A method of describing shale foliation seam direction

Abstract

The application discloses a shale shale cleat direction description method, and comprises the following steps: determining the combination form of the shale cleat formation through a sedimentary genesis model, determining the opening degree of the shale cleat through a stress amplitude model, determining the combination form of the shale cleat opening through a stress opening model, determining the shale cleat direction through a shale cleat direction restoration model, depicting the shale cleat vector channel through a shale cleat vector channel model, and identifying the shale reservoir advantage sweet spot area through a closed loop flow trap model; the effect of evaluating the sweet spot through the fluid seepage direction in the shale cleat is realized; the blank in the shale cleat direction research field is filled; and the problems that the existing conventional shale shale cleat research means lacks the theory and technology in the shale cleat direction and cannot research the shale shale cleat direction characteristics and accurately depict the shale reservoir advantage sweet spot area are solved.

Description

Technical Field

[0001] This invention relates to unconventional exploration and development, specifically a method for describing the direction of shale fractures. Background Technology

[0002] China's continental shale formations are rich in petroleum resources and are an important strategic area for vigorously enhancing domestic petroleum exploration and development and ensuring national petroleum security. Existing technologies first clarify the important significance of the existence of shale fractures for shale reservoirs in terms of reservoir accumulation; secondly, they explore the characteristics of shale fractures from the aspects of genesis, development degree, and oil content; finally, they conclude that shale fractures are one of the important factors affecting production capacity and propose targeted methods for describing the opening of shale fractures. However, the above theories only analyze shale fractures from the perspective of geological description and do not provide evaluation models or application methods to guide development and production. They have the following two main defects: (1) Limited analytical perspective; at present, the analysis of shale shale fractures is mainly concentrated in the preliminary description stage. A unified description model and evaluation system have not been established, nor have mature application methods and implementation methods been formed. (2) Lack of guidance in field application; for shale reservoir shale fractures, there is currently no technical means that can be combined with the field and guide shale oil exploration, development and production. The theoretical research has not yet formed a complete system and there is an urgent need to form effective working methods. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a method for describing the direction of shale foliation fractures, which achieves the effect of evaluating sweet spots by the direction of fluid seepage within the foliation fractures; fills the gap in the field of foliation fracture direction research; and solves the problems of the lack of theoretical and technical aspects of foliation fracture direction in existing conventional shale foliation fracture research methods, as well as the inability to study the characteristics of shale foliation fracture direction and accurately characterize the advantageous sweet spots of shale reservoirs.

[0004] To achieve the above-mentioned objective, the method for describing the direction of shale fractures includes the following steps:

[0005] Step 1: Based on the provenance direction, the formation process of foliation fractures is reconstructed from the perspective of sedimentary genesis using the foliation fracture genetic model, thereby determining the combined morphology when the foliation fractures formed;

[0006] Step 2: Based on the magnitude of the maximum horizontal principal stress, the degree of opening of the foliation fracture is determined from the perspective of geostress using the stress amplitude model;

[0007] Step 3: Based on the direction of geostress, the opening process of the foliation fracture is reconstructed from the perspective of the direction of geostress using the foliation fracture opening model, and then the combined morphology when the foliation fracture opens is determined.

[0008] Step 4: Based on the source direction and the geostress direction, determine the direction of the foliation fractures by reconstructing the foliation fracture direction model;

[0009] Step 5: Based on the page seam vector channel model, characterize the page seam vector channel;

[0010] Step 6: Based on the orientation of shale fractures at different locations within the target area, identify the dominant sweet spot regions of shale reservoirs using a closed-loop flow trap model.

[0011] Furthermore, step 1 is specifically performed as follows:

[0012] Within the same source region or the same sedimentary microfacies, after different sedimentary superposition processes, the sedimentary material perpendicular to the source direction is relatively continuous, and the closer to the source, the more stable the continuity of the sedimentary material; while parallel to the source direction, the sedimentary material gradually decreases as the source supply weakens until it pinches out.

[0013] As shown in Figure 2, A1-A2 is perpendicular to the source direction, while B1-B2 and C1-C2 are parallel to the source direction. The layered sediments are stably distributed along the A1-A2 direction, but discontinuous along the B1-B2 and C1-C2 directions. Correspondingly, the foliation fractures are stably developed parallel to the strata along the A1-A2 direction, but intersect, discontinuate, or disappear along the B1-B2 and C1-C2 directions.

[0014] Furthermore, step 2 is specifically performed as follows:

[0015] (1) Stress amplitude σ A The calculations are performed for two types of target samples, as shown in Figure 2;

[0016] ① For the target point, the stress amplitude σ A For max(abs(σ) Hi -σ Hi-1 ), abs(σ Hi -σ Hi+1 ) );

[0017] ② For the target segment, the stress amplitude σ A The maximum principal stress range σ within the internal horizontal direction Hmax -σ Hmin ;

[0018] (2) There is only vertical stress σ v At this time, foliation fractures close, and the greater the vertical stress, the tighter the closure of the fractures. Horizontal stress can cause interlayer slippage of layered sediments within the strata, thus opening foliation fractures. Laboratory experiments can determine the ability of different stress amplitudes to open foliation fractures. Considering the influence of vertical stress, the parameter σ... A / σ v Describe it;

[0019] Where σ A / σ v Stress amplitude / vertical ground stress

[0020] σ H Horizontal maximum principal stress

[0021] σ Hi The maximum horizontal principal stress at position i in the vertical direction.

[0022] σ Hi-1 The maximum horizontal principal stress at position i-1 in the vertical direction.

[0023] σ Hmax The maximum horizontal principal stress of the target segment in the vertical direction.

[0024] σ Hmin The minimum value of the maximum horizontal principal stress in the target segment in the vertical direction;

[0025] (3) As an alternative implementation method, the relative opening degree of the foliation joint can be determined directly by the magnitude of the relative value of stress amplitude / vertical ground stress in the target area.

[0026] Furthermore, step 3 is specifically implemented as follows:

[0027] Under ideal conditions of 360° full development of foliation fractures in the center of the lake basin, the maximum vertical and horizontal principal stress σ H With directional stress equilibrium, the opening degree of foliation fractures is similar, and the open foliation fractures develop relatively continuously; as the foliation fractures progress along the horizontal maximum principal stress σ... H As the opening direction continues to extend, the stress is gradually consumed, the leaf joints cannot be opened, and they remain in a closed state.

[0028] As shown in Figure 4, A1-A2 represents the maximum principal stress σ in the vertical and horizontal directions. H The direction, B1-B2 and C1-C2 are parallel horizontal principal stresses σ H Direction; the foliation fractures open continuously along the A1-A2 direction, and close intermittently along the B1-B2 and C1-C2 directions; the corresponding foliation fractures in the open state develop stably parallel to the strata along the A1-A2 direction, and are discontinuous and disappear along the B1-B2 and C1-C2 directions.

[0029] Furthermore, step 4 specifically involves determining the direction of the page seam:

[0030] First, determine the genetic direction of the deposition of foliation fractures, which is perpendicular to the depositional direction.

[0031] Secondly, determine the direction of stress opening in the pore joints; the direction of stress opening in the pore joints is perpendicular to the stress direction.

[0032] Finally, the direction of the page seam vector channel is the final direction, which is controlled by the superposition of the first two. When the two are superimposed, there is no magnitude, only direction.

[0033] As shown in Figure 5, the angle between the source direction and the stress direction is between 0 and 90°, and the angle between the two and the direction of the leaf fracture vector channel is between 0 and 45°.

[0034] Furthermore, step 5 specifically involves characterizing the page seam vector channel:

[0035] The foliation fracture vector channel will extend, turn, interrupt, and close along the direction of the foliation fracture vector channel, and is the migration channel of hydrocarbons in shale reservoirs;

[0036] like Figure 6 In the middle, the plywood seams are continuous along the A1-A2 direction and discontinuous along the A1-A3 direction.

[0037] Furthermore, step 6 is specifically implemented as follows:

[0038] The direction of the vector channel of the pore fracture determines the direction of oil and gas seepage. When the seepage direction forms a closed loop, the oil and gas in the closed loop cannot migrate to the outside of the closed loop. The inside of the loop has good oil content, thus forming a closed loop flow. In areas where no closed loop is formed, the oil and gas will diffuse to the outside further away, and the oil content is relatively poor.

[0039] like Figure 7 The direction of the vector channel of the page seam is continuous and forms a closed loop. The oil and gas seepage closes in the counterclockwise direction to form a closed loop flow. The fluid inside the closed loop flow cannot flow out, forming a closed loop flow trap.

[0040] The present invention has the following beneficial effects:

[0041] The method of this invention utilizes the source direction and geostress characteristics of the study area, and is based on sedimentary genetic models, stress amplitude models, directional stress opening models, directional recovery models, vector channel models, and closed-loop flow trap models. By characterizing the directional features of shale foliation fractures, it solves the problem that existing conventional shale foliation fracture research methods lack theoretical and technical support for foliation fracture direction, and cannot study the directional features of shale foliation fractures or accurately characterize the advantageous sweet spots of shale reservoirs. Attached Figure Description

[0042] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0043] Figure 1 This is a technical flowchart of the method of the present invention;

[0044] Figures 2(a), 2(b), and 2(c) are respectively a top view of the ply formation model of the present invention, a three-dimensional split view of the ply formation model, and a side view of the ply formation model.

[0045] Figure 3(a) and Figure 3(b) are schematic diagrams of the stress amplitude at the target point and the stress amplitude of the target segment, respectively, according to the method of the present invention.

[0046] Figures 4(a), 4(b), and 4(c) are respectively a top view of the ply formation model of the present invention, a three-dimensional split view of the ply formation model, and a side view of the ply formation model.

[0047] Figures 5(a) and 5(b) are schematic diagrams showing the source direction and stress direction being parallel and perpendicular, respectively, of the method of the present invention.

[0048] Figure 6 This is a schematic diagram of the page seam direction restoration model of the method of the present invention;

[0049] Figure 7 This is a schematic diagram of the closed-loop flow model of the method of the present invention;

[0050] Figure 8 This is a planar distribution diagram of the source direction of the JHD block according to an embodiment of the present invention;

[0051] Figure 9 This is a planar distribution diagram of the depositional origin of JHD block foliation fractures according to an embodiment of the present invention;

[0052] Figure 10 This is a plane distribution diagram of the maximum principal stress in the JHD block according to an embodiment of the present invention;

[0053] Figure 11 This is a planar distribution diagram of the stress opening direction of the JHD block pore joint in an embodiment of the present invention;

[0054] Figure 12 This is a planar distribution diagram of the JHD block page seam vector channel direction according to an embodiment of the present invention;

[0055] Figure 13 This is a closed-loop flow coil plane distribution diagram of the JHD block according to an embodiment of the present invention. Detailed Implementation

[0056] The present invention will now be described based on embodiments, but it is worth noting that the present invention is not limited to these embodiments. In the following detailed description of the invention, certain specific details are described in detail. However, those skilled in the art will fully understand the invention for the parts not described in detail.

[0057] Furthermore, those skilled in the art should understand that the accompanying drawings are provided only to illustrate the purpose, features, and advantages of the present invention, and are not actually drawn to scale.

[0058] Furthermore, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to."

[0059] Combination Figure 1 As shown, the overall steps of the technical solution of the present invention are as follows:

[0060] 1. Based on the provenance direction, the formation process of foliation fractures is reconstructed from the perspective of sedimentary genesis using a foliation fracture genetic model, thereby determining the combined morphology of foliation fractures during their formation;

[0061] 2. Based on the magnitude of the maximum horizontal principal stress, the degree of opening of the foliation fracture is determined from the perspective of geostress using a stress amplitude model;

[0062] 3. Based on the geostress direction, the opening process of the foliation fractures is reconstructed from the perspective of the geostress direction using the foliation fracture opening model, thereby determining the combined morphology when the foliation fractures open;

[0063] 4. Based on the source direction and the geostress direction, the direction of the foliation fractures is determined using a fracture direction reconstruction model;

[0064] 5. Based on the page seam vector channel model, characterize the page seam vector channel;

[0065] 6. Based on the orientation of foliation fractures at different locations within the target area, a closed-loop flow trap model is used to identify the dominant sweet spot regions of shale reservoirs.

[0066] Furthermore, the various steps of the present invention will be described in detail.

[0067] Step 1: Determine the combined morphology when the foliation seams are formed.

[0068] Within the same source region or the same sedimentary microfacies, after different stages of sedimentary superposition, the sedimentary material perpendicular to the source direction is relatively continuous, and the closer to the source, the more stable the continuity of the sedimentary material. However, parallel to the source direction, the sedimentary material gradually decreases as the source supply weakens until it pinches out.

[0069] As shown in Figures 2(a), 2(b), and 2(c), A1-A2 is perpendicular to the source direction, while B1-B2 and C1-C2 are parallel to the source direction. Layered sediments are stably distributed along the A1-A2 direction, but discontinuous along the B1-B2 and C1-C2 directions. Correspondingly, foliation fractures are stably developed parallel to the strata along the A1-A2 direction, but intersect, discontinuate, or disappear along the B1-B2 and C1-C2 directions.

[0070] Step 2: Determine the degree of opening of the page seams

[0071] (1) Stress amplitude σ A The calculations are performed for two types of target samples, as shown in Figure 2;

[0072] ① For the target point, the stress amplitude σ A For max(abs(σ) Hi -σ Hi-1 ), abs(σ Hi -σ Hi+1 ) );

[0073] ② For the target segment, the stress amplitude σ A The maximum principal stress range σ within the internal horizontal direction Hmax -σ Hmin ;

[0074] (2) There is only vertical stress σ v At this time, foliation fractures close, and the greater the vertical stress, the tighter the closure of the fractures. Horizontal stress can cause interlayer slippage of layered sediments within the strata, thus opening foliation fractures. Laboratory experiments can determine the ability of different stress amplitudes to open foliation fractures. Considering the influence of vertical stress, the parameter σ... A / σ v Describe it;

[0075] Where σ A / σ v Stress amplitude / vertical ground stress

[0076] σ H Horizontal maximum principal stress

[0077] σ Hi The maximum horizontal principal stress at position i in the vertical direction.

[0078] σ Hi-1 The maximum horizontal principal stress at position i-1 in the vertical direction.

[0079] σ Hmax The maximum horizontal principal stress of the target segment in the vertical direction.

[0080] σ Hmin The minimum value of the maximum horizontal principal stress in the target segment in the vertical direction;

[0081] As an alternative implementation method, the relative opening degree of foliation fractures can be determined directly by the magnitude of the relative value of stress amplitude / vertical ground stress within the target area. When σ A / σ v The larger the value, the greater the relative opening degree of the pore joints. In application, this allows for the measurement of σ values ​​at all points within the target area. A / σ v The values ​​are arranged from largest to smallest. A threshold is selected according to production needs, and points greater than this threshold are defined as "on". Figure 3(a) and Figure 3(b) are schematic diagrams of the stress amplitude at the target point and the stress amplitude at the target segment, respectively, of the method of the present invention.

[0082] Step 3: Determine the combined form when the page seam is open.

[0083] Under ideal conditions of 360° full development of foliation fractures in the center of the lake basin, the maximum vertical and horizontal principal stress σ H With directional stress equilibrium, the opening degree of foliation fractures is similar, and the open foliation fractures develop relatively continuously; as the foliation fractures progress along the horizontal maximum principal stress σ... H As the opening direction continues to extend, the stress is gradually consumed, the pore joints cannot be opened, and the pores remain closed.

[0084] In Figures 4(a), 4(b), and 4(c), A1-A2 represents the maximum principal stress σ in the vertical and horizontal direction. H The direction, B1-B2 and C1-C2 are parallel horizontal principal stresses σ H Direction. The foliation fractures open continuously along the A1-A2 direction, and close intermittently along the B1-B2 and C1-C2 directions. Correspondingly, the foliation fractures in the open state develop stably parallel to the strata along the A1-A2 direction, and become discontinuous and disappear along the B1-B2 and C1-C2 directions.

[0085] Step 4: Determine the direction of the lamination seam

[0086] Shale foliation fractures exhibit three directions: the sedimentary origin direction, the stress initiation direction, and the vector channel direction. The vector channel direction is the final direction, controlled by the superposition of the first two. The sedimentary origin direction is perpendicular to the sedimentary direction, and the stress initiation direction is perpendicular to the stress direction. Because sedimentation and stress occur at different times and have different mechanisms, their superposition results in a direction that exists only in terms of direction, not magnitude.

[0087] As shown in Figures 5(a) and 5(b), the angle between the source direction and the stress direction is between 0 and 90°, and the angle between the two and the direction of the leaf fracture vector channel is between 0 and 45°.

[0088] Step 5: Depict the vector channels of the page seams

[0089] Shale fractures are a geological concept, formed during sedimentation. They are typically closed under the pressure of overlying rocks, but some fractures open when stress occurs. These opened fractures maintain continuity along a specific direction, forming directional seepage channels. Hydrocarbons enriched in shale migrate outward along these fracture channels, exhibiting a unified migration direction in localized areas.

[0090] like Figure 6 In the middle, the plywood seams are continuous along the A1-A2 direction and discontinuous along the A1-A3 direction.

[0091] Step 6: Identify the dominant sweet spot region of closed circulation loops in shale reservoirs

[0092] The direction of the flow vector channel in the pore fracture determines the direction of oil and gas seepage. When the seepage direction forms a closed loop, the oil and gas within the loop cannot migrate outside the loop, and the loop has good oil-bearing properties, thus forming a closed-loop flow trap. In areas where no closed loop is formed, oil and gas will diffuse to more distant areas, and the oil-bearing properties are relatively poor.

[0093] like Figure 7 The direction of the vector channel of the page seam is continuous and forms a closed loop. The oil and gas seepage closes in the counterclockwise direction to form a closed loop flow. The fluid inside the closed loop flow cannot flow out, forming a closed loop flow trap.

[0094] Through the above six steps of processing and analysis, parameters such as regional source direction characteristics and geostress direction characteristics can be used to accurately describe the direction of shale fractures within shale reservoirs, achieve fine characterization of closed-loop flow traps, and ultimately optimize the sweet spot area.

[0095] Example:

[0096] The application process of this invention will be explained using the JHD block shale reservoir in the Songliao Basin as an example.

[0097] First, by studying the sedimentary background and sedimentary facies distribution characteristics, the provenance orientation of different locations within the region was clarified, ultimately resulting in a planar distribution map of the sedimentary genesis orientation of foliation fractures within the study area, such as... Figure 8 , Figure 9 As shown.

[0098] Furthermore, the degree of opening of the foliation joints is determined based on the magnitude of the maximum horizontal principal stress at different locations within the region.

[0099] First, determine the maximum principal stress σ at the target depth. Hi The maximum horizontal principal stress σ at the next monitoring point above and below the target depth Hi-1 σ Hi+1 Subtract the two numbers and take the absolute value. The larger of the two calculated values ​​is taken as the stress amplitude σ.A Since the difference in the maximum horizontal principal stress within the region is small, the calculated stress amplitudes are similar. Therefore, this step can be simplified by directly assuming that the degree of opening of the foliation joints is similar or the same throughout the entire region.

[0100] Furthermore, by analyzing the variation characteristics of the maximum horizontal principal stress within the study area, the opening state of the foliation fractures was determined, and the opening direction of the foliation fractures within the study area was described and characterized. Finally, a planar distribution map of the stress opening direction of the foliation fractures within the study area was obtained, as shown below. Figure 10 , 11 As shown.

[0101] Furthermore, based on the known depositional genesis direction and stress opening direction of the foliation fractures, the fracture orientation is determined, thereby characterizing the fracture vector channel, such as... Figure 12 As shown, closed circulation loops developed within the study area are identified, such as... Figure 13 As shown.

[0102] This example successfully identified three independent closed loop flow traps in the JHD block, verifying the effectiveness and feasibility of the technical solution of the present invention. It can reasonably characterize the sweet spot region of shale reservoirs according to the closed loop flow traps formed by shale fractures.

[0103] As can be seen from the above description, according to the method of the present invention, the closed circulation loop distribution characteristics of existing shale reservoirs can be determined by the characteristics of the source material and geostress, so as to further rationally select favorable sweet spots.

[0104] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications, equivalent substitutions, and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for describing the direction of shale foliation fractures, characterized in that: Includes the following steps: Step 1: Based on the provenance direction, the formation process of foliation fractures is reconstructed from the perspective of sedimentary genesis using the foliation fracture genetic model, thereby determining the combined morphology when the foliation fractures formed; Step 2: Based on the magnitude of the maximum horizontal principal stress, the degree of opening of the foliation fracture is determined from the perspective of geostress using the stress amplitude model; Step 2 specifically involves determining the degree of opening of the page seams: (1) Stress amplitude σ A The calculations are performed for two types of target samples; ① For the target point, the stress amplitude σ A For max(abs(σ) Hi -σ Hi-1 ), abs(σ Hi -σ Hi+1 ) ); ② For the target segment, the stress amplitude σ A The maximum principal stress range σ within the internal horizontal direction Hmax -σ Hmin ; (2) There is one and only vertical ground stress σ v When foliation fractures close, the greater the vertical stress, the tighter the closure. Horizontal stress causes interlayer slippage of layered sediments within the strata, thus opening foliation fractures. Laboratory experiments can determine the ability of different stress amplitudes to open foliation fractures. Considering the influence of vertical stress, the parameter σ... A / σ v Describe it; Where σ A / σ v Stress amplitude / vertical ground stress σ H Horizontal maximum principal stress σ Hi The maximum horizontal principal stress at position i in the vertical direction. σ Hi-1 The maximum horizontal principal stress at position i-1 in the vertical direction. σ Hmax The maximum horizontal principal stress of the target segment in the vertical direction. σ Hmin The minimum value of the maximum horizontal principal stress in the target segment in the vertical direction; (3) The relative opening degree of the foliation fracture is determined directly by the magnitude of the relative value of stress amplitude / vertical ground stress within the target area; Step 3: Based on the direction of geostress, the opening process of the foliation fracture is reconstructed from the perspective of the direction of geostress using the foliation fracture opening model, and then the combined morphology when the foliation fracture opens is determined. Step 4: Based on the source direction and the geostress direction, determine the direction of the foliation fractures by reconstructing the foliation fracture direction model; Step 5: Based on the page seam vector channel model, characterize the page seam vector channel; Step 6: Based on the orientation of shale fractures at different locations within the target area, identify the dominant sweet spot regions of shale reservoirs using a closed-loop flow trap model.

2. The method for describing the direction of shale foliation fractures according to claim 1, characterized in that: Step 1 specifically involves determining the combined morphology when the page seams are formed: Within the same source region or the same sedimentary microfacies, after different stages of sedimentary superposition, the sedimentary material perpendicular to the source direction is relatively continuous, and the closer to the source, the more stable the continuity of the sedimentary material. However, parallel to the source direction, the sedimentary material gradually decreases as the source supply weakens until it pinches out.

3. The method for describing the direction of shale foliation fractures according to claim 1, characterized in that: Step 3 specifically involves determining the combined form when the page seams are open: Under ideal conditions of 360° full development of foliation fractures in the center of the lake basin, the maximum vertical and horizontal principal stress σ H With directional stress equilibrium, the opening degree of foliation fractures is similar, and the open foliation fractures develop relatively continuously; as the foliation fractures progress along the horizontal maximum principal stress σ... H As the opening direction continues to extend, the stress is gradually consumed, the pore joints cannot be opened, and the pores remain closed.

4. The method for describing the direction of shale foliation fractures according to claim 1, characterized in that: Step 4 specifically involves determining the direction of the page seams: First, determine the genetic direction of the deposition of foliation fractures, which is perpendicular to the depositional direction. Secondly, determine the direction of stress opening in the pore joints; the direction of stress opening in the pore joints is perpendicular to the stress direction. Finally, the direction of the foliation fracture vector channel is determined. The direction of the foliation fracture vector channel is the final direction, which is controlled by the superposition of the foliation fracture depositional genesis direction and the foliation fracture stress initiation direction. When the two are superimposed, there is no magnitude, only direction.

5. The method for describing the direction of shale foliation fractures according to claim 1, characterized in that: Step 5 specifically involves characterizing the page seam vector channel: Shale fracture vector channels extend, turn, interrupt, and close along the direction of the shale fracture vector channel, serving as migration channels for hydrocarbons in shale reservoirs.

6. The method for describing the direction of shale foliation fractures according to claim 1, characterized in that: Step 6 specifically involves identifying the dominant sweet spot region of the closed circulation loop in the shale reservoir: The direction of the vector channel of the pore fracture determines the direction of oil and gas seepage. When the seepage direction forms a closed loop, the oil and gas in the closed loop cannot migrate to the outside of the closed loop, and the inside of the loop has good oil content, thus forming a closed loop flow loop. In areas where no closed loop is formed, the oil and gas will diffuse to the outside further away, and the oil content is relatively poor.

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