Method for estimating the kinematic vorticity of a compressional-shearing structure using seismic data

Abstract

The application provides a method for estimating the kinematic vorticity of a compresso-shear structure by using seismic data, which comprises the following steps: step 1, performing standard reflection axis interpretation and industrial mapping of a target layer in a seismic acquisition area; step 2, preparing a plane distribution map of large faults and compresso-shear related folds in a structure-controlling belt; step 3, extracting a dominant trend of the large faults in the structure-controlling belt; step 4, extracting a dominant azimuth of the related compresso-shear fold ridgeline; step 5, preparing a relationship map of a main compressive azimuth and two characteristic azimuths of the compresso-shear structure; and step 6, calculating the kinematic vorticity of the compresso-shear structure. The method for estimating the kinematic vorticity of the compresso-shear structure by using the seismic data is not limited to the theoretical research of an orogenic belt outcrop observable and a sampling area, is suitable for the field of applied science, is universally applicable to a seismic acquisition area of a compresso-shear oil and gas basin, can clearly define an interpretation model of a complex compresso-shear structure unit, and can develop a reasonable interpretation scheme.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of structural analysis and oil and gas exploration and development of pressure-shear oil and gas bearing basin, and particularly relates to a method for estimating kinematic vorticity of pressure-shear structure by using seismic data. BACKGROUND

[0002] Many oil and gas bearing basins in western China generally have the characteristics of non-coaxial compression, and contain different degrees of angular shear components in strong linear deformation, resulting in great difficulty in structural interpretation and strong multi-interpretation. Due to the lack of evaluation methods for the angular shear degree of the covered area of the oil and gas bearing basin, the selection of coaxial or non-coaxial structural interpretation model is a key problem encountered in the structural interpretation of the pressure-shear superimposed basin in the west. In the 1980s, kinematic vorticity (W k ) was introduced into geology for the analysis of the degree of non-coaxial tectonic deformation, to determine the proportion of pure shear (no rotation) and simple shear (rotation), so as to further clarify the reasonable interpretation model.

[0003] Bobyarchick A defined the kinematic vorticity (W k ) as W k =cos(υ).υ is the included angle of two characteristic directions in pressure-shear tectonic deformation, wherein the characteristic direction I is the extensional non-rotational direction, and the characteristic direction II is the compressional non-rotational direction. In theory, the included angle of the two characteristic directions in the coaxial compression model is 90°, only linear shear component is developed without angular shear component, and the kinematic vorticity is 0; the two characteristic directions overlap in the non-coaxial simple shear model, the included angle is 0°, the angular shear component is most developed, and the kinematic vorticity is 1; the kinematic vorticity W k calculated for the evaluation of the tectonic unit is usually between greater than 0 and 1, reflecting the existence of angular shear components in different degrees in the compressional deformation. If W k is greater than 0.71, a non-coaxial simple shear model needs to be used to carry out corresponding structural interpretation; if W k is not greater than 0.71, a coaxial compression model can be used to carry out corresponding structural interpretation. The structural complexity of the pressure-shear oil and gas bearing basin is high, and it is necessary to estimate the tectonic kinematic vorticity or the angular shear intensity, so as to select a reasonable structural interpretation mode to guide the structural fine interpretation of the exploration potential area.

[0004] The current methods for measuring kinematic vorticity, such as the rigid particle method, the long-short axis ratio of the finite strain ellipse, and the quartz C-axis fabric, are mainly applicable to outcrop areas of orogenic belts, and can be used in field exploration and sampling. However, the above methods have poor applicability in large-area sedimentary covered areas. In addition, the tectonic deformation area represented by the calculation method and the results thereof is limited, and it is difficult to apply in the field of oil and gas exploration, and has been only in the aspect of theoretical research.

[0005] With the wide range of seismic data acquisition and structural interpretation work in oil and gas bearing basin, it is necessary to invent targeted technology to extract the kinematic vorticity information implied in the seismic interpretation results, so as to evaluate the angle shear strength in the structural deformation, and further to determine the structural interpretation model, so as to serve the fine structural interpretation and oil and gas exploration in the oil and gas bearing basin.

[0006] Therefore, we invent a new method for estimating the kinematic vorticity of compressional-shear structure by using seismic data, which solves the above technical problems. SUMMARY

[0007] The purpose of the present application is to provide a method for estimating the kinematic vorticity of compressional-shear structure by using seismic data, which is not limited to the theoretical research of the observable and sample collection area of orogenic belt, and is suitable for the application in the field of science.

[0008] The purpose of the present application can be achieved by the following technical measures: a method for estimating the kinematic vorticity of compressional-shear structure by using seismic data, which comprises the following steps: step 1, performing standard reflection axis interpretation and industrial mapping of the target layer in the seismic acquisition area; step 2, preparing a plane distribution map of large faults and compressional-shear related folds in the structure-controlling zone; step 3, extracting the dominant trend of large faults in the structure-controlling zone; step 4, extracting the dominant direction of the ridge line of the related compressional-shear fold; step 5, preparing a relationship diagram of the main compressional direction and two characteristic directions of the compressional-shear structure; and step 6, calculating the kinematic vorticity of the compressional-shear structure.

[0009] The purpose of the present application can also be achieved by the following technical measures:

[0010] In step 1, the structural characteristics of the target layer are interpreted by using the seismic processing result data, the large faults and the compressional-shear related folds in the structure-controlling zone are finely interpreted, and the low-order faults are not interpreted, so as to complete the large-scale structural mapping.

[0011] In step 2, the large fault and the compressional-shear related fold shape distribution map in the structure-controlling zone is extracted and prepared, the position where the trend azimuth angle of the large fault changes by more than 5° is segmented and numbered, and the compressional-shear related fold is numbered and connected with the longest axis of the irregular ellipse, and the ridge line of the fold is marked.

[0012] In step 3, the trend of the segmented large fault in the structure-controlling zone is measured, a statistical table is formed according to the number, a trend rose diagram is prepared, the dominant trend is extracted, and the azimuth angle is marked.

[0013] In step 3, the azimuth angle deviation of the segmented fault with similar trend is less than 10°.

[0014] In step 4, the azimuth angle of the ridge line of the related compressional-shear fold is measured, a statistical table is formed according to the number, a ridge line trend rose diagram is prepared, a dominant direction is extracted, and the azimuth angle is marked.

[0015] In step 4, the azimuth deviation of the ridges of the compression-torsion related folds is less than 10°.

[0016] In step 5, the relationship between the main pressure orientation and characteristic orientation of the compression-torsion structure is determined; the normal to the dominant orientation of the compression-torsion related fold ridge is drawn, and the main pressure direction σ1 or ISA3 is marked; the dominant orientation of the major fault in the control structure zone and its normal are drawn, and the dominant orientation of the major fault in the control structure zone is marked as the approximate first characteristic orientation; with the main pressure orientation σ1 of the compression-torsion structure as the axis, the approximate second characteristic orientation is drawn by mirroring the orientation of the normal of the major fault in the control structure zone.

[0017] In step 6, the acute angle υ between the approximate first characteristic orientation and the second characteristic orientation is obtained, or the acute angle ξ between the main pressure orientation σ1 and the normal of the major fault controlling the structural zone is obtained.

[0018] In step 6, according to W k =cos(υ) or W k =sin(2ξ) formula for calculating kinematic vorticity W of compression-torsion structure k Using the calculated W k The value determines the degree of non-coaxial compression, and a reasonable explanatory model is constructed.

[0019] The method for estimating kinematic vorticity of compressional-torsional tectonic structures using seismic data in this invention is not limited to theoretical research in observable and sampled areas of orogenic outcrops. It is suitable for applied scientific fields and is generally applicable to seismic acquisition areas of compressional-torsional oil and gas basins. It can clarify the interpretation model of complex compressional-torsional tectonic units and formulate reasonable interpretation schemes.

[0020] Compared with existing technologies, this invention has the following advantages: The method of this invention is generally applicable to seismic acquisition areas in compressional-shear oil and gas basins, including strongly compressional-shear tectonic units such as piedmont zones and depression zones. Compared with existing technologies, this invention is not limited to theoretical research on observable and sample-collecting areas of orogenic belts, but is suitable for applied science, guiding the formulation of interpretation schemes for several complex compressional-shear tectonic belts, including the southern margin, northwestern margin, eastern margin, and northeastern margin of the Qaidam Basin.

[0021] The method of this invention was verified in the piedmont zone of the Junggar Basin, and the qualitative conclusions reached fully conform to the characteristics of tectonic deformation and modern tectonic geology theory. A preliminary comparison of the calculated kinematic vorticity values ​​using the method of this invention with those calculated using the rigid grain method in adjacent orogenic belts shows that the calculated values ​​are slightly lower (the difference is less than 0.08). This is attributed to the fact that the method is applied to a large-scale plastic deformation zone, resulting in incomplete conservation of area on the plane. Attached Figure Description

[0022] Figure 1 This is a flowchart of a specific embodiment of the method for estimating the kinematic vorticity of compressional-torsional tectonics using seismic data according to the present invention;

[0023] Figure 2 A large fault and compresso-shear fold distribution map of a specific embodiment of the invention in the middle segment of the southern margin;

[0024] Figure 3 A large fault dominant direction analysis map of a specific embodiment of the invention in the middle segment of the southern margin;

[0025] Figure 4 A compresso-shear fold ridge line dominant direction analysis map of a specific embodiment of the invention in the middle segment of the southern margin;

[0026] Figure 5 A compresso-shear structure kinematic vorticity analysis result map of a specific embodiment of the invention in the middle segment of the southern margin. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0028] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0029] In order for those skilled in the art to more clearly understand the technical solutions of the present invention, the technical solutions of the present invention will be described in detail below with specific embodiments.

[0030] The method for estimating compresso-shear structure kinematic vorticity using seismic data of the present invention comprises the following steps:

[0031] In step 1, the target layer standard reflection axis is interpreted using seismic processing result data, and the large faults and compresso-shear folds of the structural control zone are required to be interpreted in detail. The present invention does not require interpretation of low-order faults, and a large-scale structure map is completed.

[0032] In step 2, the large fault and compresso-shear fold shape distribution map of the structural control zone is extracted and prepared from the large-scale structure map of step 1, and the position where the large fault strike direction angle changes more than 5° is required to be segmented and numbered. The compresso-shear fold is required to be numbered, and the longest axis of the irregular ellipse is connected and labeled as the fold ridge line.

[0033] In step 3, the strike azimuths of the segmented major faults in the tectonic zone are measured, and statistical tables are created according to their numbers. A strike rose diagram is then compiled, and the dominant strike azimuths are extracted. Alternatively, other mathematical statistical methods can be used to calculate and label the dominant strike azimuths of the major faults in the tectonic zone.

[0034] In step 4, the azimuth angles of the compression-torsion related fold ridges are measured, a statistical table is formed according to the numbers, a ridge direction rose diagram is compiled, and the dominant azimuth angle is extracted.

[0035] In step 5, based on the dominant orientation of the major faults and the dominant orientation of the related compressional-torsional fold ridges of the control tectonic zone formed in steps 3 and 4, a diagram showing the relationship between the main compressional orientation and characteristic orientation of the compressional-torsional structure is drawn. The normal to the dominant orientation of the related compressional-torsional fold ridges is drawn, indicating the main compressional direction σ1 or ISA3; the dominant orientation of the major faults in the control tectonic zone and its normal are drawn, indicating that the dominant orientation of the major faults in the control tectonic zone is approximately the first characteristic orientation (extensional without rotation); with the main compressional orientation σ1 of the compressional-torsional structure as the axis, an approximate second characteristic orientation (compressional without rotation) is drawn by mirroring the orientation of the normal of the major faults in the control tectonic zone.

[0036] In step 6, the acute angle υ between the approximate first and second characteristic orientations is obtained according to step 5, or the acute angle ξ between the main pressure orientation σ1 and the normal of the major fault controlling the structural zone is obtained; according to W k =cos(υ) or W k =sin(2ξ) formula to calculate the kinematic vorticity of the compression-torsion structure; use the calculated W k The value determines the degree of non-coaxial compression and clarifies a reasonable structural interpretation model; return to step 1 and use the reasonable structural interpretation model to carry out further refined structural interpretation in order to better serve oil and gas exploration practice.

[0037] In a specific embodiment of the application of the present invention, such as Figure 1 As shown, Figure 1 This is a flowchart illustrating the method for estimating the kinematic vorticity of compressional-torsional tectonics using seismic data in the middle segment of the southern margin of the present invention. It includes the following steps:

[0038] In step 101, 3D and 2D seismic data from the southern margin of the Junggar Basin were used to trace the standard reflection axis of the Neogene basal layer and interpret its tectonic structure. The aim was to estimate the kinematic vorticity of the Himalayan compressional-torsional tectonics, thereby guiding the scientific selection of the tectonic interpretation model. This invention utilized the landmark seismic interpretation system to trace the standard reflection axis of the upper tectonic layer. Without a clear interpretation model, the focus was on interpreting the major faults and compressional-torsional folds controlling the tectonic deformation characteristics of the central segment of the southern Junggar Basin, completing industrial mapping as the data basis for the implementation of this invention's method. The process then proceeds to step 102.

[0039] At step 102, according to the industrial drawing of step 101, the large faults of the control structure belt in the middle segment of the quasi-southern margin are extracted, and the trend difference is greater than 5° for segmented marking processing, and 9 segments are marked in the example; the pressure-shear related fold shape is extracted, and the longest axis of the connected irregular ellipse is taken as the ridge line, and 15 pressure-shear related structural ridge lines are marked in the example; and finally, a large fault and related pressure-shear fold and ridge line distribution map of the control structure belt in the middle segment of the quasi-southern margin is prepared, as shown in Figure 2 Figure 2 It is a large fault and pressure-shear fold distribution map of the control structure belt in the middle segment of the quasi-southern margin of the present application. The flow enters step 103.

[0040] At step 103, according to the map prepared in step 102, the trend azimuth angle of the large fault in different marked segments is measured and recorded, and the statistical analysis of the fault is completed with an azimuth angle interval of 10°, and the dominant trend azimuth angle is obtained, as shown in Figure 3 Figure 3 It is a large fault dominant direction analysis map of the control structure belt in the middle segment of the quasi-southern margin of the present application, and the dominant trend azimuth angle of the large fault is NW295°. The flow enters step 104.

[0041] At step 104, according to the map prepared in step 102, the trend azimuth angle of the pressure-shear related fold ridge line is measured and recorded, and the statistical analysis is completed with an azimuth angle interval of 10°, and the dominant trend azimuth angle of the pressure-shear related fold ridge line is obtained, as shown in Figure 4 Figure 4 It is a pressure-shear related fold ridge line dominant direction analysis map of the middle segment of the quasi-southern margin of the present application, and the dominant trend azimuth angle of the related fold ridge line is NW275°. The flow enters step 105.

[0042] At step 105, the normal line of the dominant direction of the pressure-shear related fold ridge line is drawn, as shown in Figure 5 Figure 5 It is a kinematic vorticity analysis result map of the pressure-shear structure of the middle segment of the quasi-southern margin of the present application. It is required to mark the main pressure direction σ1 or ISA3 of the pressure-shear structure belt, and the azimuth angle of the main pressure direction σ1 of the middle segment of the quasi-southern margin in the example is EN25°; the dominant trend of the large fault and its normal line are drawn, and it is marked that the dominant trend of the large fault is approximately the first characteristic direction (stretching without rotation), and the azimuth angle of the approximate first characteristic direction of the middle segment of the quasi-southern margin in the example is NW295°, and the corresponding normal line direction is EN25°; the approximate second characteristic direction (extrusion without rotation) is drawn according to the mirror image of the normal line direction of the control structure belt with the main pressure direction σ1 of the pressure-shear structure belt as the center, and the azimuth angle of the approximate second characteristic direction of the middle segment of the quasi-southern margin in the example is EN5°. The flow enters step 106.

[0043] ​​​​In step 106, according to step 105, the acute angle υ between the approximate first characteristic direction and the low second characteristic direction is obtained, or the acute angle ξ between the principal stress direction σ1 and the normal of the large fault in the tectonic belt is obtained, υ = 50 and ξ = 20 in the middle segment of the quasi-southern margin in the present example; and the tectonic kinematic vorticity W of the tectonic layer in the middle segment of the quasi-southern margin is calculated according to the formula W = cos(υ) or W = sin(2ξ) k k k Since the tectonic kinematic vorticity of the quasi-southern margin in the present example is less than 0.71, the coaxial compression model can be used to carry out fine interpretation of the quasi-southern margin structure, but a certain degree of angular shear component is developed in the tectonic deformation. Thus, it can return to step 101, and further fine structural interpretation and industrial mapping are carried out under the guidance of the coaxial compression model, so as to serve the oil and gas exploration practice.

[0044] The method for estimating the tectonic kinematic vorticity of the compressional-torsional structure in the basin coverage area by using seismic data has been applied in multiple tectonic units, and the uncertainty problem of the interpretation model of the complex compressional-torsional structure belt has been solved, and the interpretation scheme formed is more scientific and reasonable, which effectively guides the oil and gas exploration practice. The method of the present application is generally applicable to the compressional-torsional oil and gas bearing basin seismic acquisition area, including the strong compressional-torsional tectonic activity units such as the piedmont zone and the depression zone. Compared with the prior art, the present application is not limited to the theoretical research of the observable and sampling area of the orogenic belt, and is suitable for the application field of science.

[0045] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and all are included in the protection scope of the present application.​​

Claims

1. A method for estimating the kinematic vorticity of a compressional-shearing structure using seismic data, characterized in that, The method for estimating the kinematic vorticity of the pressure-shear structure by using seismic data comprises the following steps: Step 1, performing standard reflection axis interpretation and industrial mapping of a target layer in a seismic acquisition area; Step 2, preparing a plane distribution map of large faults and pressure-shear related folds in a structure-controlling zone; Step 3, extracting the dominant trend of large faults in the structure-controlling zone; Step 4, extracting the dominant azimuth of the ridge line of the related pressure-shear fold; Step 5, preparing a relationship map of the main pressure azimuth and two characteristic azimuths of the pressure-shear structure; Step 6, calculating the kinematic vorticity of the pressure-shear structure; In step 1, the structural characteristics of the target layer are interpreted by using seismic processing results, and the large faults and the pressure-shear related folds in the structure-controlling zone are finely interpreted, while the low-order faults are not interpreted, so as to complete large-scale structural mapping; In step 2, the large faults and the pressure-shear related fold distribution map in the structure-controlling zone are extracted and prepared, the position where the azimuth angle of the large fault trend changes by more than 5° is segmented and numbered, and the pressure-shear related fold is numbered and connected with the longest axis of the irregular ellipse to mark the fold ridge line; In step 3, the segmented large fault trend in the structure-controlling zone is measured, a statistical table is formed according to the number, a trend rose diagram is prepared, the dominant trend is extracted, and the azimuth angle is marked; In step 4, the azimuth angle of the ridge line of the related pressure-shear fold is measured, a statistical table is formed according to the number, a ridge line trend rose diagram is prepared, the dominant azimuth is extracted, and the azimuth angle is marked; In step 5, the relationship between the main pressure azimuth and the characteristic azimuth of the pressure-shear structure is determined, the normal line of the dominant azimuth of the ridge line of the pressure-shear related fold is drawn, the main pressure direction σ1 or ISA3 is marked, the dominant azimuth of the large fault in the structure-controlling zone and its normal line are drawn, the dominant azimuth of the large fault in the structure-controlling zone is marked as the approximate first characteristic azimuth, and the approximate second characteristic azimuth is drawn according to the mirror image of the normal line azimuth of the large fault in the structure-controlling zone with the main pressure azimuth σ1 of the pressure-shear structure as the center; In step 6, the acute included angle υ between the approximate first characteristic azimuth and the second characteristic azimuth is obtained, or the acute included angle ξ between the main pressure azimuth σ1 and the normal line of the large fault in the structure-controlling zone is obtained; In step 6, according to W k = cos(υ) or W k = sin(2ξ) formula to calculate the torsional shear structure kinematic vorticity W k , using the calculated W k value to determine the degree of non-coaxial extrusion, and to clarify the reasonable structure interpretation model.

2. The method for estimating the kinematic vorticity of a pressure- shear structure using seismic data according to claim 1, wherein, In step 3, the azimuth angle deviation of the segmented fault with similar trend is less than 10°.

3. The method for estimating the kinematic vorticity of a pressure- shear structure from seismic data according to claim 1, wherein, The azimuth angle deviation of the ridge line of the pressure-shear related fold with similar trend is less than 10°.

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