Three-dimensional structure recovery rapid implementation method for eliminating structure abnormality

Abstract

The invention relates to a three-dimensional structure recovery rapid implementation method for eliminating structure anomalies, which belongs to the technical field of geological structure recovery in oil and gas field exploration, and comprises the following steps of: firstly, establishing a three-dimensional stratum fracture model based on an interpretation horizon and interpretation fracture of a target interval, and then decomposing the model into an L direction and an XL direction according to a seismic survey network; according to the method, two directions of the target interface are obtained, construction recovery is performed on the two directions respectively, and finally, recovery results of the two directions are synthesized to obtain a construction recovery result of the target interface, so that complete information of the stratum is reserved, the problem of construction abnormality is eliminated, and the accuracy and credibility of construction recovery are improved.

Description

Technical Field

[0001] The invention relates to the technical field of geological structure restoration in oil and gas field exploration, and in particular to a method for quickly realizing three-dimensional structure restoration for eliminating structural anomalies. Background Art

[0002] In the exploration of oil and gas fields where the accumulation conditions and oil-reservoir relationship are controlled by paleo-geomorphology, paleo-geomorphology plays a very important role and can qualitatively guide the distribution of oil and gas and reservoirs. Common paleo-geomorphology quantitative restoration methods mainly include the impression method and the residual thickness method. Both methods are obtained by interface subtraction and have good applicability to areas with few faults. However, in areas with large fault-throw faults, the strata on the upper and lower walls of the faults are often staggered and overlapped. The use of these two methods will cause obvious structural anomalies near the faults (see Appendix). Figure 2 ), which seriously affects the reliability of the paleo-geomorphological restoration results.

[0003] There are currently two main solutions to this problem:

[0004] (1) Simple excision method: The essential reason for the occurrence of structural anomalies is that faults cause the strata to slide along the cross section, resulting in the interlacing and overlapping of strata, which in turn leads to anomalies in the calculation of stratum thickness in the vertical direction. The simple excision method adopts the method of "excision first, then interpolation", first excises the interlaced and overlapping parts of the strata, flattens the strata, and then interpolates the missing areas, thereby avoiding structural anomalies (Cao Zhenmin, 2023; Zhang Pengfei, 2023).

[0005] (2) Balanced profile method: The balanced profile method is a technical method based on geometric principles (line length conservation, area conservation, and volume conservation) to restore structural deformation to a reasonable undeformed state, thereby eliminating the problems of stratigraphic interlacing and overlapping caused by the structure. It is currently the most accurate method for eliminating structural anomalies and has many application examples. The basic application idea of ​​this method is: select one or several typical profiles perpendicular to the structural trend; convert the profile into a two-dimensional model; perform structural restoration on the model and flatten the strata; finally, use the obtained balanced profile as the regional structural restoration result, or interpolate the three-dimensional paleogeomorphological results of the region through several such balanced profiles (Bao Hanyong, 2024; Han Yunjie, 2022; Fu Dongyang, 2020).

[0006] It is not difficult to see that the above two methods have technical problems: (1) Although the simple excision method is easy to implement, it cuts off the strata near the fault, and the subsequent interpolation results will inevitably differ from the original landforms, especially in areas with small dip angles and large fault throws. The structural restoration results have large errors, which is not conducive to the fine description of paleo-geomorphology; (2) The balanced profile method solves the structural anomaly problem from a geometric perspective, but this method is relatively computationally intensive and the calculation process is complex, which limits the application of this technology. At present, most examples of this method are applied to one or several two-dimensional typical profiles. Although some foreign commercial software has realized three-dimensional structural restoration, it also has the problems of complex calculation process and long calculation time, and lacks a fast implementation method for three-dimensional structural restoration. Summary of the invention

[0007] In view of the above technical problems, the present invention aims to invent a method for rapidly realizing three-dimensional structural restoration that eliminates structural anomalies based on the idea of ​​balanced profile technology, which can simplify the three-dimensional structural problem and realize rapid restoration of three-dimensional structure while ensuring the accuracy of paleo-geomorphological restoration. The method first establishes a three-dimensional stratigraphic fault model based on the interpreted horizon and interpreted fault of the target layer segment, then decomposes the model into the L direction and the XL direction according to the seismic network, and then performs structural restoration in the two directions respectively, and finally synthesizes the restoration results of the two directions to obtain the structural restoration (paleo-geomorphological restoration) result of the target interface.

[0008] The specific technical solutions are as follows:

[0009] S1, input the seismic horizons and faults interpreted in the time domain or depth domain;

[0010] S2, a three-dimensional stratigraphic fault model is established based on seismic layers and faults. During the modeling process: ① the seismic layers are moderately smoothed; ② some small faults are removed, and only faults with large horizontal fault throws are retained; ③ the interpretation of the layers near the faults is checked and adjusted appropriately to ensure that the layers are in contact with the faults without missing or exceeding the faults;

[0011] S3, decomposing the established fault model into the L direction and the XL direction, so that the three-dimensional model is converted into a series of two-dimensional section models consisting of layers and sections in these two directions;

[0012] S3, perform structural recovery in the L direction and select the first 2D section model according to the order of line numbers;

[0013] S4, determine the position and number of sections in the profile, and count the inclination of the sections, and take the direction with more inclination as the structural restoration calculation direction of the profile;

[0014] S5, project the target interface to the overlying stratum along the calculation direction. The projection process follows the following rules: ① The target stratum and its projection point must be on the same side of the section; ② Vertical projection is preferred, and the projection distance is recorded so that the target interface corresponds to the overlying stratum in the vertical direction; ③ When there is no corresponding vertical projection point, oblique projection is performed along the dip direction of the adjacent section, and the projection angle and distance are recorded at the projection point;

[0015] S6, flatten the overlying strata. While flattening the strata near the fault, move the upper wall of the fault horizontally so that the upper wall of the fault contacts the lower wall of the fault, without missing or exceeding the strata;

[0016] S7, according to the projection angle and projection distance recorded in the projection process, the target interface is back-projected based on the flattened overlying strata, so as to obtain the structural restoration result of the section;

[0017] S8, performing the above steps S4 to S7 for all two-dimensional sections in the L direction in the order of line numbers to obtain the structural restoration result in the L direction;

[0018] S9, repeat the recovery process of the L direction (S3-S8) for the XL direction to obtain the structural recovery result of the XL direction;

[0019] S10, integrating the structural restoration calculation results of the target interface in the L direction and the XL direction to obtain a three-dimensional structural restoration result of the target interface.

[0020] Compared with the prior art, the present invention can achieve the following positive technical effects:

[0021] 1) Compared with the simple excision method, the present invention does not excise the strata near the fault during the structural restoration process, retains the complete information of the strata, and eliminates the structural anomaly problem, which significantly improves the accuracy and credibility of structural restoration (paleogeomorphology restoration);

[0022] 2) Compared with the balanced section method, the present invention decomposes the three-dimensional structural problem into two-dimensional problems in two directions to make it easier to implement, and uses a projection method to simplify the process of structural recovery, thereby ensuring the reliability of the recovery result and realizing the rapid realization of three-dimensional structural recovery, thus solving the problem that the balanced section method is only applied in two dimensions or has a complicated implementation process in three dimensions;

[0023] 3) A rapid implementation method for three-dimensional structural restoration that can effectively eliminate structural anomalies is provided. This method follows geometric principles and has a reliable theoretical basis during the structural restoration process. At the same time, it simplifies complex three-dimensional problems and improves the computational efficiency of the method, which is conducive to the development and large-scale application of technologies in the fields of structural restoration and paleogeomorphology characterization. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the principle diagram and flow chart of the present invention;

[0025] Figure 2 The following is a simplified diagram of common fault styles and their flattening results. Figure 2 a is a simple pattern of normal faults, Figure 2 c is the corresponding flattening result, Figure 2 b is a simple pattern of reverse faults. Figure 2 d is the corresponding flattening result;

[0026] Figure 3 A seismic network map of the study area of ​​the embodiment;

[0027] Figure 4 A three-dimensional stratum fracture model diagram constructed during the implementation of the embodiment;

[0028] Figure 5 The following is a diagram showing the restoration effect of a two-dimensional cross section during the implementation of the embodiment and its comparison with simple flattening. Figure 5 a is a two-dimensional cross-section model, Figure 5 b is the simple flattening result of the model, Figure 5 c is the result obtained by applying the method of the present invention to the model, Figure 5 d is Figure 5 c Display after removing the cross section;

[0029] Figure 6 This is a simplified mode diagram of the method of the present invention when projecting the target interface;

[0030] Figure 7 The restored ancient landform plan view of the target layer finally obtained in the embodiment. DETAILED DESCRIPTION

[0031] Example 1

[0032] A method for quickly realizing three-dimensional structural restoration by eliminating structural anomalies, comprising the steps of:

[0033] Step 1, input the seismic layer H (num, x, y, d) and fault F (num, x, y, d) in the depth domain, where num is the layer and fault number, x is the line number in the L direction, y is the track number in the XL direction, and d is the depth;

[0034] Step 2: appropriately adjust the input horizon and fault to establish a three-dimensional stratigraphic fault model M(C,x,y,d), where C refers to the type of the data point, whether it is a horizon or a fault.

[0035] Step 2-1, moderately smooth the seismic horizon.

[0036] Step 2-2: remove some small faults and keep only the faults with larger horizontal fault throw.

[0037] Step 2-3, check the interpretation of the horizon near the cross section and make appropriate adjustments to ensure that the horizon is in contact with the cross section without missing or exceeding the cross section;

[0038] Step 3: Decompose the established 3D model into a series of 2D section models consisting of layers and sections in the L and XL directions. Take a section in the L direction as an example. The section is P Num (h,f), Num refers to the section number, h refers to the layer in the section, and the complete expression is h(num,x,y,d), num refers to the layer number, f refers to the cross section in the section, and the complete expression is f(num,x,y,d);

[0039] Step 4, perform structural recovery in the L direction and select the first two-dimensional section model according to the order of line numbers;

[0040] Step 5, determine the position and number of the sections in the selected section, and count the inclination of the sections, and use the direction with more inclination as the structural restoration calculation direction of the section;

[0041] Step 6: Project the target layer to the overlying layer along the calculation direction. The overlying layer after projection is represented as h(num,x,y,d,l V ,θ,l T ), l V Refers to the distance of the vertical projection, (θ,l T ) refer to the angle and distance of oblique projection respectively. The projection process follows three principles: ① The destination layer and its projection point must be on the same side of the section; ② Vertical projection is given priority and the projection distance is recorded; ③ When there is no corresponding vertical projection point, oblique projection is performed along the inclination direction of the adjacent section and the projection angle and distance are recorded at the projection point;

[0042] Step 7, flattening the overlying strata. During the flattening process, while flattening the strata near the section, the upper plate of the fault is horizontally moved so that the upper plate of the fault contacts the lower plate of the fault, and there is no missing or exceeding of the strata;

[0043] Step 8: According to the projection information recorded in the projection process, the target layer is back-projected based on the flattened overlying stratum to obtain the structural restoration result h of the target layer of the section. ′ (num,x,y,d,x_L ′ ,y_L ′ ,d_L ′ ), the result records the current coordinates of the destination layer, x, y, d and the ancient coordinates, x_L ′ ,y_L ′ ,d_L ′ ;

[0044] Step 9: Perform the above steps 5 to 8 on the two-dimensional section in the L direction in the order of line numbers to obtain the structural recovery result H in the L direction. ′ L (num,x,y,d,x_L ′ ,y_L ′ ,d_L ′ ), x_L ′ ,y_L ′ ,d_L ′ is the ancient coordinate restored along the L direction;

[0045] Step 10: Repeat the restoration process in the L direction (steps 4 to 9) for the cross section in the XL direction to obtain the structural restoration result H in the XL direction. ′ XL (num,x,y,d,x_XL ′ ,y_XL ′ ,d_XL ′ ), x_XL ′ ,y_XL ′ ,d_XL ′ is the ancient coordinate restored along the XL direction;

[0046] Step 11: Comprehensively calculate the structural restoration results of the target interface in the L direction and the XL direction to obtain the final restoration result H ′ (num,x,y,d,x_f ′ ,y_f ′ ,d_f ′ ),in

[0047] x_f ′ =(x_L ′ +x_XL ′ )÷2,y_f ′ =(y_L ′ +y_XL ′ )÷2,d_f ′ =max(d_L ′ ,d_XL ′ ).

[0048] Example 2

[0049] Figures 3 to 7 This is an embodiment of a method for quickly implementing three-dimensional structural restoration based on three-dimensional seismic data of a certain study area, wherein: Figure 3 The seismic network in the study area is Figure 4 This is a three-dimensional stratigraphic fracture model established based on the data of the study area. Figure 5 Taking a cross section in the L direction as an example, the restoration effect of the present invention and the comparison with the simple flattening effect are shown. Figure 6To illustrate the projection method during the restoration process, Figure 7 is the restored paleo-geomorphic plane map of the target layer in the embodiment (the height values ​​of the plane map only represent the relative height, and the low value represents the high potential of the landform), Figure 5 and Figure 7 It can be seen that the present invention can reasonably eliminate structural anomalies and provide a fast and accurate method for three-dimensional structural restoration.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for rapidly implementing three-dimensional structural restoration by eliminating structural anomalies comprises the following specific steps: Step 1, input the seismic layer H (num, x, y, d) and fault F (num, x, y, d) in the depth domain, where num is the layer and fault number, x is the line number in the L direction, y is the track number in the XL direction, and d is the depth; Step 2: appropriately adjust the input horizon and fault to establish a three-dimensional stratigraphic fault model M(C,x,y,d), where C refers to the type of the data point, whether it is a horizon or a fault. Step 2-1, moderately smooth the seismic horizon. Step 2-2: remove some small faults and keep only the faults with larger horizontal fault throw. Step 2-3, check the interpretation of the horizon near the cross section and make appropriate adjustments to ensure that the horizon is in contact with the cross section without missing or exceeding the cross section; Step 3: Decompose the established 3D model into a series of 2D section models consisting of layers and sections in the L and XL directions. Take a section in the L direction as an example. The section is P Num (h,f), Num refers to the section number, h refers to the layer in the section, and the complete expression is h(num,x,y,d), num refers to the layer number, f refers to the cross section in the section, and the complete expression is f(num,x,y,d); Step 4, perform structural recovery in the L direction and select the first two-dimensional section model according to the order of line numbers; Step 5, determine the position and number of the sections in the selected section, and count the inclination of the sections, and use the direction with more inclination as the structural restoration calculation direction of the section; Step 6: Project the target layer to the overlying layer along the calculation direction. The overlying layer after projection is represented as h(num,x,y,d,l V ,θ,l T ), l V Refers to the distance of the vertical projection, (θ,l T ) refer to the angle and distance of oblique projection respectively. The projection process follows three principles: ① The destination layer and its projection point must be on the same side of the section; ② Vertical projection is given priority and the projection distance is recorded; ③ When there is no corresponding vertical projection point, oblique projection is performed along the inclination direction of the adjacent section and the projection angle and distance are recorded at the projection point; Step 7, flattening the overlying strata. During the flattening process, while flattening the strata near the section, the upper plate of the fault is horizontally moved so that the upper plate of the fault contacts the lower plate of the fault, and there is no missing or exceeding of the strata; Step 8: According to the projection information recorded in the projection process, the target layer is back-projected based on the flattened overlying stratum, so as to obtain the structural restoration result h′(num,x,y,d,x_L′,y_L′,d_L′) of the target layer of the profile, which records the current coordinates, x,y,d and ancient coordinates, x_L′,y_L′,d_L′ of the target layer at the same time; Step 9: Perform the above steps 5 to 8 on the two-dimensional section in the L direction in the order of line numbers to obtain the structural recovery result H′ in the L direction. L (num,x,y,d,x_L′,y_L′,d_L′), x_L′, y_L′, d_L′ are the ancient coordinates restored along the L direction; Step 10: Repeat the restoration process in the L direction (steps 4 to 9) for the cross section in the XL direction to obtain the structural restoration result H′ in the XL direction. XL (num,x,y,d,x_XL′,y_XL′,d_XL′), x_XL′, y_XL′, d_XL′ are the ancient coordinates restored along the XL direction; Step 11, the structural restoration calculation results of the target interface in the L direction and the XL direction are integrated to obtain the final restoration result H′(num,x,y,d,x_f′,y_f′,d_f′), where x_f′=(x_L′+x_XL′)÷2, y_f′=(y_L′+y_XL′)÷2, d_f′=max(d_L′, d_XL′).

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