A method for determining the deformation properties of paleo-tectonic structures

Abstract

The present invention discloses a method for judging the deformation properties of ancient structures, and belongs to the technical field of petroleum and natural gas geology. The present invention determines the deformation properties of ancient structures through the change of stratum thickness and structural restoration of two-dimensional seismic profiles; then, the three-dimensional ancient structure morphology is established through the restoration of three-dimensional structural models; the two-dimensional seismic data is returned to determine the reliability of the three-dimensional ancient structure and the distribution of early faults; finally, the morphology and deformation properties of the three-dimensional ancient structure are implemented to support the research on favorable reservoir areas controlled by the ancient structure, and to obtain breakthroughs in oil and gas exploration and development; at the same time, the two-dimensional and three-dimensional seismic data are used in oil and gas exploration to accurately implement the properties and morphology of the ancient structure, so as to advance the work of obtaining favorable reservoir development areas.

Description

Technical Field

[0001] The invention relates to a method for judging the deformation attributes of ancient structures, and in particular to a modeling method capable of accurately judging the deformation attributes of ancient structures, and belongs to the technical field of petroleum and natural gas geology. Background Art

[0002] Oil and gas exploration and development areas generally have multiple stages of structural deformation. In areas affected by multiple stages of tectonic action, it is difficult to intuitively judge the properties of early structural deformation and determine the ancient structural morphology because the early structural deformation is transformed by the later structural deformation. The deformation sequence, fault properties and three-dimensional distribution cannot be accurately and reliably determined, resulting in the inability to determine the favorable reservoir areas and gas accumulation patterns controlled by the ancient structures. Therefore, it is necessary to use two- and three-dimensional seismic research to confirm the three-dimensional morphology and deformation properties of the ancient structures and find favorable oil and gas exploration areas.

[0003] At present, there are methods for restoring ancient structures, but they do not specifically solve the key problem that the deformation properties and morphology of ancient structures cannot be accurately and reliably determined. For example, "An ancient structure constraint modeling method, device and equipment" (patent application number: CN201811487404.2) only restores ancient structures by simply flattening the unconformity surface, without considering how to eliminate the influence of faults in complex structural areas; "A method for restoring the original sedimentary appearance of a modified fault basin" (patent application number: CN201710144840.9) does not consider the three The specific favorable oil and gas areas cannot be clearly defined in space due to the restoration of the three-dimensional structural model; the technical solutions in "A three-dimensional modeling method of structural fractures based on structural surface geometry restoration" (patent application number: CN201610029135.X) are not aimed at the restoration of ancient structural forms; "A method for restoring ancient geomorphic profiles" (patent application number: CN201610121264.1), "A fast and quantitative ancient geomorphic restoration method considering the influence of ancient structures" (patent application number: CN201511014406.6), and "An ancient structural map drawing method and device" (patent application number: CN201410043533.8) do not involve how to accurately and reliably judge the deformation attributes of ancient structures.

[0004] In short, the existing technology does not solve the key problems of accurately and reliably determining the deformation properties of ancient structures and establishing the three-dimensional morphology of ancient structures. Summary of the invention

[0005] The present invention aims to overcome the shortcomings of the prior art and proposes a method for determining the deformation properties of paleostructures. In this technical solution, the deformation properties of paleostructures are determined by the change in stratum thickness and structural restoration of the two-dimensional seismic profile; then, the three-dimensional paleostructure morphology is established by restoring the three-dimensional structural model; the two-dimensional seismic data is returned to determine the reliability of the three-dimensional paleostructure and the distribution of early faults; finally, the morphology and deformation properties of the three-dimensional paleostructure are implemented to support the research on the favorable reservoir areas controlled by the paleostructure and obtain breakthroughs in oil and gas exploration and development; at the same time, the two-dimensional and three-dimensional seismic data are used in oil and gas exploration to accurately implement the properties and morphology of the paleostructure to advance the work of obtaining favorable reservoir development areas.

[0006] In order to achieve the above technical objectives, the following technical solutions are proposed:

[0007] A method for determining the deformation attributes of paleostructures comprises the following steps:

[0008] S1: Determine the thickness change of ancient structures

[0009] According to the two-dimensional seismic profile interpretation scheme of the ancient structure whose deformation attributes are to be determined, the two-dimensional seismic profile information, reference layer information, target layer information and fault information of the ancient structure are input into the structural evolution analysis software system, and the difference in stratum thickness between the reference layer and the target layer is calculated to determine whether there is a change in stratum thickness of the ancient structure;

[0010] If there is no change in the thickness of the stratum, the judgment of the paleo-tectonic deformation attributes is terminated;

[0011] If the formation thickness changes, and the value tends to increase or decrease in the same direction, proceed to the next step;

[0012] The calculation of the difference in stratum thickness between the reference layer and the target layer means: subtracting the altitude value Z1 of the reference layer and the altitude value Z2 of the target layer at the same XY coordinate point in the geodetic coordinates to obtain the thickness difference Z', and then comparing the thickness difference Z' of the point with the thickness difference on both sides to obtain the conclusion whether there is a change in stratum thickness in the paleostructure;

[0013] Here, "the trend of increasing or decreasing the value in the same direction" means that a two-dimensional seismic profile is directional when placed in space, for example, two tops, one end is relatively to the west and the other end is relatively to the east. If it is confirmed that the thickness of the formation has changed, and at the same time, the thickness value has been increasing or decreasing in the west direction, it is "the trend of increasing or decreasing the thickness value in the same direction". It is defined according to the situation under the actual positioning state, and is a common term in this technical field, and is also a common term used by technical personnel in this field in actual use;

[0014] "Compare the thickness difference Z' of the point with the thickness difference on both sides" means: for example, point A (coordinates Xa, Ya, thickness difference Za'), point B (coordinates Xb, Yb, thickness difference Zb'), point C (coordinates Xc, Yc, thickness difference Zc'), ABC are three points arranged continuously on the same seismic profile, point B is in the middle, and the thickness difference Zb' of point B is compared with the thickness difference of points A and C on both sides of point B. It is defined according to the actual positioning state, and is a common term in this technical field, and is also a common term used by technicians in this field in actual use;

[0015] S2: Preliminary confirmation of the deformation properties of the ancient structure

[0016] Restore the structure of the 2D seismic profile to determine whether there is any fault throw in the target layer that has not been eliminated;

[0017] If the fault throw is not eliminated, determine the structural attributes of the target layer along the fault, confirm the deformation attributes caused by the change in stratum thickness, and obtain preliminary paleo-tectonic deformation attributes. Then proceed to the next step to confirm whether the preliminary paleo-tectonic deformation attributes are correct.

[0018] If the fault distance is eliminated, the reference layer is moved along the fault plane, the reference layers of the upper wall and the lower wall of the fault are connected, and after the reference layers of the upper wall and the lower wall of the fault are aligned, if the target layer still has a misalignment, it is confirmed that the change in the difference in stratum thickness in step S1 is related to the fault, and the structural attribute of the fault can be determined, that is, the next step is entered; if the target layer does not have a misalignment (i.e., it is aligned) after the reference layers of the upper wall and the lower wall of the fault are aligned, it is confirmed that the change in the difference in stratum thickness in S1 is not related to the fault, and the determination of the paleo-structural deformation attribute is terminated;

[0019] The structural restoration of the two-dimensional seismic profile includes restoring the reference layer along the fault until the two plates of the fault are aligned to eliminate the influence of the fault distance;

[0020] Among them, deformation properties caused by changes in stratum thickness include normal faults and reverse faults;

[0021] S3: Restoring 3D paleostructures

[0022] Input the stratigraphic and fault information of the two-dimensional seismic profile into the structural evolution analysis software system to establish a three-dimensional paleostructural model; extract the stratigraphic and fault data of the reference layer and the target layer to perform three-dimensional paleostructural restoration; then, eliminate the fault throw of the reference layer to obtain the three-dimensional paleostructural morphology of the target layer when the reference layer was not deposited;

[0023] The three-dimensional paleostructure restoration specifically includes: forming three-dimensional planes for the layers and faults according to the layer and fault information of the two-dimensional seismic profile, and establishing a geometric three-dimensional model; eliminating the relevant folding effect of the fault based on the kinematics of the compression structure; using the bending and sliding de-folding method to eliminate the remaining fold geometric form, and finally obtaining the paleomorphic form of the target layer, that is, the three-dimensional paleostructure;

[0024] S4: Reconfirming the deformation properties of ancient structures

[0025] The stratum thickening area of ​​the two-dimensional seismic profile is compared with the three-dimensional paleo-tectonic morphology of the target layer to determine the correctness of the three-dimensional paleo-tectonic morphology of the target layer, that is, the three-dimensional paleo-tectonic morphology of the target layer and the properties of the early faults are obtained.

[0026] In this technical solution, a 2D seismic profile can obtain a line of reference layer information with XYZ value information, where XY value is the position of the geodetic coordinate system and Z is the altitude value; similarly, a fault in a 2D seismic profile is a line, also with XYZ value information, to determine the spatial position of the fault underground. A series of 2D seismic profiles can obtain the position of the same fault plane in this series of 2D seismic profiles, and through the difference in space, the fault plane information in the fault space can be obtained.

[0027] In this technical solution, the two-dimensional seismic profile interpretation solution (including two-dimensional seismic profile information, reference layer information, target layer information and fault information), the acquisition of the stratigraphic and fault information of the two-dimensional seismic profile, etc., are the basic work contents in this industry and can be obtained through mature technologies in this field.

[0028] In this technical solution, the definitions of terms involved include:

[0029] Two-dimensional seismic profile: refers to a line in the geodetic coordinate system, corresponding to a two-dimensional seismic profile as a surface underground with elevation information. In a two-dimensional seismic profile, the reference layer has only one elevation Z value at an XY coordinate point, and the reference layer is a line. The reference layer, target layer, and fault all contain XYZ information; taking the reference layer as an example, the reference layer information refers to the distribution information of the reference layer in this two-dimensional seismic profile;

[0030] Target layer: refers to a specific underground stratum whose paleo-tectonic deformation properties need to be obtained in this technical solution, and is the target layer for oil and gas exploration; the reference layer is defined relative to the target layer and is used to assist in determining the paleo-tectonic morphology of the target layer, and is a conventional term in this technical field;

[0031] Reference layer: It is the stratigraphic position on the target layer, indicating the stratigraphic layer deposited after the target layer is deposited. In terms of geological time, the reference layer is the stratigraphic layer deposited later than the target layer;

[0032] Normal fault: Towards the fault direction, the thickness difference of the strata on the upper wall of the fault gradually increases, indicating that the paleo-tectonic structure was in a tension environment at that time;

[0033] Reverse fault: Towards the fault direction, the thickness difference of the strata in the footwall of the fault gradually decreases, indicating that the ancient structure was in a compression environment at that time.

[0034] The beneficial technical effects brought about by adopting this technical solution are:

[0035] In the present invention, the deformation properties of the ancient structure are determined by the change of stratum thickness and structural restoration of the two-dimensional seismic profile; then, the three-dimensional ancient structure morphology is established by restoring the three-dimensional structural model; the two-dimensional seismic data is returned to determine the reliability of the three-dimensional ancient structure and the distribution of early faults; finally, the morphology and deformation properties of the three-dimensional ancient structure are implemented to support the research on the favorable reservoir area controlled by the ancient structure and obtain a breakthrough in oil and gas exploration and development; at the same time, the two-dimensional and three-dimensional seismic data are used in oil and gas exploration to accurately implement the properties and morphology of the ancient structure, so as to advance the work of obtaining the favorable reservoir development area;

[0036] The present invention makes comprehensive use of two-dimensional and three-dimensional data to better constrain and establish the morphology and deformation attributes of paleostructures, solving the problem that the three-dimensional distribution and deformation attributes of paleostructures cannot be accurately and reliably determined. At the same time, the present invention can construct more accurate and precise paleostructure morphology and its deformation attributes, and can further confirm the favorable reservoir areas controlled by paleostructures. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A flowchart of the steps for determining the deformation properties of paleostructures in the present invention;

[0038] Figure 2 A schematic diagram of the thickness variation between the reference layer (T2) and the target layer (T1) when calculating the layer thickness in 10-dimensional seismic in an embodiment of the present invention;

[0039] Figure 3 A schematic diagram of the original structural morphology of the target layer (T1) thickened by restoring the reference layer (T2) strata on both sides of the fault along the fault plane to the structural morphology before the deposition of the reference layer (T2) in Example 10 of the present invention (a, eliminating the fault distance of the fault F1 on both sides of the reference layer (T2) strata);

[0040] Figure 4 A schematic diagram of the original structural morphology of the target layer (T1) thickened by restoring the reference layer (T2) strata on both sides of the fault along the fault plane to the structural morphology before the deposition of the reference layer (T2) in Example 10 of the present invention (b, eliminating the fault distance of the fault F2 on both sides of the reference layer (T2) strata);

[0041] Figure 5A schematic diagram of the original structural morphology of the target layer (T1) thickening by restoring the reference layer (T2) on both sides of the fault along the fault plane to the structural morphology before the deposition of the reference layer (T2) in Example 10 of the present invention (c, the reference layer (T2) has no fault throw on both sides of the fault, but the target layer (T1) has fault throw on both sides of the fault, and the structural restoration shows the early normal fault morphology);

[0042] Figure 6 Establishing a three-dimensional geological model of strata and faults in Example 10 of the present invention;

[0043] Figure 7 A schematic diagram of the ancient structural morphology (three-dimensional structural model) of the reference layer (T2) before deposition in Example 10 of the present invention;

[0044] Figure 8 A schematic diagram of the paleo-tectonic morphology of the reference layer (T2) before deposition by three-dimensionally restoring the reference layer (T2) stratum in Example 10 of the present invention (the paleo-tectonic morphology of the target layer (T1) before deposition of the reference layer (T2);

[0045] Fig. 9 In Example 10 of the present invention, the three-dimensional morphology of the target layer (T1) is compared with the two-dimensional seismic profile, the ancient fault height in the three-dimensional space is determined to correspond to the tensional fault in the two-dimensional profile, and the normal fault after three-dimensional restoration and the ancient fault height formed by it are determined to be reliable, and finally the properties and morphological schematic diagram of the ancient structure of the target layer (T1) are obtained. DETAILED DESCRIPTION

[0046] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1

[0048] A method for determining the deformation properties of paleostructures comprises the following steps:

[0049] S1: According to the 2D seismic profile interpretation scheme of the paleostructure whose deformation attributes are to be determined, determine the change in the stratum thickness of the paleostructure. If the stratum thickness changes and increases or decreases in a trend in the same direction, proceed to the next step;

[0050] S2: Restore the structure of the 2D seismic profile to determine whether there is an uneliminated fault throw in the target layer. If the fault throw is not eliminated, determine the structural attributes of the target layer along the fault and confirm the deformation attributes caused by the change in stratum thickness, that is, obtain preliminary paleo-structural deformation attributes and proceed to the next step;

[0051] S3: Restore the three-dimensional paleostructure to obtain the three-dimensional paleostructure of the target layer;

[0052] S4: Compare the stratigraphic thickening area of ​​the two-dimensional seismic profile with the three-dimensional paleo-tectonic morphology of the target layer to determine the correctness of the three-dimensional paleo-tectonic morphology of the target layer, that is, to obtain the three-dimensional paleo-tectonic morphology of the target layer and the properties of the early faults.

[0053] Among them, the two-dimensional seismic profile interpretation scheme is the basic work content in this industry and can be obtained through mature technologies in this field.

[0054] This technical solution comprehensively utilizes two-dimensional and three-dimensional data to better constrain and establish the morphology and deformation attributes of paleostructures, solving the problem that the three-dimensional distribution and deformation attributes of paleostructures cannot be accurately and reliably determined. At the same time, the present invention can construct more accurate and precise paleostructure morphology and its deformation attributes, and can further confirm the favorable reservoir areas controlled by paleostructures.

[0055] Example 2

[0056] Based on Example 1, further, in step S1 of the method for determining the deformation attribute of the ancient structure, the specific steps of determining the change in the thickness of the ancient structure include:

[0057] The two-dimensional seismic profile information, reference layer information, target layer information and fault information of the ancient structure whose deformation properties are to be determined are input into a known structural evolution analysis software system, the difference in stratigraphic thickness between the reference layer and the target layer is calculated, and it is determined whether there is a change in stratigraphic thickness of the ancient structure.

[0058] Among them, the two-dimensional seismic profile refers to a line in the geodetic coordinate system, and the corresponding two-dimensional seismic profile is a surface underground with altitude information. In a two-dimensional seismic profile, the reference layer has only one altitude Z value at an XY coordinate point, and the reference layer is a line. The reference layer, target layer and fault all contain XYZ information; taking the reference layer as an example, the reference layer information refers to the distribution information of the reference layer in this two-dimensional seismic profile;

[0059] Target layer: refers to a specific underground stratum whose paleo-tectonic deformation properties need to be obtained in this technical solution, and is the target layer for oil and gas exploration; the reference layer is defined relative to the target layer and is used to assist in determining the paleo-tectonic morphology of the target layer, and is a conventional term in this technical field;

[0060] Reference layer: It is the stratigraphic position on the target layer, indicating the stratigraphic layer deposited after the target layer is deposited. In terms of geological time, the reference layer is the stratigraphic layer deposited later than the target layer.

[0061] Among them, the "structural evolution analysis software system" involved is a software system among existing mature technologies.

[0062] Example 3

[0063] Based on Example 2, further, in the method for determining the deformation attributes of ancient structures,

[0064] Calculate the difference in stratum thickness between the reference layer and the target layer, including:

[0065] The altitude value Z1 of the reference layer at the same XY coordinate point in the geodetic coordinates is subtracted from the altitude value Z2 of the target layer to obtain the thickness difference Z'. Then the thickness difference Z' of the point is compared with the thickness difference on both sides to draw a conclusion on whether there is a change in the thickness of the stratum in the paleostructure.

[0066] Example 4

[0067] Based on Examples 1-3, further, in step S1 of the method for determining the deformation attributes of ancient structures,

[0068] If there is no change in the thickness of the stratum, the judgment of the paleo-tectonic deformation properties is terminated.

[0069] Example 5

[0070] Based on Examples 1-4, further, in step S2 of the method for determining the deformation attributes of ancient structures,

[0071] The structural restoration of two-dimensional seismic profiles includes restoring the reference layer along the fault until the two sides of the fault are aligned to eliminate the influence of the fault distance.

[0072] Example 6

[0073] Based on Examples 1-5, further, in the method for determining the deformation attributes of paleostructures,

[0074] Deformation properties caused by changes in formation thickness, including normal faults and reverse faults.

[0075] Among them, normal faults: the difference in stratum thickness gradually increases toward the fault direction, indicating that the paleostructure was in a tension environment at that time;

[0076] Reverse fault: Towards the fault direction, the difference in stratum thickness gradually decreases, indicating that the ancient structure was in a compression environment at that time.

[0077] Example 7

[0078] Based on Example 6, further, in step S2 of the method for determining the deformation attribute of the ancient structure,

[0079] If the fault distance is eliminated, the reference layer is moved along the fault plane, and the reference layers of the upper wall and the lower wall of the fault are connected. After the reference layers of the upper wall and the lower wall of the fault are aligned, if the target layer is still misaligned, it is confirmed that the change in the formation thickness difference in step S1 is related to the fault, and the structural attribute of the fault can be determined, that is, the next step is entered;

[0080] If the target layer does not have any misalignment after the reference layers of the fault hanging wall and the fault footwall are aligned, it is confirmed that the change in the formation thickness difference in step S1 is not related to the fault, and the judgment of the paleo-structural deformation attribute is terminated.

[0081] Example 8

[0082] Based on Examples 1-7, further, in step S3 of the method for determining the deformation attributes of paleostructures, the three-dimensional paleostructure morphology of the target layer is obtained, specifically including:

[0083] Input the stratigraphic and fault information of the two-dimensional seismic profile into the structural evolution analysis software system to establish a three-dimensional paleostructural model; extract the stratigraphic and fault data of the reference layer and the target layer to restore the three-dimensional paleostructure; eliminate the fault throw of the reference layer to obtain the three-dimensional paleostructural morphology.

[0084] The three-dimensional paleo-tectonic morphology is the three-dimensional paleo-tectonic morphology of the target layer when the reference layer has not been deposited.

[0085] Example 9

[0086] Based on Example 8, further, in step S3 of the method for determining the deformation attribute of the ancient structure, restoring the three-dimensional ancient structure specifically includes:

[0087] A. Establish 3D geometry model of structural level and cross section

[0088] Through the interpretation of strata and faults in 3D seismic data, 3D layers are formed for strata and faults respectively, and a geometric 3D structural model is established;

[0089] Among them, 3D seismic data is a set of data obtained by processing the original seismic data collected in the field with professional software. It is a set of electronic signal data, that is, the sound waves excited by the surface are transmitted to the ground. The signal obtained by the ground receiver can be used to analyze the structural morphology and sedimentary characteristics of the underground strata, and is used to find favorable areas for oil and gas storage. 3D seismic data has the concept of space, that is, within a certain range underground, each X1, Y1, and Z1 has a corresponding value, representing the underground strata information at this X1, Y1, and Z1 point. X1 and Y1 are the positions of the point in the geodetic coordinate system. , Z1 is the underground altitude value; input 3D seismic data into professional software, there is a special software function to interpret strata and faults, the strata and faults interpreted by 3D seismic data are also the information of a surface distributed in space, a stratum 3D level or a fault 3D level, in the space defined by this 3D seismic data, each corresponding spatial point has X1, Y1, Z1 information, together they are the level information in space; after obtaining the X1Y1Z1 spatial information of the stratum level and the fault level, the stratum and fault are combined separately to form a 3D spatial model;

[0090] B. Eliminating the relevant folding of faults based on compressional tectonic kinematics

[0091] Extract the target layer and the upper reference layer, as well as the faults that offset these two layers, from the stratigraphic plane. Then, based on the structural deformation steps from new to old, eliminate the folding effect of the fault along the fault plane.

[0092] Among them, when using seismic data interpretation software to interpret three-dimensional seismic data in three-dimensional layers and faults, multiple layers are interpreted from top to bottom, such as the Jurassic, Cretaceous, Permian, Carboniferous, Cambrian and the target layer for oil and gas exploration; but for a specific stratigraphic target layer and the upper reference layer, at this time, the information of the target layer and the upper reference layer can be extracted in professional software to obtain a digital file, which includes a series of X2, Y2, and Z2 information. X2 and Y2 are the geodetic coordinate values ​​of the surface, respectively, and Z2 is the underground altitude value. A series of X2Y2Z2 information together is the spatial distribution of a layer. Determine whether the fault is a reverse fault or a normal fault. In a reverse fault, the upper plate of the fault is deformed and the lower plate is immobile. The movement mode of the upper plate of the fault is selected to keep the target layer of the lower plate of the fault immobile, and the target layer of the upper plate of the fault is retreated along the fault to the point of contact with the target layer breakpoint of the lower plate of the fault, so that the target layer just touches the breakpoint of the upper and lower plates of the fault. In a normal fault, the lower plate of the fault is deformed and the upper plate is immobile. Conversely, the movement mode of the lower plate of the fault is selected to keep the target layer of the upper plate of the fault immobile, and the target layer of the lower plate of the fault is retreated along the fault to the point of contact with the target layer breakpoint of the upper plate of the fault, so that the target layer just touches the breakpoint of the upper and lower plates of the fault.

[0093] C. Use the bending and sliding wrinkle removal method to eliminate the remaining wrinkle geometry

[0094] After eliminating the folds related to the thrust fault, the reference layer still has folds. At this time, based on the bending and sliding fold removal method, the fold deformation of the reference layer is eliminated, and the reference layer is turned into a flat layer, completely eliminating the structural deformation of the reference layer.

[0095] The reference layer often still has some fold morphology. At this time, since step B has completely eliminated the fold morphology formed by movement along the fault plane, what remains are the folds that are not affected by the fault. At this time, the reference layer is fixed relative to the boundary into the basin, and then the reference layer is flattened in the direction outside the basin to achieve fold recovery and turn the reference layer into a flat layer; the reference layer of the upper plate of the fault is docked with the reference layer of the lower plate. This method is suitable for the fold deformation of sedimentary strata with obvious layered structure. The "fault removal" process is carried out from new to old. Since the slip surface of the right fault is curved and transformed by the high-angle fault on the left, the activity time is earlier. Therefore, the left fault is firstly removed. On the basis of this restoration, the low-angle fault on the right is restored. Through the above-mentioned "fault removal" process, the fold morphology of the reference layer and the target layer can be restored. During the fold removal process, the remaining fold morphology restored in step B is restored. Here, the reference layer is removed by the bending and sliding fold removal method to restore the paleo-geomorphology of the target layer.

[0096] After the influence of the folds caused by the fault is eliminated through step B, some fold forms often remain in the reference layer. At this time, since step B has completely eliminated the fold forms formed by movement along the fault plane, what remains are the folds that are not affected by the fault. At this time, the reference layer is fixed relative to the boundary inside the basin, and then the reference layer is flattened toward the outside of the basin to achieve fold recovery and turn the reference layer into a flat layer.

[0097] D. Obtain the paleo-geomorphology of the target layer

[0098] After the reference layer becomes a flat layer, the target layer still retains a slight undulating shape, which is the paleo-geomorphology of the target layer;

[0099] When the reference layer becomes a flat layer, the target layer still retains a slight undulating shape. The paleo-geomorphic information of the target layer in this step is extracted to obtain a digital file, which includes a series of X3, Y3, and Z3 information. X3 and Y3 are the geodetic coordinate values ​​of the surface, respectively, and Z3 represents the ups and downs of the target layer landform. A series of X3Y3Z3 information together is the paleo-geomorphology of the target layer. The X3Y3Z3 information is then input into the mapping software to obtain a plane map, and the color code shows the ups and downs information of the paleo-geomorphology.

[0100] Among them, after being processed by step C, the reference layer becomes a flat layer, and the target layer still retains a slight undulating shape. At this time, the display of the reference layer can be cancelled, and the ups and downs information of the ancient landform of the target layer can be displayed separately.

[0101] Due to the influence of faults, the fold morphology is complex. If a simple layer flattening method is used, the paleo-geomorphology obtained will have large errors, and the position of the fault is easily distorted, resulting in the inability to determine the favorable conditions for carbonate beach reservoir deposition, leading to oil and gas drilling failures. On the basis of removing the relevant fold morphology of the fault, the original and true paleo-geomorphology can be obtained, and a more accurate and precise paleo-geomorphology can be constructed to determine the favorable areas for reservoir development.

[0102] It provides basic support for the judgment of the deformation properties of ancient structures, ensures that the modeling of the deformation properties of ancient structures is more accurate, and constructs more accurate ancient structural forms and their deformation properties, which can further confirm the favorable reservoir areas controlled by the development of ancient structures.

[0103] Example 10

[0104] This embodiment takes a certain ancient structure as an example, determines the deformation properties of the ancient structure and models it, to further illustrate the present invention. Specifically, the following steps are included:

[0105] S1: After inputting the 2D seismic profile interpretation scheme of the paleostructure (including 2D seismic profile information, reference layer information, target layer information and fault information) into the known structural evolution analysis software system, by calculating the thickness difference between T2 (reference layer) and T1 (target layer), it is found that the thickness between T2 and T1 has obvious thickening phenomenon at the positions of F1 fault and F2 fault ( Figure 2 ), and it can be seen that the fault throw of the upper strata of T2 is larger, and the fault throw of the lower strata of T1 is smaller. Therefore, it is determined that the thickening of the strata inside T1 is caused by the early fault;

[0106] S2: restore the upper plate block of the F1 fault in the seismic data along the F1 fault plane to the direct contact between the two plates of T2 on the F1 fault ( Figure 3 ), and then restore the upper plate block of F2 fault along the F2 fault plane to the direct contact between the two plates of T2 on F1 fault ( Figure 4 ), it can be found that after the fault distance of T2 is eliminated in the two disks of F1 and F2, T1 still has a fault ( Figure 5 ), and along the F1 and F2 fault planes, T1 appears as a normal fault;

[0107] S3: Input the stratigraphic and fault information of the 2D seismic profile into the structural evolution analysis software system to establish a 3D geological model ( Figure 6 ); extract the three-dimensional data of the layers and faults of T2 and T1 ( Figure 7), and restore the three-dimensional paleostructure by restoring the T2 layer along the F1 and F2 faults until there is no fault throw on both sides of the fault, and obtain the three-dimensional paleostructure of T1 before T2 deposition ( Figure 8 );

[0108] Among them, the three-dimensional paleo-tectonic morphology of T1 specifically shows the normal faults developed in T1 at the early stage of T2 deposition;

[0109] S4: Extract the three-dimensional paleo-tectonic morphology of T1 ( Fig. 9 , the color scale shows the ups and downs of the ancient landform), corresponding to the display: the fault height position of the normal fault and the depression position of the normal fault. Compare the T1 ancient structural morphology with the two-dimensional seismic profile ( Fig. 9 superior, Fig. 9 The fault height of the normal fault in three-dimensional space is determined to correspond to the thickening position of the T2-T1 stratum in the two-dimensional seismic section. That is, the normal fault after three-dimensional restoration and the paleo-fault height formed by it are reliable. Finally, the normal fault attributes and paleo-structural morphology of the T1 paleo-structure are obtained ( Fig. 9 middle).

[0110] As described above, the embodiments of the present invention are described in detail, but it is obvious to those skilled in the art that many variations are possible without departing from the inventive point and effect of the present invention. Therefore, all such variations are also included in the protection scope of the present invention.

Claims

1. A method for determining the deformation properties of paleo-tectonic structures. It is characterized in that The steps include: S1: According to the 2D seismic profile interpretation scheme of the ancient structure whose deformation attribute is to be determined, the 2D seismic profile information, reference layer information, target layer information and fault information of the ancient structure whose deformation attribute is to be determined are input into the structural evolution analysis software system, and the difference in stratum thickness between the reference layer and the target layer is calculated to determine whether there is a change in stratum thickness of the ancient structure; If the formation thickness changes, and the value tends to increase or decrease in the same direction, proceed to the next step; S2: Restore the structure of the 2D seismic profile to determine whether there is any fault throw in the target layer that has not been eliminated; If the fault throw is not eliminated, determine the structural attributes of the target layer along the fault, confirm the deformation attributes caused by the change in stratum thickness, and obtain preliminary paleo-structural deformation attributes before proceeding to the next step. Among them, the structural restoration of the 2D seismic profile includes: restoring the reference layer along the fault until the two plates of the fault are aligned to eliminate the influence of the fault distance; S3: Restore the three-dimensional paleostructure to obtain the three-dimensional paleostructure of the target layer; Input the stratigraphic and fault information of the 2D seismic profile into the structural evolution analysis software system to establish a 3D paleo-tectonic model; extract stratigraphic and fault data of the reference layer and target layer to restore the 3D paleo-tectonic structure; eliminate the fault throw of the reference layer to obtain the 3D paleo-tectonic morphology; Among them, the restoration of three-dimensional paleostructure includes: forming three-dimensional planes for the layers and faults respectively according to the layer and fault information of the two-dimensional seismic profile, and establishing a geometric three-dimensional model; eliminating the relevant folding effect of the fault based on the kinematics of the compression structure; using the bending and sliding de-folding method to eliminate the remaining fold geometric form, and finally obtaining the paleomorphic form of the target layer, that is, the three-dimensional paleostructure; S4: Compare the stratigraphic thickening area of ​​the two-dimensional seismic profile with the three-dimensional paleo-tectonic morphology of the target layer to determine the correctness of the three-dimensional paleo-tectonic morphology of the target layer, that is, to obtain the three-dimensional paleo-tectonic morphology of the target layer and the properties of the early faults.

2. The method for determining the deformation attributes of ancient structures according to claim 1, It is characterized in that The calculating of the difference in stratum thickness between the reference layer and the target layer specifically includes: The altitude value of the reference layer at the same XY coordinate point in the geodetic coordinates is subtracted from the altitude value of the target layer to obtain the thickness difference. The thickness difference of the point is then compared with the thickness difference on both sides to draw a conclusion on whether there is a change in the thickness of the stratum in the ancient structure.

3. A method for determining the deformation attributes of ancient structures according to any one of claims 1 to 2, It is characterized in that In step S1, if there is no change in the stratum thickness, the determination of the paleo-tectonic deformation attribute is terminated.

4. The method for determining the deformation attributes of paleostructures according to claim 1, It is characterized in that The deformation properties caused by the change in formation thickness include normal faults and reverse faults.

5. The method for determining the deformation attributes of ancient structures according to claim 4, It is characterized in that In step S2, if the fault distance is eliminated, the reference layer is moved along the fault plane, and the reference layers of the upper wall and the lower wall of the fault are connected. After the reference layers of the upper wall and the lower wall of the fault are aligned, if the target layer is still misaligned, it is confirmed that the change in the formation thickness difference in step S1 is related to the fault, and the structural attribute of the fault can be determined, that is, the next step is entered; If the target layer does not have any misalignment after the reference layers of the fault hanging wall and the fault footwall are aligned, it is confirmed that the change in the formation thickness difference in step S1 is not related to the fault, and the judgment of the paleo-structural deformation attribute is terminated.

6. The method for determining the deformation attributes of ancient structures according to claim 1, It is characterized in that In step S3, the three-dimensional paleo-structural morphology is the three-dimensional paleo-structural morphology of the target layer when the reference layer is not deposited.

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