Method and device for identifying normal fault of extrusion basin

Abstract

The invention discloses an extrusion type basin normal fault identification method and device, and the method comprises the steps: building a spatial distribution pattern of a regional reverse fault based on a three-dimensional seismic data body after the inner horizon calibration of an extrusion type basin, and enabling the spatial distribution pattern to be used for determining the main trend of the regional reverse fault; the method comprises the following steps: under the background that an extrusion basin is in a compressive-torsional stress field, carrying out stress decomposition on the maximum principal compressive stress of a region to obtain a tensile stress component parallel to a main trend, and taking the tensile stress component as an optimal direction for normal fault identification; in the three-dimensional seismic data volume after horizon calibration, selecting an initial seismic section of which the orientation is parallel to a preferred direction, and executing small-interval translation scanning and / or small-angle rotation scanning on the initial seismic section to generate a series of scanning sections; and positioning the target position of the fault on a series of scanning profiles, and judging whether the hanging wall stratum moves downwards relative to the footwall stratum or not at the target position, and if so, identifying the fault as a normal fault. According to the invention, the normal fault of the extrusion basin can be accurately identified.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration technology, and in particular to a method and apparatus for identifying normal faults in compression basins. Background Technology

[0002] As active tectonic zones at plate boundaries, compressional basins require accurate identification of normal faults for geological hazard early warning, energy exploration and development, and site selection for major engineering projects. Traditional geological theory suggests that under compressional-shear combined stress fields, these basins primarily develop thrust faults, with normal faults being largely absent. However, recent studies have revealed that under compressive-torsional stress fields, tensile stress components can be generated locally within the basin, forming normal faults highly favorable for hydrocarbon migration. These normal faults, because they tend to remain open during active periods, can serve as dominant channels for vertical hydrocarbon migration, controlling hydrocarbon accumulation.

[0003] However, existing technologies have at least the following drawbacks when identifying faults in compressional basins:

[0004] (1) Limitations in theoretical understanding. Due to the technical bias that "compression basins have no normal faults", there is a lack of effective theories to predict the development law and spatial distribution direction of normal faults, resulting in blind exploration work; (2) Difficulty in identifying normal faults. Normal faults formed under compression usually have the characteristics of "small displacement, small scale and weak seismic response". In addition, reverse faults and strike-slip faults are densely developed in the basin, and the tectonic background is complex, making it difficult for conventional seismic interpretation methods to effectively capture these hidden normal fault signals, resulting in serious omissions.

[0005] There is currently no effective solution to the above problems. Summary of the Invention

[0006] This specification provides a method and apparatus for identifying normal faults in compression basins, in order to solve the problems of limited theoretical understanding of compression basins and the difficulty in identifying normal faults in the prior art.

[0007] Firstly, embodiments of this specification provide a method for identifying normal faults in compressional basins, including:

[0008] Based on the three-dimensional seismic data volume after stratigraphic calibration within the compressional basin, a spatial distribution pattern of regional reverse faults is constructed, which is used to determine the main strike of regional reverse faults.

[0009] In the context of a compressional basin under a compressive-torsional stress field, stress decomposition is performed on the pre-obtained regional maximum principal compressive stress to obtain tensile stress components parallel to the main strike, which serve as the preferred direction for normal fault identification.

[0010] In the three-dimensional seismic data volume after the layer calibration, an initial seismic profile with an azimuth parallel to the preferred direction is selected, and a series of scan profiles are generated by performing small-interval translational scans and / or small-angle rotational scans on the initial seismic profile.

[0011] On the series of scanning profiles, the target location of the fault is located, and at the target location, it is determined whether the hanging wall strata have shifted downward relative to the footwall strata. If so, the fault is identified as a normal fault.

[0012] In some embodiments, the method further includes:

[0013] The acquired post-stack 3D seismic data is loaded into the target work area of ​​the squeeze basin, and the post-stack 3D seismic data in the target work area is subjected to frequency division reconstruction processing to obtain the reconstructed 3D seismic data volume.

[0014] Based on well logging interpretation data within the target work area, the reconstructed 3D seismic data volume is subjected to stratigraphic calibration to obtain the stratigraphically calibrated 3D seismic data volume.

[0015] In some embodiments, constructing the spatial distribution pattern of regional reverse faults based on the three-dimensional seismic data volume after stratigraphic calibration within the compressional basin includes:

[0016] Identify and interpret regional reverse faults in the three-dimensional seismic data volume after stratigraphic calibration within the compressional basin;

[0017] Based on the identification and interpretation results of regional reverse faults, the spatial distribution pattern of regional reverse faults is constructed.

[0018] The spatial distribution pattern is used to determine the main strike of regional reverse faults, including:

[0019] A statistical analysis was conducted on the strike of all regional reverse faults in the spatial distribution pattern of regional reverse faults. Based on the results of the statistical analysis, the dominant development direction was selected from the strikes of all regional reverse faults as the main strike.

[0020] In some embodiments, the stress decomposition of the pre-obtained regional maximum principal compressive stress in a compressional basin under a compressive-torsional stress field includes:

[0021] In the context of a compressional basin under a compressive-torsional stress field, determine the angle between the maximum principal compressive stress and the main strike in the region;

[0022] Based on the included angle, stress decomposition is performed on the maximum principal compressive stress in the region to obtain the tensile stress component parallel to the main direction.

[0023] In some embodiments, performing small-interval translational scanning and / or small-angle rotational scanning on the initial seismic profile includes:

[0024] Perform small-interval translational scanning on the initial seismic profile to generate a series of moved profiles;

[0025] For each of the series of moved profiles, a small-angle rotation scan is performed to generate a series of scan profiles.

[0026] In some embodiments, locating the target location of the fracture on the series of scanning profiles includes:

[0027] On the series of scanning profiles, by comparing and analyzing the reflection termination and / or cross-sectional wave anomaly characteristics of the reflection phase axis, the spatial location of the fault is located as the target location.

[0028] The determination of whether the hanging wall strata have shifted downward relative to the footwall strata at the target location includes:

[0029] Select a target seismic profile with a resolution greater than a preset resolution threshold at the target location, and identify the target reflection phase axis corresponding to a specific geological stratum that crosses the fault and has been labeled from the target seismic profile;

[0030] Determine whether the target reflection phase axis located in the hanging wall strata has shifted downward relative to the same target reflection phase axis located in the footwall strata. If so, determine whether the hanging wall strata have shifted downward relative to the footwall strata.

[0031] In some embodiments, the method further includes:

[0032] In different structural locations within the target work area of ​​the compressional basin, the steps of selecting an initial seismic profile with an orientation parallel to the preferred direction, performing scanning, positioning, and identification are repeated until the entire target work area is scanned and normal faults are identified.

[0033] Secondly, embodiments of this specification also provide a device for identifying normal faults in compressional basins, comprising:

[0034] A construction module is used to construct the spatial distribution pattern of regional reverse faults based on the three-dimensional seismic data volume after the stratigraphic calibration within the compressional basin. The spatial distribution pattern is used to determine the main strike of the regional reverse faults.

[0035] The stress decomposition module is used to decompose the pre-acquired regional maximum principal compressive stress in the context of a compressional basin under a compressive-torsional stress field, and obtain the tensile stress component parallel to the main strike, which is used as the preferred direction for normal fault identification.

[0036] The scanning module is used to select an initial seismic profile with an azimuth parallel to the preferred direction in the three-dimensional seismic data volume after the layer calibration, and to perform small-interval translational scanning and / or small-angle rotational scanning on the initial seismic profile to generate a series of scanning profiles.

[0037] The identification module is used to locate the target position of the fault on the series of scanning profiles, and at the target position, determine whether the hanging wall strata have shifted downward relative to the footwall strata. If so, the fault is identified as a normal fault.

[0038] Thirdly, embodiments of this specification also provide an electronic device, including: a memory and a processor, wherein the processor and the memory are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to implement the steps of the above-described method for identifying normal faults in a compressional basin.

[0039] Fourthly, embodiments of this specification also provide a computer-readable storage medium storing computer program instructions thereon, which, when executed by a processor, implement the steps of the above-described method for identifying normal faults in a compressional basin.

[0040] This specification provides a method and apparatus for identifying normal faults in a compressional basin. First, based on the 3D seismic data volume after stratigraphic calibration within the compressional basin, a spatial distribution pattern of regional reverse faults is constructed. This spatial distribution pattern is used to determine the main strike of the regional reverse faults. Then, under the background of a compressive-torsional stress field in the compressional basin, stress decomposition is performed on the pre-obtained regional maximum principal compressive stress to obtain the tensile stress component parallel to the main strike, which serves as the preferred direction for normal fault identification. Next, in the 3D seismic data volume after stratigraphic calibration, an initial seismic profile with an azimuth parallel to the preferred direction is selected. Small-interval translational scanning and / or small-angle rotational scanning are performed on the initial seismic profile to generate a series of scanning profiles. Finally, on the series of scanning profiles, the target location of the fault is located. At the target location, it is determined whether the hanging wall strata have shifted downward relative to the footwall strata. If so, the fault is identified as a normal fault. In the embodiments of this specification, by constructing the spatial distribution pattern of regional reverse faults and determining their main strikes, and then performing stress decomposition based on the background of the compressive-torsional stress field, the tensile stress components parallel to the main strike of the regional reverse faults can be accurately calculated as the preferred direction for normal fault identification. Based on this, normal faults in compressional basins can be identified, thus overcoming the technical bias of existing technologies that compressional basins lack normal faults. Simultaneously, exploration is transformed from "blind search across the entire area" to "directional reconnaissance," avoiding blind exploration work. By selecting an initial seismic profile with an azimuth parallel to the preferred direction, small-interval translational scanning and / or small-angle rotational scanning are performed on the initial seismic profile to generate a series of scanning profiles. This enables multi-location, multi-view observation under the complex tectonic background of compressional basins, significantly amplifying the response differences of weak fault signals between different profiles, greatly improving the sensitivity of identifying hidden normal faults, and effectively solving the problem of "missed detection." Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0042] Figure 1 This is a flowchart illustrating a method for identifying normal faults in a compressional basin, as provided in the embodiments of this specification.

[0043] Figure 2 This is a schematic diagram of stress decomposition provided in the embodiments of this specification;

[0044] Figure 3This is a schematic diagram of the structural composition of a device for identifying normal faults in a compression basin, as provided in the embodiments of this specification.

[0045] Figure 4 This is a schematic diagram of the structural composition of the electronic device provided in the embodiments of this specification. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0047] As mentioned earlier, compressional basins, as active tectonic zones at plate boundaries, require accurate identification of their internal fault systems for geological disaster early warning, energy exploration and development, and site selection for major engineering projects. Traditional geological theory holds that such basins, under the combined stress fields of compression and shear, primarily develop thrust fault systems, while normal faults are largely absent. This understanding is mainly based on the following theoretical foundations: First, from a tectonic dynamics perspective, strike-slip compressional environments are dominated by compressive and shear stresses, with tensile stress components being relatively weak, making it difficult to meet the stress conditions for normal fault formation. Existing findings are mostly concentrated on reverse fault characterization within compressional basins. Second, the formation mechanism of normal faults is genetically related to extensional tectonic environments, which fundamentally contradicts the dynamic background of compressional-torsional basins, leading to a lack of awareness among researchers regarding the search for normal faults in compressional basins. Third, there are currently no clearly reported examples of normal fault development within compressional basins.

[0048] Existing technologies for fault identification in compressional basins have at least the following drawbacks:

[0049] (1) Theoretical limitations: There is a technical bias that “normal faults do not develop in compressional basins”, which leads to a lack of awareness of finding normal faults during the exploration process; (2) Difficulty in identification: Multiple thrust and strike-slip faults are densely developed in the compressional structural zone, and the structure is broken and complex, resulting in blurred fault features and abrupt changes in fault attitude. This makes it difficult to accurately determine the spatial distribution and specific location of normal faults during the fault identification process.

[0050] Therefore, there is an urgent need in this field for a method that can overcome the limitations of traditional cognition and effectively identify normal faults in complex compression backgrounds.

[0051] To address the aforementioned issues, this specification provides a method and apparatus for identifying normal faults in compressional basins. Based on 3D seismic data volume with stratigraphic calibration within the compressional basin, a spatial distribution pattern of regional reverse faults is constructed. This spatial distribution pattern is used to determine the main strike of the regional reverse faults. Then, under the background of a compressive-torsional stress field in the compressional basin, stress decomposition is performed on the pre-obtained regional maximum principal compressive stress to obtain tensile stress components parallel to the main strike, which serve as the preferred direction for normal fault identification. Next, in the 3D seismic data volume with stratigraphic calibration, an initial seismic profile with an azimuth parallel to the preferred direction is selected. Small-interval translational scanning and / or small-angle rotational scanning are performed on this initial seismic profile to generate a series of scanning profiles. Finally, on these scanning profiles, the target location of the fault is located. At the target location, it is determined whether the hanging wall strata have shifted downwards relative to the footwall strata. If so, the fault is identified as a normal fault.

[0052] The above approach overcomes the limitations of existing structural understanding. Compressional basins are not purely compressional, but rather compressional-torsional basins with extensional or tensile stress components. Discovering or identifying normal faults in compressional basins overcomes the technical bias of existing technologies that do not identify normal faults in compressional basins. By selecting an initial seismic profile with its azimuth parallel to the preferred direction, and performing short-interval translational and / or small-angle rotational scans on the initial seismic profile, the accuracy and reliability of normal fault identification can be improved, overcoming the problem of existing technologies' difficulty in identifying normal faults in compressional basins.

[0053] It should be noted that the basic principles applied in this invention may include the following:

[0054] Basin dynamics: Although the compressional environment is dominated by compressive stress, there is no absolutely single compressive stress state in actual geological processes. Due to the superposition of regional compressional and torsional environments, the basin basement undergoes torsional compressional deformation. Through the continuous action of the compressional-strike-slip composite stress field, a compressional-torsional basin with torsional characteristics is eventually formed.

[0055] The mechanism of tensile stress generation: By performing strike-slip vector decomposition on the principal stress field of a compression-torsion basin, compressive and tensile stress components can be analytically identified. The existence of the tensile stress component provides the necessary conditions for the formation of normal faults.

[0056] Normal fault identification: Based on the stress vector decomposition method, the development direction of normal faults exhibits a high degree of collinearity with the regional strike-slip direction. Therefore, a rotating profile identification technique is established: by translating and rotating the seismic interpretation profile to an azimuth parallel to the regional strike-slip direction for scanning interpretation, normal faults whose strike is nearly orthogonal to the regional strike-slip fault can be effectively identified.

[0057] It is understood that the methods described in the embodiments of this specification can be applied to electronic devices, which can refer to electronic devices with data computing, processing, and storage capabilities. These electronic devices can be terminals such as PCs (Personal Computers), tablets, smartphones, wearable devices, and intelligent robots; they can also be servers. A server can be an independent physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing cloud computing services.

[0058] See Figure 1 As shown in the embodiments of this specification, a method for identifying normal faults in compressional basins is provided. In specific implementation, this method may include the following:

[0059] S101: Based on the three-dimensional seismic data volume after stratigraphic calibration within the compressional basin, a spatial distribution pattern of regional reverse faults is constructed. This spatial distribution pattern is used to determine the main strike of the regional reverse faults.

[0060] Specifically, the aforementioned compressional basins can be compressional basins with a compressional-torsional tectonic background (referred to as "compressional-torsional basins," which are regions within compressional basins that have strike-slip components). They typically exhibit the following characteristics: 1. Tectonic style: Structures indicating a compressional environment are widely developed within the basin, such as thrust faults, folds (especially anticlines and synclines), and tectonic uplifts; 2. Stress field background: The regional stress field of the basin is dominated by horizontal compression, but also contains strike-slip shear components, which together constitute a compressional-torsional stress field; 3. In this complex compressional-torsional stress field, which is not purely compressional, tensile stress components (or extensional stress components) can be generated locally through stress vector decomposition. These tensile stress components are the direct dynamic source of the normal fault formation to be identified in this invention. The aforementioned three-dimensional seismic data volume after stratigraphic calibration refers to a data volume where seismic reflection phase axes have been assigned clear geological age significance, which is the basis for accurately identifying stratigraphic fault relationships. The aforementioned regional reverse fault refers to a fault formed under a regional compressional background with a relatively uplifted hanging wall. The aforementioned spatial distribution pattern is a dataset containing the location, morphology, and especially the orientation information of all interpreted reverse faults in three-dimensional space.

[0061] By constructing the spatial distribution pattern of regional reverse faults and determining their main strike, complex geological structural information can be quantified into a clear directional parameter (main strike) that can guide subsequent work, laying the foundation for the accurate identification of normal faults in compressional basins.

[0062] In some embodiments, prior to S101 above, the following may be included in a specific implementation:

[0063] The acquired post-stack 3D seismic data is loaded into the target work area of ​​the squeeze basin, and the post-stack 3D seismic data in the target work area is subjected to frequency division reconstruction processing to obtain the reconstructed 3D seismic data volume.

[0064] Based on well logging interpretation data within the target work area, the reconstructed 3D seismic data volume is subjected to stratigraphic calibration to obtain the stratigraphically calibrated 3D seismic data volume.

[0065] Specifically, the aforementioned post-stack seismic data volume refers to a three-dimensional data set formed after dynamic and static corrections of the original seismic data volume, possessing high resolution. Due to the widespread development of faults within compressional basins, seismic data resolution is reduced and the continuity of reflection phase axes deteriorates. Frequency-division reconstruction processing can be performed on high-resolution post-stack 3D seismic data loaded onto the target work area in the compressional basin to improve the signal-to-noise ratio and resolution of the seismic data. This lays the foundation for subsequent accurate layer tracking and precise identification of normal faults, solving the problem that existing technologies are limited by low seismic data signal-to-noise ratio, insufficient resolution, and limitations in imaging algorithms, making it difficult to clearly image key identification markers of normal faults (such as fault surface waves and fault diffraction waves), directly affecting the accurate tracking of normal faults.

[0066] Specifically, the above frequency division reconstruction process may include:

[0067] A large number of representative seismic traces are extracted from the post-stack seismic data volume, and Fourier transform is performed on the seismic traces to obtain the average amplitude spectrum. The frequency corresponding to the peak value of the average amplitude spectrum is taken as the dominant frequency. A preset multiple (such as 1.5 times) of the dominant frequency is selected as the dominant frequency. Based on the dominant frequency, the post-stack 3D seismic data volume is subjected to frequency division reconstruction processing to obtain the reconstructed 3D seismic data volume, namely the reconstructed 3D seismic data volume mentioned above.

[0068] The dominant frequency mentioned above refers to the frequency component with the strongest energy and most representative characteristics in the entire seismic data volume. It can be determined by calculating the amplitude spectrum of the seismic data and finding the frequency corresponding to the maximum amplitude. A dominant frequency, F_optimal = 1.5 * F_main, can be selected as the core. Using methods such as bandpass filtering or spectral blueing, frequency-division reconstruction processing can be performed on the post-stack 3D seismic data volume to generate a new reconstructed seismic data volume with higher signal-to-noise ratio and resolution.

[0069] Subsequently, well logging interpretation data (which may include sonic waves, density curves, and stratigraphic data) can be used to perform seismic-well logging stratigraphic calibration on the reconstructed 3D seismic data volume. This ensures that the geological significance of the reflection phase axes is clear, providing a reliable stratigraphic framework for accurate fault identification and interpretation. Seismic-well logging stratigraphic calibration refers to establishing a correspondence between the reflection phase axes (such as amplitude and phase characteristics) on the seismic profile and actual geological strata (such as stratigraphic interfaces and lithological interfaces), assigning them clear geological significance (such as specific stratum names and age). Generally, sonic and density data are used, and calibration is completed by comparing the synthetic record with the shape of the well-side seismic traces. When vertical seismic logging data is available, VSP logging data should be combined. The process of achieving calibration using synthetic seismic records can be as follows:

[0070] The reflection coefficient was calculated using sonic transit time and density curves, and then convolved with a wavelet to generate a synthetic seismic record. This synthetic seismic record was then compared and matched with seismic traces at well locations in the reconstructed seismic data volume. By finely adjusting the time-depth relationship, the geological stratigraphic depths on the well logs (e.g., the bottom boundary of the Guantao Formation) were precisely mapped to specific reflection phase axes on the seismic profile in the reconstructed 3D seismic data volume. This resulted in a stratigraphically calibrated 3D seismic data volume (i.e., each major reflection phase axis has a clear geological age label). Specific reflection phase axes refer to reflection events that can be continuously tracked on the seismic profile and possess strong amplitude and good continuity. These phase axes represent the acoustic impedance difference at subsurface lithological interfaces (e.g., the interface between mudstone and sandstone). Through well logging calibration, we assigned specific geological age meanings to these physical interfaces.

[0071] In some embodiments, the construction of the spatial distribution pattern of regional reverse faults based on the three-dimensional seismic data volume after stratigraphic calibration within the compressional basin in S101 above may, in specific implementation, include:

[0072] Identify and interpret regional reverse faults in the three-dimensional seismic data volume after stratigraphic calibration within the compressional basin;

[0073] Based on the identification and interpretation results of regional reverse faults, the spatial distribution pattern of regional reverse faults is constructed.

[0074] The spatial distribution pattern in S101 above is used to determine the main strike of the regional reverse fault. In specific implementation, it may include:

[0075] A statistical analysis was conducted on the strike of all regional reverse faults in the spatial distribution pattern of regional reverse faults. Based on the results of the statistical analysis, the dominant development direction was selected from the strikes of all regional reverse faults as the main strike.

[0076] Specifically, within the stratigraphically calibrated 3D seismic data volume of a compressional basin (i.e., on a 3D seismic profile with calibrated geological strata and frequency-division reconstruction), the system identifies and interprets regional reverse faults. The interpretation is based on the observed discontinuities, repetitions, or distortions in seismic reflection phase axes, and on the criterion of 'upward movement of the hanging wall strata relative to the footwall strata', these features are interpreted as manifestations of reverse faults. The system can identify the following characteristics of reflection phase axes on vertical profiles in any direction (usually inline or crossline directions), either manually by the interpreter or using attribute extraction (such as coherence volumes):

[0077] Discontinuity: Sudden discontinuity in the phase axis;

[0078] Repeat: The same stratigraphic sequence appears repeatedly;

[0079] Twisted / mutated form: Strong bending occurs in the phase axis.

[0080] Explanation: Based on the criterion that "the strata in the hanging wall move upward relative to the footwall", these anomalies are identified as reverse faults, and their cross sections and trajectories are plotted in three-dimensional space in the interpretation software.

[0081] The identification and interpretation results of regional reverse faults can provide a basic geological framework and key constraint information for subsequent steps to identify related normal faults under compressive stress.

[0082] Subsequently, based on the identification and interpretation results of regional reverse faults, a spatial distribution pattern including the three-dimensional orientation of all reverse faults can be constructed. Then, statistical analysis of the orientations of all reverse faults (e.g., creating a rose diagram) is performed to determine the orientation of the most developed and representative reverse fault in the work area, which is then used as the main orientation of regional reverse faults. For example, analysis reveals that 70% of the reverse fault orientations in the work area are concentrated within the range of 35°–45°E; therefore, the "main orientation of regional reverse faults" is determined to be 40°E.

[0083] Determining the main strike of the regional reverse fault lays the foundation for accurately calculating the tensile stress components parallel to the main strike of the regional reverse fault.

[0084] S102: In the context of a compressional basin under a compressive-torsional stress field, the pre-obtained regional maximum principal compressive stress is decomposed to obtain tensile stress components parallel to the main strike, which are used as preferred directions for normal fault identification.

[0085] Specifically, based on the understanding that compressional basins are in a compressive-torsional stress field (i.e., under the combined action of compression and strike-slip stress), the known maximum principal compressive stress in the region can be vector-decomposed, and the tensile stress component parallel to the main strike can be calculated as the "preferred direction" for the most likely development of normal faults.

[0086] By combining geomechanical theory with exploration practice, this study explains the genesis of normal faults in such basins and provides precise and actionable search directions, overcoming technical bias.

[0087] In some embodiments, the stress decomposition of the pre-obtained regional maximum principal compressive stress in S102, under the background of a compressional basin being in a compressive-torsional stress field, may specifically include:

[0088] In the context of a compressional basin under a compressive-torsional stress field, determine the angle between the maximum principal compressive stress and the main strike in the region;

[0089] Based on the included angle, stress decomposition is performed on the maximum principal compressive stress in the region to obtain the tensile stress component parallel to the main direction.

[0090] Specifically, assuming the maximum principal compressive stress in the region ( The direction is southeast (e.g., 110° southeast). The angle between this angle and the reverse fault strike (40° northeast) is 110° - 40° = 70°. However, in a purely compressive environment, The perpendicular fault strike and the included angle of 90° (70° in this example) prove the existence of a compressive-torsional background, indicating that the compressional basin is in a compressive-torsional stress field (the angle between the regional maximum principal compressive stress and the reverse fault strike is less than 90 degrees). Based on this, the regional maximum principal compressive stress can be decomposed, and the formula for stress decomposition is as follows:

[0091]

[0092] in, This represents the compressive stress generated perpendicular to the reverse fault (the component perpendicular to the main strike of the reverse fault). The tensile stress component parallel to the main strike of the reverse fault (the component parallel to the main strike of the reverse fault) manifests as tensile stress under a compressive-torsional background.

[0093] In compression-torsion basins, not only is tensile stress present, but its strength can also be very significant (e.g., This is sufficient to form a normal fault. A normal fault will occur along the tensile stress. The direction of development is such that it is parallel to 40° northeast. Therefore, the preferred direction for subsequent scanning is 40° northeast.

[0094] By performing strike-slip vector decomposition on the maximum principal compressive stress in the compression-torsional basin region, the compressive and tensile stress components can be analytically identified. The existence of the tensile stress component provides the necessary conditions for the formation of normal faults, and this tensile stress component is the dominant dynamic mechanism controlling the formation and development of normal faults.

[0095] S103: In the three-dimensional seismic data volume after the layer calibration, select an initial seismic profile with an azimuth parallel to the preferred direction, and perform small-interval translational scanning and / or small-angle rotational scanning on the initial seismic profile to generate a series of scanning profiles.

[0096] Specifically, an initial seismic profile can be selected from the 3D seismic data volume after stratigraphic calibration, with its azimuth strictly parallel to the preferred direction. Specifically, the initial seismic profile can be selected in the stress concentration area within the compressional basin (e.g., the core of a structural anticline). The azimuth of this initial seismic profile must be strictly parallel to the main strike of the determined reverse fault, which is the direction in which the normal fault is most likely to develop and whose fault reflection characteristics are most easily observed.

[0097] Subsequently, a "small-interval translational scan" (e.g., moving the profile position at 10-50 meter intervals) and / or a "small-angle rotational scan" (e.g., fine-tuning the profile angle by ±1° to ±5°) are performed on the initial seismic profile. These two scanning methods can be combined to generate a "series of scan profiles" containing a large number of observation perspectives.

[0098] By performing small-interval translational scanning and / or small-angle rotational scanning, the spatial distribution morphology of normal faults and other types of faults can be accurately distinguished, improving the identification ability of small faults and low-angle faults, and providing more reliable geological basis for structural analysis.

[0099] In some embodiments, performing small-interval translational scanning and / or small-angle rotational scanning on the initial seismic profile in S103 above may, in specific implementation, include:

[0100] Perform small-interval translational scanning on the initial seismic profile to generate a series of moved profiles;

[0101] For each of the series of moved profiles, a small-angle rotation scan is performed to generate a series of scan profiles.

[0102] Specifically, normal faults formed by tensile stress within compressional basins typically have small displacements, small scales, and limited ability to penetrate strata. Their reflection characteristics on seismic profiles (such as fault point reflection termination and fault wave patterns) are often weak and difficult to identify directly. To effectively capture these weak anomalies, the following refined profile scanning operation is employed:

[0103] Small-interval moving scan: The seismic profile position is gradually moved (translated) in a direction parallel to the main strike of the reverse fault at small intervals (such as equal intervals of 10 meters to 50 meters) to generate a series of adjacent parallel profiles.

[0104] Small-angle rotational scan: For each moved profile position, rotate the profile at a small angle (e.g., ±1° to ±5°) with the rotation axis perpendicular to the main construction line, generating a series of rotating profiles around that position with slight angular differences.

[0105] On a series of profiles generated by the above-mentioned small-interval movement and small-angle rotation (which may include the post-movement profile and the rotation profile), the abnormal characteristics of the seismic reflection phase axis are systematically observed and analyzed, with a focus on identifying the characteristics of the discontinuity reflection termination and the anomalies of the cross-sectional wave.

[0106] By translating and rotating the seismic profile to a position parallel to the preferred direction for scanning and interpretation, normal faults whose strike is nearly orthogonal to regional strike-slip faults can be effectively identified.

[0107] S104: On the series of scanning profiles, locate the target position of the fault, and at the target position, determine whether the hanging wall strata have shifted downward relative to the footwall strata. If so, identify the fault as a normal fault.

[0108] Specifically, on a series of scanning profiles, by comparing and analyzing anomalous features such as the termination of reflections (sudden interruption of the signal) of the reflection phase axis (or seismic reflection phase axis, i.e., the reflection signal representing the underground strata on the seismic profile) and fault waves (weak reflections from the fault plane), the target location of the fault is initially determined. Finally, on clear profiles, based on stratigraphic calibration, it is determined whether the reflection of a specific stratigraphic level in the hanging wall has shifted downward relative to the reflection of the same stratigraphic level in the footwall. If so, it is ultimately confirmed as a normal fault.

[0109] By determining whether the hanging wall strata have shifted downward relative to the footwall strata at the located fault target location, the reliability of the normal fault identification results can be ensured.

[0110] In some embodiments, locating the target position of the fracture on the series of scanning profiles in S104 above may, in specific implementation, include:

[0111] On the series of scanning profiles, by comparing and analyzing the reflection termination and / or cross-sectional wave anomaly characteristics of the reflection phase axis, the spatial location of the fault is located as the target location.

[0112] The determination of whether the hanging wall strata have shifted downward relative to the footwall strata at the target location includes:

[0113] Select a target seismic profile with a resolution greater than a preset resolution threshold at the target location, and identify the target reflection phase axis corresponding to a specific geological stratum that crosses the fault and has been labeled from the target seismic profile;

[0114] Determine whether the target reflection phase axis located in the hanging wall strata has shifted downward relative to the same target reflection phase axis located in the footwall strata. If so, determine whether the hanging wall strata have shifted downward relative to the footwall strata.

[0115] Specifically, by comparing and analyzing the above-mentioned reflection phase axis anomaly characteristics (such as reflection termination and / or cross-sectional wave anomaly characteristics) in a series of cross-sections obtained at different moving positions and different rotation angles, the spatial location of the fault (which may include planar location, dip, and approximate extension range) can be preliminarily determined, i.e., the above-mentioned target location.

[0116] Subsequently, based on the stratigraphic calibration results, it can be determined whether the hanging wall strata have shifted downwards relative to the footwall on a series of scanning profiles. Specifically, at the initially located target location, find the clearest seismic profile of the fault (i.e., the target seismic profile with a resolution greater than a preset resolution threshold), such as a profile rotated +2° from a 40° northeast direction. Then, find the reflection phase axis corresponding to the stable and continuous key geological strata that have been calibrated across both sides of the fault on this seismic profile (i.e., the target reflection phase axis corresponding to a specific geological stratum that crosses the fault and has been stratigraphically calibrated, such as the "bottom boundary of Shayi Section"). On one side of the fault (usually first on the footwall), trace this phase axis to the fault line, and move the line of sight horizontally to the other side of the fault (hanging wall) to find the phase axis of the same geological stratum. If the same phase axis of the same stratum is found on the hanging wall, and its position in the vertical direction (time or depth axis) is lower than that of the footwall strata, it is determined that "the hanging wall strata have shifted downwards relative to the footwall". In a normal fault, the side that is relatively subsided is the hanging wall. Therefore, once it is determined that the hanging wall has shifted downwards, that side can also be called the "subsided side". For example, suppose the "bottom boundary of the first segment of the sandbar" is located at 1500 milliseconds (during earthquake travel) in the hanging wall. After crossing the fault, this boundary is located at 1520 milliseconds in the hanging wall. This 20-millisecond downward shift clearly indicates the movement of the normal fault.

[0117] It should be noted that the above-mentioned "phase axis" is a general abbreviation for "reflection phase axis". The two are the same concept, both referring to the line connecting the peaks or valleys on the seismic profile formed by reflected waves from the subsurface strata interface that can be continuously traced.

[0118] In some embodiments, after determining that the hanging wall strata have shifted downward relative to the footwall strata, a supporting evidence step may also be included:

[0119] Determine whether the thickness of the strata unit in the hanging wall (descending wall) of the fault at the target location is greater than its thickness in the footwall (ascending wall);

[0120] If so, it further confirms that the fault is a syn-sedimentary normal fault that was active during the depositional period.

[0121] Specifically, the thickness of the strata units in the downthrown block is greater than that in the upthrown block. This is known as the "growing stratigraphy" phenomenon, indicating that the fault was active during the depositional period (syn-sedimentary normal fault), and the downthrown block continued to subside, absorbing thicker sediments. When signs of fault movement are weak or the assessment is uncertain, growing stratigraphy can provide decisive support.

[0122] In some embodiments, after S104 above, in specific implementation, it may further include:

[0123] In different structural locations within the target work area of ​​the compressional basin, the steps of selecting an initial seismic profile with an orientation parallel to the preferred direction, performing scanning, positioning, and identification are repeated until the entire target work area is scanned and normal faults are identified.

[0124] By repeatedly performing the steps of selecting an initial seismic profile with an azimuth parallel to the preferred direction, scanning, locating, and identifying different structural locations (such as different anticlines and slope zones) within the target work area, this invention ensures that the method can not only make discoveries at specific points but also complete systematic exploration across a wide area, ultimately producing a normal fault distribution map of the entire work area and achieving a comprehensive geological evaluation.

[0125] By accurately identifying normal faults in compressional basins, it is easier to maintain the permeability advantage of the fault structure under tensional stress regimes. During periods of fault activity, these faults can significantly enhance the ability of oil and gas to migrate across layers, forming the main migration control channels that penetrate source rocks and reservoirs. This makes it easier to control hydrocarbon fluids migrating along the dominant channels in areas with developed normal faults, thereby promoting the enrichment of oil and gas around the dominant fault channels.

[0126] Based on the above embodiments, the present invention can achieve the following technical effects:

[0127] (1) Extensional structures were discovered in a compressional environment by identifying normal faults.

[0128] To address the unique tectonic stress field characteristics of compressional basins, we first decomposed the maximum principal compressive stress in the region to clarify the development mechanism of normal faults. At the same time, we introduced small-interval movement and small-angle seismic profile rotation scanning identification technology, which can accurately distinguish the spatial distribution of normal faults from other types of faults, improve the identification ability of small faults and low-angle faults, and provide more reliable geological basis for tectonic analysis.

[0129] (2) In a pressure-torsion environment, normal faults are found to be dominant migration channels for oil and gas, which control the formation and enrichment of oil and gas reservoirs.

[0130] Compared to the low permeability of fractured zones commonly developed under compressive stress in reverse faults, normal faults are more likely to maintain their permeability advantage under tensional stress regimes. During periods of fault activity, normal faults can significantly enhance the ability of hydrocarbons to migrate across layers, forming the main migration control channels that run through source rocks and reservoirs. This makes it easier for hydrocarbon fluids migrating along the dominant channels in areas with developed normal faults to accumulate, thereby promoting the enrichment of hydrocarbons around the dominant fault channels.

[0131] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. For details, please refer to the foregoing descriptions of the relevant processing embodiments; they will not be repeated here.

[0132] The foregoing description of this method is for illustrative purposes only and describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than those shown in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0133] In a specific implementation scenario, the specific process of a method provided in the embodiments of this specification can be as follows:

[0134] Data preparation and lattice construction:

[0135] S1.1: Perform frequency division reconstruction processing on the post-stack 3D seismic data volume to obtain the reconstructed 3D seismic data volume.

[0136] S1.2: Based on the reconstructed 3D seismic data volume and well logging data, seismic-well logging horizon calibration is performed, and key geological horizons are assigned to specific reflection phase axes to obtain the 3D seismic data volume after horizon calibration.

[0137] S1.3: On the three-dimensional seismic data volume after the layer calibration, by identifying the discontinuity, repetition or distortion characteristics of the reflection phase axis, the regional reverse faults are interpreted to obtain the spatial distribution pattern of the regional reverse faults (including their strike).

[0138] Stress analysis and directional scanning:

[0139] S2.1: Based on the spatial distribution pattern of regional reverse faults, determine their main strike; based on the background of compressive and torsional stress fields, calculate the direction of tensile stress components parallel to the main strike through stress vector decomposition, and determine this direction as the preferred direction for identifying normal faults.

[0140] S2.2: In the three-dimensional seismic data volume after layer calibration, select an initial seismic profile with an azimuth parallel to the preferred direction.

[0141] S2.3: Perform small-interval translational scanning and / or small-angle rotational scanning on the initial seismic profile to generate a series of scanning profiles.

[0142] S2.4: On a series of scanning profiles, the spatial location of the fault is preliminarily determined by comparing and analyzing the reflection termination of the seismic reflection phase axis and / or the anomaly characteristics of the cross-sectional wave.

[0143] Nature determination and interpretation of the entire region:

[0144] S3: At the location fault, based on the stratigraphic calibration results, determine whether the hanging wall strata have shifted downward relative to the footwall. If so, the fault is determined to be a normal fault.

[0145] S4: Repeat steps S2 to S3 within the work area to complete the identification of normal faults throughout the area (repeat steps two to three on multiple seismic profiles until the distribution and attitude of all normal faults are identified). By identifying normal faults, dominant oil and gas migration channels can be discovered, guiding oil and gas exploration.

[0146] The specific implementation of S1.3 above is as follows:

[0147] Input: Geologically significant 3D seismic data volume (from S1.2). Operation: Scan the vertical profile to look for anomalies. Example 1 (Discontinuity and Repetition): The marked "Guantao Formation bottom boundary" phase axis (T1) is observed to suddenly break at a certain location, and another set of phase axes with the same sequence appears above it, indicating stratigraphic repetition. According to the criterion that "in repetitive strata, the lower plate is the hanging wall," the hanging wall is judged to be uplifted, interpreted as a reverse fault. Example 2 (Strong Twisting): In the core of the anticline, multiple marked horizons (T1, T2) are observed to be synchronously and sharply bent or twisted, which usually suggests the presence of a hidden reverse fault below. In the 3D interpretation system, trace and delineate the fault planes along these anomaly features. Output: Spatial distribution pattern of regional reverse faults (may include strike, dip, spatial distribution, etc. of all reverse faults).

[0148] In S2.1 above, the direction of the tensile stress component parallel to the main trend is calculated through stress vector decomposition, such as... Figure 2 As shown, This indicates the maximum compressive principal stress (maximum principal compressive stress in the region). This indicates that the maximum principal stress is the compressive stress generated perpendicular to the reverse fault. This represents the tensile stress parallel to the main strike of the reverse fault. X represents the angle between the maximum principal compressive stress in the region and the main trend. F For shear stress, Y F The stress is compressive. This analysis reveals a significant tensile stress component parallel to the strike of the main reverse fault. This tensile stress component is the dominant dynamic mechanism controlling the formation and development of normal faults. Therefore, the preferred direction for normal fault identification is parallel to the main strike of the reverse fault.

[0149] The specific implementation of the preliminary fault location in S2.4 above is as follows:

[0150] The following seismic phase axis anomaly characteristics were systematically observed on a series of cross sections:

[0151] Reflection Termination Feature: Sudden interruption or disappearance of the in-phase axis. Fault Wave Anomaly: A short, weak, tilted reflection, usually a response of the fault plane itself. Slight Downward Twist or Displacement: A small, continuous downward twisting or displacement of the in-phase axis. Comparative Analysis: Track the same anomalous feature on adjacent moving and rotating profiles. If a "suspected fault" can be continuously observed at multiple adjacent locations and small angles, the probability that this signal is a real structure (fault) is much greater than random noise. Preliminary Location: Based on these continuously trackable anomalies, preliminarily determine the fault's trajectory, dip, and approximate extent in three-dimensional space. Output: Spatial location of the suspected normal fault (target location).

[0152] The specific implementation of S3 above is as follows:

[0153] If, in a seismic profile, the reflection phase axis of the hanging wall (the wall above the fault plane) is observed to be significantly displaced downward relative to the phase axis of the footwall (the wall below the fault plane) (i.e., the hanging wall strata show a downward displacement vertically relative to the footwall strata), this indicates that the fault is a normal fault. Furthermore, if, in the seismic profile, the thickness of the stratigraphic unit within the downthrown block (the hanging wall, which is typically the more significantly subsided block in a normal fault) is observed to be significantly greater than its thickness in the upthrown block (footwall), this further corroborates that the fault exhibited normal fault characteristics during deposition.

[0154] It should be noted that when conventional methods based on velocity difference analysis of the hanging wall and footwall of a fault are limited in their discriminative capabilities due to insufficient accuracy in velocity field modeling or ambiguity in lithological interfaces, seismic tectonic attributes can be used to identify the spatial distribution of faults. For example, methods such as coherence volume technology, curvature attribute analysis, and ant-body tracking can be employed. Compared to velocity difference analysis, tectonic attribute techniques reduce reliance on velocity models and improve the imaging resolution of complex fault zone internal structures.

[0155] Based on the method of decomposing the principal stress field of compressional basins, the development law of local extensional stress under the compressional-strike-slip tectonic background is revealed, the stress field mechanism of normal fault formation is clarified, and the key law of the spatial distribution of normal faults is established: its strike is almost parallel to the direction of the local extensional stress (i.e., parallel to the main strike of the regional main reverse fault).

[0156] To address the characteristics of small fault displacement, small scale, and weak seismic response in compressional basins caused by weak tensile stress, small-angle translational scanning (e.g., equidistant intervals of 10 to 50 meters) and small-angle rotational scanning (±1° to ±5° fine-tuning of the observation angle) techniques are introduced. These techniques significantly enhance the visibility of weak fault signals (such as slight pull-down or displacement), accurately characterize the spatial morphology of normal faults, and distinguish them from other fault types. Furthermore, by controlling the angle scanning interval (e.g., 1°), an optimized balance between identification accuracy and computational efficiency is achieved.

[0157] Although this specification provides the following examples or appendices Figure 3 The method or apparatus structure shown may include more or fewer combined operational steps or module units based on conventional or non-inventive methods. In steps or structures where there is no logically necessary causal relationship, the execution order of these steps or the module structure of the apparatus is not limited to the execution order or module structure shown in the embodiments or drawings of this specification. When the method or module structure is applied in actual devices, servers, or terminal products, it can be executed sequentially or in parallel according to the method or module structure shown in the embodiments or drawings (e.g., in a parallel processor or multi-threaded processing environment, or even a distributed processing or server cluster implementation environment). Based on the above-described method for identifying normal faults in compressional basins, this specification also proposes an embodiment of an apparatus for identifying normal faults in compressional basins. Figure 3 As shown, the device may specifically include the following modules:

[0158] Module 301 can be used to construct the spatial distribution pattern of regional reverse faults based on the three-dimensional seismic data volume after the stratigraphic calibration within the compression basin. The spatial distribution pattern is used to determine the main strike of the regional reverse faults.

[0159] The stress decomposition module 302 can be used to decompose the pre-acquired regional maximum principal compressive stress in the context of a compressional basin under a compressive-torsional stress field, and obtain the tensile stress component parallel to the main strike, which can be used as the preferred direction for normal fault identification.

[0160] The scanning module 303 can be used to select an initial seismic profile with an azimuth parallel to the preferred direction in the three-dimensional seismic data volume after the layer calibration, and perform small-interval translational scanning and / or small-angle rotational scanning on the initial seismic profile to generate a series of scanning profiles.

[0161] The identification module 304 can be used to locate the target position of the fault on the series of scanning profiles, and at the target position, determine whether the hanging wall strata have shifted downward relative to the footwall strata. If so, the fault is identified as a normal fault.

[0162] In some embodiments, the aforementioned construction module 301 may further be used to load the acquired post-stack 3D seismic data into the target work area of ​​the squeezed basin, perform frequency division reconstruction processing on the post-stack 3D seismic data in the target work area to obtain the reconstructed 3D seismic data volume, and perform layer calibration on the reconstructed 3D seismic data volume based on the well logging interpretation data in the target work area to obtain the layer-calibrated 3D seismic data volume.

[0163] In some embodiments, the above-mentioned construction module 301 can be specifically used to identify and interpret regional reverse faults in the three-dimensional seismic data volume after stratigraphic calibration within a compressional basin; construct the spatial distribution pattern of regional reverse faults based on the identification and interpretation results of regional reverse faults; perform statistical analysis on the strikes of all regional reverse faults in the spatial distribution pattern of regional reverse faults; and select the dominant development azimuth from the strikes of all regional reverse faults as the main strike based on the statistical analysis results.

[0164] In some embodiments, the stress decomposition module 302 can be specifically used to determine the angle between the regional maximum principal compressive stress and the main trend in the context of a compressional basin under a compressive-torsional stress field; and to perform stress decomposition on the regional maximum principal compressive stress according to the angle to obtain the tensile stress component parallel to the main trend.

[0165] In some embodiments, the scanning module 303 can be specifically used to perform small-interval translational scanning on the initial seismic profile to generate a series of moved profiles; and to perform small-angle rotational scanning on each of the series of moved profiles to generate a series of scanning profiles.

[0166] In some embodiments, the identification module 304 can be specifically used to locate the spatial position of the fault as the target position by comparing and analyzing the reflection termination and / or cross-sectional wave anomaly characteristics of the reflection phase axis on the series of scanning profiles; select a target seismic profile with a resolution greater than a preset resolution threshold at the target position; identify the target reflection phase axis corresponding to a specific geological stratum that crosses the fault and has been stratified from the target seismic profile; determine whether the target reflection phase axis located in the hanging wall strata has shifted downward relative to the same target reflection phase axis located in the footwall strata; if so, determine that the hanging wall strata have shifted downward relative to the footwall strata.

[0167] In some embodiments, the identification module 304 may also be used to repeatedly perform the steps of selecting an initial seismic profile with an orientation parallel to the preferred direction, performing scanning, positioning, and identification at different structural locations within the target work area of ​​a compressional basin, until the full-area scanning and normal fault identification of the target work area are completed.

[0168] As can be seen from the above, the device for identifying normal faults in a compression basin provided in the embodiments of this specification can accurately identify normal faults in a compression basin.

[0169] This specification also provides an electronic device based on the above-described method for identifying normal faults in a compression basin, including a processor and a memory for storing executable programs / instructions. Specifically, the processor can execute the following steps according to the program / instructions: Based on the three-dimensional seismic data volume after stratigraphic calibration within the compression basin, a spatial distribution pattern of regional reverse faults is constructed, whereby the spatial distribution pattern is used to determine the main strike of the regional reverse faults; under the background of a compressive-torsional stress field in the compression basin, stress decomposition is performed on the pre-obtained regional maximum principal compressive stress to obtain tensile stress components parallel to the main strike, which serve as the preferred direction for normal fault identification; in the three-dimensional seismic data volume after stratigraphic calibration, an initial seismic profile with an azimuth parallel to the preferred direction is selected, and small-interval translational scanning and / or small-angle rotational scanning are performed on the initial seismic profile to generate a series of scanning profiles; on the series of scanning profiles, the target location of the fault is located, and at the target location, it is determined whether the hanging wall strata have shifted downward relative to the footwall strata; if so, the fault is identified as a normal fault.

[0170] To execute the above instructions more accurately, please refer to... Figure 4 As shown in the embodiments of this specification, another specific electronic device is also provided, wherein the electronic device includes a network communication port 401, a processor 402 and a memory 403, and the above structures are connected by internal cables so that the various structures can perform specific data interaction.

[0171] Specifically, the processor 402 can be used to construct a spatial distribution pattern of regional reverse faults based on the three-dimensional seismic data volume after stratigraphic calibration within a compressional basin. This spatial distribution pattern is used to determine the main strike of the regional reverse faults. Under the background of the compressional basin being in a compressive-torsional stress field, stress decomposition is performed on the pre-obtained regional maximum principal compressive stress to obtain tensile stress components parallel to the main strike, which serve as the preferred direction for normal fault identification. In the stratigraphically calibrated three-dimensional seismic data volume, an initial seismic profile with an azimuth parallel to the preferred direction is selected, and small-interval translational scanning and / or small-angle rotational scanning are performed on the initial seismic profile to generate a series of scanning profiles. On the series of scanning profiles, the target location of the fault is located, and at the target location, it is determined whether the hanging wall strata have shifted downward relative to the footwall strata. If so, the fault is identified as a normal fault.

[0172] The memory 403 can be used to store the corresponding instruction program.

[0173] In this embodiment, the network communication port 401 can be a virtual port bound to different communication protocols, thereby enabling the sending or receiving of different data. For example, the network communication port can be a port responsible for web data communication, a port responsible for FTP data communication, or a port responsible for email data communication. Furthermore, the network communication port can also be a physical communication interface or communication chip. For example, it can be a wireless mobile network communication chip, such as GSM or CDMA; it can also be a Wi-Fi chip; or it can be a Bluetooth chip.

[0174] In this embodiment, the processor 402 can be implemented in any suitable manner. For example, the processor can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers, etc. This specification is not limiting.

[0175] In this embodiment, the memory 403 may include multiple layers. In a digital system, anything that can store binary data can be a memory. In an integrated circuit, a circuit with storage function but no physical form is also called a memory, such as RAM, FIFO, etc. In a system, a storage device with a physical form is also called a memory, such as a memory stick, TF card, etc.

[0176] This specification also provides a computer storage medium based on the above-described method for identifying normal faults in a compression basin. The computer storage medium stores a computer program / instruction that, when executed, performs the following: Based on the three-dimensional seismic data volume after stratigraphic calibration within the compression basin, a spatial distribution pattern of regional reverse faults is constructed, which is used to determine the main strike of the regional reverse faults; under the background of a compressive-torsional stress field in the compression basin, stress decomposition is performed on the pre-obtained regional maximum principal compressive stress to obtain tensile stress components parallel to the main strike, which serve as the preferred direction for normal fault identification; in the stratigraphically calibrated three-dimensional seismic data volume, an initial seismic profile with an azimuth parallel to the preferred direction is selected, and small-interval translational scanning and / or small-angle rotational scanning are performed on the initial seismic profile to generate a series of scanning profiles; on the series of scanning profiles, the target location of the fault is located, and at the target location, it is determined whether the hanging wall strata have shifted downward relative to the footwall strata; if so, the fault is identified as a normal fault.

[0177] In this embodiment, the storage medium includes, but is not limited to, Random Access Memory (RAM), Read-Only Memory (ROM), Cache, Hard Disk Drive (HDD), or Memory Card. The memory can be used to store computer program instructions. The network communication unit can be an interface configured according to standards specified in the communication protocol for network connection communication.

[0178] In this embodiment, the specific functions and effects implemented by the program instructions stored in the computer storage medium can be explained in comparison with other implementation methods, and will not be repeated here.

[0179] While this specification provides the steps of operation for the methods described in the embodiments or flowcharts, more or fewer steps may be included based on conventional or non-inventive means. The order of steps listed in the embodiments is merely one possible order of execution among many steps and does not represent the only possible order. In actual device or client product execution, the methods shown in the embodiments or drawings may be executed sequentially or in parallel (e.g., in a parallel processor or multi-threaded processing environment, or even a distributed data processing environment). The terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, product, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, product, or apparatus. Without further limitations, the presence of other identical or equivalent elements in a process, method, product, or apparatus that includes said elements is not excluded. The terms "first," "second," etc., are used to denote names and do not indicate any particular order.

[0180] Those skilled in the art will also know that, besides implementing the controller using purely computer-readable program code, the same functions can be achieved by logically programming the method steps, making the controller function as logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers (PLCs), and embedded microcontrollers. Therefore, such a controller can be considered a hardware component, and the devices within it used to implement various functions can also be considered structures within that hardware component. Alternatively, the devices used to implement various functions can be considered as both software modules implementing the method and structures within a hardware component.

[0181] This specification can be described in the general context of computer-executable instructions that are executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc., that perform a specific task or implement a specific abstract data type. This specification can also be practiced in distributed computing environments, where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0182] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this specification can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions of this specification can essentially be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, mobile terminal, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments of this specification.

[0183] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. This specification can be used in numerous general-purpose or special-purpose computer system environments or configurations. Examples include: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable electronic devices, network PCs, minicomputers, mainframe computers, and distributed computing environments including any of the above systems or devices, etc.

[0184] Although this specification has been described by way of examples, those skilled in the art will recognize that many variations of this specification are possible without departing from its spirit, and it is intended that the appended claims cover such variations without departing from the spirit of this specification.

Claims

1. A method for identifying normal faults in compressional basins, characterized in that, include: Based on the three-dimensional seismic data volume after stratigraphic calibration within the compressional basin, a spatial distribution pattern of regional reverse faults is constructed, which is used to determine the main strike of regional reverse faults. In the context of a compressional basin under a compressive-torsional stress field, stress decomposition is performed on the pre-obtained regional maximum principal compressive stress to obtain tensile stress components parallel to the main strike, which serve as the preferred direction for normal fault identification. In the three-dimensional seismic data volume after the layer calibration, an initial seismic profile with an azimuth parallel to the preferred direction is selected, and a series of scan profiles are generated by performing small-interval translational scans and / or small-angle rotational scans on the initial seismic profile. On the series of scanning profiles, the target location of the fault is located, and at the target location, it is determined whether the hanging wall strata have shifted downward relative to the footwall strata. If so, the fault is identified as a normal fault.

2. The method according to claim 1, characterized in that, The method further includes: The acquired post-stack 3D seismic data is loaded into the target work area of ​​the squeeze basin, and the post-stack 3D seismic data in the target work area is subjected to frequency division reconstruction processing to obtain the reconstructed 3D seismic data volume. Based on well logging interpretation data within the target work area, the reconstructed 3D seismic data volume is subjected to stratigraphic calibration to obtain the stratigraphically calibrated 3D seismic data volume.

3. The method according to claim 1, characterized in that, The spatial distribution pattern of regional reverse faults is constructed based on the three-dimensional seismic data volume after stratigraphic calibration within the compressional basin, including: Identify and interpret regional reverse faults in the three-dimensional seismic data volume after stratigraphic calibration within the compressional basin; Based on the identification and interpretation results of regional reverse faults, the spatial distribution pattern of regional reverse faults is constructed. The spatial distribution pattern is used to determine the main strike of regional reverse faults, including: A statistical analysis was conducted on the strike of all regional reverse faults in the spatial distribution pattern of regional reverse faults. Based on the results of the statistical analysis, the dominant development direction was selected from the strikes of all regional reverse faults as the main strike.

4. The method according to claim 1, characterized in that, The stress decomposition of the pre-obtained regional maximum principal compressive stress in a compressional basin under a compressive-torsional stress field includes: In the context of a compressional basin under a compressive-torsional stress field, determine the angle between the maximum principal compressive stress and the main strike in the region; Based on the included angle, stress decomposition is performed on the maximum principal compressive stress in the region to obtain the tensile stress component parallel to the main direction.

5. The method according to claim 1, characterized in that, The process of performing small-interval translational scanning and / or small-angle rotational scanning on the initial seismic profile includes: Perform small-interval translational scanning on the initial seismic profile to generate a series of moved profiles; For each of the series of moved profiles, a small-angle rotation scan is performed to generate a series of scan profiles.

6. The method according to claim 1, characterized in that, Locating the target location of the fault on the series of scanning profiles includes: On the series of scanning profiles, by comparing and analyzing the reflection termination and / or cross-sectional wave anomaly characteristics of the reflection phase axis, the spatial location of the fault is located as the target location. The determination of whether the hanging wall strata have shifted downward relative to the footwall strata at the target location includes: Select a target seismic profile with a resolution greater than a preset resolution threshold at the target location, and identify the target reflection phase axis corresponding to a specific geological stratum that crosses the fault and has been labeled from the target seismic profile; Determine whether the target reflection phase axis located in the hanging wall strata has shifted downward relative to the same target reflection phase axis located in the footwall strata. If so, determine whether the hanging wall strata have shifted downward relative to the footwall strata.

7. The method according to claim 1, characterized in that, The method further includes: In different structural locations within the target work area of ​​the compressional basin, the steps of selecting an initial seismic profile with an orientation parallel to the preferred direction, performing scanning, positioning, and identification are repeated until the entire target work area is scanned and normal faults are identified.

8. A device for identifying normal faults in a compressional basin, characterized in that, include: A construction module is used to construct the spatial distribution pattern of regional reverse faults based on the three-dimensional seismic data volume after the stratigraphic calibration within the compressional basin. The spatial distribution pattern is used to determine the main strike of the regional reverse faults. The stress decomposition module is used to decompose the pre-acquired regional maximum principal compressive stress in the context of a compressional basin under a compressive-torsional stress field, and obtain the tensile stress component parallel to the main strike, which is used as the preferred direction for normal fault identification. The scanning module is used to select an initial seismic profile with an azimuth parallel to the preferred direction in the three-dimensional seismic data volume after the layer calibration, and to perform small-interval translational scanning and / or small-angle rotational scanning on the initial seismic profile to generate a series of scanning profiles. The identification module is used to locate the target position of the fault on the series of scanning profiles, and at the target position, determine whether the hanging wall strata have shifted downward relative to the footwall strata. If so, the fault is identified as a normal fault.

9. An electronic device, characterized in that, include: A memory and a processor, the processor and the memory being communicatively connected to each other, the memory storing computer instructions, the processor executing the computer instructions to implement the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having computer program instructions stored thereon, characterized in that, When the computer program instructions are executed by the processor, they implement the steps of the method according to any one of claims 1 to 7.

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