A method for restoring three-dimensional paleotopography

Abstract

The present application relates to a kind of recovery three-dimensional ancient landform method, by the present structure of fault-related fold deformation is removed, the form of the purpose layer ancient landform is obtained, so as to judge in the ancient landform background, which geomorphologic high position is deposited in the favorable carbonate rock beach facies reservoir, to improve the success rate of oil and gas industry drilling.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum and natural gas geology, and particularly relates to a method for restoring three-dimensional ancient landform. BACKGROUND

[0002] The high position of the ancient landform morphology can be a favorable area for oil and gas accumulation. However, due to the later tectonic reconstruction, it is difficult to determine the morphology and distribution characteristics of the early original ancient landform, especially in the case of complex faults, and simple layer flattening can lead to abnormal ancient landform, so it is necessary to carry out three-dimensional restoration to determine the original characteristics of the ancient landform in three-dimensional space and find the favorable oil and gas exploration area.

[0003] There are some technical methods for restoring ancient landform in the prior art, but they do not solve the key problem of first eliminating the present tectonic deformation and establishing a reliable three-dimensional ancient landform morphology. For example, the method of “ancient landform constrained modeling method, device and equipment” (application patent number: CN201811487404.2) only restores the ancient landform by simply flattening the unconformity surface, without considering how to eliminate the influence of faults in complex tectonic areas. The method of “a method for restoring original sedimentary appearance of a reformed faulted basin” (application patent number: CN201710144840.9) does not consider the restoration of three-dimensional tectonic model, and the specific oil and gas favorable area cannot be clearly determined in space; the method of “a three-dimensional modeling method for tectonic fractures based on tectonic surface geometry restoration” (application patent number: CN201610029135.X) is not a method for restoring the morphology of ancient landform. The method of “a method for restoring ancient landform profile” (application patent number: CN201610121264.1), the method of “a quick and quantitative ancient landform restoration method considering the influence of ancient landform” (application patent number: CN201511014406.6), and the method of “ancient landform mapping method and device” (application patent number: CN201410043533.8) do not involve three-dimensional restoration modeling of complex structures at all. SUMMARY

[0004] The purpose of the present application is to provide an accurate method for restoring three-dimensional ancient landform. By eliminating the fault-related fold deformation of the present structure, the morphology of the ancient landform of the target layer is obtained, so that it can be determined how the favorable carbonate rock beach facies reservoir is deposited in the original ancient landform background, and the success rate of oil and gas drilling is improved.

[0005] The technical scheme adopted by the present application to solve the technical problem is as follows:

[0006] Step S1: Establish a three-dimensional geometric model of the structural layer and the fault surface. Form three-dimensional layers of the strata and faults respectively by interpreting the strata and faults of the three-dimensional seismic data, and establish a geometric three-dimensional tectonic model.

[0007] Step S2: remove the related fold effect of the fault based on the extrusion tectonic kinematics. Extract the target layer and the upper reference layer from the stratum layer, and the fault that breaks the two horizons, then remove the fold effect of the fault along the fault plane based on the new to old tectonic deformation steps for the fold deformation related to the fault.

[0008] Step S3: remove the remaining fold geometry with the bend-slip defolding method. After removing the fold related to the thrust fault, the reference layer still has fold morphology, at this time, based on the bend-slip defolding method, remove the fold deformation of the reference layer, and make the reference layer flat, completely removing the tectonic deformation of the reference layer.

[0009] Step S4: obtain the paleogeomorphology of the target layer. After the reference layer becomes flat, the target layer still has weak undulating morphology, which is the paleogeomorphology of the target layer at this time.

[0010] Preferably, the three-dimensional seismic data is obtained by processing the original seismic data collected in the field through professional software, which is a set of electronic signal data. The surface excited sound wave is transmitted to the ground, and the signal obtained by the ground receiver can be used to analyze the structure and sedimentary characteristics of the underground stratum, and is used to find the favorable area of oil and gas reservoir. Three-dimensional seismic data has a spatial concept, that is, within a certain range underground, each X1, Y1, Z1 has corresponding values, representing the underground stratum information at the X1, Y1, Z1 point. X1, Y1 is the position of the point in the terrestrial coordinate system, and Z1 is the elevation value underground. Input three-dimensional seismic data into professional software, and use special software functions to interpret strata and faults. The strata and faults interpreted from three-dimensional seismic data are also a face of information in spatial distribution. A three-dimensional layer or fault layer in space has X1, Y1, Z1 information at each corresponding spatial point within the three-dimensional seismic data defined space, which is a layer information in space. When the X1Y1Z1 spatial information of the stratum layer and the fault layer is obtained, the strata and faults are combined separately to form a three-dimensional space model.

[0011] Preferably, in the three-dimensional layer and fault interpretation of three-dimensional seismic data using seismic data interpretation software, a plurality of layers are interpreted from top to bottom, such as Jurassic, Cretaceous, Permian, Carboniferous, Cambrian and other geological layers; but for a specific layer purpose layer and upper reference layer, at this time, the information of the purpose layer and the upper reference layer can be extracted in the 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 ground, and Z2 is the elevation value of the underground, and the series of X2Y2Z2 information together is the distribution of a layer in space. When the fault is a reverse fault, the upper wall of the fault is deformed and the lower wall is not deformed, so the movement mode of the upper wall of the fault is selected, the purpose layer of the lower wall of the fault is kept stationary, the purpose layer of the upper wall of the fault is retreated along the fault to the point of contact with the purpose layer of the lower wall of the fault, so that the purpose layer is just connected at the point of contact of the upper and lower walls of the fault. When the fault is a normal fault, the lower wall of the fault is deformed and the upper wall is not deformed, and the movement mode of the lower wall of the fault is selected, the purpose layer of the upper wall of the fault is kept stationary, the purpose layer of the lower wall of the fault is retreated along the fault to the point of contact with the purpose layer of the upper wall of the fault, so that the purpose layer is just connected at the point of contact of the upper and lower walls of the fault.

[0012] Preferably, after the step S2, the reference layer still retains some fold shapes, at this time, since the step S2 has completely eliminated the fold shapes formed along the fault plane, the remaining folds are not affected by the fault, at this time, the reference layer is fixed relative to the boundary towards the basin, and then the reference layer is flattened towards the direction out of the basin to realize fold recovery and change the reference layer into a flat layer.

[0013] Preferably, after the step S3, the purpose layer still retains weak undulating shapes, at this time, the display of the reference layer can be cancelled, and the high and low undulating information of the purpose layer paleogeomorphology is displayed alone.

[0014] Preferably, after the step S3, the purpose layer still retains weak undulating shapes, the purpose layer paleogeomorphology information at 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 ground, and Z3 represents the high and low undulating values of the purpose layer geomorphology, and the series of X3Y3Z3 information together is the paleogeomorphology of the purpose layer, and the X3Y3Z3 information is input into the mapping software to obtain a plan view, and the color scale displays the high and low undulating information of the paleogeomorphology.

[0015] The beneficial effects of the present application are as follows:

[0016] Due to the action of the fault, the fold shape is complex, if through the simple layer flattening method, the obtained paleogeomorphology error is big, the position of the fault is easy to cause distortion, leads to being unable to determine the favorable deposition of the carbonate rock beach facies reservoir, leads to the failure of oil and gas drilling. The present application obtains the original and real paleogeomorphology shape on the basis of removing the related fold shape of the fault, which has significant innovation and progressivity compared with the prior art. The present application can construct the paleogeomorphology shape with higher precision and higher accuracy, so as to implement the favorable reservoir development area. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is the geometric three-dimensional model established in step S1 of the embodiment of the present application;

[0018] Figure 2 It is the target layer and the reference layer and the fault that breaks the two horizons extracted in step S2 of the embodiment of the present application;

[0019] Figure 3 It is the related fold of the latest active fault removed in step S2 of the embodiment of the present application;

[0020] Figure 4 It is the residual fold shape after removing the related fold of the remaining fault in step S2 of the embodiment of the present application;

[0021] Figure 5 It is the reference layer and the target layer shape after removing the remaining fold in step S3 of the embodiment of the present application;

[0022] Figure 6 It is the target layer paleogeomorphology obtained in step S4 of the embodiment of the present application. DETAILED DESCRIPTION

[0023] Embodiment 1

[0024] As a most basic embodiment of the present application, the present embodiment discloses a method for restoring three-dimensional paleogeomorphology, comprising the following steps:

[0025] Step S1: Establishing a three-dimensional geometric model of the structural layer and the fault surface. Form three-dimensional layers of the strata and the faults respectively by interpreting the strata and the faults of the three-dimensional seismic data, and establishing a geometric three-dimensional structure model.

[0026] Step S2: Removing the related fold effect of the fault based on the extrusion tectonic kinematics. Extracting the target layer and the upper reference layer from the strata layer, and the fault that breaks the target layer and the upper reference layer, and then removing the fold effect of the fault along the fault surface based on the new to old tectonic deformation step for the fold deformation related to the fault.

[0027] Step S3: removing the residual fold geometry by the bending slip method. After removing the influence of the fold caused by the fault, the reference layer still retains some fold geometry. The reference layer is fixed relative to the boundary towards the basin, and then the reference layer is flattened towards the direction outside the basin to realize fold recovery, and the reference layer becomes a flat layer.

[0028] Step S4: obtaining the paleogeomorphology of the target layer. After the reference layer becomes a flat layer, the target layer still retains weak undulating morphology, so that the display of the reference layer can be cancelled, and the high and low undulating information of the paleogeomorphology of the target layer is displayed alone.

[0029] Embodiment 2

[0030] The present application is described in detail by taking a certain extrusion structure as an example.

[0031] As a most preferred embodiment of the present application, the present embodiment discloses a method for restoring a three-dimensional paleogeomorphology, comprising the following steps:

[0032] As shown in Figure 1 Step S1: three-dimensional seismic data are obtained by processing original seismic data collected in the field through professional software (the professional software is a known software), and are a set of electronic signal data. The surface excited sound waves are transmitted to the ground, and the signals obtained by using the ground receiver can be used to analyze the structure and sedimentary characteristics of the underground stratum, and are used to find favorable areas for oil and gas reservoirs. The three-dimensional seismic data have a spatial concept, that is, in a certain range underground, each X1, Y1 and Z1 has a corresponding value, representing the underground stratum information at the X1, Y1 and Z1 point. X1 and Y1 are the positions of the point in the terrestrial coordinate system, and Z1 is the underground elevation value. The three-dimensional seismic data are input into the professional software, and a special software function is used to interpret the stratum and fault. The stratum and fault interpreted by the three-dimensional seismic data are also a face information in spatial distribution. A three-dimensional layer or a three-dimensional layer of a fault has X1, Y1 and Z1 information corresponding to each spatial point in the space defined by the three-dimensional seismic data, which is a layer information in a space. When the X1, Y1 and Z1 spatial information of the stratum layer and the fault layer are obtained, the stratum and the fault are combined separately to form a three-dimensional space model.

[0033] As shown in Figure 2As shown, step S2: When interpreting three-dimensional seismic data into three-dimensional layers and faults using seismic data interpretation software (which is existing known software), multiple layers are interpreted from top to bottom, such as Jurassic, Cretaceous, Permian, Carboniferous, Cambrian and other geological layers; however, for a specific target layer and upper reference layer, the information of the target layer and upper reference layer can be extracted in professional software to obtain a digital file containing a series of X2, Y2 and Z2 information, where X2 and Y2 are the geodetic coordinates of the Earth's surface, and Z2 is the elevation value of the subsurface. A series of X2Y2Z2 information together represents the spatial distribution of a layer. To determine whether a fault is a reverse fault or a normal fault, in a reverse fault, the hanging wall deforms while the footwall remains stationary. Therefore, we select the movement pattern of the hanging wall, keeping the target layer on the footwall stationary, and move the target layer on the hanging wall back along the fault to the point of contact with the target layer on the footwall, so that the target layer is exactly connected at the point of contact between the hanging wall and the footwall. In a normal fault, the footwall deforms while the hanging wall remains stationary. Similarly, we select the movement pattern of the footwall, keeping the target layer on the hanging wall stationary, and move the target layer on the footwall back along the fault to the point of contact with the target layer on the hanging wall, so that the target layer is exactly connected at the point of contact between the hanging wall and the footwall.

[0034] like Figures 3-5 As shown, in step S3: the reference layer often still retains some fold morphology. At this time, since step S2 has completely eliminated the fold morphology formed by the 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 in the basin, and then the reference layer is pulled flat in the direction of the basin to realize fold restoration and turn the reference layer into a flat layer. The reference layer on the hanging wall of the fault is connected with the reference layer on the footwall. This method is suitable for the fold deformation of sedimentary strata with obvious layered structure. The "fault removal" process is carried out in the order from newest to oldest. Since the slip surface of the right fault is bent and modified by the high-angle fault on the left, the activity time is earlier. Therefore, the fault on the left is removed first. On the basis of this restoration, the low-angle fault on the right is restored. Through the above "fault removal" process, the fold morphology of the reference layer and the target layer can be restored. In the fold removal process, the remaining fold morphology restored in step S2 is restored. Here, the reference layer is removed by the bending slip fold removal method to restore the paleogeographic morphology of the target layer.

[0035] After the folding effect caused by the fault is eliminated through step S2, the reference layer often still retains some folding morphology. At this time, since step S2 has completely eliminated the folding morphology formed by the movement along the fault plane, what remains are the folds that are not affected by the fault. Then, the reference layer is fixed relative to the boundary in the basin, and the reference layer is pulled flat in the direction outside the basin to restore the folds and turn the reference layer into a flat layer.

[0036] Step S4: When the reference layer becomes a flat layer after being processed by step S3, the target layer still retains a weak undulating form. At this time, the display of the reference layer can be canceled, and the high and low undulating information of the target layer can be displayed alone.

[0037] Example 3

[0038] The difference between this example and example 2 is that, as shown in Figure 6 Step S4: When the reference layer becomes a flat layer after being processed by step S3, the target layer still retains a weak undulating form. The target layer paleogeomorphology information at this step is extracted to obtain a digital file, which includes a series of X3, Y3, Z3 information. X3 and Y3 are the geodetic coordinate values of the ground surface, and Z3 represents the high and low undulating values of the target layer geomorphology. The series of X3Y3Z3 information together is the target layer paleogeomorphology. The X3Y3Z3 information is input into a mapping software (the mapping software is a known software) to obtain a plan view, and a color scale is used to display the high and low undulating information of the paleogeomorphology.

[0039] As described above, the embodiments of the present application are described in detail, but as long as the essence does not deviate from the invention point and effect of the present application, there can be many modifications, which is obvious to those skilled in the art. Therefore, such modified examples are also entirely included in the protection scope of the present application.

Claims

1. A method of restoring a three-dimensional palaeotopography, Characterized in that, It comprises the following steps: Step S1: Establishing a geometric three-dimensional model of the structural level and the fault; Step S2: Removing the related fold effect of the fault based on the extrusion structure kinematics; In the step S2, the target layer and the upper reference layer are extracted from the stratum level, and the fault that breaks the target layer and the upper reference layer is extracted, and then for the fold deformation related to the fault, the fold effect of the fault is removed along the fault surface based on the new to old structural deformation step; In the step S2, the stratum target layer and the upper reference are extracted from the geometric three-dimensional model to obtain a set of digital files including X2, Y2, Z2 underground stratum information, X2 and Y2 are the geodetic coordinate values of the ground surface, and Z2 is the underground elevation value. Determine whether the fault is a reverse fault or a normal fault. When it is a reverse fault, keep the target layer under the fault foot still, and make the target layer on the fault foot retreat along the fault to the point of contact with the target layer under the fault foot, so that the target layer is just connected at the breakpoint of the fault foot. The target layer on the fault foot is kept still, and the target layer under the fault foot is retreated along the fault to the point of contact with the target layer on the fault foot, so that the target layer is just connected at the breakpoint of the fault foot. Step S3: Removing the remaining fold geometry by bending and sliding; Step S4: Obtaining the paleogeomorphic shape of the target layer.

2. The method for restoring three-dimensional paleogeomorphology according to claim 1, characterized in that: In the step S1, the three-dimensional stratum and fault are formed by interpreting the three-dimensional seismic data to form a three-dimensional layer, and a geometric three-dimensional model is established.

3. The method for restoring three-dimensional paleogeomorphology according to claim 2, characterized in that: In the step S1, the three-dimensional seismic data is a set of underground stratum information including X1, Y1, Z1 obtained by processing the original seismic data by software, X1 and Y1 are the positions of the point in the geodetic coordinate system, and Z1 is the underground elevation value.

4. The method for restoring three-dimensional paleogeomorphology according to claim 3, characterized in that: In the step S1, the three-dimensional seismic data is input into the seismic data interpretation software to obtain the three-dimensional layer of the stratum and the three-dimensional layer of the fault, and the stratum and the fault are separately combined to form a geometric three-dimensional model.

5. The method for restoring three-dimensional paleogeomorphology according to claim 4, characterized in that: In the step S3, after removing the fold related to the fault, the reference layer still has a fold shape, at this time, based on the bending and sliding fold removal method, the fold deformation of the reference layer is removed, and the reference layer is changed into a flat layer, completely removing the structural deformation of the reference layer.

6. The method for restoring three-dimensional paleogeomorphology according to claim 5, characterized in that: In the step S3, after the fold effect caused by the fault is removed through S2, the reference layer often still has some fold shapes. The reference layer is fixed relative to the boundary towards the basin, and then the reference layer is flattened towards the direction outside the basin to realize fold restoration and change the reference layer into a flat layer.

7. The method for restoring three-dimensional paleogeomorphology according to claim 6, characterized in that: In step S4, the reference layer becomes flat, and the target layer still has weak undulating morphology. Then, the display of the reference layer is canceled, and the high and low relief information of the target layer is displayed alone.

8. The method of claim 7, wherein: In step S4, the reference layer becomes flat, and the target layer still has weak undulating morphology. Then, the display of the reference layer is canceled, and the high and low relief information of the target layer is displayed alone. In step S4, the reference layer becomes flat, and the target layer still has weak undulating morphology. Then, the display of the reference layer is canceled, and the high and low relief information of the target layer is displayed alone.

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