Method for identifying hidden reverse fault of raised abrupt slope zone of broken basin

Abstract

The invention relates to the technical field of oil exploration, and discloses a method for identifying a hidden reverse fault of a raised abrupt slope zone of a broken basin, which comprises the following steps of: 1, spatially rotating a seismic section in the raised abrupt slope zone of the broken basin, scanning the section to identify a breakpoint and a section wave, and determining the position of the fault; 2, determining the speed difference between the hanging wall and the footwall of the convex abrupt slope zone fault, correcting the section depth error of the fault, and recovering the real occurrence of the ancient section and the inner curtain thereof; 3, determining the fault as a reverse fault according to the rising of the hanging wall of the fault relative to the footwall; and a fourth step of repeating the first step to the third step on the plurality of seismic sections until the distribution range and occurrence of the reverse fault are determined. According to the method, the reverse fault is identified in the raised abrupt slope zone of the broken basin, and the technical limitation that the reverse fault cannot be identified in the raised abrupt slope zone of the broken basin in the prior art is overcome. Breakpoints and section waves are identified through section scanning of the spatial rotation seismic section, and the speed difference of the upper wall and the lower wall of the fault is analyzed, so that the accuracy and the reliability of identification of the hidden reverse fault are improved.

Description

Technical Field

[0001] The present invention generally relates to the field of oil exploration technology. More specifically, the present invention relates to a method for identifying hidden reverse faults in a bulge steep slope zone of a fault basin. Background Art

[0002] The paleo-uplift steep slope zone at the edge of the fault basin is an area with frequent crustal movement and frequent tectonic fault activities. The identification of hidden reverse faults is of great significance for the prevention of natural disasters, mineral resource development, and geological engineering. However, the geological structure of this area is complex, and the traditional geological understanding is mainly based on the normal fault structure style. Reverse faults are difficult to identify due to technical limitations.

[0003] The existing technology generally believes that there are no reverse faults in the uplifted steep slope zone of the fault basin, and extension and slip are the genesis type of the basin. In this type, tensile stress and shear stress are dominant, and the compressive stress is relatively small. According to conventional knowledge, it is difficult to form reverse faults when the compressive stress is small. The genesis type of reverse faults is compression. Based on the above cognition, it is judged that there should be no reverse faults in the fault basin in the extension and slip stage.

[0004] Existing reverse fault identification technologies are often limited by the signal-to-noise ratio, resolution, and imaging and interpretation methods of seismic data. The breakpoints of bedrock reverse faults are unclear, and the top surface of the hanging plate is eroded, so the breakpoints of the bedrock top surface are unclear. It is difficult to identify multiple breakpoints, and it is impossible to accurately identify reverse faults and their specific locations, which affects oil and gas exploration and development in complex steep slopes. Summary of the invention

[0005] In order to at least solve one or more of the technical problems mentioned above, an embodiment of the present invention provides a method for identifying hidden reverse faults in a bulge steep slope zone of a fault basin, comprising: a first step, rotating a seismic profile in the bulge steep slope zone of the fault basin, identifying breakpoints and cross-section waves by cross-section scanning, and determining the position of the fault; a second step, determining the velocity difference between the upper plate and the lower plate of the fault in the bulge steep slope zone, correcting the cross-section depth error of the fault, and restoring the true attitude of the ancient cross-section and its interior; a third step, determining that the fault is a reverse fault based on the rise of the upper plate of the fault relative to the lower plate; and a fourth step, repeating the first step to the third step on multiple seismic profiles until the distribution range and attitude of the reverse fault are determined.

[0006] According to one embodiment of the present invention, in the first step, the scanning interval between adjacent seismic sections is 1 to 30°.

[0007] According to one embodiment of the present invention, the scanning interval between adjacent seismic sections is 5° or 10°.

[0008] According to one embodiment of the present invention, the first step includes: determining the direction of the section according to the spatial continuity relationship between the breakpoints and the section waves on the seismic section.

[0009] According to one embodiment of the present invention, the first step includes: connecting the breakpoints identified on the seismic section and the discontinuously distributed fault waves to form a dividing line on the seismic section and determine the section of the fault.

[0010] According to one embodiment of the present invention, the discontinuity point of the seismic reflection axis is determined as the discontinuity point on the seismic section.

[0011] According to one embodiment of the present invention, in the third step, the chronological horizons of the hanging wall and the footwall are calibrated, and the relationship between the hanging wall and the footwall is determined based on the chronological horizons.

[0012] According to one embodiment of the present invention, a three-dimensional interpretation data volume of the reverse fault is constructed based on the distribution range and occurrence of the reverse fault.

[0013] According to another aspect of the present invention, there is provided a device for identifying hidden reverse faults in uplifted steep slope zones of fault basins, comprising: a processor for executing program instructions; and a memory storing program instructions, wherein when the program instructions are loaded and executed by the processor, the processor executes the aforementioned method.

[0014] According to another aspect of the present invention, a non-volatile computer-readable storage medium is provided, on which computer-readable instructions are stored. When the computer-readable instructions are executed by one or more processors, the aforementioned method is implemented.

[0015] In the present invention, reverse faults are identified in the uplifted steep slope zone of the fault basin, thus overcoming the problem that the prior art cannot identify reverse faults in the uplifted steep slope zone of the fault basin.

[0016] In the present invention, by spatially rotating the seismic profile cross-sectional scanning, it is possible to identify inconspicuous breakpoints and cross-sectional waves, thereby improving the accuracy and reliability of the identification of hidden reverse faults. By setting multiple rotation axes, the accuracy of identification can be further improved. By setting the scanning interval between adjacent seismic profiles to 1-30 degrees, the amount of scanned data can be controlled as needed, taking into account both the identification accuracy and the identification efficiency.

[0017] In the present invention, the velocity difference between the upper and lower walls of the steep slope zone is determined according to the fault, the depth error of the steep slope zone section and its interior is corrected, and the true occurrence of the ancient section and its interior is restored, which can improve the accuracy of identifying the fault properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0019] Figure 1 A schematic diagram of a three-dimensional seismic survey system is shown;

[0020] Figure 2 A schematic diagram showing the steps of a method for identifying hidden reverse faults in a bulge scarp zone of a fault basin;

[0021] Figure 3 A schematic diagram of a selected seismic section is shown;

[0022] Figure 4 A schematic diagram of a seismic profile is shown. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0024] It should be understood that the terms "include" and "comprising" used in the description and claims of the present invention indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0025] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the claims, the singular forms of "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in the specification of the present invention and the claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0026] As used in this specification and claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0027] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] Figure 1 A schematic diagram of a three-dimensional seismic survey system is shown.

[0029] like Figure 1 As shown, in the system 100, a plurality of mutually spaced detectors 110 for detecting seismic waves are arranged on the surface 101 of the exploration target area, forming a detector array covering the target area on a plane. These detectors 110 are connected to the seismic information processing device by wired or wireless connection, and a plurality of seismic sources 120 are also provided. The seismic information processing device can perform preliminary processing on the seismic data. The working process of the three-dimensional seismic exploration system is: artificially excite the seismic sources 120 located at multiple positions to generate seismic waves, which are reflected from the boundary of the stratum 102 and received by the detector array to form seismic information collected on a plane and changing with time. The seismic information received by the detector array represents certain measures of seismic wave energy as a function of time, such as displacement, velocity, wave impedance, pressure, etc. This information can be grouped in different ways, such as traces, sets, etc., and then processed or format-converted according to the corresponding relationship between time and space to form a three-dimensional seismic data body in the form of a three-dimensional array. It can also be said that the three-dimensional seismic data body is formed by stacking interface points in space. The interpretation of three-dimensional seismic data can observe the morphology of geological interfaces from different directions and study the changes of geological bodies in three-dimensional space by cutting cross sections, longitudinal sections and horizontal slices.

[0030] In the stratigraphic model, the stratigraphic layer 102 includes faults. Faults refer to the phenomenon that the stratigraphic layer undergoes relative displacement along the fracture surface and are a byproduct of tectonic activity. Faults play a very important role in controlling the migration, accumulation or destruction of oil and gas, and are closely related to the formation, distribution and enrichment of oil and gas reservoirs, and are important migration channels.

[0031] Figure 2 A schematic diagram showing the steps of a method for identifying hidden reverse faults in the uplift steep slope zone of a fault basin.

[0032] like Figure 2As shown, the method 200 for identifying hidden reverse faults in the uplift steep slope zone of the fault basin comprises: a first step S201, rotating the seismic profile in the uplift steep slope zone of the fault basin, identifying the breakpoints and the cross-section waves by cross-section scanning, and determining the fault position; a second step S202, determining the velocity difference between the upper wall and the lower wall of the fault in the uplift steep slope zone, correcting the cross-section depth error of the fault, and restoring the true attitude of the ancient cross-section and its interior; a third step S203, determining that the fault is a reverse fault based on the rise of the upper wall of the fault relative to the lower wall; and a fourth step S204, repeating the first step to the third step on multiple seismic profiles until the distribution range and attitude of the reverse fault are determined.

[0033] In the uplifted steep slope zone of the fault basin, the existing technology generally believes that there are no reverse faults. This technical bias has led to people not identifying reverse faults in this type of area. Moreover, even if seismic data in this area is obtained, the breakpoints of the bedrock reverse faults are unclear, and the top surface of the hanging plate is eroded, the breakpoints of the bedrock top surface are unclear, resulting in the inability to accurately identify the reverse faults and their specific locations. This also leads to the lack of records of identifying hidden reverse faults in the uplifted steep slope zone of the fault basin in the existing technology.

[0034] In the present invention, according to Figure 1 The method shown is used to obtain seismic geological data of the uplifted steep slope zone of the fault basin, including seismic pre-stack data, seismic profiles, stratigraphic distribution, structural characteristics and other information. The obtained data is pre-processed, including: signal enhancement processing, steep slope zone velocity scanning, pre-stack multi-angle stack imaging. Using the seismic pre-stack time-varying velocity scanning imaging technology, reliable seismic imaging velocity in the steep slope zone is obtained, forming multi-angle seismic imaging data of the steep slope zone, and constructing a high-definition three-dimensional seismic data volume of the uplifted steep slope zone of the fault basin.

[0035] In the first step S201, a rotation axis is set on the obtained three-dimensional seismic data volume, and the data is rotated spatially along the same rotation axis. The seismic sections are selected as a group, and the breakpoints and the cross-section waves are identified on the same group of seismic sections. The breakpoints and cross-section waves are both responses of the fault plane on the seismic data, but the characteristics of the two are different. The breakpoints highlight the discontinuity characteristics of the strata on both sides of the fault plane, and are generally developed in the shallow and medium strata with steep cross sections, while the cross-section waves highlight the differences in lithology and wave impedance above and below the fault plane, and are usually developed in the medium and deep environment with gentle cross sections.

[0036] Figure 3 A schematic diagram of the selected seismic profile is shown.

[0037] like Figure 3 As shown, a rotation axis S is set in the three-dimensional seismic data volume, and the seismic section 301 and the seismic section 302 are rotated and selected with the axis S as the center, and the breakpoints and the fault waves are identified on the seismic sections respectively.

[0038] The position of the rotation axis S can be adjusted according to the identification results of the hidden reverse fault, or multiple rotation axes can be set, and the identification results of the seismic profiles selected at the positions of each rotation axis can be comprehensively considered. Spatial rotation refers to rotation in three-dimensional space, and in the present invention, rotation along the rotation axis extending in the depth direction is preferred.

[0039] Preferably, under the same rotation axis, the scanning interval between adjacent seismic sections is 1 to 30°. More preferably, the scanning interval between adjacent seismic sections is 5° or 10°.

[0040] In the present invention, by rotating the seismic profile in space and scanning the cross section to identify the breakpoints and cross section waves, as much cross section information as possible can be obtained in the uplift steep slope zone of the fault basin where the reverse fault characteristics are relatively hidden, thereby improving the sensitivity of identification and effectively identifying the reverse fault. Cross section scanning refers to taking seismic profiles at multiple angles of seismic data and comprehensively identifying geological and structural information from multiple seismic profiles.

[0041] Figure 4 A schematic diagram of a seismic profile is shown.

[0042] like Figure 4 As shown in Figure 1, there are breakpoints and cross-section waves that continue in space. a represents the cross section formed by the connection of the breakpoint and cross-section waves, B represents the hanging wall, and C represents the footwall.

[0043] In the first step S201, the direction of the section is determined according to the spatial continuation relationship between the breakpoint and the section wave. The breakpoint and the section wave are both the basic basis for identifying the fault. By identifying whether there is a spatial continuation relationship between the breakpoint and the section wave, the breakpoints and section waves with the continuation relationship can be classified, and the position and direction of the section can be basically determined. The spatial continuation relationship means that the breakpoint existing in the direction of the section wave has a continuation relationship with the section wave.

[0044] Preferably, the first step further comprises: connecting the identified breakpoints and discontinuously distributed fault waves to determine the position of the fault section. The occurrence of the fault section can be depicted by connecting the breakpoints and fault waves with a continuous relationship through interpolation.

[0045] In the second step S202, the structure of the fault is corrected by velocity difference. Specifically, the depth error of the section is adjusted so that the section is close to the actual occurrence of the ancient section and its interior, so as to determine the relationship between the upper wall and the lower wall of the fault based on this.

[0046] In the third step S203, the relative motion relationship between the hanging plate and the footwall is identified based on the identification of the section. In the process of identifying the relative relationship between the hanging plate and the footwall, various parameters such as velocity characteristics, energy characteristics, frequency characteristics or structural characteristics can be used for identification. For example, it is identified that the speed of the hanging plate is higher than that of the footwall, the energy of the hanging plate is higher than that of the footwall, the frequency of the hanging plate is low and the frequency of the footwall is high. According to the overall seismic reflection characteristics of the hanging plate and the footwall on the section and the relative movement direction of the local marker layer, in accordance with the principle that the relative rise of the hanging plate relative to the footwall belongs to the reverse fault, it is determined that the hanging plate and the footwall belong to the reverse fault.

[0047] Preferably, the third step S203 further includes calibrating the chronological horizons of the upper plate and the lower plate, and determining the relative relationship between the upper plate and the lower plate.

[0048] In the fourth step S204, when it is determined that a reverse fault exists on a certain seismic section, other seismic sections in the same group as the seismic section can be selected to identify the reverse fault. Seismic sections in different groups from the seismic section can also be selected to identify the same reverse fault, and the identification results are combined to obtain the distribution range and occurrence of the reverse fault.

[0049] In order to present the complete reverse fault, a three-dimensional interpretation data volume of the reverse fault can be constructed according to the distribution range and occurrence of the reverse fault.

[0050] According to another aspect of the present invention, there is provided an apparatus for identifying hidden reverse faults in uplifted steep slope zones of fault basins, comprising: a processor for executing program instructions; and a memory storing program instructions, wherein when the program instructions are loaded and executed by the processor, the processor executes the aforementioned method.

[0051] According to another aspect of the present invention, a non-volatile computer-readable storage medium is provided, on which computer-readable instructions are stored, and when the computer-readable instructions are executed by one or more processors, the aforementioned method is implemented. The computer-readable storage medium can be any suitable magnetic storage medium or magneto-optical storage medium, such as resistive random access memory RRAM (Resistive Random Access Memory), dynamic random access memory DRAM (Dynamic Random Access Memory), static random access memory SRAM (Static Random-Access Memory), enhanced dynamic random access memory EDRAM (Enhanced Dynamic Random Access Memory), high-bandwidth memory HBM (High-Bandwidth Memory), hybrid memory cube HMC (Hybrid Memory Cube), etc., or any other medium that can be used to store the required information and can be accessed by an application, a module, or both. Any such computer storage medium can be part of a device or accessible or connectable to a device. Any application or module described in the present invention can be implemented using computer-readable / executable instructions that can be stored or otherwise maintained by such a computer-readable medium.

[0052] In the present invention, reverse faults are identified in the uplifted steep slope zone of the fault basin, which overcomes the technical prejudice in the prior art that there are no reverse faults in the uplifted steep slope zone of the fault basin. By scanning and identifying the spatially rotating seismic profile, it is possible to identify inconspicuous breakpoints and fracture waves, thereby improving the accuracy and reliability of the identification of hidden reverse faults. By setting multiple rotation axes, the accuracy of identification can be further improved. By setting the scanning interval between adjacent seismic profiles to 1-30 degrees, the amount of scanned data can be controlled as needed, taking into account both the identification accuracy and the identification efficiency. By constructing a three-dimensional interpretation data body of the reverse fault, the identification results can be presented intuitively.

[0053] In the present invention, the velocity difference between the upper and lower walls of the steep slope zone is determined according to the fault, the depth error of the inner section of the steep slope zone is corrected, and the true occurrence of the ancient section and its inner section is restored, so as to improve the accuracy of identifying the fault properties.

[0054] Although multiple embodiments of the present invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art may conceive of many changes, modifications, and alternatives without departing from the thought and spirit of the present invention. It should be understood that in the process of practicing the present invention, various alternatives to the embodiments of the present invention described herein may be adopted. The appended claims are intended to define the scope of protection of the present invention, and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A method for identifying hidden reverse faults in the uplift steep slope zone of a fault basin, characterized in that: include: The first step is to rotate the seismic profile in the uplift steep slope zone of the fault basin, identify the fault points and fault waves through cross-section scanning, and determine the fault location; The second step is to determine the velocity difference between the upper wall and the lower wall of the fault in the uplift steep slope zone, correct the section depth error of the fault, and restore the true occurrence of the ancient section and its interior; The third step is to determine that the fault is a reverse fault based on the rise of the hanging wall relative to the footwall of the fault; The fourth step is to repeat the first step to the third step on multiple seismic sections until the distribution range and attitude of the reverse fault are determined.

2. The method according to claim 1, characterized in that In the first step, the scanning interval between adjacent seismic sections is 1 to 30 degrees.

3. The method according to claim 2, characterized in that The scanning interval between adjacent seismic sections is 5° or 10°.

4. The method according to claim 1, characterized in that: The first step includes: determining the direction of the section according to the spatial continuity relationship between the breakpoint and the section wave.

5. The method according to claim 1, characterized in that The first step includes: connecting the identified breakpoints and the discontinuously distributed fault waves to determine the section of the fault.

6. The method according to claim 1, characterized in that In the third step, the relative relationship between the hanging wall and the footwall is determined by calibrating the chronological horizons of the hanging wall and the footwall.

7. The method according to claim 1, characterized in that Also includes, According to the distribution range and occurrence of the reverse fault, a three-dimensional interpretation data volume of the reverse fault is constructed.

8. A device for identifying hidden reverse faults in the uplift steep slope zone of a fault basin, characterized in that: include: a processor for executing program instructions; and a memory storing program instructions, which, when loaded and executed by a processor, enables the processor to execute the method according to any one of claims 1 to 7.

9. A non-volatile computer-readable storage medium, characterized in that: Computer-readable instructions are stored thereon, and when the computer-readable instructions are executed by one or more processors, the method according to any one of claims 1 to 7 is implemented.

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