Basin-scale carbonate rock karst ancient landform recovery method

Abstract

The invention discloses a basin-scale carbonate rock karst ancient landform recovery method, and relates to the technical field of petroleum and natural gas exploration, and the technical scheme is characterized in that a stratum section of a karst ancient landform recovery marker bed is established; forming a stratigraphic contrast network by each drilling well and the adjacent field outcrop, and comparing the stratigraphic contrast network with a stratigraphic section to obtain boundary positions of the top and the bottom of a karst ancient landform restoration marker bed between each drilling well and the field outcrop; compiling a stratum thickness plane contour map of the karst ancient landform restoration marker bed; drawing a lithofacies paleogeography map of the karst ancient landform recovery marker bed; identifying types of karst ancient landform units developed in the basin, and on a reference map obtained by fusing the stratum thickness plane contour map and the lithofacies ancient geographic map, dividing the karst ancient landform units based on a preset stratum thickness range and sedimentary facies types; and compiling a karst ancient landform map on the stratum thickness plane contour map according to the karst ancient landform units.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas exploration, and more specifically, to a basin-scale carbonate karst paleo-geomorphology restoration method. Background Art

[0002] Karst paleo-geomorphology restoration is one of the important methods for paleo-karst prediction and has been widely used in the field of oil and gas exploration technology. For carbonate strata, the commonly used karst paleo-geomorphology restoration methods include residual thickness method, impression method, sedimentology method, etc. These methods have their own advantages and can accurately complete paleo-geomorphology restoration when used in local research areas. However, carbonate rocks at the basin scale are affected by the differentiation of sedimentary phase types, and the original stratum thickness is different. The stratum erosion thickness during the subsequent paleo-karst period is also different. Therefore, there are multiple solutions to the causes of the current stratum thickness.

[0003] The currently commonly used methods for restoring karst paleo-geomorphology cannot distinguish the ambiguity of the present-day stratum thickness, and thus it is difficult to accurately characterize the basin-scale karst paleo-geomorphology, and therefore it is also impossible to accurately analyze the relative height and steepness trend of the basin-scale karst paleo-geomorphology.

[0004] Based on the actual demand for lateral comparison of basin-scale carbonate paleokarst development conditions generated during the oil and gas exploration stage, how to qualitatively reflect the relative height and steepness trend of basin-scale karst paleo-geomorphology is an urgent problem to be solved. Summary of the invention

[0005] The purpose of this application is to provide a basin-scale carbonate karst paleo-geomorphology restoration method, which solves the problem that the existing technology cannot accurately analyze the relative height and steepness trend of basin-scale karst paleo-geomorphology.

[0006] The present application provides a basin-scale carbonate karst paleo-geomorphology restoration method, the method comprising:

[0007] Field outcrops were selected from the basin periphery, and based on the field outcrops and stratigraphic division standards, stratigraphic sections of the landmark layers for karst paleo-geomorphological restoration were established;

[0008] At least one well in the stratum is selected, each well and adjacent field outcrop are combined into a stratigraphic correlation network, the stratigraphic correlation network is compared with the stratigraphic section, and the top and bottom boundary positions of the karst paleo-geomorphology restoration marker layer between each well and the field outcrop are obtained;

[0009] The stratum thickness of the field outcrop is determined based on the boundary position of the top and bottom of the marker layer, and the variation trend of the stratum thickness is analyzed in combination with the seismic data. Based on the various wells, stratum thickness and variation trend, a stratum thickness plane contour map of the karst paleo-geomorphology restoration marker layer is compiled;

[0010] Combining the lithological and lithofacies characteristics of the wells and field outcrops, a lithofacies paleogeographic map of the landmark layer of karst paleo-geomorphological restoration was drawn;

[0011] According to the characteristics of paleokarst development, the types of karst paleo-geomorphological units developed in the basin are identified, and on the reference obtained by the fusion of the stratigraphic thickness plane contour map and the lithofacies paleogeography map, the karst paleo-geomorphological units are divided based on the stratigraphic thickness range and sedimentary facies type of the preset karst paleo-geomorphological unit types, and a karst paleo-geomorphological map is compiled according to the karst paleo-geomorphological units on the stratigraphic thickness plane contour map.

[0012] In one implementation scheme, a stratigraphic profile of a marker layer for karst paleo-geomorph restoration is established based on field outcrops and stratigraphic division standards. Specifically, a stratigraphic profile of a marker layer for karst paleo-geomorph restoration is established based on the stratigraphic thickness, lithology and carbonate carbon isotopes of field outcrops and with reference to stratigraphic division standards.

[0013] In one implementation, before comparing the formation comparison network with the formation profile, the method further includes: selecting a well located at a node of the formation comparison network from at least one well as a benchmark well.

[0014] In one implementation, the stratigraphic comparison network is compared with the stratigraphic profile to obtain the top and bottom boundary positions of the marker layers between each well and the field outcrop. Specifically, with the benchmark well as the reference point, along each direction of the stratigraphic comparison network, comparison is performed according to the morphological characteristics of the logging curve and the reflection characteristics of the phase axis of the seismic line to obtain the top and bottom boundary positions of the marker layers between each well and the field outcrop.

[0015] In one implementation, when compiling a plane contour map of the stratum thickness of the karst paleo-geomorphology restoration marker layer, the variation trend of the stratum thickness is analyzed based on a two-dimensional seismic line grid or a three-dimensional seismic data volume.

[0016] In one implementation, the stratigraphic thickness plane contour map and the lithofacies paleogeography map are fused in the following manner: based on the distribution of different sedimentary phases in the lithofacies paleogeography map, the contour lines in the stratigraphic thickness plane contour map are classified and marked according to the sedimentary phase type to obtain a reference map.

[0017] In one implementation, the paleokarst development characteristics include the development and distribution characteristics of solution pores, solution caves, solution fractures, and weathering crusts.

[0018] In one implementation scheme, the stratigraphic thickness range and sedimentary facies type of karst paleo-geomorphological unit types are preset in the following manner: the differences in the development and distribution of paleo-karst in different zones of the basin are determined, and based on the relationship between the differences and the stratigraphic thickness and sedimentary facies type, the stratigraphic thickness range and sedimentary facies type corresponding to each karst paleo-geomorphological unit are preset.

[0019] In one implementation scheme, before compiling a karst paleo-geomorphological map on a stratigraphic thickness plane contour map according to the karst paleo-geomorphological units, the method further includes: analyzing the sedimentary phase and thickness distribution characteristics of the overlying strata of the karst paleo-geomorphological restoration marker layer to obtain analysis results, and correcting the karst paleo-geomorphological units divided according to the analysis results.

[0020] In one implementation, field outcrops are screened from the basin periphery, specifically, field outcrops that meet the characteristics of the marker layer for karst paleo-geomorphological restoration are found inside or around the basin.

[0021] Compared with the prior art, this application has the following beneficial effects:

[0022] In a basin-scale carbonate karst paleo-geomorphology restoration method provided in the present application, following the principles of sequence stratigraphy, sedimentology and karstology, when applied to basin-scale carbonate karst paleo-geomorphology restoration, the karst paleo-geomorphology map produced by integrating sequence stratigraphy, sedimentology and karstology research methods can isochronously depict the large-scale and long-distance changes in the thickness of the marker layer, and can effectively identify the genetic type of the current stratum thickness changes in the basin. The present invention helps to more accurately delineate the impact zone of paleokarst action, reflect the relative height and steepness trend of basin-scale paleo-geomorphology, and provide a reliable basis for the prediction of the development and distribution of paleokarst. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0024] Figure 1 A schematic diagram of a process for restoring carbonate karst paleo-geomorphology at a basin scale provided in an embodiment of the present application;

[0025] Figure 2 A carbon isotope stratigraphic comparison diagram of carbonate rocks in the Maokou Formation of Well A in the basin and field outcrops 1 and 2 provided in the embodiments of the present application;

[0026] Figure 3 A comparison diagram of the Maokou Formation well-connected strata in the western and northern areas of the basin passing through Well A provided in the embodiment of the present application;

[0027] Figure 4The embodiments of the present application provide Figure 3 2D seismic interpretation section of the Maokou Formation in the same direction;

[0028] Figure 5 A plane contour map of the thickness of the TR3 sequence stratigraphic layer of the Maokou Formation in the basin provided in the embodiment of the present application;

[0029] Figure 6 A lithofacies paleogeographic map of the TR3 sequence of the Maokou Formation in the basin provided in the examples of this application;

[0030] Figure 7 A reference map for restoration of karst paleo-geomorphology of the Maokou Formation obtained by merging a stratum thickness plane contour map and a lithofacies paleo-geography map provided in an embodiment of the present application;

[0031] Figure 8 This is a karst paleo-geomorphological map of the Maokou Formation in the basin provided in the embodiments of the present application. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with examples and drawings. The illustrative implementation scheme of the present application and its description are only used to explain the present application and are not intended to limit the present application.

[0033] It should be noted that the terms "include" or "may include" used in various embodiments of the present application indicate the presence of the function, operation or element applied for, and do not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their cognates are only intended to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items.

[0034] Please refer to Figure 1 , Figure 1 A schematic diagram of a process for restoring carbonate karst paleo-geomorphology at a basin scale provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the method includes:

[0035] S101, screen outcrops from the basin periphery, and establish stratigraphic profiles of the landmark layers for karst paleo-geomorphological restoration based on outcrops and stratigraphic division standards.

[0036] In this embodiment, field outcrops are screened from the basin periphery in the following manner. Specifically, field outcrops that meet the characteristics of the marker layer for karst paleo-geomorphological restoration are found inside or around the basin.

[0037] Here, it should be noted that when screening outcrops in the field, the characteristics of the marker layer for karst paleo-geomorphological restoration refer to marker layers with complete strata preservation and unclear paleo-karst characteristics. The number of outcrops in the field can be multiple or single, and this embodiment does not impose any unnecessary restrictions.

[0038] After screening out the field outcrops, the formation thickness, lithology and carbonate carbon isotope sampling tests are carried out. Then, based on the formation thickness, lithology and carbonate carbon isotope of the field outcrops obtained from the tests and referring to the stratigraphic division standards, the stratigraphic profile of the marker layer for karst paleo-landform restoration is established.

[0039] The stratigraphic division standards are currently known standards, such as lithology standards, fossil standards, age standards, sedimentary cycle standards, etc. This embodiment does not illustrate the above standards one by one.

[0040] This example takes the restoration of karst paleo-geomorphology of carbonate rocks of the Maokou Formation in the Sichuan Basin as an example. Figure 2 As shown, firstly, through field geological survey, field outcrops 1 and 2 with intact strata of Maokou Formation in the periphery of Sichuan Basin were selected to measure the stratum thickness and lithology and sample and test the carbon isotope of carbonate rocks. Combining with the existing research results, the stratigraphic sections of lithology and carbon isotope of these two field outcrops were established; secondly, the stratigraphic sections of lithology and carbon isotope of field outcrops 1 and 2 were compared with the global boundary stratotype section of the top of Guadeloupe System in Penglai Beach, Laibin, Guangxi, and the TR1, TR2 and TR3 sequence stratigraphic units were divided, so as to establish the stratigraphic section of the marker layer of karst paleo-geomorphic restoration of Maokou Formation in the periphery of the basin.

[0041] S102, selecting at least one well in the formation, combining each well with adjacent field outcrops to form a stratigraphic comparison network, comparing the stratigraphic comparison network with the stratigraphic profile, and obtaining the top and bottom boundary positions of the karst paleo-geomorphology restoration marker layer between each well and the field outcrop.

[0042] In this embodiment, wells with complete logging data and connected two-dimensional seismic lines in the Sichuan Basin are selected to obtain at least one well contained in the formation, and then these wells and adjacent field outcrops are combined into a formation comparison network.

[0043] Secondly, a well located at a node of the stratigraphic comparison network is selected from at least one well as a benchmark well. It can be understood that the benchmark well is also a well with a carbonate carbon isotope profile. Finally, the carbon isotope and lithology changes of the marker layer are compared with the stratigraphic profile established in step S101 to complete the stratigraphic division of well A. Figure 2As shown. It can be seen that compared with the field outcrop 1 where the Maokou Formation is relatively well preserved, the upper part of the TR3 sequence in Well A lacks strata with negative carbon isotopes. Combined with the paleokarst development background of the Maokou Formation in the Sichuan Basin, it can be confirmed that the most extensively developed section of the Maokou Formation in the basin is the TR3 sequence. Therefore, the TR3 sequence stratigraphy is used as the marker layer for the restoration of karst paleo-geomorphology.

[0044] For other wells and field outcrops without carbonate carbon isotope profiles, this embodiment uses the benchmark well as the reference point, and compares the morphological characteristics of the logging curves and the reflection characteristics of the phase axis of the seismic line along various directions of the stratigraphic comparison network to obtain the boundary positions of the top and bottom of the marker layer between each well and the field outcrop.

[0045] Specifically, taking the benchmark well A as the benchmark, the morphological characteristics of the well logging curves (such as Figure 3 as shown) and the distribution characteristics of the event axes of the seismic lines connected to the wells (as shown Figure 4 The top and bottom boundary positions of the TR3 sequence of the Maokou Formation at each well and outcrop data point were obtained by stratigraphic correlation (as shown in Figure 5).

[0046] S103, determine the stratigraphic thickness of the field outcrop according to the boundary position between the top and bottom of the marker layer, and analyze the variation trend of the stratigraphic thickness in combination with the seismic data, and compile a stratigraphic thickness plane contour map of the marker layer for karst paleo-geomorphological restoration based on the various wells, stratigraphic thickness and variation trend.

[0047] In this embodiment, according to the boundary position of the top and the bottom obtained in step S102, the current stratigraphic thickness of the TR3 sequence of the Maokou Formation at each data point in the stratigraphic correlation network is statistically analyzed. At the same time, the variation trend of the stratigraphic thickness is analyzed based on the two-dimensional seismic line grid or the three-dimensional seismic data body. Specifically, the seismic interpretation of the top and bottom surfaces of the TR3 sequence of the Maokou Formation is performed based on the two-dimensional seismic line grid of the Sichuan Basin and the three-dimensional seismic data body of the local zone, and the variation trend of the stratigraphic thickness of the marker layer in the Sichuan Basin is analyzed.

[0048] Then, according to the formation thickness of the data points and the formation thickness variation trend obtained by seismic interpretation, the formation thickness contour lines of the TR3 sequence were outlined in the Sichuan Basin, and the formation thickness plane contour line map was compiled, as shown in the figure below: Figure 5 shown.

[0049] S104, combining the lithological and lithofacies characteristics of the drilling and field outcrops, draws a lithofacies paleogeographic map of the landmark layer for karst paleo-geomorphological restoration.

[0050] In this example, first, based on the public data of lithofacies paleogeography of the Maokou Formation, combined with the lithology and lithofacies data of the 147 wells and measured field outcrops provided above, a lithofacies paleogeography map of the TR3 sequence of the Maokou Formation was compiled, as shown in FIG. Figure 6 shown.

[0051] Secondly, the relationship between the sedimentary facies and stratigraphic thickness of the TR3 sequence of the Maokou Formation was established. Figure 6 The sedimentary facies distribution of Figure 5 The thickness changes of the strata in the strata are classified and marked according to the sedimentary facies type, such as Figure 7 As shown; the relationship between various sedimentary facies and stratigraphic thickness based on the statistics of data points is shown in Table 1. It can be seen that the stratigraphic thickness of only the open platform and platform edge sedimentary facies can be greater than 60m, while the stratigraphic thickness of 0-60m corresponds to the combination of two types of sedimentary facies: open platform, platform edge facies and slope and shelf facies.

[0052] Table 1 Relationship between sedimentary facies and stratigraphic thickness of TR3 sequence of Maokou Formation

[0053] Sedimentary phase Layer thickness (m) Open Terrace 0-150 Mesa edge 55-160 Slope 20-60 Continental Shelf 0-20

[0054] S105, based on the characteristics of paleokarst development, identify the types of karst paleo-geomorphic units developed in the basin, and divide the karst paleo-geomorphic units based on the stratigraphic thickness range and sedimentary facies type of the preset karst paleo-geomorphic unit types on the reference map obtained by merging the stratigraphic thickness plane contour map and the lithofacies paleo-geograph map, and compile a karst paleo-geomorphic map based on the karst paleo-geomorphic units on the stratigraphic thickness plane contour map.

[0055] In this embodiment, firstly, based on the regional tectonic evolution history, the history of relative sea level changes and the history of global sea level changes, it is analyzed that the main causes of paleokarst are regional tectonic activities, global sea level changes or other factors; secondly, the paleokarst development characteristics are the product of paleokarst action in the drilling and field outcrop data points. The paleokarst development characteristics include the development and distribution characteristics of solution pores, solution caves, solution fractures and weathering crusts.

[0056] Secondly, a reference reference is obtained by fusing the stratigraphic thickness plane contour map and the lithofacies paleogeography map. On the reference reference, according to the preset stratigraphic thickness range and sedimentary facies type of the karst paleogeography unit type, specifically, this embodiment fuses the stratigraphic thickness plane contour map and the lithofacies paleogeography map in the following manner: according to the different sedimentary facies distributions in the lithofacies paleogeography map, the contour lines in the stratigraphic thickness plane contour map are classified and marked according to the sedimentary facies type to obtain the reference reference. Specifically, this embodiment presets the stratigraphic thickness range and sedimentary facies type of the karst paleogeography unit type in the following manner: the differences in the distribution of paleokarst development in different zones of the basin are determined, and according to the relationship between the differences and the stratigraphic thickness and sedimentary facies type, the stratigraphic thickness range and sedimentary facies type corresponding to each karst paleogeography unit are preset.

[0057] In some embodiments, before compiling a karst paleo-geomorphological map on a stratigraphic thickness plane contour map according to the karst paleo-geomorphological units, the method further includes: analyzing the sedimentary phase and thickness distribution characteristics of the overlying strata of the karst paleo-geomorphological restoration marker layer to obtain analysis results, and correcting the karst paleo-geomorphological units divided according to the analysis results.

[0058] In this embodiment, the karst paleo-geomorphological units divided according to the analysis results are corrected in order to increase the basis for paleo-geomorphological restoration, so as to ensure the reliability of subsequent landform restoration results.

[0059] In combination with the contents described in step S105 of this embodiment, the specific steps for compiling a karst paleo-geomorphological map are given below:

[0060] Step 1: Based on the regional tectonic evolution history, relative sea level change history and global sea level change history during the deposition period of the Maokou Formation in the Sichuan Basin, it is judged that the main genetic mechanism of paleokarst is global sea level change. Therefore, the terrain was flat during the development period of paleokarst, and most areas of the Sichuan Basin belonged to the karst basin geomorphic unit. Karst slopes were only formed around the karst highland, and the karst basin and karst slope could not be divided by the thickness of the stratum. It can only reflect the relative height of the paleo-geomorphic position. The study on the development and distribution characteristics of paleokarst products in drilling and field outcrop data points shows that the Maokou Formation in the Sichuan Basin has developed four types of karst paleo-geomorphic unit types: karst highland, karst slope, karst basin and valley. The karst highlands have a high density of karst fractures, large scale of karst caves, thick weathering crust, and completely denuded TR3 sequence stratigraphy; the karst slopes have a low density of karst fractures, a large density of karst caves, but their scale is relatively small compared to the karst highlands, the thickness of the weathering crust is small, and the thickness of the TR3 sequence stratigraphy is small; karst basins have few karst fractures and caves, the characteristics of the weathering crust are not significant, the thickness of the TR3 sequence stratigraphy is large, and a small number of layered karst pores are developed below the top of the stratigraphy; the valleys are areas where local karst fractures and caves are abnormally developed in the karst slopes and karst basins, and the thickness of the TR3 sequence stratigraphy is abnormally small;

[0061] Step 2: Based on the drilling and field outcrop data points, the scale analysis and comparison of the distribution characteristics of paleokarst development in different zones in the entire Sichuan Basin show that paleokarst phenomena are rare in slope and shelf phase belts, while paleokarst phenomena are very developed in open platform and platform edge phase belts, especially in the range of stratum thickness <60m. This difference indicates that the open platform and platform edge phase belts are the main development areas of paleokarst, while the slope and shelf phase belts are not paleokarst development areas, and the smaller stratum thickness in this phase belt has nothing to do with paleokarst. Therefore, the relationship between the TR3 sequence karst paleogeomorphic unit of the Maokou Formation and the current stratum thickness and sedimentary facies type is defined as follows: the slope and shelf phases have no obvious paleokarst characteristics, do not participate in the division of karst paleogeomorphic units, and are defined as sedimentary areas. In the open platform and platform edge phase belt, the area where the TR3 sequence strata are completely eroded is divided into karst highlands; the area where there are remnants is divided into karst slopes and karst basins, and the relative height of the paleo-geomorphic position is marked by the thickness contour lines; the area with abnormally small stratum thickness in the karst slopes and karst basins is divided into valleys;

[0062] Step 3: Based on the relationship between the karst paleo-geomorphological units and the current stratigraphic thickness and sedimentary facies types in the second step, the karst paleo-geomorphological units of the Maokou Formation in various zones within the Sichuan Basin were preliminarily divided; then the distribution position and thickness of the Emeishan basalt overlying the Maokou Formation were analyzed, and it was considered that the basalt-covered area was a local uplift area; finally, according to the division scheme, the stratigraphic thickness plane contour map was converted into a karst paleo-geomorphological map (such as Figure 8 It can be seen that the karst paleo-geomorphological units of the Maokou Formation in the Sichuan Basin change from the karst highlands in the south to the karst slopes and karst basins in the north, while the northernmost end of the basin is a sedimentary area where no significant karstification has occurred. At the same time, the thickness contour lines of the formation change from dense to sparse, showing that the karst paleo-geomorphology of the Maokou Formation in the Sichuan Basin has an overall trend from high to low and from steep to gentle from south to north.

[0063] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation method of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A basin-scale carbonate karst paleo-geomorphology restoration method, characterized in that: Methods include: Field outcrops were selected from the basin periphery, and based on the field outcrops and stratigraphic division standards, stratigraphic sections of the landmark layers for karst paleo-geomorphological restoration were established; At least one well in the stratum is selected, each well and adjacent field outcrop are combined into a stratigraphic correlation network, the stratigraphic correlation network is compared with the stratigraphic section, and the top and bottom boundary positions of the karst paleo-geomorphology restoration marker layer between each well and the field outcrop are obtained; The stratum thickness of the field outcrop is determined based on the boundary position of the top and bottom of the marker layer, and the variation trend of the stratum thickness is analyzed in combination with the seismic data. Based on the various wells, stratum thickness and variation trend, a stratum thickness plane contour map of the karst paleo-geomorphology restoration marker layer is compiled; Combining the lithological and lithofacies characteristics of the wells and field outcrops, a lithofacies paleogeographic map of the landmark layer of karst paleo-geomorphological restoration was drawn; According to the characteristics of paleokarst development, the types of karst paleo-geomorphological units developed in the basin are identified, and on the reference obtained by the fusion of the stratigraphic thickness plane contour map and the lithofacies paleogeography map, the karst paleo-geomorphological units are divided based on the stratigraphic thickness range and sedimentary facies type of the preset karst paleo-geomorphological unit types, and a karst paleo-geomorphological map is compiled according to the karst paleo-geomorphological units on the stratigraphic thickness plane contour map.

2. The method according to claim 1, characterized in that Based on the field outcrops and stratigraphic division standards, the stratigraphic profile of the marker layer for karst paleo-geomorphic restoration is established. Specifically, according to the stratigraphic thickness, lithology and carbonate carbon isotope of the field outcrops and referring to the stratigraphic division standards, the stratigraphic profile of the marker layer for karst paleo-geomorphic restoration is established.

3. The method according to claim 1, characterized in that Before comparing the formation comparison network with the formation section, the method further comprises: selecting a well located at a node of the formation comparison network from at least one well as a benchmark well.

4. The method according to claim 3, characterized in that The stratigraphic correlation network is compared with the stratigraphic profile to obtain the top and bottom boundary positions of the marker layers between each well and the field outcrop. Specifically, taking the benchmark well as the reference point, the morphological characteristics of the logging curve and the reflection characteristics of the event axis of the seismic line are compared in each direction of the stratigraphic correlation network to obtain the top and bottom boundary positions of the marker layers between each well and the field outcrop.

5. The method according to claim 1, characterized in that: When compiling the plane contour map of the stratigraphic thickness of the karst paleo-geomorphological restoration marker layer, the variation trend of the stratigraphic thickness is analyzed based on the two-dimensional seismic survey line grid or the three-dimensional seismic data volume.

6. The method according to claim 1, characterized in that The stratigraphic thickness plane contour map and the lithofacies paleogeography map are integrated in the following way: based on the distribution of different sedimentary facies in the lithofacies paleogeography map, the contour lines in the stratigraphic thickness plane contour map are classified and marked according to the sedimentary facies type to obtain a reference map.

7. The method according to claim 1, characterized in that The paleokarst development characteristics include the development and distribution characteristics of karst pores, karst caves, karst fractures, and weathering crusts.

8. The method according to claim 1, characterized in that The stratigraphic thickness range and sedimentary facies type of karst paleo-geomorphological unit types are preset in the following ways: the differences in the development and distribution of paleo-karst in different zones of the basin are determined, and based on the relationship between the differences and the stratigraphic thickness and sedimentary facies type, the stratigraphic thickness range and sedimentary facies type corresponding to each karst paleo-geomorphological unit are preset.

9. The method according to claim 1, characterized in that: Before compiling a karst paleo-geomorphological map on a stratigraphic thickness plane contour map according to the karst paleo-geomorphological units, the method further includes: analyzing the sedimentary phase and thickness distribution characteristics of the overlying strata of the karst paleo-geomorphological restoration marker layer to obtain analysis results, and correcting the karst paleo-geomorphological units divided according to the analysis results.

10. The method according to claim 1, characterized in that Screen out the field outcrops from the basin periphery, specifically: find out the field outcrops that meet the characteristics of the marker layer for karst paleo-geomorphological restoration inside or around the basin.

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