A planar representation method based on spatial activity of growth faults

Abstract

The present invention provides a planar characterization method based on the spatial activity of growth faults. The growth index equivalent plane diagram obtained by the characterization method is used to simultaneously display the activity of the faults in different periods on a plane diagram, which can intuitively show the activity strength of the faults in different periods, realize the planar characterization of the spatial activity of the faults, and play a guiding role in studying the structural changes, reservoir development range, and reservoir physical property changes caused by the strength of fault activity.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration and development, and in particular to a planar characterization method based on growth fault spatial activity. Background Art

[0002] Growth faults, also known as synsedimentary faults, refer to faults that develop during the sedimentation process, which occurs simultaneously with the sedimentation of sedimentary rocks. During the formation and development of growth faults, the hanging wall continues to sink, sedimentation continues, and the footwall continues to rise. As the sedimentation time continues, the sedimentary layer thickens and the fault throw increases. Therefore, the sedimentary thickness of the two walls of the fault is inconsistent. The sedimentary thickness of the descending wall is greater than that of the relatively ascending wall, and the height difference increases with depth.

[0003] During the reservoir deposition and accumulation period, the activity of the fault has an impact on regional structural changes, reservoir development range, reservoir physical property changes, and oil and gas migration. For example, the strength of the growth fault activity, the supply of material from the uplifted plate, and the structural characteristics of the downlifted plate can be used to determine the material transportation distance and reservoir development location. For example, when the fault is active, it serves as an oil and gas migration channel; when the fault stops being active, oil and gas accumulation occurs in areas with better lateral conditions on the fault. Therefore, studying fault activity is of great significance for oil and gas exploration.

[0004] Currently, existing technologies provide different methods for analyzing fault activity. Existing methods for quantitatively studying the activity intensity of growth faults reflect the growth and activity of faults to a certain extent. However, their specific applications have their own limitations and cannot comprehensively and accurately provide an intuitive planar representation of the activity intensity of the fault at different periods. This greatly limits the application of fault activity analysis. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a planar characterization method based on growth fault spatial activity that overcomes the above problems or at least partially solves the above problems.

[0006] According to one aspect of the present invention, a planar characterization method based on growth fault spatial activity is provided, the characterization method comprising:

[0007] Step 100: Obtain a sequence stratigraphic framework;

[0008] Step 200: Obtaining the breakpoint location from the seismic profile;

[0009] Step 300: Obtaining the spatial distribution surface of the fault;

[0010] Step 400: Obtaining a fault plane distribution map;

[0011] Step 500: extracting sampling profile lines;

[0012] Step 600: Obtaining fault polygons of each layer;

[0013] Step 700: Calculate the stratum thickness value of each layer in the seismic section corresponding to the sampling section line;

[0014] Step 800: Calculate the growth index of a certain layer segment in a certain sampling profile;

[0015] Step 900: defining the growth index of a growth fault in a certain layer in the same sampling profile as the growth index scatter value of the intersection of the fault line in the layer and the sampling profile in the sampling profile;

[0016] Step 1000: repeat steps 600-900 for the remaining layers, and define the growth index scatter values ​​of the intersection points of the fault lines and the sampling profile lines of all layers in the fault plane diagram;

[0017] Step 1100: Draw a growth index isovalue plane map according to the growth index values ​​defined in the fault plane map.

[0018] Optionally, the step 100 of obtaining a sequence stratigraphic framework specifically includes: constructing a sequence stratigraphic framework within the target interval by using fine structural interpretation of 3D seismic data and identification of sequence interfaces.

[0019] Optionally, the step 200 of obtaining the breakpoint location from the seismic profile specifically includes:

[0020] The breakpoint location is determined by the event interruption of the standard horizon in the time slice;

[0021] Assume T i,j (x, y) is the coordinate of a point on the standard horizon, where x and y are geodetic coordinates, and T is the time at (x, y);

[0022] i and j represent the vertical and horizontal line numbers of the standard layer respectively. The horizontal line number remains unchanged. When slicing along the time of the standard layer, let T i+1,j (x,y)-T i,j When (x,y)>t, it means that the common-phase axis is interrupted, which can be recorded as T i+1,j (x,y) is the breakpoint position;

[0023] Where t is a threshold value, and by analogy, the coordinates of the breakpoints at all vertical and horizontal lines are determined.

[0024] Optionally, the step 300 of obtaining the spatial distribution surface of the fault specifically includes:

[0025] Interpolate and fit the breakpoints on each standard layer into a spatial curve;

[0026] A three-dimensional space interpolation method is used to interpolate curves on multiple standard layers to obtain a space surface, where the space surface is a cross section.

[0027] Optionally, interpolating and fitting the breakpoints on each standard layer into a spatial curve specifically includes:

[0028] When interpolating into a curve based on breakpoints, the spline interpolation method is used;

[0029] The basic principle of spline interpolation is: assuming that n+1 points are given, x1 <x2<x3……<x n , the corresponding values ​​are y1, y2, y3..., y n , where (x i ,y i ) represents the coordinates of each breakpoint;

[0030] Determine a curve function y=b(x) with n-th order continuous first-order derivatives, connect all points, and fit to obtain a spatial curve.

[0031] Optionally, the method of interpolating the curves on multiple standard layers using a three-dimensional space interpolation method to obtain a spatial surface, wherein the spatial surface is a cross section, specifically includes: fitting all curves using an inverse distance weighted method to obtain a surface.

[0032] Optionally, the step 600 of obtaining the fault polygons of each layer specifically includes:

[0033] Extract the intersection points of the target fault section and each layer from the seismic section;

[0034] projecting the intersection point into a plane;

[0035] Connect all the intersection points of the same layer and the cross section into a line, which is the fault line of the layer;

[0036] The line that defines the intersection point of the downthrown plate stratum and the section is called the downthrown plate line, and the line that defines the intersection point of the upthrown plate stratum and the section is called the upthrown plate line. The combination of the downthrown plate line and the upthrown plate line is called the fault polygon.

[0037] Optionally, the step 700 of calculating the stratum thickness value of each layer in the seismic section corresponding to the sampling section line specifically includes:

[0038] If the seismic profile is a depth profile, in the seismic profile corresponding to the sampling profile line, extract the depth values ​​at the intersection of the bottom surface, top surface and cross section respectively, and subtract them to obtain the thickness value of the layer at a certain plate;

[0039] If the seismic profile is a time profile, extract the time values ​​at the intersection of the bottom and top of the stratum with the section in the seismic profile corresponding to the sampling profile line.

[0040] According to the time-depth relationship measured by actual drilling, the depth value is calculated, and finally the thickness value of the layer in a certain plate is obtained by subtracting it.

[0041] Optionally, the step 800: calculating the growth index of a layer segment in a sampling profile line specifically includes: calculating the growth index of a growth fault on the sampling profile line as the ratio of the thickness of the downthrown layer to the thickness of the upthrown layer in the same layer segment in the sampling profile line.

[0042] Optionally, the step 900: defines the growth index of a growth fault in a certain layer in the same sampling profile as the growth index scatter value of the intersection of the fault line of the layer in the sampling profile and the sampling profile.

[0043] The present invention provides a planar characterization method based on the spatial activity of growth faults. The method comprises: obtaining a sequence stratigraphic framework; obtaining breakpoint locations from a seismic profile; obtaining a spatial distribution surface of the fault; obtaining a fault planar distribution diagram; extracting sampling profile lines; obtaining fault polygons for each layer; calculating the stratigraphic thickness values ​​of each layer segment in the seismic profile corresponding to the sampling profile line; calculating the growth index of a layer segment in a sampling profile line; defining the growth index of a growth fault in a layer segment in the same sampling profile line as the growth index scatter point value at the intersection of the fault line and the sampling profile line in the layer segment in the sampling profile; repeating steps 600-900 for the remaining layers to define the growth index scatter point values ​​at the intersection of the fault line and the sampling profile line in all layers in the fault plan diagram; and drawing a growth index isovalue plan diagram based on the growth index values ​​defined in the fault plan diagram. The method simultaneously displays the fault activity of different depositional periods in time and the fault activity of different regions in space.

[0044] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 A flow chart of a planar characterization method based on growth fault spatial activity provided by an embodiment of the present invention;

[0047] Figure 2 It is a sequence stratigraphic framework and cross-section diagram provided by an embodiment of the present invention;

[0048] Figure 3 This is a planar distribution diagram of the Shengbei fault provided by an embodiment of the present invention;

[0049] Figure 4 is a schematic diagram of setting a sampling profile line according to an embodiment of the present invention;

[0050] Figure 5 It is a schematic diagram of the intersection of the fault section and each layer in the stratigraphic framework provided by an embodiment of the present invention;

[0051] Figure 6 A polygonal display diagram of the faults at each layer provided by an embodiment of the present invention;

[0052] Figure 7 The sampling point provided for the embodiment of the present invention is the intersection of the bottom surface of the downthrown plate stratum and the cross section;

[0053] Figure 8 This is a Shengbei fault growth index map provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0054] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0055] The terms "comprises" and "comprising" and any variations thereof in the description, embodiments, claims and drawings of the present invention are intended to cover non-exclusive inclusions, for example, including a series of steps or units.

[0056] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0057] like Figure 1 As shown, a planar characterization method based on growth fault spatial activity specifically includes the following steps:

[0058] Step 01: Obtain the sequence stratigraphic framework.

[0059] In step 01, the sequence stratigraphic framework within the target interval is generally constructed using the fine structural interpretation of 3D seismic data and the identification of sequence interfaces, such as Figure 2 shown.

[0060] Step 02, obtain the breakpoint location from the seismic profile.

[0061] In step 02, the breakpoint position is determined by the phase axis interruption of the standard layer in the time slice. Specific implementation method: Assume T i,j (x, y) is the coordinate of a point on the standard layer, where x and y are geodetic coordinates, and T is the time at (x, y). i and j represent the vertical and horizontal line numbers of the standard layer, respectively. The horizontal line number remains unchanged (j remains unchanged). When slicing along the time of the standard layer: Let T i+1,j (x,y)-T i,j When (x,y)>t, it means that the common-phase axis is interrupted, which can be recorded as T i+1,j (x, y) is the breakpoint location; t is a threshold value, usually set to 30ms. Similarly, the breakpoint coordinates of all vertical and horizontal lines can be determined.

[0062] Step 03: Obtain the spatial distribution surface of the fault. First, interpolate and fit the breakpoints on each standard layer obtained in step 02 into a spatial curve. Then, use the three-dimensional spatial interpolation method to interpolate the curves on multiple standard layers to obtain a spatial surface. This surface is the cross section.

[0063] In step 03, when interpolating the breakpoints into a curve, the spline interpolation method can be used. The basic principle of spline interpolation is: assuming that n+1 points are given, x1 <x2<x3……<x n , the corresponding values ​​are y1, y2, y3..., y n , where (x i ,y i ) represents the coordinates of each breakpoint. These points determine a curve function y = b(x) with n-th order continuous first-order derivatives. By connecting all the points, we can get a curve.

[0064] In step 03, all curves are fitted using the inverse distance weighted method to obtain a surface, which is the cross section. Figure 2 shown.

[0065] Step 4: Obtain the fault plane distribution map. The cross section is presented on the plane according to the equal depth value, which is the growth fault plane distribution map. Figure 3 shown.

[0066] Step 05: Extract sampling profile lines. Define one end of the target growth fault as the starting end on the growth fault plane distribution map, and extract sampling profile lines perpendicular to the fault direction starting from the starting end along the fault direction.

[0067] In step 05, the sampling profiles can be sampled at equal intervals or at unequal intervals according to the complexity of the fracture, such as Figure 4 shown.

[0068] Step 06: Obtain the fault polygon for each horizon. On the sampling profile line extracted in Step 05, using the sequence stratigraphic framework obtained in Step 01 and the intersection points of the cross section obtained in Step 03, a line is connected to form all the intersection points between the same horizon and the cross section, which is the fault line for that horizon, also known as the fault polygon.

[0069] Step 601: extract the intersection points of the target fault section and each layer from the seismic section, such as Figure 5 shown.

[0070] Step 602: Project the intersection point onto a plane.

[0071] Step 603: connect all intersection points of the same layer and the cross section to form a line, which is the fault line of the layer.

[0072] Step 604: define the line connecting the intersection of the descending stratum and the cross section as the descending line, and the line connecting the intersection of the ascending stratum and the cross section as the ascending line. The combination of the descending line and the ascending line is called the fault polygon. Figure 6 shown.

[0073] Step 07, calculate the stratum thickness value of each layer segment in the seismic section corresponding to the sampling section line.

[0074] In step 07, if the seismic profile is a depth profile, the depth values ​​at the intersection of the bottom and top surfaces of the stratum with the section are extracted in the seismic profile corresponding to the sampling section line, and the thickness value of the layer at a certain level is obtained by subtracting them.

[0075] In step 07, if the seismic profile is a time profile, then in the seismic profile corresponding to the sampling profile line, the time values ​​at the intersection of the bottom and top of the formation with the section are extracted respectively. Then, according to the time-depth relationship measured by actual drilling, the depth value is calculated, and finally the thickness value of the layer at a certain plate is obtained by subtracting them.

[0076] Step 08: Calculate the growth index of a certain layer segment in a certain sampling profile line.

[0077] In step 08, the growth index of a growth fault on a certain sampling section line is the ratio of the thickness of the downthrown stratum to the thickness of the upthrown stratum in the same layer segment of the sampling section line.

[0078] Step 09: Define the growth index scatter value of the sampling point in the target growth fault plane. The growth index of a growth fault in a layer in the same sampling profile is defined as the growth index scatter value of the intersection of the fault line and the sampling profile in the layer in the sampling profile.

[0079] In step 09, the sampling point is the intersection of the fault line and the sampling profile line, or the intersection of the bottom surface of the downthrown plate stratum and the cross section, or the intersection of the top surface of the downthrown plate stratum and the cross section, or the intersection of the bottom surface of the upthrown plate stratum and the cross section, or the intersection of the top surface of the upthrown plate stratum and the cross section, but it is required to be consistent. That is, if the growth index value of a certain layer segment calculated previously is defined as the growth index scatter value at the intersection of the bottom surface of the downthrown plate stratum and the cross section, then the growth index of all subsequent layers must be defined as the growth index scatter value at the intersection of the bottom surface of the downthrown plate stratum and the cross section. In this way, the standardization of the overall sampling point position can be guaranteed. For example Figure 7 shown.

[0080] Step 10: Repeat steps 06-09 for other layers to define the growth index scatter values ​​of the intersection points of the fault lines and sampling profile lines of all layers in the fault plane diagram.

[0081] Step 11: Draw a growth index isovalue plane map according to the growth index value defined in the target growth fault plane map, such as Figure 8 shown.

[0082] Beneficial effect: The growth index isovalue plane map obtained through the above steps can simultaneously display the fault activity in different depositional periods in time and the fault activity in different regions in space. Vertically, the fault in the embodiment began to be active during the deposition of segment 2, but the activity range was relatively small and not intense. From the end of the deposition of segment 3, the fault in the embodiment began to be active continuously and intensely. During the deposition of segments 5 and 6, the activity of the fault in the embodiment reached its peak, and then the activity weakened until it stabilized. Horizontally, from west to east, the degree of activity of the fault in different regions in each period was also different, which can all be well displayed on the plane map. The planar representation of the spatial activity of the fault is achieved, which plays a guiding role in studying the structural changes, reservoir development range, and reservoir physical property changes caused by the strength of the fault activity.

[0083] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A planar characterization method based on growth fault spatial activity, characterized in that: The characterization method includes: Step 100: Obtain a sequence stratigraphic framework; Step 200: Obtaining the breakpoint location from the seismic profile; Step 300: Obtaining a spatial distribution surface of the fault, including: Interpolate and fit the breakpoints on each standard layer into a spatial curve; Using a three-dimensional space interpolation method, the curves on multiple standard layers are interpolated to obtain a space surface, where the space surface is a cross section; Step 400: Obtain a fault plane distribution diagram, and present the cross section on a plane according to the equal depth values ​​as a growth fault plane distribution diagram; Step 500: extracting sampling profile lines; Step 600: Obtaining fault polygons of each layer; Step 700: Calculate the stratum thickness value of each layer in the seismic section corresponding to the sampling section line; Step 800: Calculating the growth index of a layer segment in a sampling profile, including: The growth index of a growth fault on a sampling profile is calculated as the ratio of the thickness of the downthrown strata to the thickness of the upthrown strata in the same layer segment of the sampling profile. Step 900: defining the growth index of a growth fault in a certain layer in the same sampling profile as the growth index scatter value of the intersection of the layer fault line and the sampling profile in the sampling profile; Step 1000: repeat steps 600-900 for the remaining layers, and define the growth index scatter values ​​of the intersection points of the fault lines and the sampling profile lines of all layers in the fault plane diagram; Step 1100: Draw a growth index isovalue plane map according to the growth index values ​​defined in the fault plane map.

2. A planar characterization method based on growth fault space activity according to claim 1, characterized in that: The step 100 of obtaining a sequence stratigraphic framework specifically includes: constructing a sequence stratigraphic framework within the target interval by using fine structural interpretation of 3D seismic data and identification of sequence interfaces.

3. The planar characterization method based on growth fault space activity according to claim 1, characterized in that: The step 200 of obtaining the breakpoint location from the seismic profile specifically includes: The breakpoint location is determined by the event interruption of the standard horizon in the time slice; Assume T i,j (x, y) is the coordinate of a point on the standard horizon, where x and y are geodetic coordinates, and T is the time at (x, y); i and j represent the vertical and horizontal line numbers of the standard layer respectively. The horizontal line number remains unchanged. When slicing along the time of the standard layer, let T i+1,j (x,y)-T i,j When (x,y)>t, it means that the common-phase axis is interrupted, which can be recorded as T i+1,j (x,y) is the breakpoint position; Where t is a threshold value, and by analogy, the coordinates of the breakpoints at all vertical and horizontal lines are determined.

4. The method for plane characterization based on growth fault space activity according to claim 1, characterized in that: The interpolation fitting of the breakpoints on each standard layer into a spatial curve specifically includes: When interpolating into a curve based on breakpoints, the spline interpolation method is used; The basic principle of spline interpolation is: assuming that n+1 points are given, x1 <x2<x3……<x n , the corresponding values ​​are y1, y2, y3..., y n , where (x i ,y i ) represents the coordinates of each breakpoint; Determine a curve function y=b(x) with n-th order continuous first-order derivatives, connect all points, and fit to obtain a spatial curve.

5. The method for plane characterization based on growth fault space activity according to claim 4, characterized in that: The method of interpolating the curves on multiple standard layers using a three-dimensional space interpolation method to obtain a space surface, wherein the space surface is a cross section, specifically includes: fitting all curves using an inverse distance weighted method to obtain a surface.

6. The method for plane characterization based on growth fault space activity according to claim 1, characterized in that: The step 600 of obtaining the fault polygons of each layer specifically includes: Extract the intersection points of the target fault section and each layer from the seismic section; projecting the intersection point into a plane; Connect all the intersection points of the same layer and the cross section into a line, which is the fault line of the layer; The line that defines the intersection point of the downthrown plate stratum and the section is called the downthrown plate line, and the line that defines the intersection point of the upthrown plate stratum and the section is called the upthrown plate line. The combination of the downthrown plate line and the upthrown plate line is called the fault polygon.

7. The method for plane characterization based on growth fault space activity according to claim 1, characterized in that: The step 700 of calculating the stratum thickness value of each layer in the seismic section corresponding to the sampling section line specifically includes: If the seismic profile is a depth profile, in the seismic profile corresponding to the sampling profile line, extract the depth values ​​at the intersection of the bottom surface, top surface and cross section respectively, and subtract them to obtain the thickness value of the layer at a certain plate; If the seismic profile is a time profile, extract the time values ​​at the intersection of the bottom and top of the stratum with the section in the seismic profile corresponding to the sampling profile line. According to the time-depth relationship measured by actual drilling, the depth value is calculated, and finally the thickness value of the layer in a certain plate is obtained by subtracting it.

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