Method for judging relative movement intensity of different parts of strike-slip fracture

Abstract

The invention discloses a method for judging the relative movement intensity of different parts of strike-slip fracture, which is used for determining the difference of the relative movement intensity of different parts in the same section by fitting the vertical displacement change curve of different sections and calculating the vertical displacement change rate in the same section. And determining the relative activity intensity of different sections of the strike-slip fracture through a mathematical method of calculating the area of the broken line enveloping range of the depth values of the vertical displacement of different sections and the length-to-surface ratio. By applying the method, the relative activity intensity of different segments of the strike-slip fracture can be effectively judged, and an effective scheme is provided for professional technicians for researching storage control and reservoir control of the strike-slip fracture. And the phenomena of activity intensity difference between different sections of the strike-slip fracture and relatively large personal error in the statistical process are neglected.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas geological exploration, and in particular to a method for determining the relative activity intensity of different parts of a strike-slip fault. Background Art

[0002] There are many strike-slip faults in my country's craton basins with high density. They play an important constructive role in the development of reservoirs and have a significant control effect on the migration and enrichment of oil and gas. At present, domestic and foreign scholars have explored the control of strike-slip fault zones in terms of reservoir and reservoir by analyzing the geometric and kinematic characteristics of strike-slip faults, the matching relationship between the activity period of strike-slip faults and the time of oil and gas filling, and the detailed characterization of the internal configuration of strike-slip faults. In recent years, with the continuous breakthroughs in oil and gas exploration and development around strike-slip faults, the research on strike-slip faults has continued to deepen. Many scholars have found that strike-slip faults are not a continuous section, but are composed of multiple discontinuous segments spliced ​​together during the evolution process. Different segments are subjected to different tectonic stresses during the tectonic evolution process, which leads to different relative activity intensities of different segments, which in turn affects the degree of fragmentation of different segmented strata, resulting in significantly different oil and gas enrichment laws along strike-slip faults. Therefore, it is particularly important to establish a method for judging the relative activity intensity of different segments of strike-slip faults for oil and gas exploration and development.

[0003] At present, most studies on the activity intensity of strike-slip faults focus on the entire strike-slip fault, and analyze the difference in activity intensity between the left and right sides of the strike-slip fault along the axis of the entire strike-slip fault. However, although this method can show the variation in activity intensity of different parts of the entire strike-slip fault along the fault direction, it ignores the difference in activity intensity between different segments of the strike-slip fault, which makes it difficult to effectively judge the difference in relative activity intensity between different segments in the actual research process, restricting the refinement of oil and gas exploration and development.

[0004] In the current study of the activity intensity of strike-slip faults, it can be found that the method of using the entire strike-slip fault to analyze the activity intensity difference will cause large artificial statistical errors when encountering overlapping parts of different segments of the strike-slip fault, thereby leading to the amplification of the fluctuations in the activity intensity data of the strike-slip fault, which cannot truly reflect the activity intensity differences in different parts of the strike-slip fault. Summary of the invention

[0005] The present application provides a method for determining the relative activity intensity of different parts of a strike-slip fault, aiming to solve the problem that the existing technology for studying the activity intensity of a strike-slip fault ignores the difference in activity intensity of different segments, leading to statistical errors and amplified data fluctuations, thus limiting the refinement of oil and gas exploration and development.

[0006] A method for determining the relative activity intensity of different parts of a strike-slip fault, the method comprising:

[0007] Step 1: Use the seismic data of the target area to carry out strike-slip fault profile analysis, and combine the seismic attributes to clarify the main plate of strike-slip fault activity analysis;

[0008] Step 2: Determine the target research horizon, clarify the segmentation characteristics of the fault plane, calculate the vertical displacement within different segments and draw a line graph of the vertical displacement change;

[0009] Step 3: Fit the vertical displacement change curves of different segments, calculate the vertical displacement change rate within the same segment, and determine the difference in relative intensity of activities of different parts within the same segment;

[0010] Step 4: Calculate the envelope area and “length-to-surface ratio” of the vertical displacement depth values ​​of different segments to determine the relative activity intensity of different segments and the differences in relative activity intensity of different segments.

[0011] In the above scheme, optionally, step 1 includes:

[0012] Step 11: using the seismic data of the target area, identify and carve strike-slip faults on the seismic profile, and clarify the spatial distribution pattern of strike-slip faults; specifically, when identifying strike-slip faults on the seismic profile, clarify the overall strike-slip fault trend through seismic data, select a profile perpendicular to the overall strike-slip fault trend to carve the strike-slip fault, combine the carving results of strike-slip faults in different profiles, and clarify the spatial distribution pattern of strike-slip faults;

[0013] Step 12: Based on the seismic data, extract the seismic attribute volume, and determine the main plate for the strike-slip fault activity analysis in combination with the spatial distribution pattern of the strike-slip fault.

[0014] In the above scheme, optionally, step 2 includes:

[0015] Step 21: According to actual production needs, determine the target research layer and clarify the segmented characteristics of the strike-slip fault plane on the target research layer;

[0016] Step 22: Calculate the vertical displacement inside different segments of the strike-slip fault;

[0017] Step 23: Based on the calculation results of the vertical displacement, draw a line graph of the vertical displacement changes in different segments.

[0018] In the above solution, optionally, step 21 includes:

[0019] According to actual production needs, the studied layer is selected as the target research layer, and the plane segmentation characteristics of the strike-slip fault are characterized for the selected layer, the plane distribution pattern of different segments of the strike-slip fault is clarified, and the number of segments M and the length Hn of different segments are clarified.

[0020] In the above solution, optionally, step 22 includes:

[0021] The planes of different segments are named. The naming principle is determined by the strike of the strike-slip fault. After determining the due north direction of the study area, if the strike-slip fault is NE-striking, the segments are numbered from SW to NE, and the segment number at the SW end of the strike-slip fault is the starting value D1, and the segment number at the NE end of the strike-slip fault is the ending value Dn; if the strike-slip fault is NW-striking, the segments are numbered from SE to NW, and the segment number at the SE end of the strike-slip fault is the starting value D1, and the segment number at the NW end of the strike-slip fault is the ending value Dn;

[0022] Before calculating the vertical displacement of different segments of the strike-slip fault, the number Sn of vertical displacement statistical data is determined according to the strike and length H of the different segments of the strike-slip fault, wherein Sn is determined by obtaining a suitable step length Ln for different segments of the strike-slip fault;

[0023] The actual step length L is determined according to the segment length Hn, and the step length is selected as 4*10n times or 8*10n times of the application interval V as the optimal statistical step length. The number Sn of vertical displacement statistical data is determined by the ratio of the segment length Hn to the optimal statistical step length Ln; wherein,

[0024]

[0025] After determining the number Sn of vertical displacement statistics, a unified vertical displacement data statistical direction is selected to select and number vertical displacement statistical sections of different segments. The numbering principle is to number the sections from 1 to n in a unified direction; wherein the sections of data statistics are always kept perpendicular to the fault strike; the vertical displacement is calculated by taking the corresponding depth of the active plate of the strike-slip fault in the research layer as the minuend Bn and the corresponding depth of the passive plate as the subtrahend Jn, and the vertical displacement Cn of the corresponding section is obtained by difference; wherein,

[0026] C n =B n -J n ;

[0027] According to the determined optimal statistical step size, the vertical displacement data Cn of each profile in the same segment are obtained in turn; in the process of calculating the vertical displacement Cn of the strike-slip fault, the corresponding depth Bn of the active plate is subtracted from the corresponding depth Jn of the passive plate, and there are two cases where the vertical displacement Cn is positive and negative; a positive number indicates that the corresponding burial depth Bn of the active plate is deeper than the corresponding depth Jn of the passive plate; a negative number indicates that the corresponding burial depth Bn of the active plate is shallower than the corresponding depth Jn of the passive plate.

[0028] In the above solution, optionally, step 23 includes:

[0029] For the same segment, different sections are numbered from 1 to n, and the horizontal axis is compiled in order from small to large. The vertical displacement Cn is used as the vertical axis. After the plane rectangular coordinate system is established, a line graph of the change in vertical displacement of different segments is drawn.

[0030] In the above solution, optionally, step 3 includes:

[0031] Step 31: fitting a vertical displacement change curve based on the vertical displacement change line graphs of different segments;

[0032] Step 32: Calculate the vertical displacement change rate within the same segment according to the vertical displacement change curve;

[0033] Step 33: Based on the vertical displacement change rate, the difference in relative intensity of activities at different locations within the same segment of the strike-slip fault is determined. The difference in relative intensity of activities at different locations within the same segment of the strike-slip fault is determined by comparing the vertical displacement change rate Xn of each curve segment.

[0034] In the above solution, optionally, in step 32,

[0035] After fitting the vertical displacement change curve, by determining the maximum value Zd, minimum value Zx and 0 of the vertical displacement in the vertical displacement change curve, the entire vertical displacement change curve is divided into four sections, namely, the curve segment M1 encircled by the curve endpoint near the maximum value and the maximum value Zd, the curve segment M2 encircled by the maximum value Zd and the 0 value, the curve segment M3 encircled by the 0 value and the minimum value Zx, and the curve segment M4 encircled by the curve endpoint near the minimum value and the minimum value Zx;

[0036] The slope Xn of the two end points of each curve segment is obtained by using the absolute values ​​of the vertical displacement endpoints ZQ, ZZ, the maximum value Zd, and the minimum value Zx on both sides of the vertical displacement change curve, and the corresponding step lengths LQ, LZ, the maximum value Ld, and the minimum value Lx of the vertical displacement endpoints, which is the vertical displacement change rate of each curve segment; where,

[0037]

[0038] In the above solution, optionally, step 4 includes:

[0039] Step 41: Based on the vertical displacement change line graph of different segments, calculate the envelope range area Sn of the vertical displacement depth value line of different segments and the X-axis through time-depth conversion;

[0040] Step 42: Calculate the "length-to-surface ratio Qn" corresponding to different segments according to the length Hn and envelope area Sn of different segments, and determine the relative activity intensity of different segments; specifically, compare the envelope area Sn calculated for different segments with the length Hn of the corresponding segment to obtain the "length-to-surface ratio Qn" of different segments; wherein,

[0041]

[0042] The size of the Qn value indicates the degree of stratum fluctuation change per unit length in different segments. The larger the Qn value, the more intense the stratum fluctuation change and the greater the relative activity intensity.

[0043] Step 43: Based on the “length-surface ratio Qn” calculated for each segment, a line graph of “length-surface ratio Qn-different segments of strike-slip fault” is drawn to compare and analyze the differences in relative activity intensity of different segments;

[0044] Specifically, after calculating the "length-to-surface ratio Qn" of each segment of the strike-slip fault, the horizontal axis is compiled in ascending order according to the numbers of the different segments of the strike-slip fault, and the "length-to-surface ratio Qn" of the corresponding segment is used as the vertical axis to establish a plane rectangular coordinate system, and a line graph of "length-to-surface ratio Qn-different segments of strike-slip fault" of different segments is drawn.

[0045] In the above solution, optionally, step 41 includes:

[0046] When calculating the envelope area Sn of the vertical displacement line and the X-axis, if the vertical displacement Cn is a positive number, the envelope area Sn of the vertical displacement Cn and the X-axis is directly calculated; if the vertical displacement Cn is a negative number, the absolute value of the vertical displacement Cn is taken and then the envelope area Sn of the vertical displacement Cn and the X-axis is calculated;

[0047] By consulting the time-depth conversion relationship of the study area, the absolute value of the vertical displacement |Cn| is converted into the corresponding depth value |CSn|, and a line graph of the vertical displacement depth value change is made;

[0048] When calculating the envelope range area Sn of the vertical displacement depth value broken line and the X-axis, draw a vertical line from each scattered point to the X-axis to cut the envelope range of the vertical displacement depth value broken line and the X-axis into 1 to z single trapezoids; the length of the vertical line is the absolute value of the vertical displacement depth value |Cn|, and after calculating the area Sz of each trapezoid, the envelope range area Sn of the vertical displacement depth value broken line and the X-axis of the corresponding segment is obtained by summing the areas of each trapezoid;

[0049]

[0050] Compared with the prior art, this application has at least the following beneficial effects:

[0051] This application is based on further analysis and research of existing technical problems. It is recognized that the existing technology ignores the difference in activity intensity of different segments when studying the activity intensity of strike-slip faults, resulting in statistical errors and data fluctuation amplification, which limits the refinement of oil and gas exploration and development. It provides a method for fitting the vertical displacement change curves of different segments, calculating the vertical displacement change rate within the same segment, to determine the difference in relative activity intensity of different parts within the same segment, and then calculating the area of ​​the envelope range of the vertical displacement depth value of different segments and the mathematical method of "length-to-surface ratio" to determine the relative activity intensity of different segments of the strike-slip fault. This method can be used to effectively judge the relative activity intensity of different segments of the strike-slip fault, and provides a set of effective solutions for professional and technical personnel who study the control of storage and reservoir by strike-slip faults.

[0052] This application solves the problems of insufficient research accuracy in the study of the activity intensity of strike-slip fault zones, neglect of the differences in activity intensity between different segments of strike-slip faults, and large human errors in the statistical process. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A schematic flow chart of a method for determining the relative activity intensity of different parts of a strike-slip fault provided by an embodiment of the present application;

[0054] Figure 2 A comparison of the number of stratum faults on both sides of the strike-slip fault of the T74 interface of the coherent seismic body provided in one embodiment of the present application and a main plate discrimination diagram;

[0055] Figure 3 A diagram showing the distribution characteristics, segmentation characteristics and actual length of a strike-slip fault provided by an embodiment of the present application;

[0056] Figure 4 A diagram of a statistical cross-section division scheme for vertical displacement data of different segments provided by an embodiment of the present application;

[0057] Figure 5A line graph showing changes in vertical displacement of strike-slip fault segments D1 and D2 provided in one embodiment of the present application;

[0058] Figure 6 A vertical displacement variation curve diagram of strike-slip fault segments D1 and D2 provided in one embodiment of the present application;

[0059] Figure 7 A line graph showing the change in the vertical displacement depth value of the strike-slip fault segments D1 and D2 and a diagram showing the calculation scheme for the envelope range area provided in one embodiment of the present application;

[0060] Figure 8 A line graph of “long face ratio Qn-different segments of a strike-slip fault” for different segments of a strike-slip fault provided by one embodiment of the present application. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0062] In one embodiment, Figure 1 As shown, a method for determining the relative activity intensity of different parts of a strike-slip fault is provided, comprising the following steps:

[0063] Step 1: Use the seismic data of the target area to carry out strike-slip fault profile analysis, and combine the seismic attributes to clarify the main plate of strike-slip fault activity analysis;

[0064] Step 2: Determine the target research horizon, clarify the segmentation characteristics of the fault plane, calculate the vertical displacement within different segments and draw a line graph of the vertical displacement change;

[0065] Step 3: Fit the vertical displacement change curves of different segments, calculate the vertical displacement change rate within the same segment, and determine the difference in relative intensity of activities of different parts within the same segment;

[0066] Step 4: Calculate the envelope area and “length-to-surface ratio” of the vertical displacement depth values ​​of different segments to determine the relative activity intensity of different segments and the differences in relative activity intensity of different segments.

[0067] In this embodiment, step 1 includes:

[0068] Step 11: using the seismic data of the target area, identify and carve strike-slip faults on the seismic profile, and clarify the spatial distribution pattern of strike-slip faults; specifically, when identifying strike-slip faults on the seismic profile, clarify the overall strike-slip fault trend through seismic data, select a profile perpendicular to the overall strike-slip fault trend to carve the strike-slip fault, combine the carving results of strike-slip faults in different profiles, and clarify the spatial distribution pattern of strike-slip faults;

[0069] Combined with the carving results of strike-slip faults in different sections, the spatial distribution pattern of strike-slip faults is clarified;

[0070] It should be noted that when identifying strike-slip faults on seismic sections, the overall strike-slip fault direction should be clarified through seismic data. Secondly, according to the overall strike-slip fault direction, a section perpendicular to its direction should be selected to carve the strike-slip fault. Finally, the carving results of strike-slip faults in different sections are combined to clarify the spatial distribution pattern of strike-slip faults.

[0071] Step 12: Based on the seismic data, extract the seismic attribute volume, and determine the main plate for the strike-slip fault activity analysis in combination with the spatial distribution pattern of the strike-slip fault.

[0072] It should be noted that the seismic attribute body extracted based on seismic data must be able to reflect the distribution of faults of different scales in the underground space. Combining the coherence attribute body, curvature attribute body and ant body seismic attributes can determine the distribution of faults of different scales in the underground space to the greatest extent. After the seismic attribute body is extracted, combined with the strike-slip fault carving results, the distribution of faults of different scales in the strata on both sides of the strike-slip fault is observed, and the one with the largest number of faults of different scales is defined as the main plate for activity analysis.

[0073] In this embodiment, step 2 includes:

[0074] Step 21: According to actual production needs, determine the target research layer and clarify the segmented characteristics of the strike-slip fault plane on the target research layer;

[0075] Step 22: Calculate the vertical displacement inside different segments of the strike-slip fault;

[0076] Step 23: Based on the calculation results of the vertical displacement, draw a line graph of the vertical displacement changes in different segments.

[0077] In this embodiment, step 21 includes:

[0078] According to actual production needs, the studied layer is selected as the target research layer, and the plane segmentation characteristics of the strike-slip fault are characterized for the selected layer, the plane distribution pattern of different segments of the strike-slip fault is clarified, and the number of segments M and the length Hn of different segments are clarified.

[0079] It should be noted that since strike-slip faults have the characteristics of longitudinal stratified deformation in space, the plane segmentation characteristics of strike-slip faults in different strata will be different. Therefore, before studying the plane segmentation characteristics of strike-slip faults, the studied strata should be selected according to actual production needs.

[0080] In this embodiment, step 22 includes:

[0081] The planes of different segments are named. The naming principle is determined by the strike of the strike-slip fault. After determining the due north direction of the study area, if the strike-slip fault is NE-striking, the segments are numbered from SW to NE, and the segment number at the SW end of the strike-slip fault is the starting value D1, and the segment number at the NE end of the strike-slip fault is the ending value Dn; if the strike-slip fault is NW-striking, the segments are numbered from SE to NW, and the segment number at the SE end of the strike-slip fault is the starting value D1, and the segment number at the NW end of the strike-slip fault is the ending value Dn;

[0082] Before calculating the vertical displacement of different segments of the strike-slip fault, the number Sn of vertical displacement statistical data is determined according to the strike and length H of the different segments of the strike-slip fault, wherein Sn is determined by obtaining a suitable step length Ln for different segments of the strike-slip fault;

[0083] The actual step length L is determined according to the segment length Hn, and the step length is selected as 4*10n times or 8*10n times of the application interval V as the optimal statistical step length. The number Sn of vertical displacement statistical data is determined by the ratio of the segment length Hn to the optimal statistical step length Ln; wherein,

[0084]

[0085] It should be noted that the appropriate step length refers to the step length that can fully cover and display the vertical displacement changes of the strata on both sides of the intersection. Usually, the interval V between Inline and Xline in the seismic interpretation software is 15m. After determining the different segment lengths Hn, the actual step length L is determined according to the segment length Hn. In the statistics of vertical displacement data, it is found that overly dense data statistics will cause a surge in workload and have no obvious promoting effect on the reflection of the relative activity intensity of strike-slip faults. Therefore, in the actual step length selection, 4*10n times or 8*10n times of the interval V are often used as the optimal statistical step length. After the statistical step length is selected, the number Sn of vertical displacement statistical data is determined by the ratio of the segment length Hn to the actual optimal statistical step length Ln.

[0086] After determining the number Sn of vertical displacement statistics, a unified vertical displacement data statistical direction is selected to select and number vertical displacement statistical sections of different segments. The numbering principle is to number the sections from 1 to n in a unified direction; wherein the sections of data statistics are always kept perpendicular to the fault strike; the vertical displacement is calculated by taking the corresponding depth of the active plate of the strike-slip fault in the research layer as the minuend Bn and the corresponding depth of the passive plate as the subtrahend Jn, and the vertical displacement Cn of the corresponding section is obtained by difference; wherein,

[0087] C n =B n -J n ;

[0088] According to the determined optimal statistical step size, the vertical displacement data Cn of each profile in the same segment are obtained in turn; in the process of calculating the vertical displacement Cn of the strike-slip fault, the corresponding depth Bn of the active plate is subtracted from the corresponding depth Jn of the passive plate, and there are two cases where the vertical displacement Cn is positive and negative; a positive number indicates that the corresponding burial depth Bn of the active plate is deeper than the corresponding depth Jn of the passive plate; a negative number indicates that the corresponding burial depth Bn of the active plate is shallower than the corresponding depth Jn of the passive plate.

[0089] In this embodiment, step 23 includes:

[0090] For the same segment, different sections are numbered from 1 to n, and the horizontal axis is compiled in order from small to large. The vertical displacement Cn is used as the vertical axis. After the plane rectangular coordinate system is established, a line graph of the change in vertical displacement of different segments is drawn.

[0091] In this embodiment, step 3 includes:

[0092] Step 31: fitting a vertical displacement change curve based on the vertical displacement change line graphs of different segments;

[0093] Step 32: Calculate the vertical displacement change rate within the same segment according to the vertical displacement change curve;

[0094] Step 33: Based on the vertical displacement change rate, the difference in relative intensity of activities at different locations within the same segment of the strike-slip fault is determined. The difference in relative intensity of activities at different locations within the same segment of the strike-slip fault is determined by comparing the vertical displacement change rate Xn of each curve segment.

[0095] In this embodiment, in step 32,

[0096] After fitting the vertical displacement change curve, by determining the maximum value Zd, minimum value Zx and 0 of the vertical displacement in the vertical displacement change curve, the entire vertical displacement change curve is divided into four sections, namely, the curve segment M1 encircled by the curve endpoint near the maximum value and the maximum value Zd, the curve segment M2 encircled by the maximum value Zd and the 0 value, the curve segment M3 encircled by the 0 value and the minimum value Zx, and the curve segment M4 encircled by the curve endpoint near the minimum value and the minimum value Zx;

[0097] The slope Xn of the two end points of each curve segment is obtained by using the absolute values ​​of the vertical displacement endpoints ZQ, ZZ, the maximum value Zd, and the minimum value Zx on both sides of the vertical displacement change curve, and the corresponding step lengths LQ, LZ, the maximum value Ld, and the minimum value Lx of the vertical displacement endpoints, which is the vertical displacement change rate of each curve segment; where,

[0098]

[0099] In this embodiment, step 4 includes:

[0100] Step 41: Based on the vertical displacement change line graph of different segments, calculate the envelope range area Sn of the vertical displacement depth value line of different segments and the X-axis through time-depth conversion;

[0101] Step 42: Calculate the "length-to-surface ratio Qn" corresponding to different segments according to the length Hn and envelope area Sn of different segments, and determine the relative activity intensity of different segments; specifically, compare the envelope area Sn calculated for different segments with the length Hn of the corresponding segment to obtain the "length-to-surface ratio Qn" of different segments; wherein,

[0102]

[0103] The size of the Qn value indicates the degree of stratum fluctuation change per unit length in different segments. The larger the Qn value, the more intense the stratum fluctuation change and the greater the relative activity intensity.

[0104] Step 43: Based on the “length-surface ratio Qn” calculated for each segment, a line graph of “length-surface ratio Qn-different segments of strike-slip fault” is drawn to compare and analyze the differences in relative activity intensity of different segments;

[0105] Specifically, after calculating the "length-to-surface ratio Qn" of each segment of the strike-slip fault, the horizontal axis is compiled in ascending order according to the numbers of the different segments of the strike-slip fault, and the "length-to-surface ratio Qn" of the corresponding segment is used as the vertical axis to establish a plane rectangular coordinate system, and a line graph of "length-to-surface ratio Qn-different segments of strike-slip fault" of different segments is drawn.

[0106] In this embodiment, step 41 includes:

[0107] When calculating the envelope area Sn of the vertical displacement line and the X-axis, if the vertical displacement Cn is a positive number, the envelope area Sn of the vertical displacement Cn and the X-axis is directly calculated; if the vertical displacement Cn is a negative number, the absolute value of the vertical displacement Cn is taken and then the envelope area Sn of the vertical displacement Cn and the X-axis is calculated;

[0108] By consulting the time-depth conversion relationship of the study area, the absolute value of the vertical displacement |Cn| is converted into the corresponding depth value |CSn|, and a line graph of the vertical displacement depth value change is made;

[0109] When calculating the envelope range area Sn of the vertical displacement depth value broken line and the X-axis, draw a vertical line from each scattered point to the X-axis to cut the envelope range of the vertical displacement depth value broken line and the X-axis into 1 to z single trapezoids; the length of the vertical line is the absolute value of the vertical displacement depth value |Cn|, and after calculating the area Sz of each trapezoid, the envelope range area Sn of the vertical displacement depth value broken line and the X-axis of the corresponding segment is obtained by summing the areas of each trapezoid;

[0110]

[0111] S n =S 1 +…+S z .

[0112] It should be noted that since there are a large number of segments of strike-slip faults, it is difficult to intuitively show the difference in relative activity of different segments of strike-slip faults by comparing the "length ratio Qn" data of a large number of different segments by comparing the size. Therefore, by compiling and observing the line graph of "length ratio Qn-different segments of strike-slip faults" of strike-slip faults, the relative activity intensity differences of different segments of strike-slip faults can be quickly compared and analyzed.

[0113] This embodiment mainly provides a method for the study of the relative activity intensity of strike-slip faults by fitting the vertical displacement change curves of different segments, calculating the vertical displacement change rate within the same segment, and determining the difference in the relative activity intensity of different parts within the same segment. Then, by calculating the area of ​​the envelope range of the vertical displacement depth value broken line of different segments and the mathematical method of "length-to-surface ratio", a method is used to determine the relative activity intensity of different segments of the strike-slip fault. This method can be used to accurately, objectively, conveniently and intuitively evaluate the relative activity intensity of different parts within the same segment of the strike-slip fault and between different segments. It effectively solves the problem of insufficient research accuracy, ignoring the difference in activity intensity between different segments of the strike-slip fault, and the existence of large human errors in the statistical process. It provides a set of effective solutions for structural analysts who study strike-slip faults in oil and gas geological exploration.

[0114] In one embodiment, the example applies a method for determining the relative activity intensity of different parts of a strike-slip fault to a northeast-trending strike-slip fault along the Toguole low uplift in the Tarim Basin to study the activity intensity of different parts of the strike-slip fault.

[0115] First, using the three-dimensional seismic data of the study area of ​​the Shuntoguole low uplift in the Tarim Basin, strike-slip fault analysis was carried out on the profile. The overall trend of the strike-slip fault can be clearly defined in three-dimensional space through the combination of faults. The overall trend of the strike-slip fault in this area is NE. Secondly, by carving the strike-slip fault according to the overall trend of the strike-slip fault, the spatial distribution pattern of the strike-slip fault is clarified. Through the analysis and carving of the strike-slip faults in the area, it can be found that the strike-slip faults in the area are spatially stratified. The deep layer is manifested as a vertical fault and the shallow layer is a flower-shaped structure. It can be seen that under the influence of the shallow flower-shaped structure, the stratum of this strike-slip fault is more strongly broken. After extracting coherent attributes from seismic data, it was found that the number of faults in the strata on the NW side of the strike-slip fault was significantly stronger than that in the strata on the SE side of the strike-slip fault. Therefore, it can be determined that the strata on the NW side of the strike-slip fault are the main plate of the strike-slip fault activity, such as Figure 2 shown.

[0116] According to actual production needs, the main research layer of the study area is determined to be the T74 layer. Therefore, it is necessary to first clarify the planar distribution pattern of the strike-slip fault at the T74 level. The strike-slip fault in this study is divided into two sections M=2 at the T74 level, and the lengths of the two sections are H1=17.29km and H2=14.89km respectively. Because the strike-slip fault is NE-oriented, the section at the SW end of the strike-slip fault is numbered as the starting value D1, and the section at the NE end is numbered as the ending value D2, such as Figure 3 As shown. Since the length of this strike-slip fault is a kilometer-level strike-slip fault, and the interval V between Inline and Xline in the seismic interpretation software is only 15m, which is too small compared with the actual length of the strike-slip fault, in the statistics of this vertical displacement data, 4*10 times the step length L is used as the optimal statistical step length, and the optimal statistical step length L = 600m is obtained. For this reason, it can be determined that the number of vertical displacement statistical data of segment D1 is S1 = 28, and the number of vertical displacement statistical data of segment D2 is S2 = 24.

[0117] After determining the optimal statistical step length L and the number of vertical displacement statistical data Sn, a statistical profile perpendicular to the fault direction is made from the starting point of each segment with the optimal statistical step length L as the interval, such as Figure 4As shown. Read the corresponding depth Bn of the active disk and the corresponding depth Jn of the passive disk of each section, and calculate the vertical displacement Cn of the corresponding section. Since the strike-slip fault has the typical "dolphin effect" characteristics, the active disk of the strike-slip fault will undergo large fluctuations along the fault direction. Therefore, in actual data statistics, it often appears that the vertical displacement Cn along the strike-slip fault direction will show a data trend of first positive and then negative or first negative and then positive. These phenomena are all normal phenomena. In the data statistics of the study area, it is shown that at the starting end of segment D1, the corresponding depth of the active disk is B1=3823ms, the corresponding depth of the passive disk is J1=3805ms, and the vertical displacement C1=B1-J1=18ms. At this time, it means that the corresponding burial depth B1 of the active disk is deeper than the corresponding depth J1 of the passive disk. At the end of the segment, the active disk corresponds to a depth B28 = 3867ms, the passive disk corresponds to a depth J28 = 3877ms, and the vertical displacement C28 = B28-J28 = -10ms, which means that the active disk corresponds to a buried depth B28 that is shallower than the passive disk. Similarly, at the start of segment D2, the active disk corresponds to a depth B1 = 3845ms, the passive disk corresponds to a depth J1 = 3836ms, and the vertical displacement C1 = B1-J1 = 9ms, which means that the active disk corresponds to a buried depth B1 that is deeper than the passive disk. At the end of the segment, the active disk corresponds to a depth B24 = 3855ms, the passive disk corresponds to a depth J24 = 3863ms, and the vertical displacement C24 = B24-J24 = -8ms, which means that the active disk corresponds to a buried depth B28 that is shallower than the passive disk. By calculating the vertical displacement Cn of each section of segments D1 and D2, the horizontal axis is compiled in the order of the section numbers from small to large, and the vertical displacement of the corresponding section is used as the vertical axis. After establishing the plane rectangular coordinate system, a line graph of the vertical displacement changes of segments D1 and D2 is drawn, as shown in Figure 5 shown.

[0118] According to the vertical displacement change line graphs of segments D1 and D2, the vertical displacement change curves of the two segments are fitted respectively, as shown in Figure 6 As shown. The vertical displacement endpoint values ​​of segment D1 are ZQ=14.31, ZZ=-9.52, maximum value Zd=18.79, and minimum value Zx=-13.75. According to the formula: By calculation, we can obtain the curve slope X1=1.49 of the two ends of the curve segment M1 encircled by the curve endpoints near the maximum value and the maximum value Zd, the curve slope X2=1.98 of the two ends of the curve segment M2 encircled by the maximum value Zd and the 0 value, the curve slope X3=1.64 of the two ends of the curve segment M3 encircled by the 0 value and the minimum value Zx, and the curve slope X4=0.84 of the curve segment M4 encircled by the curve endpoints near the minimum value and the minimum value Zx. By comparison, it can be found that the vertical displacement change rate of the four curves in segment D1 is X2>X3>X1>X4, from which it can be judged that the relative activity intensity of the four curve segments in segment D1 is M2>M3>M1>M4. The vertical displacement endpoint values ​​of segment D2 are ZQ=2.41, ZZ=-16.71, the maximum value Zd=27.89, and the minimum value Zx=-19.12. According to the formula: By calculation, we can get the curve slope X1=2.83 of the two ends of the curve segment M1 encircled by the curve endpoints near the maximum value and the maximum value Zd, the curve slope X2=3.93 of the two ends of the curve segment M2 encircled by the maximum value Zd and the 0 value, the curve slope X3=3.12 of the two ends of the curve segment M3 encircled by the 0 value and the minimum value Zx, and the curve slope X4=2.41 of the two ends of the curve segment M4 encircled by the curve endpoints near the minimum value and the minimum value Zx. By comparison, it can be found that the vertical displacement change rate of the four curves in segment D1 is X2>X3>X1>X4, from which it can be judged that the relative activity intensity of the four curve segments in segment D1 is M2>M3>M1>M4.

[0119] On the basis of the existing segmented vertical displacement change line graphs D1 and D2, first convert the vertical displacement time value into a vertical displacement depth value through time-to-depth conversion, and draw a vertical displacement depth value change line graph, such as Figure 7 As shown. Then calculate the envelope range area Sn of the vertical displacement depth value broken line and the X-axis of segments D1 and D2 respectively. By drawing a vertical line to the X-axis for the vertical displacement depth value scattered data of segment D1, the envelope range of the vertical displacement depth value broken line and the X-axis can be cut into 27 single trapezoids. At this time, the vertical line length is used as the absolute value of the vertical displacement depth value |Cn| and the optimal statistical step length L=600m to calculate the area S1~27 of each trapezoid, and then the area of ​​each trapezoid is summed to obtain the envelope range area S1=0.74km2 of the vertical displacement broken line and the X-axis of the corresponding segment. According to the formula The length-to-surface ratio of segment D1 is obtained as Q1 = 0.042. The areas of each trapezoid of segment D2 are obtained in the same way as above. S1 to 23, and then the areas of each trapezoid are summed to obtain the envelope area of ​​the vertical displacement line of the corresponding segment and the X-axis as S2 = 0.75 km2. According to the formula The length-surface ratio of segment D2 is obtained as Q2 = 0.050. By comparing the length-surface ratios Qn of the two segments, it can be found that Q2>Q1, which means that the stratum fluctuations in segment D2 are more intense, and the relative activity intensity is greater than that in segment D1. Figure 8 Although there are fewer strike-slip fault segments in this study, the relative activity intensity differences of different segments can still be easily observed in the line graph of "long surface ratio Qn-strike-slip fault different segments" in different segments.

[0120] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for determining the relative activity intensity of different parts of a strike-slip fault, characterized in that: The method comprises: Step 1: Use the seismic data of the target area to carry out strike-slip fault profile analysis, and combine the seismic attributes to clarify the main plate of strike-slip fault activity analysis; Step 2: Determine the target research horizon, clarify the segmentation characteristics of the fault plane, calculate the vertical displacement within different segments and draw a line graph of the vertical displacement change; Step 3: Fit the vertical displacement change curves of different segments, calculate the vertical displacement change rate within the same segment, and determine the difference in relative intensity of activities of different parts within the same segment; Step 4: Calculate the envelope area and "length-to-surface ratio" of the vertical displacement depth values ​​of different segments to determine the relative activity intensity of different segments and the differences in relative activity intensity of different segments.

2. The method according to claim 1, characterized in that The step 1 comprises: Step 11: using the seismic data of the target area, identify and carve strike-slip faults on the seismic profile, and clarify the spatial distribution pattern of strike-slip faults; specifically, when identifying strike-slip faults on the seismic profile, clarify the overall strike-slip fault trend through seismic data, select a profile perpendicular to the overall strike-slip fault trend to carve the strike-slip fault, combine the carving results of strike-slip faults in different profiles, and clarify the spatial distribution pattern of strike-slip faults; Step 12: Based on the seismic data, extract the seismic attribute volume, and determine the main plate for the strike-slip fault activity analysis in combination with the spatial distribution pattern of the strike-slip fault.

3. The method according to claim 1, characterized in that The step 2 comprises: Step 21: According to actual production needs, determine the target research layer and clarify the segmented characteristics of the strike-slip fault plane on the target research layer; Step 22: Calculate the vertical displacement inside different segments of the strike-slip fault; Step 23: Based on the calculation results of the vertical displacement, draw a line graph of the vertical displacement changes in different segments.

4. The method according to claim 3, characterized in that The step 21 comprises: According to actual production needs, the studied layer is selected as the target research layer, and the plane segmentation characteristics of the strike-slip fault are characterized for the selected layer, the plane distribution pattern of different segments of the strike-slip fault is clarified, and the number of segments M and the length Hn of different segments are clarified.

5. The method according to claim 3, characterized in that: The step 22 comprises: The planes of different segments are named. The naming principle is determined by the strike of the strike-slip fault. After determining the due north direction of the study area, if the strike-slip fault is NE-striking, the segments are numbered from SW to NE, and the segment number at the SW end of the strike-slip fault is the starting value D1, and the segment number at the NE end of the strike-slip fault is the ending value Dn; if the strike-slip fault is NW-striking, the segments are numbered from SE to NW, and the segment number at the SE end of the strike-slip fault is the starting value D1, and the segment number at the NW end of the strike-slip fault is the ending value Dn; Before calculating the vertical displacement of different segments of the strike-slip fault, the number Sn of vertical displacement statistical data is determined according to the strike and length H of the different segments of the strike-slip fault, wherein Sn is determined by obtaining a suitable step length Ln for different segments of the strike-slip fault; The actual step length L is determined according to the segment length Hn, and the step length is selected as 4*10n times or 8*10n times of the application interval V as the optimal statistical step length. The number Sn of vertical displacement statistical data is determined by the ratio of the segment length Hn to the optimal statistical step length Ln; wherein, After determining the number Sn of vertical displacement statistics, a unified vertical displacement data statistical direction is selected to select and number vertical displacement statistical sections of different segments. The numbering principle is to number the sections from 1 to n in a unified direction; wherein the sections of data statistics are always kept perpendicular to the fault strike; the vertical displacement is calculated by taking the corresponding depth of the active plate of the strike-slip fault in the research layer as the minuend Bn and the corresponding depth of the passive plate as the subtrahend Jn, and the vertical displacement Cn of the corresponding section is obtained by difference; wherein, C n =B n -J n ; According to the determined optimal statistical step size, the vertical displacement data Cn of each profile in the same segment are obtained in turn; in the process of calculating the vertical displacement Cn of the strike-slip fault, the corresponding depth Bn of the active plate is subtracted from the corresponding depth Jn of the passive plate, and there are two cases where the vertical displacement Cn is positive and negative; a positive number indicates that the corresponding burial depth Bn of the active plate is deeper than the corresponding depth Jn of the passive plate; a negative number indicates that the corresponding burial depth Bn of the active plate is shallower than the corresponding depth Jn of the passive plate.

6. The method according to claim 3, characterized in that The step 23 comprises: For the same segment, different sections are numbered from 1 to n, and the horizontal axis is compiled in order from small to large. The vertical displacement Cn is used as the vertical axis. After the plane rectangular coordinate system is established, a line graph of the change in vertical displacement of different segments is drawn.

7. The method according to claim 1, characterized in that The step 3 comprises: Step 31: fitting a vertical displacement change curve based on the vertical displacement change line graphs of different segments; Step 32: Calculate the vertical displacement change rate within the same segment according to the vertical displacement change curve; Step 33: Based on the vertical displacement change rate, the difference in relative intensity of activities at different locations within the same segment of the strike-slip fault is determined. The difference in relative intensity of activities at different locations within the same segment of the strike-slip fault is determined by comparing the vertical displacement change rate Xn of each curve segment.

8. The method according to claim 7, characterized in that In the step 32, After fitting the vertical displacement change curve, by determining the maximum value Zd, minimum value Zx and 0 of the vertical displacement in the vertical displacement change curve, the entire vertical displacement change curve is divided into four sections, namely, the curve segment M1 encircled by the curve endpoint near the maximum value and the maximum value Zd, the curve segment M2 encircled by the maximum value Zd and the 0 value, the curve segment M3 encircled by the 0 value and the minimum value Zx, and the curve segment M4 encircled by the curve endpoint near the minimum value and the minimum value Zx; The slope Xn of the two end points of each curve segment is obtained by using the absolute values ​​of the vertical displacement endpoints ZQ, ZZ, the maximum value Zd, and the minimum value Zx on both sides of the vertical displacement change curve, and the corresponding step lengths LQ, LZ, the maximum value Ld, and the minimum value Lx of the vertical displacement endpoints, which is the vertical displacement change rate of each curve segment; where, 9. The method according to claim 1, characterized in that: The step 4 comprises: Step 41: Based on the vertical displacement change line graph of different segments, calculate the envelope range area Sn of the vertical displacement depth value line of different segments and the X-axis through time-depth conversion; Step 42: Calculate the "length-to-surface ratio Qn" corresponding to different segments according to the length Hn and envelope area Sn of different segments, and determine the relative activity intensity of different segments; specifically, compare the envelope area Sn calculated for different segments with the length Hn of the corresponding segment to obtain the "length-to-surface ratio Qn" of different segments; wherein, The size of the Qn value indicates the degree of stratum fluctuation change per unit length in different segments. The larger the Qn value, the more intense the stratum fluctuation change and the greater the relative activity intensity. Step 43: Based on the "length ratio Qn" calculated for each segment, draw a line graph of "length ratio Qn-different segments of strike-slip faults" to compare and analyze the differences in relative activity intensity of different segments; Specifically, after calculating the "length-to-surface ratio Qn" of each segment of the strike-slip fault, the horizontal axis is compiled in ascending order according to the numbers of the different segments of the strike-slip fault, and the "length-to-surface ratio Qn" of the corresponding segment is used as the vertical axis to establish a plane rectangular coordinate system, and a line graph of "length-to-surface ratio Qn-different segments of strike-slip fault" of different segments is drawn.

10. The method according to claim 9, characterized in that The step 41 comprises: When calculating the envelope area Sn of the vertical displacement line and the X-axis, if the vertical displacement Cn is a positive number, the envelope area Sn of the vertical displacement Cn and the X-axis is directly calculated; if the vertical displacement Cn is a negative number, the absolute value of the vertical displacement Cn is taken and then the envelope area Sn of the vertical displacement Cn and the X-axis is calculated; By consulting the time-depth conversion relationship of the study area, the absolute value of the vertical displacement |Cn| is converted into the corresponding depth value |CSn|, and a line graph of the vertical displacement depth value change is made; When calculating the envelope range area Sn of the vertical displacement depth value broken line and the X-axis, draw a vertical line from each scattered point to the X-axis to cut the envelope range of the vertical displacement depth value broken line and the X-axis into 1 to z single trapezoids; the length of the vertical line is the absolute value of the vertical displacement depth value |Cn|, and after calculating the area Sz of each trapezoid, the envelope range area Sn of the vertical displacement depth value broken line and the X-axis of the corresponding segment is obtained by summing the areas of each trapezoid; S n =S1+…+S z 。

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