capability index of Well Y, as shown in Table 5. Then, the above-mentioned plane fracture network construction capability index, hydraulic fracture penetration expansion capability index and multi-cluster hydraulic fracture balanced expansion capability index are substituted into formula (13)' to obtain the compressibility index of Well Y, as shown in Table 5.

[0133] Table 5

[0134]

[0135] In the embodiment of the present invention, in step S2, the compressibility of the continental shale reservoir is evaluated based on the compressibility index of the well to be evaluated. Specifically, the compressibility of the continental shale reservoir is positively correlated with the compressibility index of the well to be evaluated, that is, the larger the value of the compressibility index FI is, the better the compressibility of the corresponding continental shale reservoir is;

[0136] Specifically, the compressibility index of the entire well section of Well Y is compared with the production profile test results to form a graph as shown in FIG. Figure 6 As shown, it can be seen that the compressibility index calculated according to the method provided by the present invention is basically consistent with the change trend of the production profile test results after fracturing of Well Y, that is, the higher the compressibility index of the fracturing section, the more complete the fracturing transformation, and the higher the contribution rate to the production of the entire well section.

[0137] like Figure 7 As shown, in an embodiment of the present invention, a system for evaluating the compressibility of continental shale reservoirs is provided, comprising a calculation module 1 and an evaluation module 2;

[0138] The calculation module 1 is used to obtain the compressibility index of the well to be evaluated based on the calculation model of the compressibility of the continental shale reservoir, as well as the plane fracture network parameters, the layer penetration expansion parameters and the equilibrium expansion parameters of the well to be evaluated;

[0139] The evaluation module 2 is used to evaluate the compressibility of the continental shale reservoir based on the compressibility index of the well to be evaluated.

[0140] In certain embodiments of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the method for evaluating the compressibility of continental shale reservoirs in the above-mentioned embodiment is implemented.

[0141] According to an embodiment of the present invention, the computer-readable storage medium may be a non-volatile computer-readable computer-readable storage medium, for example, may include but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, apparatus, or device.

[0142] 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 substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the compressibility of continental shale reservoirs, characterized in that: include: Based on the calculation model of the compressibility of continental shale reservoirs, as well as the plane fracture network parameters, layer penetration expansion parameters and equilibrium expansion parameters of the well to be evaluated, the compressibility index of the well to be evaluated is obtained; Based on the compressibility index of the well to be evaluated, the compressibility evaluation of the continental shale reservoir is completed.

2. The method for evaluating the compressibility of continental shale reservoirs according to claim 1, characterized in that: The plane fracture network parameters include natural fracture density, horizontal stress difference and mechanical brittleness index Young's modulus; the interlayer expansion parameters include interlayer interface friction coefficient, interlayer stress difference, interlayer tensile strength difference and vertical stress difference; The equilibrium expansion parameters include the minimum horizontal ground stress difference and the fracture toughness difference within the fracturing section.

3. The method for evaluating the compressibility of continental shale reservoirs according to claim 1, characterized in that: The calculation model based on the compressibility of continental shale reservoirs, as well as the plane fracture network parameters, layer penetration expansion parameters and equilibrium expansion parameters of the well to be evaluated, obtain the compressibility index of the well to be evaluated, including: Establish a computational model for the compressibility of continental shale reservoirs; Normalize the plane fracture network parameters, layer penetration expansion parameters and balanced expansion parameters of the well to be evaluated; The normalized plane fracture network parameters, layer penetration expansion parameters and equilibrium expansion parameters of the well to be evaluated are substituted into the calculation model of the compressibility of continental shale reservoirs to obtain the compressibility index of the well to be evaluated.

4. The method for evaluating the compressibility of continental shale reservoirs according to claim 3, characterized in that: The method of establishing a calculation model for the compressibility of continental shale reservoirs comprises: Based on the plane fracture network parameters of any well, a calculation model for the plane fracture network construction capability index is obtained; Based on the penetration expansion parameters of any well, a calculation model for the penetration expansion capacity index of hydraulic fractures is obtained; Based on the balanced expansion parameters of any well, a calculation model for the balanced expansion capacity index of multiple cluster hydraulic fractures can be obtained; Based on the density of microseismic event points, microseismic monitoring fracture height, multi-cluster fracture balanced development index and output contribution rate, the weight coefficients corresponding to the plane fracture network construction capability index, hydraulic fracture penetration expansion capability index and multi-cluster hydraulic fracture balanced expansion capability index are obtained. Based on the plane fracture network construction capability index, hydraulic fracture penetration expansion capability index and multi-cluster hydraulic fracture balanced expansion capability index and their corresponding weight coefficients, the calculation model of the compressibility index is obtained.

5. The method for evaluating the compressibility of continental shale reservoirs according to claim 4, characterized in that: The calculation model for obtaining the plane fracture network construction capability index based on the plane fracture network parameters of any well includes: Normalize the plane fracture network parameters of any well; Based on the plane fracture network parameters of any well after normalization and the density of microseismic event points, a weight coefficient corresponding to the plane fracture network parameters of any well after normalization is determined; Based on the normalized plane fracture network parameters of any well and the corresponding weight coefficients, a calculation model for the plane fracture network construction capability index is obtained.

6. The method for evaluating the compressibility of continental shale reservoirs according to claim 4, characterized in that: The calculation model for obtaining the hydraulic fracture penetration expansion capability index based on the penetration expansion parameters of any well includes: Normalize the layer-crossing expansion parameters; Based on the normalized penetration extension parameter and the microseismic monitoring fracture height, the weight coefficient of the normalized penetration extension parameter is determined; Based on the normalized penetration expansion parameters and the corresponding weight coefficients, the calculation model of the hydraulic fracture penetration expansion capacity index is obtained.

7. The method for evaluating the compressibility of continental shale reservoirs according to claim 4, characterized in that: Based on the balanced expansion parameters of any well, a multi-cluster hydraulic fracture balanced expansion capacity index calculation model can be obtained, including: Normalize the equalization expansion parameters; Based on the normalized balanced expansion parameters and the multi-cluster fracture balanced development index, the weight coefficient corresponding to the normalized balanced expansion parameters is determined; Based on the normalized balanced expansion parameters and the corresponding weight coefficients, a calculation model for the balanced expansion capacity index of multi-cluster hydraulic fractures is obtained.

8. The method for evaluating the compressibility of continental shale reservoirs according to any one of claims 1 to 7, characterized in that: The compressibility of the continental shale reservoir is positively correlated with the compressibility index of the well to be evaluated.

9. A system for evaluating the compressibility of continental shale reservoirs, characterized in that: It includes calculation module and evaluation module; The calculation module is used to obtain the compressibility index of the well to be evaluated based on the calculation model of the compressibility of the continental shale reservoir, as well as the plane fracture network parameters, the layer penetration expansion parameters and the equilibrium expansion parameters of the well to be evaluated; The evaluation module is used to complete the evaluation of the compressibility of the continental shale reservoir based on the compressibility index of the well to be evaluated.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for evaluating the compressibility of a continental shale reservoir according to any one of claims 1 to 8 is implemented.

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