Method and device for analyzing the compressibility of a shale formation

Abstract

The application discloses a shale formation compressibility analysis method and device, and relates to the technical field of oil and gas exploration and development, wherein the method comprises the following steps: determining a brittleness index according to clay mineral content and total organic carbon content; determining a horizontal stress difference index according to an in-situ horizontal stress difference, a maximum horizontal stress difference when a horizontal fracture network is formed by fracturing, and a minimum horizontal stress difference; determining a vertical stress difference index according to an in-situ vertical stress difference, a maximum vertical stress difference when a vertical fracture network is formed by fracturing, and a minimum vertical stress difference; determining a natural fracture index according to a natural fracture density, a natural fracture width, and an angle between a natural fracture direction and a vertical direction of the maximum horizontal stress; determining a bedding index according to a bedding density and a bedding width; and determining a compressibility index according to the brittleness index, the horizontal stress difference index, the vertical stress difference index, the natural fracture index, and the bedding index. The application can improve the precision of shale formation compressibility analysis.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, and in particular to a method and apparatus for analyzing the compressibility of shale formations. Background Technology

[0002] This section is intended to provide background or context for the embodiments of the invention set forth in the claims. The description herein is not an admission that it is prior art simply because it is included in this section.

[0003] Shale oil and gas has emerged as a new area for exploration, development, and reserve / production growth. However, due to the tightness of shale reservoirs, fluid flow is restricted. Commercial-scale development is typically only possible through volumetric fracturing to create artificial fractures and enhance fluid permeability. Compressibility is a key factor controlling whether fractures can form in shale formations during fracturing, the complexity of the fractures, the initial production of a single well after fracturing, and the final recoverable oil and gas volume. Therefore, compressibility analysis of shale formations is crucial for shale oil and gas exploration and development.

[0004] The brittleness of shale formations, horizontal stress differences, and natural fractures are commonly used parameters in traditional methods for analyzing compressibility. Existing techniques are based on the application of a single method, resulting in low agreement between the analytical results and actual conditions. Research has found that the compressibility of shale formations is also influenced by factors such as bedding density and width, vertical stress differences, the minimum and maximum horizontal stress differences when fracturing forms a horizontal fracture network, and the minimum and maximum vertical stress differences when fracturing forms a vertical fracture network. Furthermore, research has revealed that during fracturing, the compressibility of formations is affected by a comprehensive effect, rather than the influence of a single factor. Therefore, existing techniques for analyzing compressibility all have shortcomings and deficiencies.

[0005] Brittleness is an inherent property of rocks when they fracture under stress, influencing the number and morphology of hydraulic fracturing fractures. Rock brittleness is closely related to its mineral composition, microstructure, and mechanical properties. Most existing brittleness analysis methods study compressibility from the perspective of brittle minerals, such as mineralogical methods, mechanical parameter methods, deformation characteristic methods, and energy evolution methods. However, the essential influencing factors of compressibility are the clay mineral content and total organic carbon content in the formation. Therefore, a brittleness index analysis method based on clay mineral content and total organic carbon content is proposed. Geostress determines the orientation and morphology of artificial fractures. When the horizontal geostress difference is small, hydraulic fracturing fractures tend to propagate in multiple directions, which is conducive to the formation of complex fracture networks. As the horizontal geostress difference increases, the control effect of the geostress difference on hydraulic fracturing fractures gradually strengthens. At this point, hydraulic fracturing fractures mainly propagate along the direction of maximum horizontal geostress, and the fracture morphology is relatively simple. The vertical geostress difference controls the development degree of vertical fractures induced by hydraulic fracturing. Existing technologies all study the effect of geostress difference on compressibility based on analytical equations or simulation calculations, without considering the inherent differences in stress difference itself. Monitoring during on-site fracturing operations revealed that fracturing fractures tend to propagate preferentially along natural fractures, and the complexity of these natural fractures largely determines the complexity of the fracturing fracture network. Existing compressibility analysis techniques for natural fractures typically rely on analytical equations or empirical formulas, which have significant limitations. Bedding density and bedding width in shale formations also play a crucial role in controlling the formation of fracturing fracture networks and compressibility; however, current techniques lack analytical models for the impact of bedding on compressibility.

[0006] Since the compressibility of shale formations is comprehensively controlled by factors such as minerals, horizontal stress differences, vertical stress differences, natural fractures, and bedding, reliable analytical results can only be obtained by comprehensively considering the main factors affecting compressibility when conducting shale formation compressibility analysis. Existing techniques are all based on a single controlling factor and a single method for compressibility analysis, and the accuracy of their analytical results is usually low. Summary of the Invention

[0007] This invention provides a method for analyzing the compressibility of shale formations to improve the accuracy of compressibility analysis results. The method includes: The brittleness index is determined by obtaining the analyzed shale strata from the analyzed strata and based on the clay mineral content and total organic carbon content of the analyzed samples. The horizontal stress difference index is determined based on the in-situ horizontal stress difference, the maximum horizontal stress difference when fracturing forms a horizontal fracture network, and the minimum horizontal stress difference when fracturing forms a horizontal fracture network. The vertical stress difference index is determined based on the in-situ vertical stress difference, the maximum vertical stress difference when fracturing forms a vertical fracture network, and the minimum vertical stress difference when fracturing forms a vertical fracture network. The natural crack index is determined based on the density of natural cracks, the width of natural cracks, and the angle between the direction of natural cracks and the vertical direction of the maximum horizontal stress. The bedding index is determined based on the bedding density and bedding width. The compressibility index is determined based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural fracture index, and bedding index. The compressibility analysis results of the analyzed shale formation are then determined based on the compressibility index.

[0008] This invention also provides an apparatus for analyzing the compressibility of shale formations to improve the accuracy of compressibility analysis results. The apparatus includes: The brittleness index determination module is used to obtain the analyzed sample from the analyzed shale formation and determine the brittleness index based on the clay mineral content and total organic carbon content of the analyzed sample. The horizontal stress difference index determination module is used to determine the horizontal stress difference index based on the in-situ horizontal stress difference, the maximum horizontal stress difference when fracturing forms a horizontal fracture network, and the minimum horizontal stress difference when fracturing forms a horizontal fracture network. The vertical stress difference index determination module is used to determine the vertical stress difference index based on the in-situ vertical stress difference, the maximum vertical stress difference when fracturing forms a vertical fracture network, and the minimum vertical stress difference when fracturing forms a vertical fracture network. The Natural Fracture Index Determination Module is used to determine the natural fracture index based on the natural fracture density, natural fracture width, and the angle between the natural fracture orientation and the vertical direction of the maximum horizontal ground stress. The bedding index determination module is used to determine the bedding index based on bedding density and bedding width. The compressibility analysis result determination module is used to determine the compressibility index based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural fracture index, and bedding index, and then determine the compressibility analysis result of the analyzed shale formation based on the compressibility index.

[0009] This invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the above-described method for analyzing the compressibility of shale formations.

[0010] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for analyzing the compressibility of shale formations.

[0011] This invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described method for analyzing the compressibility of shale formations.

[0012] In this embodiment of the invention, samples are obtained from the shale formation being analyzed. The brittleness index is determined based on the clay mineral content and total organic carbon content of the samples. The horizontal stress difference index is determined based on the in-situ horizontal stress difference, the maximum horizontal stress difference when a horizontal fracture network is formed by fracturing, and the minimum horizontal stress difference when a horizontal fracture network is formed by fracturing. The vertical stress difference index is determined based on the in-situ vertical stress difference, the maximum vertical stress difference when a vertical fracture network is formed by fracturing, and the minimum vertical stress difference when a vertical fracture network is formed by fracturing. The natural fracture index is determined based on the natural fracture density, natural fracture width, and the angle between the natural fracture orientation and the direction perpendicular to the maximum horizontal stress. The bedding index is determined based on the bedding density and bedding width. The compressibility index is determined based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural fracture index, and bedding index. The compressibility analysis results of the analyzed shale formation are then determined based on the compressibility index. In this way, by comprehensively considering the key influencing factors that control the compressibility of shale formations, the technical shortcomings of existing technologies that only consider a small number of influencing factors or use analytical model methods to analyze compressibility are overcome, thus improving the accuracy of shale formation compressibility analysis. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a flowchart of a method for analyzing the compressibility of shale formations provided in an embodiment of the present invention; Figure 2 This is a flowchart of a method for determining the natural crack index based on the natural crack density, natural crack width, and the angle between the natural crack orientation and the vertical direction of the maximum horizontal stress, provided in an embodiment of the present invention. Figure 3 This is an example diagram illustrating the relationship between the compressibility index and the oil production intensity index of a vertical well, provided in an embodiment of the present invention. Figure 4 This is a correlation diagram between the shale compressibility index and the oil production intensity index in different fractured sections of a horizontal well, provided in an embodiment of the present invention. Figure 5 This is a graph showing the relationship between the compressibility index and the oil production intensity index of a certain horizontal well, provided in an embodiment of the present invention. Figure 6 This is a schematic diagram of an analysis system for the compressibility of shale formations provided in an embodiment of the present invention; Figure 7This is a schematic diagram of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0015] The acquisition, storage, use, and processing of data in this application all comply with the relevant provisions of national laws and regulations.

[0016] In this document, the term "and / or" merely describes a relationship, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0017] In the description of this specification, the terms "comprising," "including," "having," and "containing" are open-ended terms, meaning that they include but are not limited to. The terms "an embodiment," "a specific embodiment," "some embodiments," and "for example," etc., refer to specific features, structures, or characteristics described in connection with that embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. The order of steps involved in the various embodiments is used to illustrate the implementation of this application, and the order of steps is not limited and can be adjusted appropriately as needed.

[0018] Research has shown that the compressibility of shale formations is comprehensively controlled by factors such as minerals, horizontal stress differences, vertical stress differences, natural fractures, and bedding. Therefore, when analyzing the compressibility of shale formations, the main factors affecting compressibility should be considered comprehensively to obtain reliable analytical results. Existing techniques are all based on a single controlling factor and a single method for compressibility analysis, resulting in generally low accuracy.

[0019] Regarding the above research, such as Figure 1 As shown, this embodiment of the invention provides a method for analyzing the compressibility of shale formations, including: S101: Obtain the sample to be analyzed from the shale formation being analyzed, and determine the brittleness index based on the clay mineral content and total organic carbon content of the sample being analyzed; S102: Determine the horizontal stress difference index based on the in-situ horizontal stress difference, the maximum horizontal stress difference when fracturing forms a horizontal fracture network, and the minimum horizontal stress difference when fracturing forms a horizontal fracture network; S103: Determine the vertical stress difference index based on the in-situ vertical stress difference, the maximum vertical stress difference when fracturing forms a vertical fracture network, and the minimum vertical stress difference when fracturing forms a vertical fracture network. S104: The natural crack index is determined based on the natural crack density, natural crack width, and the angle between the direction of the natural crack and the vertical direction of the maximum horizontal ground stress. S105: Determine the bedding index based on bedding density and bedding width; S106: Determine the compressibility index based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural fracture index, and bedding index. Then, determine the compressibility analysis results of the analyzed shale formation based on the compressibility index.

[0020] In this embodiment of the invention, samples are obtained from the shale formation being analyzed. The brittleness index is determined based on the clay mineral content and total organic carbon content of the samples. The horizontal stress difference index is determined based on the in-situ horizontal stress difference, the maximum horizontal stress difference when a horizontal fracture network is formed by fracturing, and the minimum horizontal stress difference when a horizontal fracture network is formed by fracturing. The vertical stress difference index is determined based on the in-situ vertical stress difference, the maximum vertical stress difference when a vertical fracture network is formed by fracturing, and the minimum vertical stress difference when a vertical fracture network is formed by fracturing. The natural fracture index is determined based on the natural fracture density, natural fracture width, and the angle between the natural fracture orientation and the direction perpendicular to the maximum horizontal stress. The bedding index is determined based on the bedding density and bedding width. The compressibility index is determined based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural fracture index, and bedding index. The compressibility analysis results of the analyzed shale formation are then determined based on the compressibility index. In this way, by comprehensively considering the key influencing factors that control the compressibility of shale formations, the technical shortcomings of existing technologies that only consider a small number of influencing factors or use analytical model methods to analyze compressibility are overcome, thus improving the accuracy of shale formation compressibility analysis.

[0021] The analytical methods for the compressibility of the aforementioned shale formations are explained in detail below.

[0022] For the aforementioned S101, the clay mineral content and total organic carbon content of the analyzed sample were obtained through core analysis.

[0023] In one embodiment of the present invention, the clay mineral content includes: clay mineral volume; the total organic carbon content includes: total organic carbon volume; determining the brittleness index based on the clay mineral content and total organic carbon content of the analyzed sample includes: determining the brittleness index based on the clay mineral content and total organic carbon content of the analyzed sample using the following formula:

[0024] in, For brittleness index, IGV For interparticle volume, The volume of clay minerals in the sample being analyzed, The total organic carbon volume of the sample being analyzed The volume of the sample being analyzed.

[0025] The volume of the sample and its different components is obtained by dividing the weight by the corresponding average density, and the interparticle volume is obtained by scanning electron microscopy analysis of the polished sample.

[0026] Regarding S102 above, the in-situ horizontal stress difference can be determined, for example, based on indoor experimental measurements and field fracturing test parameters. Specifically, this includes determining the in-situ horizontal stress difference based on experimental data or calculating the in-situ horizontal stress difference based on field fracturing and monitoring data.

[0027] Among them, the difference in in-situ horizontal stress can be calculated using, for example, the maximum and minimum horizontal stresses measured experimentally:

[0028] in, For the in-situ horizontal stress difference, For the maximum horizontal ground stress in place, This represents the minimum horizontal ground stress in situ.

[0029] In one embodiment of the present invention, a horizontal stress difference index is determined based on the in-situ horizontal stress difference, the maximum horizontal stress difference when fracturing forms a horizontal fracture network, and the minimum horizontal stress difference when fracturing forms a horizontal fracture network, including: The horizontal stress difference index is determined using the following formula based on the in-situ horizontal stress difference, the maximum horizontal stress difference during fracturing to form a horizontal fracture network, and the minimum horizontal stress difference during fracturing to form a horizontal fracture network:

[0030] in, For the horizontal stress difference index, For the in-situ horizontal stress difference, To form the maximum horizontal stress difference when forming a horizontal seam mesh, This represents the minimum horizontal stress difference required to form a horizontal mesh.

[0031] Regarding S103 above, for example, the in-situ vertical stress difference can be determined based on experimental data or calculated based on field fracturing and monitoring data.

[0032] Among them, the difference in in-situ vertical stress can be calculated using, for example, the maximum and minimum vertical stresses measured experimentally:

[0033] in, For the in-situ vertical stress difference, For the maximum vertical ground stress in place, This represents the minimum vertical ground stress in situ.

[0034] In one embodiment of the present invention, a vertical stress difference index is determined based on the in-situ vertical stress difference, the maximum vertical stress difference when fracturing forms a vertical fracture network, and the minimum vertical stress difference when fracturing forms a vertical fracture network, including: Based on the in-situ vertical stress difference, the maximum vertical stress difference when fracturing forms a vertical fracture network, and the minimum vertical stress difference when fracturing forms a vertical fracture network, the vertical stress difference index is determined using the following formula:

[0035] in, This is the vertical stress difference index; This represents the vertical stress difference in situ. The maximum vertical stress difference when forming a vertical mesh; This is the minimum vertical stress difference required to form a vertical mesh.

[0036] For example, based on core measurements, the density and width of natural fractures in the core can be calculated, or the density and width of natural fractures calculated from core measurements can be used to calibrate logging data, and the density and width of natural fractures can be calculated from the logging data.

[0037] like Figure 2 The diagram shows a flowchart of a method for determining a natural fracture index based on natural fracture density, natural fracture width, and the angle between the natural fracture orientation and the direction perpendicular to the maximum horizontal stress, according to an embodiment of the present invention. The method includes: S201: Determine the natural crack density and width index based on the natural crack density and natural crack width.

[0038] In one embodiment of the present invention, the natural crack density includes: multiple measured natural crack density values; the natural crack width includes: multiple measured natural crack width values; determining the natural crack density and width index based on the natural crack density and natural crack width includes: determining the natural crack density and width index using the following formula based on the natural crack density and natural crack width:

[0039] in, For the density and width index of natural cracks, For any measured natural crack density value in the natural crack density, The minimum measured natural crack density value among natural crack densities. The maximum measured natural crack density value among natural crack densities. For any measured natural crack width value in the natural crack width range, The minimum measured natural crack width among natural crack widths. This represents the maximum measured width of a natural crack.

[0040] S202: Determine the natural crack angle index based on the angle between the direction of the natural crack and the vertical direction of the maximum horizontal ground stress.

[0041] Specifically, the angle between the orientation of natural fractures and the vertical direction of the maximum horizontal stress includes, for example, the angle between the orientation of the main natural fractures and the vertical direction of the maximum horizontal stress. For instance, the angle between the orientation of the main natural fractures and the vertical direction of the maximum horizontal stress can be calculated based on the orientation of the natural fractures and the direction of the maximum horizontal stress obtained from core measurements or well logging data.

[0042] Among them, the main natural cracks include, for example, natural cracks whose crack width is greater than a preset width threshold, or natural cracks whose crack width is sorted within a preset sorting range; the orientation of the main natural cracks includes, for example, the average orientation of the main natural cracks.

[0043] In one embodiment of the present invention, determining the natural fracture angle index based on the angle between the direction of the natural fracture and the vertical direction of the maximum horizontal stress includes: determining the natural fracture angle index using the following formula based on the angle between the direction of the natural fracture and the vertical direction of the maximum horizontal stress:

[0044] in, For the natural crack angle index, The angle between the direction of the main natural crack and the vertical direction of the maximum horizontal ground stress.

[0045] S203: Determine the natural crack index based on the natural crack density and width index, as well as the natural crack angle index.

[0046] In one embodiment of the present invention, determining the natural crack index based on the natural crack density and width index and the natural crack angle index includes: determining the natural crack index using the following formula based on the natural crack density and width index and the natural crack angle index:

[0047] in, This represents the natural crack index.

[0048] Regarding S105 above, for example, the bedding density and bedding width of the core can be calculated based on core measurements. Alternatively, the bedding density and bedding width calculated from the core measurements can be used to calibrate logging data, and the bedding density and bedding width can be calculated from the logging data.

[0049] Specifically, the bedding density includes, for example, multiple measured bedding density values; the bedding width includes, for example, multiple measured bedding width values; in one embodiment of the present invention, determining the bedding index based on the bedding density and the bedding width includes: determining the bedding index based on the bedding density and the bedding width using the following formula:

[0050] in, For stratification index, For any measured bedding density value in the bedding density, For any measured bedding width value in the bedding width, The minimum measured bedding density value in bedding density, The minimum measured bedding width value in the bedding width, The maximum measured bedding density value in bedding density, This represents the maximum measured bedding width value.

[0051] Regarding S106 above, in one embodiment of the present invention, the compressibility index is determined based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural crack index, and bedding index, including: determining the compressibility index using the following formula based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural crack index, and bedding index:

[0052] in, The compressibility index, , , For empirical coefficients, empirical coefficients , , The sum is 1.

[0053] Specifically, after obtaining the compressibility index, the compressibility of shale can be graded and evaluated based on the magnitude of the compressibility index to determine the compressibility of the shale. In another embodiment of the present invention, determining the compressibility analysis result of the analyzed shale formation based on the compressibility index includes, for example, determining the compressibility analysis result of the analyzed shale formation based on a positive correlation between the compressibility index and the compressibility analysis result of the analyzed shale formation.

[0054] Compared to existing technologies, this invention proposes a comprehensive analysis method that integrates controlling factors such as minerals, horizontal stress difference, vertical stress difference, natural fractures, and bedding to conduct shale formation compressibility analysis. This overcomes the shortcomings of existing technologies, which rely on single-factor analysis and cannot comprehensively analyze shale formation compressibility, resulting in low analytical accuracy. This invention also proposes a brittleness index analysis method based on clay mineral content and total carbon content, overcoming the limitation of existing technologies that do not consider the influence of organic matter on compressibility, thus improving the analytical accuracy of this method. Furthermore, this invention proposes calculating horizontal and vertical stress difference indices based on horizontal and vertical stress differences, the maximum and minimum horizontal and vertical stress differences when fracturing forms a horizontal fracture network, and the maximum and minimum vertical stress differences when fracturing forms a vertical fracture network. This overcomes the limitation of existing technologies that do not consider the stress differences between horizontal and vertical fractures during fracturing. This invention proposes a method for quantitatively analyzing compressibility by comprehensively considering natural fracture density, natural fracture width, the angle between the natural fracture orientation and the vertical direction of the maximum horizontal geostress, and bedding density and bedding width. This overcomes the deficiency in existing technologies where natural fractures and bedding have been found to significantly influence compressibility, but no analytical methods were available. This invention improves the accuracy of compressibility analysis. Testing shows that the linear correlation coefficient R between the compressibility index obtained by this invention and oil production intensity is >0.9, while the linear correlation coefficient R between the compressibility index (such as brittleness or fracturing volume) obtained by existing technologies and oil production intensity is typically less than 0.7.

[0055] like Figure 3 The figure shown is an example of the relationship between the compressibility index and the oil production intensity index of a vertical well according to an embodiment of the present invention. Specifically, it is a graph showing the relationship between the compressibility index and the oil production intensity calculated for 36 fracturing sections in one vertical well. Figure 3 It can be seen that there is a good linear relationship between the compressibility index and the oil production intensity, with a positive correlation coefficient of 0.98. The compressibility index can be used to predict the oil production intensity of different fracturing sections in vertical wells, and thus can be used to predict the initial production of a single vertical well.

[0056] like Figure 4 The image shows a correlation diagram between the shale compressibility index and the oil production index in different fractured sections of a horizontal well, provided in an embodiment of the present invention; specifically, it is a correlation diagram between the compressibility index and the oil production intensity of 12 fractured sections in one horizontal well. Figure 4 It is evident that there is a strong positive correlation between the compressibility index and oil production intensity. Shale with a high compressibility index has high oil production intensity in the fractured section, while shale with a low compressibility index has low oil production intensity in the fractured section. The compressibility index can be used to predict the oil production intensity of different fractured sections in horizontal wells, and thus can be used to predict the initial production of a single horizontal well.

[0057] like Figure 5The figure shown is a graph illustrating the relationship between the compressibility index and the oil production index of a horizontal well according to an embodiment of the present invention. Figure 5 It can be seen that there is a good linear relationship between the compressibility index and the oil production intensity, with a positive correlation coefficient of 0.97. The compressibility index can be used to predict the oil production intensity of horizontal wells, and thus can be used to predict the initial production of horizontal wells.

[0058] This invention also provides an apparatus for analyzing the compressibility of shale formations, as described in the following embodiments. Since the principle by which this apparatus solves the problem is similar to the method for analyzing the compressibility of shale formations, the implementation of this apparatus can refer to the implementation of the method for analyzing the compressibility of shale formations; repeated details will not be elaborated further.

[0059] like Figure 6 The diagram shown is an example of an analytical apparatus for the compressibility of shale formations provided in an embodiment of the present invention, comprising: The brittleness index determination module 601 is used to obtain the analyzed sample from the analyzed shale stratum and determine the brittleness index based on the clay mineral content and total organic carbon content of the analyzed sample. The horizontal stress difference index determination module 602 is used to determine the horizontal stress difference index based on the in-situ horizontal stress difference, the maximum horizontal stress difference when fracturing forms a horizontal fracture network, and the minimum horizontal stress difference when fracturing forms a horizontal fracture network. The vertical stress difference index determination module 603 is used to determine the vertical stress difference index based on the in-situ vertical stress difference, the maximum vertical stress difference when fracturing forms a vertical fracture network, and the minimum vertical stress difference when fracturing forms a vertical fracture network. The natural crack index determination module 604 is used to determine the natural crack index based on the natural crack density, natural crack width, and the angle between the natural crack orientation and the vertical direction of the maximum horizontal ground stress. The bedding index determination module 605 is used to determine the bedding index based on the bedding density and bedding width; The compressibility analysis result determination module 606 is used to determine the compressibility index based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural fracture index, and bedding index, and to determine the compressibility analysis result of the analyzed shale formation based on the compressibility index.

[0060] In one possible implementation, the clay mineral content includes: clay mineral volume; the total organic carbon content includes: total organic carbon volume; the brittleness index determination module is specifically used to obtain the intergranular volume through scanning electron microscopy analysis of the polished sample being analyzed; the brittleness index is determined using the following formula based on the clay mineral content and total organic carbon content of the sample being analyzed:

[0061] in, For brittleness index, IGV For interparticle volume, The volume of clay minerals in the sample being analyzed, The total organic carbon volume of the sample being analyzed The volume of the sample being analyzed.

[0062] In one possible implementation, the horizontal stress difference determination module is further configured to calculate the in-situ horizontal stress difference based on the experimentally determined maximum and minimum horizontal stresses using the following formula:

[0063] in, For the in-situ horizontal stress difference, For the maximum horizontal ground stress in place, This represents the minimum horizontal ground stress in situ.

[0064] In one possible implementation, the horizontal stress difference index determination module is specifically used to determine the horizontal stress difference index using the following formula, based on the in-situ horizontal stress difference, the maximum horizontal stress difference when fracturing forms a horizontal fracture network, and the minimum horizontal stress difference when fracturing forms a horizontal fracture network:

[0065] in, For the horizontal stress difference index, For the in-situ horizontal stress difference, To form the maximum horizontal stress difference when forming a horizontal seam mesh, This represents the minimum horizontal stress difference required to form a horizontal mesh.

[0066] In one possible implementation, the vertical stress difference index determination module is further configured to calculate the in-situ vertical stress difference based on the experimentally measured maximum and minimum vertical ground stress using the following formula:

[0067] in, For the in-situ vertical stress difference, For the maximum vertical ground stress in place, This represents the minimum vertical ground stress in situ.

[0068] In one possible implementation, the vertical stress difference index determination module is specifically used to determine the vertical stress difference index using the following formula, based on the in-situ vertical stress difference, the maximum vertical stress difference when fracturing forms a vertical fracture network, and the minimum vertical stress difference when fracturing forms a vertical fracture network:

[0069] in, This is the vertical stress difference index; This represents the vertical stress difference in situ. The maximum vertical stress difference when forming a vertical mesh; This is the minimum vertical stress difference required to form a vertical mesh.

[0070] In one possible implementation, the natural crack index determination module is specifically used to determine the natural crack density and width index based on the natural crack density and the natural crack width. The natural crack angle index is determined based on the angle between the direction of the natural crack and the vertical direction of the maximum horizontal ground stress. The natural crack index is determined based on the natural crack density and width index, as well as the natural crack angle index.

[0071] In one possible implementation, the natural crack density includes: multiple measured natural crack density values; the natural crack width includes: multiple measured natural crack width values; and the natural crack index determination module is specifically used to determine the natural crack density and width index based on the natural crack density and natural crack width using the following formulas:

[0072] in, For the density and width index of natural cracks, For any measured natural crack density value in the natural crack density, The minimum measured natural crack density value among natural crack densities. The maximum measured natural crack density value among natural crack densities. For any measured natural crack width value in the natural crack width range, The minimum measured natural crack width among natural crack widths. This represents the maximum measured width of a natural crack.

[0073] In one possible implementation, the natural fracture index determination module is specifically used to determine the natural fracture angle index based on the angle between the natural fracture orientation and the direction perpendicular to the maximum horizontal geostress, using the following formula:

[0074] in, For the natural crack angle index, The angle between the direction of the main natural crack and the vertical direction of the maximum horizontal ground stress.

[0075] In one possible implementation, the natural crack index determination module is specifically used to determine the natural crack index using the following formula based on the natural crack density and width index and the natural crack angle index:

[0076] in, This represents the natural crack index.

[0077] In one possible implementation, the bedding density includes: multiple measured bedding density values; the bedding width includes: multiple measured bedding width values; and the bedding index determination module is specifically used to determine the bedding index based on the bedding density and bedding width using the following formula:

[0078] in, For stratification index, For any measured bedding density value in the bedding density, For any measured bedding width value in the bedding width, The minimum measured bedding density value in bedding density, The minimum measured bedding width value in the bedding width, The maximum measured bedding density value in bedding density, This represents the maximum measured bedding width value.

[0079] In one possible implementation, the compressibility analysis result determination module is specifically used to determine the compressibility index based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural crack index, and bedding index, using the following formula:

[0080] in, The compressibility index, , , For empirical coefficients, empirical coefficients , , The sum is 1.

[0081] In one possible implementation, the compressibility index is positively correlated with the compressibility analysis results of the analyzed shale formation, and the compressibility analysis results of the analyzed shale formation are determined based on the compressibility index.

[0082] Based on the aforementioned inventive concept, such as Figure 7As shown, the present invention also proposes a computer device 700, including a memory 710, a processor 720, and a computer program 730 stored in the memory 710 and executable on the processor 720. When the processor 720 executes the computer program 730, it implements the aforementioned method for analyzing the compressibility of shale formations.

[0083] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for analyzing the compressibility of shale formations.

[0084] This invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described method for analyzing the compressibility of shale formations.

[0085] In this embodiment of the invention, samples are obtained from the shale formation being analyzed. The brittleness index is determined based on the clay mineral content and total organic carbon content of the samples. The horizontal stress difference index is determined based on the in-situ horizontal stress difference, the maximum horizontal stress difference when a horizontal fracture network is formed by fracturing, and the minimum horizontal stress difference when a horizontal fracture network is formed by fracturing. The vertical stress difference index is determined based on the in-situ vertical stress difference, the maximum vertical stress difference when a vertical fracture network is formed by fracturing, and the minimum vertical stress difference when a vertical fracture network is formed by fracturing. The natural fracture index is determined based on the natural fracture density, natural fracture width, and the angle between the natural fracture orientation and the direction perpendicular to the maximum horizontal stress. The bedding index is determined based on the bedding density and bedding width. The compressibility index is determined based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural fracture index, and bedding index. The compressibility analysis results of the analyzed shale formation are then determined based on the compressibility index. In this way, by comprehensively considering the key influencing factors that control the compressibility of shale formations, the technical shortcomings of existing technologies that only consider a small number of influencing factors or use analytical model methods to analyze compressibility are overcome, thus improving the accuracy of shale formation compressibility analysis.

[0086] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0087] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0088] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0089] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0090] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for analyzing the compressibility of shale formations, characterized in that, include: Samples were obtained from the analyzed shale formation, and the brittleness index was determined based on the clay mineral content and total organic carbon content of the samples. ; The horizontal stress difference index is determined based on the in-situ horizontal stress difference, the maximum horizontal stress difference during fracturing to form a horizontal fracture network, and the minimum horizontal stress difference during fracturing to form a horizontal fracture network. ; The vertical stress difference index is determined based on the in-situ vertical stress difference, the maximum vertical stress difference when fracturing forms a vertical fracture network, and the minimum vertical stress difference when fracturing forms a vertical fracture network. ; The natural fracture index is determined based on the density, width, and angle between the direction of the natural fractures and the perpendicular direction of the maximum horizontal ground stress. ; Determine the bedding index based on bedding density and bedding width. ; The compressibility index is determined based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural crack index, and bedding index, including: The compressibility index is determined using the following formula: in, The compressibility index, , , For empirical coefficients, empirical coefficients , , The sum is 1; The compressibility analysis results of the analyzed shale formation are determined based on the compressibility index.

2. The method for analyzing the compressibility of shale formations as described in claim 1, characterized in that, Clay mineral content includes: clay mineral volume; Total organic carbon content includes: total organic carbon volume. The brittleness index is determined based on the clay mineral content and total organic carbon content of the analyzed sample, including: Interparticle volume was obtained by scanning electron microscopy analysis of the polished sample. The brittleness index is determined using the following formula based on the clay mineral content, total organic carbon content, and intergranular volume of the analyzed sample: in, For brittleness index, IGV For interparticle volume, The volume of clay minerals in the sample being analyzed, The total organic carbon volume of the sample being analyzed The volume of the sample being analyzed.

3. The method for analyzing the compressibility of shale formations as described in claim 1, characterized in that, Also includes: Based on the experimentally measured maximum and minimum horizontal ground stresses, the in-situ horizontal ground stress difference is calculated using the following formula: in, For the in-situ horizontal stress difference, For the maximum horizontal ground stress in place, This represents the minimum horizontal ground stress in situ.

4. The method for analyzing the compressibility of shale formations as described in claim 1, characterized in that, The horizontal stress difference index is determined based on the in-situ horizontal stress difference, the maximum horizontal stress difference during fracturing to form a horizontal fracture network, and the minimum horizontal stress difference during fracturing to form a horizontal fracture network. This index includes: The horizontal stress difference index is determined using the following formula based on the in-situ horizontal stress difference, the maximum horizontal stress difference during fracturing to form a horizontal fracture network, and the minimum horizontal stress difference during fracturing to form a horizontal fracture network: in, For the horizontal stress difference index, For the in-situ horizontal stress difference, To form the maximum horizontal stress difference when forming a horizontal seam mesh, This represents the minimum horizontal stress difference required to form a horizontal mesh.

5. The method for analyzing the compressibility of shale formations as described in claim 1, characterized in that, Also includes: Based on the experimentally measured maximum and minimum vertical ground stress, the in-situ vertical ground stress difference is calculated using the following formula: in, For the in-situ vertical stress difference, For the maximum vertical ground stress in place, This represents the minimum vertical ground stress in situ.

6. The method for analyzing the compressibility of shale formations as described in claim 1, characterized in that, The vertical stress difference index is determined based on the in-situ vertical stress difference, the maximum vertical stress difference during fracturing to form a vertical fracture network, and the minimum vertical stress difference during fracturing to form a vertical fracture network. This index includes: Based on the in-situ vertical stress difference, the maximum vertical stress difference when fracturing forms a vertical fracture network, and the minimum vertical stress difference when fracturing forms a vertical fracture network, the vertical stress difference index is determined using the following formula: in, This is the vertical stress difference index; This represents the vertical stress difference in situ. The maximum vertical stress difference when forming a vertical mesh; This is the minimum vertical stress difference required to form a vertical mesh.

7. The method for analyzing the compressibility of shale formations as described in claim 1, characterized in that, The natural fracture index is determined based on the density, width, and angle between the direction of the natural fracture and the vertical direction of the maximum horizontal ground stress. This index includes: The density and width indices of natural cracks are determined based on the density and width of natural cracks. The natural crack angle index is determined based on the angle between the direction of the natural crack and the vertical direction of the maximum horizontal ground stress. The natural crack index is determined based on the natural crack density and width index, as well as the natural crack angle index.

8. The method for analyzing the compressibility of shale formations as described in claim 7, characterized in that, Natural crack density includes: multiple measured natural crack density values; natural crack width includes: multiple measured natural crack width values; The density and width indices of natural cracks are determined based on their density and width, including: The density and width indices of natural cracks are determined using the following formulas: in, For the density and width index of natural cracks, For any measured natural crack density value in the natural crack density, The minimum measured natural crack density value among natural crack densities. The maximum measured natural crack density value among natural crack densities. For any measured natural crack width value in the natural crack width range, The minimum measured natural crack width among natural crack widths. This represents the maximum measured width of a natural crack.

9. The method for analyzing the compressibility of shale formations as described in claim 8, characterized in that, The natural fracture angle index is determined based on the angle between the orientation of the natural fracture and the direction perpendicular to the maximum horizontal ground stress, including: The angle index of a natural fracture is determined using the following formula, based on the angle between the orientation of the natural fracture and the direction perpendicular to the maximum horizontal stress: in, For the natural crack angle index, The angle between the direction of the main natural crack and the vertical direction of the maximum horizontal ground stress; the main natural crack includes: natural cracks with a crack width greater than a preset width threshold, or natural cracks whose crack width is within a preset sorting range; the direction of the main natural crack includes: the average direction of the main natural crack.

10. The method for analyzing the compressibility of shale formations as described in claim 9, characterized in that, The natural fracture index is determined based on the natural fracture density and width index, as well as the natural fracture angle index, including: The natural fracture index is determined using the following formula based on the natural fracture density and width index, as well as the natural fracture angle index: in, This represents the natural crack index.

11. The method for analyzing the compressibility of shale formations as described in claim 1, characterized in that, Bedding density includes: multiple measured bedding density values; bedding width includes: multiple measured bedding width values; Based on bedding density and bedding width, bedding indices are determined, including: Based on bedding density and bedding width, the bedding index is determined using the following formula: in, For stratification index, For any measured bedding density value in the bedding density, For any measured bedding width value in the bedding width, The minimum measured bedding density value in bedding density, The minimum measured bedding width value in the bedding width, The maximum measured bedding density value in bedding density, This represents the maximum measured bedding width value.

12. The method for analyzing the compressibility of shale formations as described in claim 1, characterized in that, The compressibility analysis results of the analyzed shale formation are determined based on the compressibility index, including: The compressibility index is positively correlated with the compressibility analysis results of the analyzed shale formation. The compressibility analysis results of the analyzed shale formation are determined based on the compressibility index.

13. An analytical apparatus for the compressibility of shale formations, characterized in that, include: The brittleness index determination module is used to obtain the analyzed sample from the shale formation and determine the brittleness index based on the clay mineral content and total organic carbon content of the analyzed sample. ; The horizontal stress difference index determination module is used to determine the horizontal stress difference index based on the in-situ horizontal stress difference, the maximum horizontal stress difference during fracturing to form a horizontal fracture network, and the minimum horizontal stress difference during fracturing to form a horizontal fracture network. ; The vertical stress difference index determination module is used to determine the vertical stress difference index based on the in-situ vertical stress difference, the maximum vertical stress difference when fracturing forms a vertical fracture network, and the minimum vertical stress difference when fracturing forms a vertical fracture network. ; The natural fracture index determination module is used to determine the natural fracture index based on the natural fracture density, natural fracture width, and the angle between the natural fracture orientation and the direction perpendicular to the maximum horizontal ground stress. ; The bedding index determination module is used to determine the bedding index based on bedding density and bedding width. ; The compressibility analysis result determination module is used to determine the compressibility index based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural fracture index, and bedding index, and to determine the compressibility analysis result of the analyzed shale formation based on the compressibility index. The compressibility analysis result determination module is specifically used to determine the compressibility index based on the brittleness index, horizontal stress difference index, vertical stress difference index, natural crack index, and bedding index, using the following formula: in, The compressibility index, , , For empirical coefficients, empirical coefficients , , The sum is 1.

14. The analytical apparatus for the compressibility of shale formations as described in claim 13, characterized in that, Clay mineral content includes: clay mineral volume; Total organic carbon content includes: total organic carbon volume. The brittleness index determination module is specifically used to obtain the interparticle volume through scanning electron microscopy analysis of the polished sample being analyzed. The brittleness index is determined using the following formula based on the clay mineral content, total organic carbon content, and intergranular volume of the analyzed sample: in, For brittleness index, IGV For interparticle volume, The volume of clay minerals in the sample being analyzed, The total organic carbon volume of the sample being analyzed The volume of the sample being analyzed.

15. The analytical apparatus for the compressibility of shale formations as described in claim 13, characterized in that, Also includes: The horizontal stress difference determination module is used to calculate the in-situ horizontal stress difference based on the experimentally measured maximum and minimum horizontal stresses using the following formula: in, For the in-situ horizontal stress difference, For the maximum horizontal ground stress in place, This represents the minimum horizontal ground stress in situ.

16. The analytical apparatus for the compressibility of shale formations as described in claim 13, characterized in that, The horizontal stress difference index determination module is specifically used to determine the horizontal stress difference index based on the in-situ horizontal stress difference, the maximum horizontal stress difference when fracturing forms a horizontal fracture network, and the minimum horizontal stress difference when fracturing forms a horizontal fracture network, using the following formula: in, For the horizontal stress difference index, For the in-situ horizontal stress difference, To form the maximum horizontal stress difference when forming a horizontal seam mesh, This represents the minimum horizontal stress difference required to form a horizontal mesh.

17. The apparatus for analyzing the compressibility of shale formations as described in claim 13, characterized in that, The Natural Crack Index Determination Module is specifically used to determine the natural crack density and width index based on the natural crack density and natural crack width. The natural crack angle index is determined based on the angle between the direction of the natural crack and the vertical direction of the maximum horizontal ground stress. The natural crack index is determined based on the natural crack density and width index, as well as the natural crack angle index.

18. The apparatus for analyzing the compressibility of shale formations as described in claim 13, characterized in that, Bedding density includes: multiple measured bedding density values; bedding width includes: multiple measured bedding width values; The bedding index determination module is specifically used to determine the bedding index based on the bedding density and bedding width using the following formula: in, For stratification index, For any measured bedding density value in the bedding density, For any measured bedding width value in the bedding width, The minimum measured bedding density value in bedding density, The minimum measured bedding width value in the bedding width, The maximum measured bedding density value in bedding density, This represents the maximum measured bedding width value.

19. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method of any one of claims 1 to 12.

20. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method of any one of claims 1 to 12.

21. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the method of any one of claims 1 to 12.

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