Method for recovering ancient landform of multi-stage differential uplift region

Abstract

The invention discloses a multi-stage difference uplift area ancient landform restoration method, and the method comprises the following specific steps: S100, carrying out the detailed interpretation of a seismic section, and recognizing a main unconformity surface; s200, finding out a stratum denudation original point and a maximum denudation point position, solving a stratum thinning rate, and calculating an original thickness of a denudation section; s300, an original deposition boundary is determined on the seismic backbone section, and denudation thickness recovery is carried out in combination with the residual thickness map; s400, identifying the mark layer; and S500, recovering the form of the ancient landform by using a marker bed-thickness analysis method based on a residual thickness method and an impression method. According to the method, partition difference recovery of stratum denudation thicknesses of different structure parts by tectonic movement is comprehensively considered, deposition-settlement compensation consistency is considered, the paleo-structure recovery precision is higher, the situation that whether erosion depression and residual hillocks exist on a paleo-erosion surface after paleo-denudation is not considered in a paleo-landform recovery method is improved, and the recovery efficiency of the paleo-landform recovery method is improved. And the problems of incomplete factors and limitation are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil exploration, in particular to a method for restoring paleogeomorphology in a multi-period differential uplift area. BACKGROUND

[0002] Paleogeomorphology is an important factor controlling the development and distribution of sedimentary facies in oil and gas bearing basins, and to some extent controls the reservoir-seal combination in the later stage. Restoring the shape of paleogeomorphology and discussing the control of paleogeomorphology on sedimentary environment, sedimentary facies and oil and gas reservoirs provides favorable support for finding favorable oil and gas reservoir development areas. At present, sandstone porosity method, mudstone acoustic time difference method, paleogeothermal method, vitrinite reflectance method, sedimentation rate method, material balance method, back stripping method, layer flattening method, seismic paleogeomorphology method, sedimentology analysis method, residual thickness method and impression method are used in different stages to guide oil and gas exploration and development. However, when these methods are used to restore paleogeomorphology, factors such as whether there are erosion depressions and residual hills on the paleo-erosion surface after the paleo-erosion, and whether it is nearly horizontal are not considered, which may restore an erosion depression or a sedimentation thinning area to a paleogeomorphology high.

[0003] For example, the patent for invention with publication number CN202011211430.X discloses a method for restoring paleogeomorphology, which belongs to the technical field of oil exploration. The method comprises the following steps: obtaining core samples; performing lithofacies analysis on the core samples to determine the lithology types of each stratum; detecting the content of trace elements in the core samples; dividing the strata; selecting marker layers; determining the oxidation-reduction environment of each stratum according to the content of trace elements; determining the residual stratum thickness of each stratum according to the lithology types of each stratum, the sedimentary stratum thickness and the oxidation-reduction environment of each stratum; and restoring the paleogeomorphology according to the residual stratum thickness of each stratum.

[0004] Although this method for restoring paleogeomorphology restores the paleogeomorphology through the residual stratum thickness of each stratum, thereby effectively guiding oil and gas exploration, the method does not consider whether there are erosion depressions and residual hills on the paleo-erosion surface after the paleo-erosion, and the considered factors are not complete and have limitations, which need to be further improved. SUMMARY

[0005] The present application aims to provide a method for restoring paleogeomorphology in a multi-period differential uplift area, and aims to improve the problem that the method for restoring paleogeomorphology does not consider whether there are erosion depressions and residual hills on the paleo-erosion surface after the paleo-erosion, and the considered factors are not complete and have limitations, which need to be further improved.

[0006] The present application is implemented in the following manner: a method for restoring paleogeomorphology in a multi-period differential uplift area, and the specific steps of the method are as follows:

[0007] S100, finely interpret a seismic profile and identify main unconformity surfaces;

[0008] S200, find out the denudation origin point and the maximum denudation point, calculate the stratum thinning rate, and calculate the original thickness of the denudation section;

[0009] S300, select the original sedimentary boundary on the seismic backbone profile, combine the residual thickness map, and restore the denudation thickness;

[0010] S400, identify the marker layer;

[0011] S500, restore the ancient landform morphology by using the marker layer-thickness analysis method based on the residual thickness method + the impression method.

[0012] Preferably, the characteristics of the main unconformity in S100 include development characteristics, extension trend, fault cutting relationship, and fold deformation characteristics.

[0013] Preferably, the specific steps of S200 are as follows:

[0014] S210, first find out the stratum denudation origin point A, and the maximum denudation point A';

[0015] S220, then determine the stratum thinning rate, find out the apparent layer section with relatively stable stratum thickness change from A to the basin, that is, the layer section that can be reliably identified, and determine the stratum thickness change starting point B point, set the distance of AB as L, and the apparent layer section thicknesses of A point and B point as H2 and H1 respectively, and use the following formula to calculate the thinning rate K=(H1-H2) / L*COSθ*100%;

[0016] S230, calculate the original thickness Hi of the denudation section, determine the calculation points C1, C2, C3... Cn and the distances L1, L2, L3... Ln from B to the denudation section from the apparent denudation origin point A, and use the formula: Hi=H1-K*Li*COSθ(i=1, 2, 3... n) to calculate the original thickness of each point;

[0017] S240, then calculate the denudation thickness, use the original thickness Hi of each point to subtract the residual thickness hi of each point, that is, the denudation thickness HBi of each point is obtained, i.e. HBi=Hi-hi(i=1, 2, 3... n);

[0018] S250, finally, perform denudation thickness compaction correction, the denudation thickness calculated by the above method is called theoretical denudation thickness, and the theoretical denudation amount obtained before is corrected by compaction to accurately measure the true thickness of the denuded stratum, that is, HA-ei=hT-ei*Cp(i=1, 2, 3... n).

[0019] Preferably, the S210 finds the original denudation point and the maximum denudation point A' according to the correlation deformation characteristics and extension trend of the multi-stage differential uplift area.

[0020] Preferably, the θ in the S220 formula is the angle between the apparent layer top boundary and the overlying stratum, and H1 and H2 are both the apparent original layer thickness, which is considered to be not denuded.

[0021] Preferably, the Cp in the S250 formula is a stratum compaction correction coefficient.

[0022] Preferably, the specific steps of the S300 are as follows:

[0023] S310, on the basis of the unconformity tracking interpretation of a plurality of regional seismic profiles covering the entire study area, the unconformity interface and denudation characteristics are identified and compared, and the denudation starting point is determined;

[0024] S320, the thickness points between the denudation starting point and the maximum onlap point are removed;

[0025] S330, the original thickness and the denudation thickness are calculated according to the trend surface.

[0026] Preferably, the specific steps of the S400 are as follows:

[0027] S410, an isochronous reference surface is selected as a marker layer, and the reference surface is a widely distributed and approximately isochronous sedimentary interface with a small sedimentary thickness and a filling and smoothing feature;

[0028] S400, an overlying stratum not denuded is selected as an isochronous reference surface for paleogeomorphology restoration, and the target layer and the overlying stratum not denuded are taken as a whole.

[0029] Preferably, the sedimentary interface in the S410 refers to above the unconformity erosion surface in the pre-restoration period, can represent the sea level at that time, is less affected by later tectonic activities, and should be easily identified on seismic profiles and well logging curves.

[0030] Preferably, the specific steps of the marker layer-thickness analysis method in the S500 are as follows:

[0031] S510, first, the geological data of the study area are analyzed to understand the paleogeological background, the experienced paleo-tectonic movement stages, the unconformity interface, and the macroscopic characteristics of the paleo-structure;

[0032] S520, second, an isochronous reference surface is selected as a marker layer in combination with the three-dimensional seismic data;

[0033] S530, then, on the isochronous seismic profile, the target layer and the marker layer are calibrated according to the seismic synthetic record, the isochronous reference surface is accurately found, and layer flattening operation is performed on the isochronous reference surface.

[0034] S540, then the stratum thickness below the flattened reference surface is corrected, at this time the topography below the reference surface can be approximately considered as the relative paleogeomorphology of the target layer before the deposition of the reference surface, then according to the superimposed profile after the layer is flattened, the residual thickness of the target layer can be obtained;

[0035] S550, subsequently, the residual thickness is superimposed with the denudation amount calculated in the first step, and the paleogeomorphology thickness (time domain) of the research area in the recovery period can be obtained;

[0036] S560, then the time-depth relationship conversion is carried out through the well-seismic joint method, the time domain is converted into the depth domain, and the paleogeomorphology thickness map of the target layer can be drawn;

[0037] S570, then an isochronous interface above the target layer is selected as a reference surface, and the reference surface is flattened, and the stratum thickness between the target layer and the reference surface is the imprint thickness;

[0038] S580, subsequently, the relative deposition thickness after the denudation amount correction is calculated by using the calculated imprint thickness and residual thickness;

[0039] S590, finally, the relative deposition thickness is used to draw a deposition paleogeomorphology map, which is compared and corrected with the paleogeomorphology thickness map, and the paleogeomorphology recovery of the target layer is completed.

[0040] Compared with the prior art, the present application has the beneficial effects that:

[0041] 1, the present application comprehensively considers the zonal difference recovery of stratum denudation thickness in different tectonic parts by tectonic movement, and considers the consistency of deposition-subsidence compensation, so that the paleostructure recovery precision is higher, the paleogeomorphology form is more in line with the actual situation, and the problem that the paleostructure recovery method cannot consider whether there is a leaching depression and a residual hill on the paleoerosion surface after the paleoerosion is considered, the consideration factor is not complete, and the problem of limitation is solved.

[0042] 2, the present application can not only be used for structure analysis and improving the paleostructure recovery precision, but also be used for sedimentary environment, sedimentary facies analysis and oil and gas reservoir analysis of different blocks and oil and gas fields, and can help the oil and gas field exploration and development to obtain better geological results. DETAILED DESCRIPTION

[0043] Figure 1 is a flowchart of the present application;

[0044] Figure 2 is a characteristic diagram of the main unconformity of the present application;

[0045] Figure 3 is a flowchart of S200 in the present application;

[0046] Figure 4 This is a schematic diagram of the process of S300 in this invention;

[0047] Figure 5 This is a schematic diagram of the S400 process in this invention;

[0048] Figure 6 This is a flowchart illustrating the marker layer thickness analysis method in S500 of this invention.

[0049] Figure 7 This is a schematic diagram illustrating the principle of the trend thickness method of this invention;

[0050] Figure 8 This is a schematic diagram illustrating the principle of the present invention, which combines the marking layer, thickness analysis, residual thickness method, and impression method. Detailed Implementation

[0051] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0052] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details:

[0053] Example 1

[0054] like Figures 1-7 As shown, a method for paleogeographic reconstruction of multi-phase differential uplift zones is presented. The specific steps of this method are as follows:

[0055] S100, detailed interpretation of seismic profiles, identification of major unconformities;

[0056] The main characteristics of unconformities in S100 include developmental features, extension trends, fracture and cutting relationships, and folding and deformation features.

[0057] S200. Find the origin and maximum erosion point of the strata, calculate the thinning rate of the strata, and calculate the original thickness of the eroded section.

[0058] The specific steps for S200 are as follows:

[0059] S210. First, find the origin of erosion A and the maximum erosion point A'. S210. According to the deformation characteristics and extension trend of the multi-stage differential uplift zone, find the origin of erosion and the maximum erosion point. The maximum erosion point A' is the maximum overshoot point.

[0060] S220, then determine the formation thinning rate, find out the apparent layer section which is relatively stable in thickness from A to the basin, that is, the layer section which can be reliably identified, and determine the starting point B of the formation thickness change, set the distance of AB as L, the thickness of the apparent layer section under A point and B point as H2 and H1 respectively, and use the following formula to calculate the thinning rate K=(H1-H2) / L*COSθ*100%; θ in the formula S220 is the angle between the apparent layer section top boundary and the overlying formation, and H1 and H2 are both the apparent original layer thickness, that is, it is considered to be not eroded;

[0061] S230, calculate the original thickness Hi of the eroded section, determine the calculation points C1, C2, C3... Cn and the distances L1, L2, L3... Ln from B of the eroded section from the apparent eroded origin A, and use the formula: Hi=H1-K*Li*COSθ(i=1, 2, 3... n) to calculate the original thickness of each point;

[0062] S240, then calculate the eroded thickness, use the original thickness Hi of each point minus the residual thickness hi of each point, that is, the eroded thickness HBi of each point is obtained: HBi=Hi-hi(i=1, 2, 3... n);

[0063] S250, finally, carry out the compaction correction of the eroded thickness, the eroded thickness calculated by the above method is called the theoretical eroded thickness, and the theoretical eroded thickness obtained before is subjected to compaction correction to accurately measure the true thickness of the eroded formation: HA-ei=hT-ei*Cp(i=1, 2, 3... n); Cp in the formula S250 is the formation compaction correction coefficient.

[0064] S300, select the original sedimentary boundary on the seismic backbone profile, combine the residual thickness map, and carry out the eroded thickness recovery;

[0065] The specific steps of S300 are as follows:

[0066] S310, first, on the basis of the unconformity tracking interpretation of a plurality of regional seismic profiles covering the entire study area, identify and compare the unconformity interface and the eroded characteristics, and determine the eroded starting point;

[0067] S320, remove the thickness points between the eroded starting point and the maximum onlap point;

[0068] S330, calculate the original thickness and the eroded thickness according to the trend surface.

[0069] S400, identify the marker layer;

[0070] The specific steps of S400 are as follows:

[0071] S410, select the isochronous reference surface as the marker bed, and the reference surface is a widely distributed and approximately isochronous sedimentary interface with small sedimentary thickness and the characteristics of filling and patching; the sedimentary interface in S410 refers to the interface above the adjacent pre-restoration period unconformity erosion surface, which can represent the sea level at that time and is less affected by later tectonic activity, and should be easily identified on seismic profiles and well logging curves;

[0072] S420, select the overlying strata not eroded as the isochronous reference surface for paleogeomorphology restoration, and take the target layer and its overlying strata not eroded as a whole.

[0073] S500, restore the paleogeomorphology using the marker bed thickness analysis method based on the residual thickness method + the impression method.

[0074] The specific steps of the marker bed thickness analysis method in S500 are as follows:

[0075] S510, first analyze the geological data of the study area to understand the paleogeological background, the experienced paleo-tectonic movement period, the unconformity interface and the macroscopic characteristics of the paleo-structure;

[0076] S520, secondly, select the isochronous reference surface as the marker bed in combination with the three-dimensional seismic data;

[0077] S530, then on the isochronous seismic profile, calibrate the target layer and the marker bed according to the seismic synthetic record, accurately find the isochronous reference surface, and perform layer flattening operation on it;

[0078] S540, then perform compaction correction on the thickness of the strata below the flattened reference surface, at this time the geomorphology below the reference surface can be approximately considered as the relative paleogeomorphology of the target layer before the deposition of the reference surface, and then according to the layer-flattened stacking section, the residual thickness of the target layer can be obtained;

[0079] S550, subsequently, superimpose the residual thickness with the denudation amount calculated in the first step, and the paleogeomorphology thickness (time domain) of the restoration period in the study area can be obtained;

[0080] S560, then convert the time domain to the depth domain through the well-seismic joint method, and the paleogeomorphology thickness map of the target layer can be drawn;

[0081] S570, then select an isochronous interface above the target layer as the reference surface and flatten it, and the thickness of the strata between the target layer and the reference surface is the impression thickness;

[0082] S580, subsequently, calculate the relative sedimentary thickness corrected by the denudation amount using the obtained impression thickness and residual thickness;

[0083] S590. Finally, the obtained relative sedimentary thickness is used to draw a sedimentary paleogeographic map, which is then compared and corrected with the paleogeographic thickness map to complete the paleogeographic restoration of the target layer.

[0084] Example 2

[0085] like Figures 1-7 As shown, a method for paleogeographic reconstruction of multi-phase differential uplift zones is presented. The specific steps of this method are as follows:

[0086] S100, detailed interpretation of seismic profiles, identification of major unconformities;

[0087] The main unconformities in S1 00 include developmental features, extension trends, fracture and cutting relationships, and folding and deformation characteristics.

[0088] S200. Find the origin and maximum erosion point of the strata, calculate the thinning rate of the strata, and calculate the original thickness of the eroded section.

[0089] The specific steps for S200 are as follows:

[0090] S210. First, find the origin of erosion A and the maximum erosion point A'. S210. According to the deformation characteristics and extension trend of the multi-stage differential uplift zone, find the origin of erosion and the maximum erosion point. The maximum erosion point A' is the maximum overshoot point.

[0091] S220. Then determine the thinning rate of the strata. From A towards the basin, find the apparent strata with relatively stable changes in thickness, i.e., the strata that can be reliably identified, and determine the starting point of the change in strata thickness, point B. Let the distance between AB be L, and the thicknesses of the apparent strata below points A and B be H2 and H1, respectively. Use the following formula to calculate the thinning rate K = (H1-H2) / L*COSθ×100%; In the formula S220, θ is the angle between the top boundary of the apparent strata and the overlying strata, and H1 and H2 are both the apparent original strata thickness, i.e., it is considered to be uneroded.

[0092] S230. Calculate the original thickness Hi of the eroded section. Determine the calculation points C1, C2, C3...Cn from the apparent erosion origin A to the eroded section, and the distances L1, L2, L3...Ln from each point to B. Use the formula: Hi=H1-K×LiCOS θ (i=1, 2, 3...n) to calculate the original thickness of the strata at each point.

[0093] S240. Next, calculate the erosion thickness by subtracting the residual thickness hi from the original thickness Hi at each point. This gives the erosion thickness HBi = Hi - hi (i = 1, 2, 3...n).

[0094] S250, finally, erosion thickness compaction correction is carried out, the erosion thickness calculated according to the above method is called theoretical erosion thickness, and the theoretical erosion thickness is corrected to accurately measure the real thickness of the eroded stratum HA-ei=hT-ei×Cp(i=1, 2, 3...n); in the formula of S250, Cp is the stratum compaction correction coefficient.

[0095] S300, selecting the original sedimentary boundary determined on the seismic backbone profile, combining the residual thickness map, erosion thickness recovery is carried out;

[0096] The specific steps of S300 are as follows:

[0097] S310, first, on the basis of unconformity tracking interpretation of a plurality of regional seismic profiles covering the entire study area, the unconformity interface and erosion characteristics are identified and compared to determine the stripping point; according to the above principle, the erosion thickness of each profile target layer is calculated on the regional geological profile, and the erosion closure is carried out, so as to determine the original sedimentary boundary as the control boundary for trend thickness calculation;

[0098] S320, removing the thickness point between the stripping point and the maximum onlap point;

[0099] S330, calculating the original thickness and erosion thickness according to the trend surface;

[0100] S400, identifying the marker layer;

[0101] The specific steps of S400 are as follows:

[0102] S410, selecting an isochronous reference surface as a marker layer, and the reference surface is a widely distributed and approximately isochronous sedimentary interface, the sedimentary thickness is not large, and has the characteristics of filling and patching; the sedimentary interface in S410 refers to the upper adjacent unconformity erosion surface of the pre-restoration period, which can represent the sea level at that time and is less affected by later tectonic activity, and should be easily identified on seismic profiles and well logging curves;

[0103] S420, selecting an overlying stratum not eroded as an isochronous reference surface for paleogeomorphology restoration, and taking the target layer and the overlying stratum not eroded as a whole.

[0104] S500, restoring the paleogeomorphology using the marker layer thickness analysis method based on residual thickness method + impression method.

[0105] The specific steps of the marker layer thickness analysis method in S500 are as follows:

[0106] S510, first, the geological data of the study area is analyzed to understand the paleogeological background, the paleo-tectonic movement period, the unconformity interface and the paleo-tectonic macroscopic characteristics;

[0107] S520, second, combined with three-dimensional seismic data, an isochronous reference surface is selected as a marker layer; the reference surface is a widely distributed and approximately isochronous sedimentary interface, the sedimentary thickness is not large, and has the characteristics of filling and patching. The interface should be adjacent to the pre-restored unconformity erosion surface, can represent the sea level at that time, is less affected by later tectonic activity, and should be easily identifiable on seismic profiles and well logging curves. Select the overlying strata which are not eroded as the isochronous reference surface for paleogeomorphology restoration, and take the target layer and its overlying strata which are not eroded as a whole, because the present form of the overlying strata which are not eroded retains the basic form of the paleogeomorphology, and the residual thickness is closely related to the paleo-tectonic amplitude;

[0108] S530, then on the isochronous seismic profile, the target layer and the marker layer are calibrated according to the seismic synthetic record, the isochronous reference surface is accurately found, and the layer flattening operation is performed on it;

[0109] S540, then the strata thickness below the flattened reference surface is compacted, at this time the geomorphology below the reference surface can be approximately considered as the relative paleogeomorphology of the target layer before the reference surface deposition, and then according to the layer flattened stacking section, the residual thickness of the target layer can be obtained;

[0110] S550, subsequently, the residual thickness is superimposed with the erosion amount calculated in the first step, and the paleogeomorphology thickness of the study area in the restoration period (time domain) can be obtained;

[0111] S560, then the time-depth relationship is converted by the well-seismic joint method, the time domain is converted into the depth domain, and the paleogeomorphology thickness map of the target layer can be drawn;

[0112] S570, then an isochronous interface above the target layer is selected as a reference surface, and it is flattened, and the strata thickness between the target layer and the reference surface is the impression thickness;

[0113] S580, subsequently, the relative sedimentary thickness after the erosion amount correction is calculated by using the obtained impression thickness and residual thickness;

[0114] H==H1 / H2

[0115] H —— relative sedimentary thickness;

[0116] H1 —— residual thickness, m;

[0117] H2 —— impression thickness, m;

[0118] When the residual thickness H1 becomes small, it indicates that the denudation amount is large, and the area with large denudation amount is often located in the high-landform terrain, so the impression thickness H2 also becomes small, that is, H1 and H2 have the same change trend, so it can indicate the original relative deposition thickness;

[0119] S590, finally, the relative deposition thickness obtained is used to draw a deposition paleogeomorphology map, which is compared and corrected with the paleogeomorphology thickness map, so as to complete the paleogeomorphology recovery of the target layer.

[0120] In summary, the present application considers the partition difference recovery of the denudation thickness of strata in different tectonic parts by structural movement, and considers the consistency of deposition-subsidence compensation, so that the paleostructure recovery precision is higher, the paleogeomorphology shape is more in line with the actual situation, and the problem that the paleogeomorphology recovery method cannot consider whether there is a leaching depression and a residual hill on the ancient erosion surface after the ancient denudation is improved, the consideration factors are not complete, and the problem of limitation is solved; not only can be used for structural analysis and improving the paleostructure recovery precision, but also can be used for sedimentary environment, sedimentary facies analysis and oil and gas reservoir analysis of different blocks and oil and gas fields, and can help to obtain better geological results in oil and gas field exploration and development.

[0121] The above is only the preferred embodiment of the present application, and is not used to limit the present application, and the present application can have various changes and variations for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for paleogeographic reconstruction of multi-phase differential uplift zones, characterized in that, The specific steps of this multi-phase differential uplift zone paleogeographic restoration method are as follows: S100, detailed interpretation of seismic profiles, identification of major unconformities; S200. Locate the origin and maximum erosion point of the strata, calculate the thinning rate of the strata, and calculate the original thickness of the eroded section. S300. Select the original sedimentary boundary on the seismic backbone profile and combine it with the residual thickness map to restore the erosion thickness; S400, identification marker layer; S500: Paleomorphological features are restored using marker layer thickness analysis based on residual thickness method and impression method.

2. The method for paleogeographic restoration of multi-phase differential uplift zones according to claim 1, characterized in that, The main unconformities in S100 include developmental features, extension trends, fracture and cutting relationships, and folding and deformation features.

3. The method for paleogeographic restoration of multi-phase differential uplift zones according to claim 1, characterized in that, The specific steps of S200 are as follows: S210. First, find the origin of erosion A, and the maximum erosion point is A'. S220. Then determine the thinning rate of the strata. From A towards the basin, find the apparent strata with relatively stable changes in strata thickness, that is, the strata that can be reliably identified, and determine the starting point of the strata thickness change, point B. Let the distance between AB be L, and the thicknesses of the apparent strata below points A and B be H2 and H1, respectively. Use the following formula to calculate the thinning rate K = (H1-H2) / L*COSθ×100%. S230. Calculate the original thickness Hi of the eroded section. Determine the calculation points C1, C2, C3...Cn from the apparent erosion origin A to the eroded section, and the distances L1, L2, L3...Ln from each point to B. Use the formula: Hi=H1-K×LiCOSθ (i=1, 2, 3...n) to calculate the original thickness of the strata at each point. S240. Next, calculate the erosion thickness by subtracting the residual thickness hi from the original thickness Hi at each point. This gives the erosion thickness HBi = Hi - hi (i = 1, 2, 3...n). S250. Finally, the erosion thickness is compacted and corrected. The erosion thickness calculated according to the above method is called the theoretical erosion thickness. The theoretical erosion amount obtained earlier is compacted and corrected to accurately measure the true thickness of the eroded stratum HA-ei=hT-ei×Cp (i=1、2、3......n).

4. The method for paleogeographic restoration of multi-phase differential uplift zones according to claim 3, characterized in that, According to the deformation characteristics and extension trends of the multi-stage differential uplift zone, S210 identifies the origin and maximum erosion point of the strata, where the maximum erosion point A' is the maximum overshoot point.

5. The method for paleogeographic restoration of multi-phase differential uplift zones according to claim 3, characterized in that, In the S220 formula, θ is the angle between the top boundary of the apparent layer and the overlying strata, and H1 and H2 are both the apparent original layer thickness, which is considered to be uneroded.

6. The method for paleogeographic restoration of multi-phase differential uplift zones according to claim 3, characterized in that, In the S250 formula, Cp is the formation compaction correction coefficient.

7. The method for paleogeographic restoration of multi-phase differential uplift zones according to claim 1, characterized in that, The specific steps of S300 are as follows: S310. First, based on the unconformity tracking interpretation of multiple regional seismic profiles covering the entire study area, the unconformity interface and erosion characteristics are identified and compared to determine the erosion initiation point. S320, Remove the thickness points between the peeling start point and the maximum overhang point; S330, calculate the original thickness and erosion thickness based on the trend surface.

8. The method for paleogeographic restoration of multi-phase differential uplift zones according to claim 1, characterized in that, The specific steps of S400 are as follows: S410. Select an isochronous reference surface as the marker layer. The reference surface is a widely distributed and approximately isochronous deposition interface with a small deposition thickness and has the characteristics of filling and leveling. S400. Select the uneroded overlying strata as the isochronous reference surface for paleogeographic reconstruction, and treat the target layer and its uneroded overlying strata as a whole.

9. The method for paleogeographic restoration of multi-phase differential uplift zones according to claim 8, characterized in that, The sedimentary interface in S410 refers to the unconformity erosion surface adjacent to the pre-recovery period, which can represent the sea level at that time, is less affected by later tectonic activities, and should be easily identifiable on seismic profiles and well logging curves.

10. The method for paleogeographic restoration of multi-phase differential uplift zones according to claim 1, characterized in that, The specific steps of the marker layer thickness analysis method in S500 are as follows: S510. First, analyze the geological data of the study area to understand the paleogeological background, the periods of paleotectonic movement, unconformities, and macroscopic characteristics of paleotectonic structures. S520, and secondly, by combining three-dimensional seismic data, an isochronous reference surface is selected as a marker layer; S530. Next, on the isochronous seismic profile, the target layer and marker layer are marked according to the seismic synthetic record, the isochronous reference surface is accurately located, and the layer flattening operation is performed on it. S540. Then, the thickness of the strata below the flattened reference surface is compacted and corrected. At this time, the landform below the reference surface can be approximately considered as the relative paleogeography of the target layer before the reference surface was deposited. Then, based on the superimposed profile after the layer is flattened, the residual thickness of the target layer can be obtained. S550. Then, the residual thickness is superimposed with the erosion amount calculated in the first step to obtain the paleogeographic thickness (time domain) of the study area during the restoration period. S560. Then, by combining well and seismic methods, the time-depth relationship is transformed into the depth domain, and the paleogeographic thickness map of the target stratum can be drawn. S570. Next, select an isochronous interface above the target layer as a reference surface and flatten it. The thickness of the formation between the target layer and the reference surface is the impression thickness. S580. Then, the relative deposition thickness after erosion correction is calculated using the obtained impression thickness and residual thickness. S590. Finally, the obtained relative sedimentary thickness is used to draw a sedimentary paleogeographic map, which is then compared and corrected with the paleogeographic thickness map to complete the paleogeographic restoration of the target layer.

Images