A multi-parameter fusion shale compressibility evaluation method and system

Abstract

The present application relates to a kind of multi-parameter fusion shale compressibility evaluation method and system, comprising: the present method directly from the characteristics of shale compressibility, by the quantitative calculation of shale reservoir fracturing index, on the basis of porosity, permeability Young's modulus, brittleness index, fracture toughness, and tensile strength such as key parameters, integrated comprehensive sand liquid ratio, slickwater proportion, above medium sand proportion three field fracturing construction parameters, after evaluation parameter normalization processing, all become positive index, then using variation coefficient method calculates each parameter weight, finally creates can all aspects, reasonable quantitative reflection shale oil reservoir fracturing evaluation method, the model evaluates the fracturing of shale reservoir from multiple angles.Compressibility can be objectively, comprehensively, scientifically evaluated to shale reservoir, reduce human factor interference, significantly improve the overall efficiency and effect of fracturing operation, improve the fracturing effect and reservoir producing degree of shale reservoir.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oilfield development, and particularly relates to a multi-parameter fusion shale compressibility evaluation method and system. BACKGROUND

[0002] The shale reservoir compressibility depends on factors such as stress difference, rock brittleness, natural fracture development condition, and is a comprehensive index. At present, international and domestic research mainly focuses on how to quantify the brittleness index of shale, and directly evaluates the reservoir compressibility by using the brittleness index. However, the index for evaluating the shale compressibility is not limited to the brittleness index itself, and many factors will also affect the fracturing effect of shale, especially the brittleness index and the production after shale fracturing. It is difficult to establish a direct relationship in many cases. Breyer et al. emphasized the importance of shale brittleness and toughness to compressibility; Chen Yun et al. proposed a new method for evaluating rock brittleness based on energy dissipation; Yuan Junliang et al. combined the brittleness index with rock mechanics parameters to evaluate the compressibility of the formation; Rickman et al. introduced the elastic parameter method, which is a widely used brittleness evaluation method; Li Qinghui et al. pointed out that the mineral composition of rock has a significant impact on the brittleness index. In addition, some researchers proposed to evaluate the shale compressibility based on the inversion of construction pressure, but this method may have some experience judgment components in practical application due to the difficulty in accurately identifying the breaking point.

[0003] Shale oil reservoirs have very poor physical properties, and hydraulic fracturing is an essential technology for its economic and effective exploitation. Before reservoir hydraulic fracturing, it is essential to evaluate the compressibility of the reservoir. Reservoir compressibility refers to the possibility of forming a complex fracture network structure and achieving significant volume modification in the reservoir under the same fracturing technology conditions, and the probability of ultimately achieving high recovery. At present, the international evaluation of shale oil compressibility is not comprehensive enough, and the existing evaluation methods mainly focus on the identification of geological "sweet spots" or engineering "sweet spots", and the combination of the two is relatively general. In the field of shale gas, especially for the areas with stable distribution of geological static indicators (such as porosity, permeability, oil and gas saturation, total organic carbon content, gas content, etc.), forming a persistent and interconnected complex fracture network is the core goal of hydraulic fracturing modification. In order to achieve this goal, it is necessary to evaluate the key shale physical parameters with high quality.

[0004] In the engineering "dessert" evaluation, the rock brittleness index is an indispensable parameter to characterize the reservoir fracturing property, but there are deficiencies in the application of a single brittleness index to evaluate the reservoir fracturing property. In view of the fact that the rock brittleness is difficult to accurately characterize the reservoir fracturing property, domestic and foreign scholars introduce the rock fracture toughness, and propose a fracturing property index combining the brittleness index and the fracture toughness for the evaluation of the shale gas reservoir fracturing property, but a single brittleness index and fracture toughness may not comprehensively and accurately evaluate the reservoir fracturing property. For example, some reservoirs with high brittleness index and fracture toughness may not have ideal actual fracturing property due to the influence of other factors (such as stress state, fracture development degree, etc.). SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a multi-parameter fusion shale fracturing property evaluation method and system;

[0006] In order to create a fracturing property evaluation model that can comprehensively consider multiple factors, the present application adds three field fracturing construction parameters such as comprehensive sand fluid ratio, slick water ratio and medium sand ratio to the key geological parameters such as porosity, permeability Young's modulus, brittleness index, fracture toughness and tensile strength. The present application proposes a comprehensive evaluation method that can quantitatively measure the fracturing property of shale oil reservoirs. This model evaluates the fracturing potential of shale reservoirs from multiple dimensions.

[0007] In the present application, first, the key parameter calculation models of porosity, permeability Young's modulus, brittleness index, fracture toughness and tensile strength are constructed through core description and logging curves; then, on this basis, the field fracturing construction parameters (comprehensive sand fluid ratio, slick water ratio and medium sand ratio) are added; finally, the weights of the evaluation parameters are obtained by using the coefficient of variation method, the weights are multiplied by the normalized evaluation parameters respectively and added in turn, and the result is taken as the formation fracturing property evaluation index. The method of the present application improves the overall efficiency and effect of fracturing operation and solves the deficiencies of the existing evaluation methods.

[0008] The present application also provides a shale fracturing property evaluation system based on stress inversion.

[0009] The technical scheme of the present application is:

[0010] A multi-parameter fusion shale fracturing property evaluation method, comprising:

[0011] S1, calculate the rock porosity fracturing property evaluation index through core description and logging curves, wherein the rock porosity fracturing property evaluation index is obtained by using the multiple regression equation of acoustic travel time, density, organic carbon content, shale index and porosity, and the permeability is obtained by the flow unit method;

[0012] S2, according to the conventional logging interpretation result, the elastic rock mechanics parameters are counted, and the Young's modulus and Poisson's ratio of the rock are calculated;

[0013] S3, the brittleness index compressibility evaluation index is calculated based on the Young's modulus and Poisson's ratio calculated in S2, and the brittleness index compressibility evaluation index is obtained;

[0014] S4, based on the analysis of the reservoir and the mechanical parameters, the function regression is carried out with the shale density, gamma, acoustic time difference logging data as independent variables to obtain a multiple regression fitting function, and the I-type and II-type fracture toughness indexes of each fracturing interval are calculated;

[0015] S5, the compressibility evaluation index of the tensile strength index is taken as a target function, the function regression is carried out with the shale density, longitudinal wave velocity conventional logging data as independent variables, and the compressibility evaluation index of the tensile strength index is obtained;

[0016] S6, the comprehensive sand fluid ratio, slick water proportion and medium sand above proportion are calculated;

[0017] S7, eight parameters are normalized by using the range transformation method, and each parameter with different units and dimensions is divided into positive indicators and negative indicators, and after normalization, all become positive indicators; the eight parameters include rock porosity, permeability, Young's modulus, brittleness index, fracture toughness index, tensile strength, comprehensive sand fluid ratio, slick water proportion and medium sand above proportion;

[0018] S8, the weights of the eight parameters of rock porosity, permeability, Young's modulus, brittleness index, fracture toughness index, tensile strength, comprehensive sand fluid ratio, slick water proportion and medium sand above proportion are calculated by using the coefficient of variation method, the weights are multiplied with the normalized evaluation parameters respectively and are added in turn, and the result is taken as the formation compressibility evaluation index, and the shale compressibility evaluation is completed.

[0019] According to the preferred embodiment of the present application, the rock porosity is obtained by using logging interpretation data, and the calculation formula is as follows:

[0020]

[0021] TOC=40.6-15.6*DEN+0.013*GR+0.009*CNL (2)

[0022] Phi=0.32*AC-0.55*DEN+0.84*TOC-0.48*SH+8.67 (3)

[0023] In the formula, SH is a shale index, TOC is organic carbon content, DEN is rock density, GR is an estimated natural gamma logging value of a well section, GR max is a natural gamma logging value at a pure shale; GRmin CNL is the compensated neutron log value; AC is the acoustic time difference; and Φ is the rock porosity.

[0024] According to the present application, the permeability is calculated by the flow index, and the calculation formula is as follows:

[0025]

[0026] K=0.0012×I n (5)

[0027] In the formula, K is the permeability, mD; I is the flow index, μs / m; S is the total Stonely wave time difference, μs / m, which is extracted from the array acoustic logging time difference; ρm is the mud density, g / cm 3 ; Km is the mud bulk modulus, MPa, which is obtained from the mud density and the longitudinal and transverse wave velocities; and G is the formation shear modulus, MPa, which is obtained from the density logging and the transverse wave velocity.

[0028] According to the present application, the Young's modulus is calculated by the following formula:

[0029]

[0030] In the formula, E is the Young's modulus; Δt is the longitudinal wave time difference; Δt s is the transverse wave time difference; and ρ is the rock density.

[0031] According to the present application, the Poisson's ratio is calculated by the following formula:

[0032]

[0033] In the formula, v is the static Poisson's ratio of the rock; Δt s is the transverse wave time difference; and Δt is the longitudinal wave time difference.

[0034] According to the present application, the brittleness index is calculated by the Young's modulus and the Poisson's ratio, and the calculation formula is as follows:

[0035]

[0036] In the formula, Brit is the brittleness index of the rock, dimensionless; E is the Young's modulus, GPa; and v is the static Poisson's ratio of the rock.

[0037] According to the present application, the I-type and II-type fracture toughness indexes K Ⅰ and K Ⅱ are obtained by using the logging interpretation data, and the calculation formula is as follows:

[0038]

[0039] In the formula, p is shale density; Vcl is shale argillan content; DT is acoustic time difference, μm / s.

[0040] According to the present application, the tensile strength is calculated by the following formula:

[0041] σ t = 14.91ln(V p )+22.41ln(p)-140.2 (11)

[0042] In the formula, σ t is tensile strength; p is shale density; V p is longitudinal wave velocity.

[0043] According to the present application, each parameter is normalized by using range transformation method, and each parameter with different units and dimensions is divided into positive index and negative index, and after normalization, all the parameters become positive index, and the calculation methods of positive index and negative index are as follows:

[0044] In the formula, the positive index is as follows:

[0045]

[0046] In the formula, the negative index is as follows:

[0047]

[0048] In the formula, S1 is the normalized value of positive parameter; S2 is the normalized value of negative parameter; X max is the maximum value of parameter; X min is the minimum value of parameter; and X is the value of parameter.

[0049] According to the present application, the weight of each parameter is calculated by using coefficient of variation method, and the calculation formula is as follows:

[0050]

[0051] In the formula, i=1,…,m; j=1,…,n; m is the total number of evaluation indexes to be determined; n is the sample number of each evaluation index; w i is the weight of the i th parameter; C i is the coefficient of variation of the i th parameter; σ i is the standard deviation of the i th parameter; μ i is the average value of the i th parameter; r ij is the sample matrix of the i th parameter evaluation index.

[0052] Preferably, the weight is multiplied by the normalized evaluation parameter respectively and added in sequence, and the result is taken as the formation compressibility evaluation index; the calculation formula is as follows:

[0053]

[0054] In the formula, I CF is the formation compressibility evaluation index; x i is the normalized i-th evaluation index; W i is the eighth parameter weight determined by the coefficient of variation method.

[0055] A computer device comprises a memory and a processor, the memory stores a computer program, and the processor implements the steps of the multi-parameter fusion shale compressibility evaluation method when executing the computer program.

[0056] A computer readable storage medium stores a computer program, and the computer program implements the steps of the multi-parameter fusion shale compressibility evaluation method when executed by a processor.

[0057] A multi-parameter fusion shale compressibility evaluation system comprises:

[0058] A rock porosity and permeability compressibility evaluation index calculation module is configured to calculate a rock porosity compressibility evaluation index through core description and logging curves, wherein the rock porosity compressibility evaluation index is obtained by using a multiple regression equation of acoustic travel time, density, organic carbon content, shale index and porosity, and the permeability is obtained by a flow unit method.

[0059] A Young's modulus and Poisson's ratio calculation module is configured to calculate the Young's modulus and Poisson's ratio of the rock according to conventional logging interpretation results and statistics of elastic rock mechanics parameters.

[0060] A brittleness index compressibility evaluation index calculation module is configured to calculate the brittleness index compressibility evaluation index based on the calculated Young's modulus and Poisson's ratio, and obtain the brittleness index compressibility evaluation index.

[0061] A fracture toughness index calculation module is configured to obtain a multiple regression fitting function by function regression with shale density, gamma and acoustic travel time logging data as independent variables based on analysis of reservoir and mechanics parameters, and calculate the I-type and II-type fracture toughness indexes of each fracturing interval.

[0062] A tensile strength index compressibility evaluation index calculation module is configured to take the tensile strength index compressibility evaluation index as a target function, perform function regression with shale density and longitudinal wave velocity conventional logging data as independent variables, and obtain the tensile strength index compressibility evaluation index.

[0063] The comprehensive sand-liquid ratio, slick water ratio and medium sand ratio calculation module is configured to calculate the comprehensive sand-liquid ratio, slick water ratio and medium sand ratio; and the normalization processing module is configured to normalize the eight parameters by using a range transformation method, and divide the parameters with different units and dimensions into positive indicators and negative indicators, so that the normalized parameters are all positive indicators; the eight parameters include rock porosity, permeability, Young's modulus, brittleness index, fracture toughness index, tensile strength, comprehensive sand-liquid ratio, slick water ratio and medium sand ratio.

[0064] The shale compressibility evaluation module is configured to calculate the weights of the eight parameters of rock porosity, permeability, Young's modulus, brittleness index, fracture toughness index, tensile strength, comprehensive sand-liquid ratio, slick water ratio and medium sand ratio by using a coefficient of variation method, multiply the weights with the normalized evaluation parameters respectively, add them in sequence, take the result as a formation compressibility evaluation index, and complete the shale compressibility evaluation.

[0065] Compared with the prior art, the shale compressibility evaluation method and system have the following beneficial effects.

[0066] 1. The shale compressibility evaluation method and system combine the main influencing factors of five formation compressibility indexes of porosity, permeability, Young's modulus, brittleness index, fracture toughness and tensile strength, determine the weight of each influencing factor according to the coefficient of variation method, and integrate the three field fracturing construction parameters of comprehensive sand-liquid ratio, slick water ratio and medium sand ratio to create a shale reservoir compressibility evaluation method that can comprehensively and reasonably reflect the shale reservoir compressibility.

[0067] 2. The shale compressibility evaluation method and system are established based on the fact that shale compressibility is a comprehensive representation of reservoir rock properties and construction parameters, and the method and system comprehensively consider the reservoir rock properties and construction parameters, and propose a new shale compressibility evaluation method from the perspective of crack rupture, extension and filling.

[0068] 3. The shale compressibility evaluation method and system provide a new method for evaluating the shale fracturing reconstruction effect by using construction data, and the method can effectively evaluate the fracturing effect in the absence of microseismic monitoring and production profile test data, and has important significance for realizing the shale gas well “one segment one strategy, fine fracturing”. BRIEF DESCRIPTION OF DRAWINGS

[0069] Figure 1 is a technical route schematic diagram of the shale compressibility evaluation method and system;

[0070] Figure 2 is an interpretation schematic diagram of the shale compressibility evaluation method and system;

[0071] Figure 3 is a schematic diagram of regression data of comprehensive compressibility results evaluated by the multi-parameter fusion shale compressibility evaluation method of the application and field production. DETAILED DESCRIPTION

[0072] The application will be further limited by the description and examples in the accompanying drawings and embodiments, but not limited thereto.

[0073] Example 1

[0074] A multi-parameter fusion shale compressibility evaluation method, comprising:

[0075] S1, calculating rock porosity compressibility evaluation indexes through core description and logging curves, wherein the rock porosity compressibility evaluation indexes are obtained by using a multi-element regression equation of acoustic travel time, density, organic carbon content, shale index and porosity, and the permeability compressibility evaluation indexes can be calculated by flow unit parameters;

[0076] S2, calculating the Young's modulus and Poisson's ratio of the rock according to the conventional logging interpretation results and statistics of elastic rock mechanics parameters;

[0077] S3, calculating the brittle index compressibility evaluation index based on the Young's modulus and Poisson's ratio calculated in S2 to obtain the brittle index compressibility evaluation index;

[0078] S4, on the basis of analyzing the reservoir and mechanical parameters, taking shale density, gamma and acoustic travel time logging data as independent variables to obtain a multi-element regression fitting function by function regression, and calculating the type I and type II fracture toughness indexes of each fracturing interval;

[0079] S5, taking the compressibility evaluation index of the tensile strength index as the target function, taking the shale density and longitudinal wave velocity conventional logging data as the independent variables to perform function regression, and thereby obtaining the compressibility evaluation index of the tensile strength index;

[0080] S6, using the sand addition amount, total fluid volume, slick water volume, 40 / 70 mesh proppant volume, 30 / 50 mesh proppant volume and total proppant volume obtained from the actual field fracturing data to calculate the comprehensive sand fluid ratio, slick water proportion and above medium sand proportion; the comprehensive sand fluid ratio refers to the ratio of the sand addition amount to the total fluid volume; the slick water proportion refers to the ratio of the slick water volume to the total fluid volume; and the above medium sand proportion refers to the ratio of the 40 / 70 mesh and 30 / 50 mesh proppant volumes to the total proppant volume;

[0081] S7, eight parameters are normalized by using range transformation method, and each parameter with different units and dimensions is divided into positive index and negative index, and after normalization, all become positive index; the eight parameters include rock porosity, permeability, Young's modulus, brittleness index, fracture toughness index, tensile strength, comprehensive sand fluid ratio, slick water ratio and medium sand ratio;

[0082] S8, the weight of eight parameters of rock porosity (rock porosity compressibility evaluation index), Young's modulus, brittleness index (brittleness index compressibility evaluation index), fracture toughness index, tensile strength (tensile strength index compressibility evaluation index), comprehensive sand fluid ratio, slick water ratio and medium sand ratio is calculated by using coefficient of variation method, the weight is multiplied with the normalized evaluation parameter respectively and added in turn, the result is taken as the formation compressibility evaluation index, and the shale compressibility evaluation is completed.

[0083] Example 2

[0084] According to the multi-parameter fusion shale compressibility evaluation method described in example 1, the difference lies in that:

[0085] Rock porosity is obtained by using logging interpretation data, and the calculation formula is as follows:

[0086]

[0087] TOC = 40.6-15.6*DEN+0.013*GR+0.009*CNL (2)

[0088] Φ = 0.32*AC-0.55*DEN+0.84*TOC-0.48*SH+8.67 (3)

[0089] In the formula: SH is mudstone index; TOC is organic carbon content; DEN is rock density; GR is estimated natural gamma logging value of well section; GR max is the natural gamma logging value at pure mudstone; GR min is the natural gamma logging value at pure sandstone; CNL is compensated neutron; AC is acoustic time difference; Φ is rock porosity.

[0090] Permeability needs to be further processed by flow index, and the related calculation formula is as follows:

[0091]

[0092] K = 0.0012* I n (5)

[0093] Where K is permeability, mD; I is flow index, μs / m; S is total Stonely slowness, μs / m, which is extracted from array sonic log; ρm is mud density, g / cm 3 ; Km is mud bulk modulus, which is derived from mud density and P and S wave velocities, MPa; G is formation shear modulus, which is derived from density log and S wave velocity, MPa;

[0094] The Young's modulus is calculated by the following formula:

[0095]

[0096] Where E is Young's modulus; Δt is P-wave slowness; Δt s is S-wave slowness; and ρ is rock density.

[0097] The Poisson's ratio is calculated by the following formula:

[0098]

[0099] Where v is static Poisson's ratio of rock; Δt s is S-wave slowness; and Δt is P-wave slowness.

[0100] The brittleness index is calculated by the following formula:

[0101]

[0102] Where Brit is brittleness index of rock, dimensionless; E is Young's modulus, GPa; and v is static Poisson's ratio of rock.

[0103] The fracture toughness index K Ⅰ and K Ⅱ are calculated by the following formula:

[0104]

[0105] Where ρ is shale density; Vcl is shale clay content; and DT is acoustic slowness, μm / s.

[0106] The tensile strength is calculated by the following formula:

[0107] σ t = 14.91 ln(V p ) + 22.41 ln(ρ) - 140.2 (11)

[0108] Where σ t is tensile strength; ρ is shale density; and V p is P-wave velocity.

[0109] The parameters are normalized by using the range transformation method, and the parameters with different units and dimensions are divided into positive indicators and negative indicators. After normalization, the positive indicators and the negative indicators are all positive indicators. The calculation methods of the positive indicators and the negative indicators are as follows:

[0110] The positive indicators are as follows:

[0111]

[0112] The negative indicators are as follows:

[0113]

[0114] In the formula, S1 is a normalized value of a positive parameter; S2 is a normalized value of a negative parameter; X max is a maximum value of the parameter; X min is a minimum value of the parameter; and X is a parameter value.

[0115] The weights of the parameters are calculated by using the coefficient of variation method. The calculation formula is as follows:

[0116]

[0117] In the formula, i=1, …, m; j=1, …, n; m is the total number of evaluation indicators to be determined; n is the number of samples of each evaluation indicator; w i is the weight of the i-th parameter; C i is the coefficient of variation of the i-th parameter; σ i is the standard deviation of the i-th parameter; μ i is the average value of the i-th parameter; and r ij is the sample matrix of the i-th parameter evaluation indicator.

[0118] Table 1 shows the weights of the parameters calculated by the coefficient of variation method.

[0119]

[0120] The weights are multiplied by the normalized evaluation parameters, and the results are added in sequence to obtain the formation compressibility evaluation index. The calculation formula is as follows:

[0121]

[0122] In the formula, I CF is the formation compressibility evaluation index; x i is the i-th evaluation indicator after normalization; and w i is the i-th weight of the eight parameters determined by the coefficient of variation method.

[0123] Figure 1 Fig. 1 is a schematic diagram of electrical measurement interpretation of the TKC1-1H-3Ckl well. Figure 2TKC1-3H-3CK1 well electric logging interpretation diagram.

[0124] Embodiment 3

[0125] A computer device comprises a memory and a processor, the memory stores a computer program, and the processor implements the steps of the multi-parameter fusion shale compressibility evaluation method of embodiment 1 or 2 when executing the computer program.

[0126] Embodiment 4

[0127] A computer readable storage medium, which stores a computer program, the computer program implements the steps of the multi-parameter fusion shale compressibility evaluation method of embodiment 1 or 2 when executed by a processor.

[0128] Embodiment 5

[0129] A multi-parameter fusion shale compressibility evaluation system comprises:

[0130] The rock porosity and permeability compressibility evaluation index calculation module is configured to calculate the rock porosity compressibility evaluation index through core description and logging curves, wherein the rock porosity compressibility evaluation index is obtained by using the acoustic travel time, density, organic carbon content, mud shale index and porosity multiple regression equation, and the permeability compressibility evaluation index can be calculated by the flow unit parameter;

[0131] The Young's modulus and Poisson's ratio calculation module is configured to calculate the Young's modulus and Poisson's ratio of the rock according to the conventional logging interpretation results and the statistical elastic rock mechanics parameters;

[0132] The brittle index compressibility evaluation index calculation module is configured to calculate the brittle index compressibility evaluation index based on the calculated Young's modulus and Poisson's ratio, and obtain the brittle index compressibility evaluation index;

[0133] The fracture toughness index calculation module is configured to obtain a multiple regression fitting function by function regression with shale density, gamma and acoustic travel time logging data as independent variables based on analysis of reservoir and mechanical parameters, and calculate the I-type and II-type fracture toughness index of each fracturing interval;

[0134] The tensile strength index compressibility evaluation index calculation module is configured to take the tensile strength index compressibility evaluation index as the objective function, and perform function regression with shale density and longitudinal wave velocity conventional logging data as independent variables, so as to obtain the tensile strength index compressibility evaluation index;

[0135] The comprehensive sand fluid ratio, slick water ratio and medium sand ratio calculation module is configured to calculate the comprehensive sand fluid ratio, slick water ratio and medium sand ratio; and the normalization processing module is configured to normalize the eight parameters by using a range transformation method, and divide the parameters with different units and dimensions into positive indexes and negative indexes, and normalize the parameters into positive indexes; the eight parameters include rock porosity, permeability, Young's modulus, brittleness index, fracture toughness index, tensile strength, comprehensive sand fluid ratio, slick water ratio and medium sand ratio.

[0136] The shale compressibility evaluation module is configured to calculate the weights of the eight parameters of rock porosity, permeability, Young's modulus, brittleness index, fracture toughness index, tensile strength, comprehensive sand fluid ratio, slick water ratio and medium sand ratio by using a variation coefficient method, multiply the weights with the normalized evaluation parameters respectively, add them in sequence, take the result as a formation compressibility evaluation index, and complete the shale compressibility evaluation.

[0137] The above description is only some preferred embodiments of the present application, and any person skilled in the art can modify the above-described technical solutions or modify them into equivalent technical solutions. Therefore, the corresponding simple modifications or equivalent transformations according to the technical solutions of the present application are within the scope of protection claimed by the present application.

Claims

1. A multi-parameter fusion method for evaluating the compressibility of shale, characterized in that, include: S1. Calculate the rock porosity compressibility evaluation index through core description and well logging curves. The rock porosity compressibility evaluation index is obtained by using a multiple regression equation of sonic transit time, density, organic carbon content, mudstone index and porosity. S2. Based on the results of conventional well logging interpretation, statistical analysis of elastic rock mechanical parameters was conducted, and the Young's modulus and Poisson's ratio of the rock were calculated. S3. Based on the Young's modulus and Poisson's ratio calculated in S2, the brittleness index compressibility evaluation index is calculated to obtain the brittleness index compressibility evaluation index. S4. Based on the analysis of reservoir and mechanical parameters, a multivariate regression fitting function is obtained by using shale density, gamma, and sonic transit time logging data as independent variables, and the Type I and Type II fracture toughness indices of each fracturing zone are calculated. S5. Using the compressibility evaluation index of tensile strength index as the objective function, and conventional logging data of shale density and P-wave velocity as independent variables, a function regression is performed to obtain the compressibility evaluation index of tensile strength index. S6. Calculate the comprehensive sand-liquid ratio, the proportion of slippery water, and the proportion of medium sand and above. S7. The eight parameters are normalized using the range transformation method, and the parameters with different units and dimensions are divided into positive and negative indices. After normalization, they all become positive indices. The eight parameters include rock porosity, Young's modulus of permeability, brittleness index, fracture toughness index, tensile strength, comprehensive sand-liquid ratio, slickwater ratio, and the ratio of medium sand and above. S8. Using the coefficient of variation method, calculate the weights of eight parameters: rock porosity, Young's modulus of permeability, brittleness index, fracture toughness index, tensile strength, comprehensive sand-liquid ratio, proportion of slickwater, and proportion of medium sand and above. Multiply each weight by the normalized evaluation parameter and add them in sequence. Use the result as the formation compressibility evaluation index to complete the shale compressibility evaluation.

2. The multi-parameter fusion shale compressibility evaluation method according to claim 1, characterized in that, Rock porosity is obtained using well logging interpretation data, and the calculation formula is as follows: TOC=40.6-15.6*DEN+0.013*GR+0.009*CNL (2) Φ=0.32*AC-0.55*DEN+0.84*TOC-0.48*SH+8.67 (3) Where: SH is the mudstone index; TOC is the organic carbon content; DEN is the rock density; GR is the estimated natural gamma logging value of the well section; GR max Natural gamma ray logging values ​​for pure mudstone; GR min 1 represents the natural gamma ray logging value in pure sandstone; CNL represents compensated neutrons; AC represents sonic transit time; Φ represents rock porosity. The formula for calculating Young's modulus is as follows: In the formula: E is Young's modulus; Δt is the longitudinal wave time difference; Δt s ρ is the transverse wave time difference; ρ is the rock density.

3. The multi-parameter fusion shale compressibility evaluation method according to claim 1, characterized in that, The formula for calculating Poisson's ratio is as follows: In the formula: ν is the static Poisson's ratio of the rock; Δt s Δt is the transverse wave time difference; Δt is the longitudinal wave time difference; The brittleness index is calculated using Young's modulus and Poisson's ratio, and the calculation formula is as follows: In the formula: Brit is the brittleness index of the rock, which is dimensionless; E is Young's modulus, in GPa; v is the static Poisson's ratio of the rock; Type I and Type II fracture toughness index K Ⅰ and K Ⅱ The calculation formula is obtained using well logging interpretation data: In the formula: ρ is the density of shale; Vcl is the mud content of shale; DT is the sonic transit time, μm / s.

4. The multi-parameter fusion shale compressibility evaluation method according to claim 1, characterized in that, Tensile strength is calculated using the following formula: s t =14.91ln(V p )+22.41ln(ρ)-140.2 (9) In the formula: σ t ρ is the tensile strength; ρ is the density of shale; V p This refers to the longitudinal wave velocity.

5. The multi-parameter fusion method for evaluating the compressibility of shale according to claim 1, characterized in that, The range transformation method is used to normalize the parameters, and the parameters with different units and dimensions are divided into positive and negative indices. After normalization, they all become positive indices. The calculation methods for positive and negative indices are as follows: Among them, the positive indicators are as follows: The negative indicators are as follows: In the formula, S1 is the standardized value of the positive parameter; S2 is the standardized value of the negative parameter; X max X is the maximum value of the parameter. min X is the minimum value of the parameter; X is the parameter value.

6. The multi-parameter fusion method for evaluating the compressibility of shale according to claim 1, characterized in that, The weights of each parameter are determined using the coefficient of variation method, and the calculation formula is as follows: In the formula: i = 1, ..., m; j = 1, ..., n; m represents the total number of evaluation indicators whose weights need to be determined; n represents the sample size for each evaluation indicator; w i The weight of the i-th parameter; C i σ is the coefficient of variation of the i-th parameter; i μ is the standard deviation of the i-th parameter; i r is the average value of the i-th parameter; ij Let be the sample matrix of the evaluation index for the i-th parameter.

7. The multi-parameter fusion method for evaluating the compressibility of shale according to claim 1, characterized in that, The weights are multiplied by the normalized evaluation parameters and then summed sequentially. The result is used as the formation compressibility evaluation index; the calculation formula is as follows: In the formula: I CF x is the index for evaluating the compressibility of the formation; i w is the i-th evaluation index after normalization. i The weight of the i-th parameter among the eight parameters determined by the coefficient of variation method.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the multi-parameter fusion shale compressibility evaluation method according to any one of claims 1-7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the multi-parameter fusion shale compressibility evaluation method according to any one of claims 1-7.

10. A multi-parameter fusion shale compressibility evaluation system, characterized in that, include: The rock porosity and permeability compressibility evaluation index calculation module is configured to: calculate the rock porosity compressibility evaluation index through core description and well logging curves. The rock porosity compressibility evaluation index is obtained by using a multiple regression equation of sonic transit time, density, organic carbon content, mudstone index and porosity, and permeability is obtained by the flow unit method. The Young's modulus and Poisson's ratio calculation module is configured to: calculate the Young's modulus and Poisson's ratio of the rock based on the statistical elastic rock mechanics parameters obtained from conventional well logging interpretation results. The brittleness index compressibility evaluation index calculation module is configured to: calculate the brittleness index compressibility evaluation index based on the calculated Young's modulus and Poisson's ratio, and obtain the brittleness index compressibility evaluation index. The fracture toughness index calculation module is configured to: based on the analysis of reservoir and mechanical parameters, use shale density, gamma, and sonic transit time logging data as independent variables to perform function regression to obtain a multivariate regression fitting function, and calculate the Type I and Type II fracture toughness indices for each fracturing interval; The module for calculating the compressibility evaluation index of the tensile strength index is configured to: use the compressibility evaluation index of the tensile strength index as the objective function, and use conventional logging data of shale density and P-wave velocity as independent variables to perform function regression, thereby obtaining the compressibility evaluation index of the tensile strength index. The module for calculating the comprehensive sand-liquid ratio, the proportion of slickwater, and the proportion of medium sand and above is configured to: calculate the comprehensive sand-liquid ratio, the proportion of slickwater, and the proportion of medium sand and above; the normalization module is configured to: normalize the eight parameters using the range transformation method, and divide the parameters with different units and dimensions into positive and negative indices, which are all converted into positive indices after normalization; the eight parameters include rock porosity, Young's modulus of permeability, brittleness index, fracture toughness index, tensile strength, comprehensive sand-liquid ratio, slickwater proportion, and the proportion of medium sand and above; The shale compressibility evaluation module is configured to: calculate the weights of eight parameters—rock porosity, Young's modulus of permeability, brittleness index, fracture toughness index, tensile strength, comprehensive sand-liquid ratio, slickwater ratio, and the proportion of medium sand and above—using the coefficient of variation method; multiply each weight by the normalized evaluation parameters and sum them sequentially; and use the result as the formation compressibility evaluation index to complete the shale compressibility evaluation.

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