Complex strike-slip fault structure modeling method and application

Abstract

The invention belongs to the field of oil and gas field exploration, and discloses a structure modeling method based on a complex strike-slip fault. A strike-slip fault of a time slice before construction guiding filtering processing is represented as a long-strip-shaped area with a certain width and disordered reflection, fusion body attributes are obtained based on coherent body attributes and seismic data bodies after construction guiding filtering, matching work of a complex strike-slip fault space lap joint relation is carried out, and construction modeling is completed. And constructing a modeling method to deconstruct a complex fault system. The method is applied to Jilin oil field fault system deconstruction.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas field exploration and relates to a structural modeling method and application of a complex strike-slip fault. Background Art

[0002] A strike-slip fault is a fault whose main movement feature is relative strike-slip displacement between two fault blocks. It can be divided into right-lateral strike-slip faults and left-lateral strike-slip faults according to the direction of mutual movement. In the process of mutual movement, the shape of the strata above the strike-slip fault will change, and the nearby structure close to the displacement vector is called a strike-slip structure. In oil and gas geological exploration work, it can be divided into five levels: plate level, basin level, zone level, trap level and microscopic level. Among them, the strike-slip structure of the Fushuang fault is zone level, which affects the formation of secondary structural belts in the basin.

[0003] The Fushuangda (Fulongquan, Shuangtuozi, and Dalaoyefu structures) area is located in the eastern uplift zone of the Changling fault depression in the southern Songliao Basin. It is bordered by the Huazijing terrace to the west, the Diaoyutai uplift to the east, and the Lishu fault depression to the south. It is located on the Chaoyanggou-Changchunling-Denglouku-Fulongquan anticline belt with a strong inversion. It is a key area for the efficient exploration and development of deep natural gas in Jilin Oilfield. The entire exploration area is about 2000km 2 . After experiencing multiple structural deformations, a complex fault system has been formed. The faults are mainly distributed in the north-south, northeast and northwest directions. Most of them have experienced multiple activities. The same structural deformation stage can form faults in multiple directions. The deformation properties and deformation characteristics of different sections of the same fault are also different. It is the most favorable and profitable exploration zone for Songnan hydrocarbon-generating depressions and structural configuration conditions. It is also the key production block for deep natural gas in the past two years.

[0004] Due to the complexity of strike-slip fault development zones, such as many faults, rapid changes in cross-section and stratigraphic dips, the different positions of strike-slip faults on seismic sections, the profile and plane morphology of the faults, and the stratigraphic occurrences on both wings of the faults are different. The stratigraphic continuity and traceability are relatively poor, which brings multiple solutions to the artificial interactive interpretation based on seismic sections. At the same time, the relatively dense feather-shaped faults and fold belts further increase the difficulty of fault interpretation and identification of related closures. The fault system plays an important role in the migration of oil and gas in the depression. Oil and gas usually migrate along the faults. The main strike-slip faults of compression and torsion have a blocking effect on the migration of oil and gas, while the associated tensile faults are the main channels for oil and gas migration. The strike-slip faults in the northeast and near north-south directions are mostly vertically cut with the compression faults in the near east-west directions, resulting in a structural pattern of north-south zoning and east-west division. Strike-slip fault zones are mostly distributed along the direction of oil and gas migration and accumulation, and are easy to form channels for oil and gas migration. Thrust fault zones perpendicular to the direction of oil and gas are favorable areas for oil and gas accumulation, and are easy to form zones and blocks for oil and gas accumulation. Since strike-slip structural belts can effectively transform reservoirs and form compression-torsion closures, they are superior in oil and gas migration and accumulation, and can also form favorable accumulation zones and cause linear distribution of oil and gas. A structural modeling method is urgently needed to deconstruct its complex fault system. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a structural modeling method and application of complex strike-slip faults, the structural modeling method deconstructs complex fault systems, and is applied to the deconstruction of the fault system in Jilin Oilfield.

[0006] The above object of the present invention is achieved through the following technical solutions:

[0007] A structural modeling method based on complex strike-slip faults, the method comprising the following steps:

[0008] (1) Using 3D seismic interpretation, the stratigraphic interpretation of the strata on both sides of the strike-slip fault is realized on the seismic section, and the characteristics of the strike-slip fault section are clarified;

[0009] (2) Using 3D seismic data, make time slices along each stratum;

[0010] (3) Start the structural guidance filtering process. First, conduct guidance analysis, that is, scan and calculate the dip and azimuth information of the data body. Guidance analysis is the key to structural guidance filtering. For strike-slip fault zones, where faults are well developed and the formation dip changes rapidly, the dip body parameters greater than 45 degrees are used for calculation;

[0011] (4) Edge detection processing is the process of detecting and identifying the reflection termination of the seismic reflection event axis;

[0012] (5) Edge preservation guided smoothing filtering;

[0013] (6) The coherence volume and curvature volume have different recognition capabilities for faults with different shapes on the cross section. Faults with bending and slight distortion on the cross section are easy to distinguish on the curvature attribute map; when the fault shows obvious syncline misalignment, the strata on both sides of the fault have no bending deformation, which can be clearly identified on the coherence volume. Considering the misalignment characteristics of the strike-slip fault and the three-dimensional data volume after structural guidance filtering, the breakpoint section is clearer, and the interpretation of the strike-slip fault zone is mainly based on the coherence volume processing technology;

[0014] (7) Match the spatial overlap relationship of complex strike-slip faults to complete structural modeling.

[0015] The geophysical auxiliary interpretation of complex strike-slip faults mainly includes filtering processing to improve the signal-to-noise ratio of seismic data, extraction of fault attributes (coherence volume, dip volume, curvature volume, etc.) based on high signal-to-noise ratio data, image enhancement processing and fault detection technology, and fusion technology of fault attribute volume and seismic data volume.

[0016] The structural guidance filtering technology is a special denoising method for post-stack seismic data. The key to this method is to add the seismic reflection dip, azimuth control and lateral continuity judgment functions during the processing, so as to maintain the discontinuous characteristics while increasing the signal-to-noise ratio of the seismic data. This method only smoothes the information parallel to the seismic event axis, and does not smooth the information perpendicular to the seismic event axis. No smoothing operation will be performed at the end of the reflection of the seismic event axis. Therefore, this filtering method fully maintains the characteristics of the fault and lithology boundary while smoothing the continuous event axis. The volume attributes of fault identification using three-dimensional seismic data volumes mainly include dip data volume, coherence volume, curvature volume, etc. The coherence volume attribute is the first-order derivative of the seismic data volume and is a discontinuous attribute calculation method. The algorithm includes eigenvalue coherence, similarity coherence, edge detection, etc. Curvature is a two-dimensional feature of a curve, which describes the degree of curvature of a point on the curve. For a specific point on a curve, the curvature is defined as the rate of change along the curve direction. The curvature attribute with smoothing effect has a good characterization of the small flexural faults on the seismic section. Due to the difference in algorithms, the coherence body and the curvature body have different recognition capabilities for faults with different shapes on the section. Faults with flexure and slight distortion on the section are easy to distinguish on the curvature attribute map; when the fault shows obvious syncline faulting, there is no flexural deformation on both sides of the fault, which can be clearly identified on the coherence body. Considering the fault characteristics of the strike-slip fault and the three-dimensional data body after the structural guidance filter, the breakpoint section is clearer.

[0017] On the time slice of the coherent volume after the structural guidance filtering, the noise is significantly suppressed, the trajectories of the main fault and the secondary goose-shaped fault are very clear, and the continuity of the fault blocks between the faults is also significantly improved. The main fault also presents a multi-segment feature; in order to better reflect the stratigraphic continuity between the fault system and its faults, the coherent volume attributes after the structural guidance filtering and the seismic data volume are combined to obtain the fusion volume attributes. In the fusion volume attributes, the diamond-shaped fault block, fault trajectory, and stratigraphic orientation between faults are very clear, which is very conducive to the interpretation and combination of complex faults, and the distribution map of strike-slip faults after comprehensive interpretation is obtained. At the same time, the distribution characteristics of the spatial structural overlap relationship can be carried out.

[0018] The specific implementation of fault sign analysis and interpretation based on strike-slip fault zones shows that the structural guidance filtering technology and coherence volume processing technology can significantly improve the clarity of the section and the stratigraphic continuity between faults, providing convenience for profile interpretation and fault plane combination.

[0019] The beneficial effects of the present invention compared with the prior art are:

[0020] The present invention provides a geophysical interpretation structural modeling method based on complex strike-slip faults. The strike-slip faults in the time slice before the structural guidance filtering process are shown as long strips with a certain width and disorderly reflections, and there are no obvious traces of faults. Combined with the profile interpretation, the direction of a main strike-slip fault can be basically determined, but the specific position of the main fault is unclear; on the time slice after the conventional three-dimensional data coherence body processing, the overall outline of the strike-slip fault zone, including the main strike-slip fault and some branch faults, can be shown. However, due to the heavy noise, the characterization, combination and cutting relationship of the branch faults with the main fault are not very clear; on the time slice after the structural guidance filtering, the middle strip with disorderly reflections has attenuated noise, the image is clearer, and the obvious characteristics of the diamond-shaped plots can be seen. There are traces of faults at the junction of the diamond-shaped plots; on the coherence body time slice after the structural guidance filtering process, the noise is significantly suppressed, the trajectories of the main fault and the secondary goose-shaped fault are very clear, and the continuity of the fault blocks between the faults is also significantly improved. The main fault also presents a multi-segment feature; in order to better reflect the stratigraphic continuity between the fault system and its faults, the fusion body attributes are obtained based on the coherent body attributes and seismic data body after structural guidance filtering. In terms of the fusion body attributes, the diamond-shaped fault block, fault trajectory, and stratigraphic direction between faults are all very clear, which is very conducive to the interpretation and combination of complex faults.

[0021] The strike-slip fault zone plays an important role in controlling the transportation, accumulation and reservoir formation of oil and gas in the Fushuang area. On the one hand, the strike-slip fault, controlled by the torsional tectonic stress field, can derive structural closures such as secondary torsional fault blocks, flower-shaped structures, fault-bend folds and fault-propagation folds, becoming a favorable place for oil and gas accumulation; on the other hand, the fault itself connects the oil source layers of different strata and depths and plays a channel role in the migration of oil and gas. Strike-slip tension easily forms valleys, which is conducive to the formation of reservoirs. The fault zone is open and is conducive to fluid conduction. In the strike-slip compression zone, moderate torsional structures often appear in areas with large sedimentary thickness, while in areas with thin sedimentary thickness, relatively strong torsional structures often appear, which are easy to form ridges, which is not conducive to the formation of reservoirs. The fault zone is closed and is not conducive to fluid conduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present invention or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 Shown is a strike-slip structural style diagram of the Fushuang area in the example of the present invention;

[0024] Figure 2 The figure shows the multi-window scanning in the example of the present invention, and the window with the maximum similarity is used as the inclination angle of the analysis point;

[0025] Figure 3 Shown is a flow chart of constructing guided filtering in an example of the present invention;

[0026] Figure 4 The figure shows the cross-sectional view before and after the structure-guided filtering process in the example of the present invention.

[0027] Figure 5 The edge detection effect diagram in the example of the present invention is shown as follows

[0028] Figure 6 The schematic diagram of curvature calculation in the present invention is shown as follows

[0029] Figure 7 The maximum positive and negative curvature slices in the present invention are shown.

[0030] Figure 8 Shown are the coherent superimposed plan sections and pattern diagrams of strike-slip faults after structural guidance filtering in the examples of the present invention;

[0031] Fig. 9 Shown is a diagram of the structure modeling after the guided filtering in the example of the present invention. DETAILED DESCRIPTION

[0032] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0033] Example 1

[0034] The method in the embodiment is applied in the Fushuang area of ​​Jilin Oilfield.

[0035] A structural modeling method based on geophysical interpretation of complex strike-slip faults, comprising the following steps:

[0036] (1) Figure 1 As shown, by using 3D seismic fine interpretation, the stratigraphic interpretation of each stratum on both sides of the strike-slip fault is realized on the seismic section, and the section characteristics of the strike-slip fault are clarified;

[0037] (2) Using 3D seismic data, make time slices along each stratum;

[0038] (3) Start constructing the guided filtering process, such as Figure 2 As shown in Figure 1, firstly, the guidance analysis is performed, that is, by scanning and calculating the inclination and azimuth information of the data body, the guidance analysis is the key to constructing the guidance filter processing. Figure 4 As shown, for strike-slip fault zones with well-developed faults and fast changes in stratum dip, it is appropriate to use larger dip body parameters for calculation;

[0039] (4) Figure 5 As shown, edge detection processing is the process of detecting and identifying the reflection termination of the seismic reflection event axis;

[0040] (5) Edge preservation guided smoothing filtering;

[0041] (6) Figure 6 As shown in Figure 2, the coherence volume and curvature volume have different abilities to identify faults with different shapes on the cross section. Figure 7 Faults with bending and slight distortion in the cross section are easy to distinguish on the curvature attribute map; when the fault shows obvious phase axis dislocation, the strata on both sides of the fault have no bending deformation, which can be clearly identified on the coherence volume. Considering the dislocation characteristics of the strike-slip fault and the three-dimensional data volume after structural guidance filtering, the breakpoint section is clearer, such as Figure 8 As shown, this study mainly uses coherent volume processing technology to interpret strike-slip fault zones;

[0042] (7) Fig. 9 As shown in the figure, the spatial overlapping relationship of complex strike-slip faults is matched to complete the structural modeling.

[0043] Strike-slip faults and inversion structures are contemporaneous in regional stress, so the associated structural characteristics have similar control effects on gas reservoirs. The late strike-slip faults in the Jubaoshan strike-slip structural belt mainly play a destructive role on the primary gas reservoirs, resulting in gas reservoir characteristics similar to those of the inversion structural belt, which are characterized by vertical dispersion of gas reservoirs, multiple gas-bearing strata, small gas-bearing traps, and generally low gas saturation.

[0044] The above-established geophysical interpretation structural modeling method based on complex strike-slip faults reflects a messy middle strip on the time slice after structural guidance filtering, the noise is attenuated, the image is clearer, and the obvious diamond block features can be seen. There are traces of faults at the junction of the diamond blocks; on the coherent volume time slice after structural guidance filtering, the noise is significantly suppressed, the trajectories of the main fault and the secondary goose-shaped fault are very clear, and the continuity of the fault blocks between the faults is also significantly improved. The main fault also presents a multi-segment feature; in order to better reflect the stratigraphic continuity between the fault system and its faults, the coherent volume attributes after structural guidance filtering and the seismic data volume are combined to obtain the fusion volume attributes. In the fusion volume attributes, the diamond block, fault trajectory, and stratigraphic orientation between faults are all very clear, which is very conducive to the interpretation and combination of complex faults.

[0045] The strike-slip fault zone plays an important role in controlling the transportation, accumulation and reservoir formation of oil and gas in the Fushuang area. On the one hand, the strike-slip fault, controlled by the torsional tectonic stress field, can derive structural closures such as secondary torsional fault blocks, flower-shaped structures, fault-bend folds and fault-propagation folds, becoming a favorable place for oil and gas accumulation; on the other hand, the fault itself connects the oil source layers of different strata and depths and plays a channel role in the migration of oil and gas. The strike-slip tension zone is prone to form valleys, which is conducive to the formation of reservoirs, and the fault zone is open, which is conducive to fluid conduction; in the strike-slip compression zone, moderate torsional structures often appear in areas with large sedimentary thickness, while in areas with thin sedimentary thickness, relatively strong torsional structures often appear, which are easy to form ridges, which is not conducive to the formation of reservoirs, and the fault zone is closed, which is not conducive to fluid conduction. Comprehensive analysis of the geological characteristics of the strike-slip fault profile and the typical signs of the strike-slip fault is a prerequisite for accurate interpretation; the structural guidance filtering in the present invention can effectively smooth the continuity of the strata between faults, especially improve the regularity of the strike-slip fault zone, and highlight the clarity of the main fault and the feather fault; based on the seismic data body after structural guidance filtering, the coherent body fault attribute characterization and attribute fusion are carried out, which can effectively assist in describing the structural characteristics of the strike-slip fault system. The analysis of the strike-slip fault system and oil and gas reservoirs in the Fushuang area shows that the configuration of the strike-slip fault and the reservoir unit causes the block distribution of oil, gas and water. Due to the differences in the distribution of strike-slip faults, the differences in the configuration of faults and unconformities and reservoirs, relatively independent and different oil and gas migration and accumulation systems of Fu 19 Well, Fu 246 Well and Fu 14 Well are formed. In the same migration and accumulation system, the gas-oil ratio gradually decreases on the migration path close to the gas source fault, the early gas cap may be preserved in the upward direction, and the parts with less natural gas filling in the downdip low position are water. The gas and water in the same migration and accumulation unit are differentiated. In summary, strike-slip faults play an important role in controlling the distribution of oil and gas, and are an important factor in causing the block distribution of oil and gas. From the perspective of the current structure, the basin is low in the northwest and high in the southeast, and small-scale positive structures are developed locally, which is a favorable location for oil and gas accumulation. The southeastern part of the basin is an inherited nose-shaped structure, and the amplitude of the basement-Denglouku anticline gradually increases, which is the main migration direction of oil and gas convergence. It can be considered that the Fushuang area is the most favorable profitable exploration zone in the Songnan hydrocarbon-generating trough and structural configuration conditions.

[0046] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A structural modeling method for complex strike-slip faults, characterized in that: By slicing the strike-slip fault in time before the structural guidance filtering processing, it is shown as a long strip area with a certain width and messy reflection. Based on the coherent body attributes after the structural guidance filtering and the seismic data body, the fusion body attributes are obtained, and the spatial overlapping relationship of the complex strike-slip fault is matched to complete the structural modeling.

2. A structural modeling method for a complex strike-slip fault according to claim 1, characterized in that: The method comprises the following steps: (1) Using 3D seismic interpretation, the stratigraphic interpretation of the strata on both sides of the strike-slip fault is realized on the seismic profile, and the characteristics of the strike-slip fault profile are clarified; (2) Using 3D seismic data, make time slices along each stratum; (3) Start constructing guided filtering processing; (4) Edge detection processing is the process of detecting and identifying the reflection termination of the seismic reflection event axis; (5) Edge preservation guided smoothing filtering; (6) The coherence volume and curvature volume have different recognition capabilities for faults with different shapes on the cross section. Faults with bending and slight distortion on the cross section are easy to distinguish on the curvature attribute map; when the fault is manifested as obvious event axis dislocation, the strata on both sides of the fault have no bending deformation, which can be clearly identified on the coherence volume; considering the dislocation characteristics of the strike-slip fault and the three-dimensional data volume after structural guidance filtering, the breakpoint section is clearer, and the interpretation of the strike-slip fault zone is mainly based on the coherence volume processing technology; (7) Match the spatial overlap relationship of complex strike-slip faults to complete structural modeling.

3. A structural modeling method for a complex strike-slip fault according to claim 2, characterized in that: First, the guidance analysis is carried out, that is, by scanning and calculating the dip and azimuth information of the data body, the guidance analysis is the key to the structural guidance filtering process; for the strike-slip fault zone, the fault is well developed and the formation dip changes rapidly, and the dip body parameters greater than 45 degrees are used for calculation.

4. A structural modeling method for a complex strike-slip fault according to claim 2, characterized in that: Valleys are easily formed in strike-slip extensional zones, which is conducive to the formation of reservoirs.

5. A structural modeling method for a complex strike-slip fault according to claim 4, characterized in that: The fault zone is open, which is conducive to fluid transport.

6. A structural modeling method for a complex strike-slip fault according to claim 5, characterized in that: In the strike-slip compression zone, moderate torsional structures are more likely to appear in areas with thick sediments, while stronger torsional structures are more likely to appear in areas with thin sediments, which are prone to form ridges and are not conducive to reservoir formation.

7. A structural modeling method for a complex strike-slip fault according to claim 6, characterized in that: The fault zone is closed and not conducive to fluid transport.

8. Application of the structural modeling method of a complex strike-slip fault as claimed in claim 1 in the Fushuang area of ​​Jilin Oilfield.

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