Method for analyzing fault activity time based on seismic section

Abstract

The invention discloses a method for analyzing fault activity time based on a seismic section, which belongs to the technical field of petroleum geological exploration, and is characterized by comprising the following steps of: a, establishing a fault structure geometric model; b, fitting analysis is carried out based on geometric features of geologic horizon, encryption is carried out between the geologic horizon, all seismic wave crest and wave trough interfaces of upper and lower walls around a fault are explained, and a geometric model of the fault structure is refined; c, selecting a reference surface, and measuring the residual area generated by stratum deformation in the geometric model of the fault structure and the height from the stratum to the reference surface; d, establishing a coordinate system, and projecting depth and area data of all stratums in the geometric model of the fault structure to a depth-area map; and e, judging whether the fault is an early active fault or a later active fault through depth-area map analysis. According to the method, the fault activity time can be accurately judged based on fine interpretation and quantitative analysis of the three-dimensional seismic data.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum geological exploration, and in particular to a method for analyzing fault activity time based on seismic profiles. Background Art

[0002] Accurately determining the deformation time and period of basin structure is a difficult problem in regional structural geology research. Basin-mountain coupling zones are hot spots in current geological research because they are closely related to earthquakes and resource exploration. Under the continuous influence of interplate activities, these areas often experience multiple periods of structural deformation in the history of geological evolution, forming relatively complex structures.

[0003] The structural geometry analysis to study the time and period of structural deformation is mainly carried out in the following ways: 1. It is judged by fault-displaced strata, the contact relationship between faults and faults, and stratigraphic unconformity, but the upper and lower limits of deformation time are relatively broad and inaccurate. 2. The determination of tectonic growth strata can accurately obtain the upper and lower limits of tectonic deformation, and further explore the kinematic mechanism of tectonic deformation. However, if the quality of seismic data is limited or the tectonic deformation is relatively weak, it will be difficult to identify obvious growth strata, and it will be difficult to constrain the time and period of tectonic deformation based on this method.

[0004] A Chinese patent document with publication number CN115616663A and publication date January 17, 2023 discloses a method for determining the start time of a strike-slip fault, comprising the following steps: S1: Analyze the three-dimensional data volume of the strike-slip fault to obtain the interpretation grid of each layer; S2: Interpretation based on strike-slip faults based on coherent body attributes; S3: Select the layers with obvious folds on the seismic section; S4: Make a structural map of the obvious fold layers; S5: Identify folds based on depth contours on structural maps; S6: Calculate the strike direction of each fold axis and the angle between the fold strike and the strike-slip fault; S7: Determine the type of wrinkles; S8: Sorting out the horizons where the overlapping phenomenon of oblique fold strata occurs; S9: Determine when the strike-slip fault begins to become active.

[0005] The method disclosed in the patent document for determining the start time of a strike-slip fault is based on the interpretation of faults and strata, and the related folds of the strike-slip fault are analyzed. The formation time of the oblique folds of the strike-slip fault is used to determine the start time of the strike-slip fault. The analysis method is simple. However, the accuracy of determining the fault activity time is poor. Summary of the invention

[0006] In order to overcome the defects of the above-mentioned prior art, the present invention provides a method for analyzing fault activity time based on seismic profile. The present invention is based on the detailed interpretation and quantitative analysis of three-dimensional seismic data and can more accurately determine the fault activity time.

[0007] The present invention is achieved through the following technical solutions: A method for analyzing fault activity time based on seismic profiles, characterized by comprising the following steps: a. Select the seismic section of the fault center that is perpendicular to the fault in the 3D seismic work area, complete the fault interpretation work, and establish the fault structure geometric model; b. Fitting analysis is performed based on the geometric characteristics of geological layers, encryption is performed between geological layers, all seismic peaks and trough interfaces around the upper and lower plates of the fault are interpreted, and a fine fault structural geometric model is constructed; c. Select a reference surface and measure the residual area caused by stratum deformation in the fault structure geometric model and the height of the stratum from the reference surface; d. Establish a coordinate system and project the depth and area data of all strata in the fault structure geometric model onto the depth-area map; e. Determine whether the fault is an early active fault or a late active fault through depth-area map analysis.

[0008] In step a, the fault interpretation work specifically refers to completing the interpretation of the target fault geological layer according to the drilling layer calibration and three-dimensional seismic layer tracking in the three-dimensional work area, and constructing the geometric characteristics of the fault through isopiped domain analysis.

[0009] In the step b, the fine fault structure geometric model refers to determining the number of geological layers used for fitting analysis.

[0010] The geological layers used for fitting analysis are 10-30 layers.

[0011] In the step c, selecting a reference surface refers to determining and identifying the position of a deformed detachment layer in the fault structure geometric model, and selecting the detachment layer as a reference surface.

[0012] In the step c, measuring the residual area caused by stratum deformation in the fault structure geometric model specifically refers to measuring by determining the sedimentary interface.

[0013] In step d, establishing a coordinate system means taking the height difference h from the reference surface as n is the horizontal axis, and the remaining area S of each stratum n Establish the vertical axis.

[0014] In the step e, the determination of an early active fault specifically refers to that if all stratigraphic data in the fault structure geometric model are fitted as a non-linear line in the depth-area map and there is an inflection point, it is determined to be an early active fault.

[0015] In the step e, the determination of a late active fault specifically refers to when all stratigraphic data in the fault structure geometric model are fitted into a straight line in the depth-area map, it is determined to be a late active fault.

[0016] In the step e, the start time of the early active fault is the deposition time of the stratum where the inflection point data is located.

[0017] The basic principles of the present invention are as follows: Through detailed interpretation of seismic profiles, a complete geological model of strata and faults is constructed. Digital measurement and analysis of strata caused by fault activity is carried out to establish a depth-area map. Through the map analysis, it is determined whether the fault is an early active fault or a late active fault, and the time when the fault began to be active is accurately determined. Since it does not involve the rock mechanical properties, deformation kinematic mechanism and evolution history of the structure under study, it is not necessary to follow the conservation of layer length and layer thickness, only the conservation of area is required; there is no need to perform prior structural balance restoration before analysis and calculation. Therefore, compared with the human eye based on geological experience observation and judgment, the accuracy and resolution have been greatly improved, which effectively overcomes the defects of the existing technology and can more easily judge the activity time of the fault.

[0018] The beneficial effects of the present invention are mainly manifested in the following aspects: 1. The present invention, a. selects a seismic profile of a normal fault layer at the center of a fault in a three-dimensional seismic work area, completes fault interpretation, and establishes a fault structure geometric model; b. performs fitting analysis based on the geometric characteristics of geological strata, performs encryption between geological strata, interprets all seismic wave peaks and trough interfaces around the upper and lower plates of the fault, and refines the fault structure geometric model; c. selects a reference surface, measures the residual area generated by stratum deformation in the fault structure geometric model and the height of the stratum from the reference surface; d. establishes a coordinate system, and projects the depth and area data of all strata in the fault structure geometric model onto a depth-area map; e. determines whether the fault is an early active fault or a late active fault through depth-area map analysis. As a complete technical solution, compared with the prior art, the fine interpretation and quantitative analysis of three-dimensional seismic data can more accurately determine the time of fault activity.

[0019] 2. The present invention greatly improves the operability and accuracy of fault activity time judgment by constructing a detailed interpretation, selecting a stratigraphic reference surface, measuring the stratigraphic depth and the remaining area, and establishing a depth-area map.

[0020] 3. The present invention is suitable for structural geometry modeling, structural evolution analysis and oil and gas reservoir analysis matching, and has good applicability.

[0021] 4. The present invention has low data requirements and does not require a complete structural model of the region. It only requires geological layers with good reflection in the grid profile, making the processing simpler and more efficient.

[0022] 5. The present invention has a simple and friendly implementation process, a small workload, and a fast speed for seismic profile interpretation and depth area mapping. It does not require structural restoration or sampling operations and can be completed quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 It is a flowchart of the present invention; Figure 2 This is a seismic interpretation diagram of two fault sections in the Permian System of the Sichuan Basin; Figure 3 for Figure 2 The depth-area maps of the two profiles in the middle. The left map is an early active fault with an inflection point in the map; the right map is a later active fault with a linear correlation in the map. DETAILED DESCRIPTION

[0024] Example 1 See also Figure 1 , a method for analyzing fault activity time based on seismic profiles, comprising the following steps: a. Select the seismic section of the fault center that is perpendicular to the fault in the 3D seismic work area, complete the fault interpretation work, and establish the fault structure geometric model; b. Fitting analysis is performed based on the geometric characteristics of geological layers, encryption is performed between geological layers, all seismic peaks and trough interfaces around the upper and lower plates of the fault are interpreted, and a fine fault structural geometric model is constructed; c. Select a reference surface and measure the residual area caused by stratum deformation in the fault structure geometric model and the height of the stratum from the reference surface; d. Establish a coordinate system and project the depth and area data of all strata in the fault structure geometric model onto the depth-area map; e. Determine whether the fault is an early active fault or a late active fault through depth-area map analysis.

[0025] This embodiment is the most basic implementation method, a. Select the seismic profile of the fault center position positive fault layer in the three-dimensional seismic work area, complete the fault interpretation work, and establish the fault structure geometric model; b. Perform fitting analysis based on the geometric characteristics of the geological strata, encrypt between the geological strata, interpret all seismic wave peaks and trough interfaces around the fault and the upper and lower plates, and refine the fault structure geometric model; c. Select a reference surface, measure the residual area generated by the stratum deformation in the fault structure geometric model and the height of the stratum from the reference surface; d. Establish a coordinate system, and project the depth and area data of all strata in the fault structure geometric model onto the depth-area map; e. Determine whether the fault is an early active fault or a late active fault through depth-area map analysis. As a complete technical solution, compared with the existing technology, based on the detailed interpretation and quantitative analysis of three-dimensional seismic data, it can more accurately determine the time of fault activity.

[0026] Example 2 See also Figure 1 , a method for analyzing fault activity time based on seismic profiles, comprising the following steps: a. Select the seismic section of the fault center that is perpendicular to the fault in the 3D seismic work area, complete the fault interpretation work, and establish the fault structure geometric model; b. Fitting analysis is performed based on the geometric characteristics of geological layers, encryption is performed between geological layers, all seismic peaks and trough interfaces around the upper and lower plates of the fault are interpreted, and a fine fault structural geometric model is constructed; c. Select a reference surface and measure the residual area caused by stratum deformation in the fault structure geometric model and the height of the stratum from the reference surface; d. Establish a coordinate system and project the depth and area data of all strata in the fault structure geometric model onto the depth-area map; e. Determine whether the fault is an early active fault or a late active fault through depth-area map analysis.

[0027] In step a, the fault interpretation work specifically refers to completing the interpretation of the target fault geological layer according to the drilling layer calibration and three-dimensional seismic layer tracking in the three-dimensional work area, and constructing the geometric characteristics of the fault through isopiped domain analysis.

[0028] This embodiment is a preferred implementation method, which greatly improves the operability and accuracy of fault activity time judgment by constructing a detailed interpretation, selecting a stratigraphic reference surface, measuring the stratigraphic depth and remaining area, and establishing a depth-area map.

[0029] Example 3 See also Figure 1 , a method for analyzing fault activity time based on seismic profiles, comprising the following steps: a. Select the seismic section of the fault center that is perpendicular to the fault in the 3D seismic work area, complete the fault interpretation work, and establish the fault structure geometric model; b. Fitting analysis is performed based on the geometric characteristics of geological layers, encryption is performed between geological layers, all seismic peaks and trough interfaces around the upper and lower plates of the fault are interpreted, and a fine fault structural geometric model is constructed; c. Select a reference surface and measure the residual area caused by stratum deformation in the fault structure geometric model and the height of the stratum from the reference surface; d. Establish a coordinate system and project the depth and area data of all strata in the fault structure geometric model onto the depth-area map; e. Determine whether the fault is an early active fault or a late active fault through depth-area map analysis.

[0030] In step a, the fault interpretation work specifically refers to completing the interpretation of the target fault geological layer according to the drilling layer calibration and three-dimensional seismic layer tracking in the three-dimensional work area, and constructing the geometric characteristics of the fault through isopiped domain analysis.

[0031] Furthermore, in step b, the fine fault structure geometric model refers to determining the number of geological strata used for fitting analysis.

[0032] The geological layers used for fitting analysis are 10 layers.

[0033] This embodiment is another preferred implementation method, which is suitable for structural geometry modeling, structural evolution analysis and oil and gas reservoir analysis matching, and has good applicability.

[0034] Example 4 See also Figure 1 , a method for analyzing fault activity time based on seismic profiles, comprising the following steps: a. Select the seismic section of the fault center that is perpendicular to the fault in the 3D seismic work area, complete the fault interpretation work, and establish the fault structure geometric model; b. Fitting analysis is performed based on the geometric characteristics of geological layers, encryption is performed between geological layers, all seismic peaks and trough interfaces around the upper and lower plates of the fault are interpreted, and a fine fault structural geometric model is constructed; c. Select a reference surface and measure the residual area caused by stratum deformation in the fault structure geometric model and the height of the stratum from the reference surface; d. Establish a coordinate system and project the depth and area data of all strata in the fault structure geometric model onto the depth-area map; e. Determine whether the fault is an early active fault or a late active fault through depth-area map analysis.

[0035] In step a, the fault interpretation work specifically refers to completing the interpretation of the target fault geological layer according to the drilling layer calibration and three-dimensional seismic layer tracking in the three-dimensional work area, and constructing the geometric characteristics of the fault through isopiped domain analysis.

[0036] In the step b, the fine fault structure geometric model refers to determining the number of geological layers used for fitting analysis.

[0037] The geological layers used for fitting analysis are 20 layers.

[0038] Furthermore, in the step c, selecting a reference surface refers to determining and identifying the position of a deformed detachment layer in the fault structure geometric model, and selecting the detachment layer as a reference surface.

[0039] In the step c, measuring the residual area caused by stratum deformation in the fault structure geometric model specifically refers to measuring by determining the sedimentary interface.

[0040] In step d, establishing a coordinate system means taking the height difference h from the reference surface as n is the horizontal axis, and the remaining area S of each stratum n Establish the vertical axis.

[0041] This embodiment is another preferred implementation method, which has low data requirements and does not require a complete structural model of the region. It only requires geological layers with good reflections in the grid profile, making the processing simpler and more efficient.

[0042] Example 5 See also Figure 1-Figure 3 , a method for analyzing fault activity time based on seismic profiles, comprising the following steps: a. Select the seismic section of the fault center that is perpendicular to the fault in the 3D seismic work area, complete the fault interpretation work, and establish the fault structure geometric model; b. Fitting analysis is performed based on the geometric characteristics of geological layers, encryption is performed between geological layers, all seismic peaks and trough interfaces around the upper and lower plates of the fault are interpreted, and a fine fault structural geometric model is constructed; c. Select a reference surface and measure the residual area caused by stratum deformation in the fault structure geometric model and the height of the stratum from the reference surface; d. Establish a coordinate system and project the depth and area data of all strata in the fault structure geometric model onto the depth-area map; e. Determine whether the fault is an early active fault or a late active fault through depth-area map analysis.

[0043] In step a, the fault interpretation work specifically refers to completing the interpretation of the target fault geological layer according to the drilling layer calibration and three-dimensional seismic layer tracking in the three-dimensional work area, and constructing the geometric characteristics of the fault through isopiped domain analysis.

[0044] In the step b, the fine fault structure geometric model refers to determining the number of geological layers used for fitting analysis.

[0045] The geological layers used for fitting analysis are 30 layers.

[0046] In the step c, selecting a reference surface refers to determining and identifying the position of a deformed detachment layer in the fault structure geometric model, and selecting the detachment layer as a reference surface.

[0047] In the step c, measuring the residual area caused by stratum deformation in the fault structure geometric model specifically refers to measuring by determining the sedimentary interface.

[0048] In step d, establishing a coordinate system means taking the height difference h from the reference surface as n is the horizontal axis, and the remaining area S of each stratum n Establish the vertical axis.

[0049] In the step e, the determination of an early active fault specifically refers to that if all stratigraphic data in the fault structure geometric model are fitted as a non-linear line in the depth-area map and there is an inflection point, it is determined to be an early active fault.

[0050] In the step e, the determination of a late active fault specifically refers to when all stratigraphic data in the fault structure geometric model are fitted into a straight line in the depth-area map, it is determined to be a late active fault.

[0051] In the step e, the start time of the early active fault is the deposition time of the stratum where the inflection point data is located.

[0052] This embodiment is the best implementation method, the implementation process is simple and friendly, the workload is small, the seismic profile interpretation and depth area mapping are fast, no structural recovery or sampling operations are required, and the completion speed is fast.

[0053] The principle of analyzing the depth-area map characteristics and determining the fault activity time is as follows: The depth-area map has two different typical characteristics: First, all the layers in the fault structure geometry model belong to the pre-growth strata, that is, the fault and folding occurred after the deposition of all the strata in the fault structure geometry model, so all the strata have experienced the same structural shortening D, and the residual area of ​​each layer satisfies S n =D*h n , the remaining area S of different strata n and height difference from reference surface h nLinear correlation, so all stratigraphic data in the fault structural geometry model are fitted into a straight line in the depth-area map, and the slope is the structural shortening D. Therefore, the linear depth-area map characterizes that the fault is active in the later period, that is, after all the strata in the fault structural geometry model are deposited; secondly, there are growing strata in the fault structural geometry model, that is, some strata are deposited during the deformation of faults and folds, indicating that at the beginning of the fault activity, some strata in the fault structural geometry model have not yet been deposited. Therefore, the structural shortening D in the fault structural geometry model is no longer the same value. The newer the strata, the shorter the deformation time, the smaller the structural shortening D, and the remaining area S n =D*h n In this case, the data fitting of all strata in the fault structure geometry model in the depth-area spectrum is no longer a straight line, and there will be an inflection point at a certain position, indicating the decrease of the structural shortening D, and also representing the beginning of fault activity. Therefore, if the depth-area spectrum of the fault structure geometry model is not a straight line, it indicates that the fault is an early active fault, and the time when it began to be active is the time when the stratum where the inflection point data is located is deposited.

Claims

1. A method for analyzing fault activity time based on seismic profiles, characterized in that: The following steps are involved: a. Select the seismic section of the fault center that is perpendicular to the fault in the 3D seismic work area, complete the fault interpretation work, and establish the fault structure geometric model; b. Fitting analysis is performed based on the geometric characteristics of geological layers, encryption is performed between geological layers, all seismic peaks and trough interfaces around the upper and lower plates of the fault are interpreted, and a fine fault structure geometric model is constructed; c. Select a reference surface and measure the residual area caused by stratum deformation in the fault structure geometric model and the height of the stratum from the reference surface; d. Establish a coordinate system and project the depth and area data of all strata in the fault structure geometric model onto the depth-area map; e. Determine whether the fault is an early active fault or a late active fault through depth-area map analysis.

2. The method for analyzing fault activity time based on seismic profile according to claim 1, characterized in that: In step a, the fault interpretation work specifically refers to completing the interpretation of the target fault geological layer according to the drilling layer calibration and three-dimensional seismic layer tracking in the three-dimensional work area, and constructing the geometric characteristics of the fault through isopiped domain analysis.

3. The method for analyzing fault activity time based on seismic profile according to claim 1, characterized in that: In the step b, the fine fault structure geometric model refers to determining the number of geological layers used for fitting analysis.

4. The method for analyzing fault activity time based on seismic profile according to claim 3, characterized in that: The geological layers used for fitting analysis are 10-30 layers.

5. The method for analyzing fault activity time based on seismic profile according to claim 1, characterized in that: In the step c, selecting a reference surface refers to determining and identifying the position of a deformed detachment layer in the fault structure geometric model, and selecting the detachment layer as a reference surface.

6. The method for analyzing fault activity time based on seismic profile according to claim 1, characterized in that: In the step c, measuring the residual area caused by stratum deformation in the fault structure geometric model specifically refers to measuring by determining the sedimentary interface.

7. The method for analyzing fault activity time based on seismic profile according to claim 1, characterized in that: In step d, establishing a coordinate system means taking the height difference h from the reference surface as n is the horizontal axis, and the remaining area S of each stratum n Establish the vertical axis.

8. The method for analyzing fault activity time based on seismic profile according to claim 1, characterized in that: In the step e, the determination of an early active fault specifically refers to that if all stratigraphic data in the fault structure geometric model are fitted as a non-linear line in the depth-area map and there is an inflection point, it is determined to be an early active fault.

9. The method for analyzing fault activity time based on seismic profile according to claim 1, characterized in that: In the step e, the determination of a late active fault specifically refers to when all stratigraphic data in the fault structure geometric model are fitted into a straight line in the depth-area map, it is determined to be a late active fault.

10. The method for analyzing fault activity time based on seismic profile according to claim 8, characterized in that: In the step e, the start time of the early active fault is the deposition time of the stratum where the inflection point data is located.

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