Ancient landform restoration method and storage medium

Abstract

The invention discloses an ancient landform restoration method and a storage medium. The method comprises the following steps: S1, acquiring data of a stratum top surface and a stratum bottom surface of a to-be-restored area; s2, acquiring a convergence surface and leveling the convergence surface to obtain data of the recovered stratum top surface and the recovered stratum bottom surface; and S3, determining a denudation area range according to the recovered data of the stratum top surface and the stratum bottom surface, and completing ancient landform recovery according to the denudation area range. According to the method, a more accurate denudation region is obtained through leveling treatment of the convergence surface, so that the error between ancient landform recovery and essence is reduced, and the ancient landform recovery is more reasonable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of palaeogeomorphology, and in particular to a palaeogeomorphology recovery method and a storage medium. BACKGROUND

[0002] Recovering palaeogeomorphology can reproduce the surface topography of a specific geological period. The evolving palaeogeomorphology plays an important role in the accumulation of oil and gas. However, as oil and gas exploration continues to advance to the deep, the current pattern of palaeogeomorphology is often incomplete or even has disappeared, which hinders us from intuitively and comprehensively understanding its evolution process, and becomes a difficulty in palaeogeomorphology recovery. Accurate and reasonable recovery of palaeogeomorphology is helpful to effectively guide the exploration and development of oil and gas resources. At present, Chinese scholars mainly focus on the palaeodepositional appearance during the deposition period and its control effect on the depositional system and favorable reservoirs, and more use the above overlying strata filling method characterized by impression, cutting point trend surface extension method, sequence stratigraphy datum determination and other means to recover the stratum morphology of palaeogeomorphology. Due to the differences in principles and key points, these methods are not suitable for the same research environment. At present, in the region with strong magmatic modification in the Pearl River Mouth Basin, the factors to be considered for palaeogeomorphology recovery are further increased, and the existing technology has a large substantial error in palaeogeomorphology recovery. It is an urgent technical problem to provide a palaeogeomorphology recovery method with operability and high scientificity. SUMMARY

[0003] The technical problem solved by the present application is that the related technology mentioned in the background technology has at least one defect: how to solve the large substantial error of the existing technology in palaeogeomorphology recovery, and provide a palaeogeomorphology recovery method and a storage medium.

[0004] The technical solution adopted by the present application to solve the technical problem is: a palaeogeomorphology recovery method is constructed, which comprises the following steps:

[0005] S1: obtaining data of a stratum top surface and a stratum bottom surface of a region to be recovered;

[0006] S2: obtaining a convergence surface and performing a flattening process on the convergence surface to obtain data of the recovered stratum top surface and stratum bottom surface;

[0007] S3: determining an erosion area range according to the data of the recovered stratum top surface and stratum bottom surface, and completing palaeogeomorphology recovery according to the erosion area range.

[0008] In some embodiments, the step S1 further comprises:

[0009] S01: selecting a region meeting magmatic uplift conditions as the region to be recovered;

[0010] S02: determining the geological period of the area to be restored; the geological period includes the Cenozoic period, and the top and bottom of the stratum are the interfaces of the Cenozoic period;

[0011] The step S1 includes: obtaining the data of the top and bottom of the stratum of the area to be restored according to the geological period.

[0012] In some embodiments, the step S1 includes:

[0013] According to the geological period, the three-level sequence stratigraphic interpretation is completed for the area to be restored, and the interpreted depth of the top and bottom of the stratum of the area to be restored is obtained.

[0014] In some embodiments, the step S2 includes:

[0015] S21: interpreting the pre-existing fault below the base interface of the Cenozoic period to obtain the convergence surface;

[0016] S22: identifying the deep uplift reflection to determine the fault morphology, and performing the flattening processing on the convergence surface;

[0017] S23: obtaining the interpreted horizon and interpreted depth of the restored top and bottom of the stratum according to the flattened convergence surface.

[0018] In some embodiments, the step S3 includes:

[0019] S31: extending the restored top and bottom of the stratum according to the data of the restored top and bottom of the stratum, and determining the range of the denudation area according to the trend extension endpoint;

[0020] S32: determining the paleo-residual topography and denudation thickness according to the range of the denudation area, and completing the paleo-geomorphology restoration according to the paleo-residual topography and the denudation thickness.

[0021] In some embodiments, the step S32 includes:

[0022] S321: subtracting the depth of the top of the stratum below the unconformity surface from the depth of the bottom of the stratum to obtain the paleo-residual topography;

[0023] S322: subtracting the depth of the trend extension part of the top and bottom of the stratum above the unconformity surface to obtain the denudation thickness;

[0024] S323: superimposing the paleo-residual topography and the denudation thickness based on the unconformity surface to obtain the denuded stratum superimposed area;

[0025] S324: performing the depth numerical superposition of the residual area and the denuded stratum superimposed area to complete the paleo-geomorphology restoration.

[0026] In some embodiments, the residual area is the difference between the interpreted depth of the top and bottom of the stratum.

[0027] In some embodiments, the method further comprises:

[0028] The ridge line of the palaeogeomorphology is identified as a water divide, and the area between each water divide is taken as an erosion subarea, and palaeogeomorphology recovery is completed on the erosion subarea.

[0029] In some embodiments, the method further comprises:

[0030] After the flattening treatment of the convergence surface, the tilt trend of the top surface and the bottom surface of the stratum is adjusted, so that the volume difference of the extended part of the top surface and the bottom surface of the stratum above the unconformity surface follows the law of conservation of mass.

[0031] The law of conservation of mass is that the total amount of material recovered in the erosion area is equal to the total amount of material deposited in the residual area.

[0032] The application also provides a computer readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the palaeogeomorphology recovery method.

[0033] By implementing the application, the following beneficial effects are achieved:

[0034] The application obtains the data of the top surface and the bottom surface of the stratum in the area to be recovered, then obtains the convergence surface and performs flattening treatment on the convergence surface to obtain the data of the recovered top surface and bottom surface of the stratum, and finally determines the erosion area range according to the data of the recovered top surface and bottom surface of the stratum, and completes palaeogeomorphology recovery according to the erosion area range, so that the palaeogeomorphology recovery and the substantial error are smaller, and the palaeogeomorphology recovery result is more reasonable. BRIEF DESCRIPTION OF DRAWINGS

[0035] The application will be further described below with reference to the drawings and embodiments, and the drawings show:

[0036] Figure 1 A flowchart of an embodiment of the palaeogeomorphology recovery method of the application is shown;

[0037] Figure 2 A flowchart of the analysis step S2 of an embodiment of the palaeogeomorphology recovery method of the application is shown;

[0038] Figure 3-a A diagram of the analysis of an embodiment of the palaeogeomorphology recovery method of the application using a traditional sedimentary layer recovery method is shown; Figure 3-b A diagram of the analysis of an embodiment of the palaeogeomorphology recovery method of the application using a sedimentary layer palaeogeomorphology recovery method under the background of magmatic uplift is shown;

[0039] Figure 4 A flowchart of the analysis step S32 of an embodiment of the palaeogeomorphology recovery method of the application is shown;

[0040] Figure 5 Fig. 1 shows a prototype basin distribution map of a certain work area Wenwu segment sedimentary layer after restoration according to an embodiment of the palaeogeomorphology restoration method of the present application;

[0041] Figure 6 Fig. 2 shows a palaeogeomorphology form map of a certain work area Wenwu segment sedimentary layer after restoration according to an embodiment of the palaeogeomorphology restoration method of the present application. DETAILED DESCRIPTION

[0042] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0043] It should be noted that the flowchart shown in the accompanying drawings is only illustrative, and does not necessarily include all the contents and operations / steps, nor does it necessarily execute in the order described. For example, some operations / steps can be further decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may be changed according to the actual situation.

[0044] The block diagram shown in the accompanying drawings is only a functional entity, which does not necessarily correspond to a physically independent entity. That is, these functional entities can be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0045] As shown in Fig. 1, some embodiments of the present application disclose a palaeogeomorphology restoration method, which comprises the following steps: Figure 1

[0046] S1: obtaining data of the top surface and the bottom surface of the stratum in the area to be restored;

[0047] S2: obtaining a convergence surface and performing a flattening process on the convergence surface to obtain data of the restored top surface and bottom surface of the stratum;

[0048] S3: determining the range of the denudation area according to the data of the restored top surface and bottom surface of the stratum, and completing the palaeogeomorphology restoration according to the range of the denudation area.

[0049] In some embodiments, before step S1, it further comprises: S01: selecting an area meeting the magmatic uplift condition as the area to be restored; S02: determining the geological period of the area to be restored; the geological period includes the Cenozoic period, and the top surface and the bottom surface of the stratum are the Cenozoic period interface.

[0050] Step S1 comprises: obtaining the data of the top surface and the bottom surface of the stratum in the area to be restored according to the geological period.

[0051] ​In some embodiments, step S01 comprises: selecting a variable-source basin meeting the magmatic uplift condition as the to-be-restored area based on the evolution law of the work area;

[0052] Step S1 comprises: collecting a three-dimensional seismic data volume covering the work area, and obtaining data of the top surface and the bottom surface of the strata of the to-be-restored area according to the geological period.

[0053] The magmatic uplift condition refers to the influence of magmatic uplift on the basin at a certain period in the formation and evolution process, which is mainly based on the surrounding discovered magmatic rock samples and the tectonic analysis of regional geology and seismology; the variable-source type refers to the change of the scale of the denudation area with the geological period; the denudation area refers to the material source area of the basin sediments in the concept of sedimentology.

[0054] At present, the influence of magmatism on the basin shape and even the entire source-sink process has become a new focus, and the existing technical method has the following problems: first, the role of magmatism in the uplift area is not finely described, resulting in unreasonable basin restoration of the basin where the magmatic action is strong but the present strata residual is insufficient, and second, the supply of the material source is unstable, and the boundary of the early rifting basin cannot be accurately restored, which makes it difficult to achieve the purpose of accurately describing the scale of the hidden material source. Therefore, how to identify the position and period of the magmatic uplift in the material source uplift area has become a major problem to be solved.

[0055] However, there are still some difficulties in identifying the position and period of the magmatic uplift in the material source uplift area, which leads to the lack of effective restoration means for the paleogeomorphology of the magmatic reconstruction basin: the influence of the magmatic uplift in the depression can be identified by the sudden change of the sedimentary characteristics of the overlying strata, but during the period of strong tectonic movement, the superposition effect of magmatic uplift and regional tectonic movement makes it difficult to distinguish and decouple the restoration factors, and the error between the restoration result and the actual situation is also large.

[0056] In some embodiments, step S1 comprises: obtaining the interpreted depth of the top surface and the bottom surface of the strata of the to-be-restored area according to the geological period.

[0057] The third-order sequence refers to the division of strata into different levels of sequence units according to the sedimentary characteristics and unconformity of the strata in stratigraphy. At least 20m x 20m high-density grid interpretation of the third-order sequence strata of the to-be-restored area is completed.

[0058] As shown in Figure 2 In some embodiments, step S2 comprises:

[0059] S21: interpreting the pre-existing fault below the basement interface in the Cenozoic period to obtain a convergence surface;

[0060] S22: identifying the deep uplift reflection to determine the fault shape, and performing a flattening process on the convergence surface;

[0061] S23: Based on the convergence surface after flattening, obtain the interpretation level and interpretation depth of the restored top and bottom surfaces of the strata.

[0062] The basement interface of the Cenozoic era, also known as the Tg interface, indicates the lowest layer of the Cenozoic interface. Geological periods include the Cenozoic era, and the top and bottom surfaces of strata are the Cenozoic interfaces.

[0063] Interpreting pre-existing faults requires the formation of a high-density grid of 20m × 20m. Pre-existing faults are existing fractures that can connect to deep magma, meaning they extend very deep downwards and can directly connect to magma sources in the deep crust or upper mantle, allowing magma to rise along the fracture and potentially leading to volcanic eruptions or intrusions.

[0064] In some embodiments, step S3 includes:

[0065] S31: Based on the data of the restored top and bottom surfaces of the strata, the trend of the restored top and bottom surfaces of the strata is extended, and the extent of the erosion zone is determined based on the endpoint of the trend extension;

[0066] S32: Determine the ancient residual landforms and erosion thickness based on the extent of the erosion zone, and complete the ancient landform restoration based on the ancient residual landforms and erosion thickness.

[0067] like Figure 3-a As shown, traditional sedimentary layer reconstruction methods, without determining the fault plane morphology, only extend the existing stratigraphic interpretation. The intersection of the extensions of the top and bottom stratigraphic surfaces is directly affected by the stratigraphic interpretation and the dip angle of its extension lines.

[0068] like Figure 3-b As shown, flattening the convergence surface after determining the fault morphology can restore the top and bottom surfaces of the strata above the area affected by magma uplift, correct the intersection of the restored strata extension lines, and thus affect the calculation of subsequent erosion.

[0069] Sedimentary layers, also known as sedimentary strata, are defined by their top and bottom surfaces. Sedimentary layers are loose deposits or consolidated rock units with a distinct layered structure, formed on the Earth's surface or at the bottom of a body of water by the transportation and deposition of weathering and erosion products, biological remains, chemical deposits, or volcanic debris. Extending the top and bottom surfaces of the strata aims to more accurately reconstruct the sedimentary layers before erosion.

[0070] like Figure 4 As shown, in some embodiments, step S32 includes:

[0071] S321: subtract the depth of the top surface of the stratum below the unconformity surface from the depth of the bottom surface of the stratum to obtain a paleo-residual landform;

[0072] S322: subtract the depth of the top surface of the stratum above the unconformity surface from the depth of the trend extension part of the bottom surface of the stratum to obtain an erosion thickness;

[0073] S323: superimpose the paleo-residual landform and the erosion thickness with the unconformity surface as a reference to obtain an eroded stratum superimposition area;

[0074] S324: perform depth numerical superposition on the residual area and the eroded stratum superimposition area to complete paleo-landform restoration.

[0075] The obtained paleo-residual landform is a paleo-residual landform excluding the influence of magmatic uplift.

[0076] The unconformity surface refers to a feature interface that can be identified due to the erosion of strata caused by geological movement between different periods of deposition, and is usually distributed at the edge of a basin or other local areas, and is a local top surface of residual sedimentary strata.

[0077] In some embodiments, the residual area is the difference between the interpreted depths of the top surface and the bottom surface of the stratum.

[0078] The difference between the interpreted depth data of the top surface and the bottom surface of the stratum of the geological period is the residual stratum thickness that has not been restored, i.e., the residual area.

[0079] The identification of magmatic uplift has another difficulty, which leads to a lack of effective restoration means for the paleo-landform of a magmatic reconstruction basin: for a paleo-uplift area, the erosion degree is stronger, and the residual sedimentary stratum is extremely limited, and it is usually difficult to consider the influence of the magmatic uplift factor when restoring the paleo-structural morphology through sedimentary characteristics, which also leads to difficulty in estimating the original basin boundary. The uplift stratum of the basin boundary is eroded to different degrees, as shown in Table 1:

[0080] Table 1: Stratum erosion intensity type

[0081] In some embodiments, the method further comprises identifying the ridge lines of the paleo-landform as the divide lines, taking the area between each divide line as an erosion subarea, and completing the paleo-landform restoration of the erosion subarea.

[0082] The paleo-landform restoration of all erosion subareas in the erosion range is completed by performing material distribution in accordance with the law of conservation of mass on the erosion subareas.

[0083] The paleo-landform is a variable-source basin, and the variable source is changed with the geological period, and the scale of the erosion subarea has changed; the erosion subarea refers to a subarea of a material source area of basin sediments in the concept of sedimentology.

[0084] In some embodiments, step S22 is followed by further adjusting the tilt tendency of the top and bottom surfaces of the strata after the convergence surface is flattened, so that the volume difference of the extended part of the top and bottom surfaces of the strata above the unconformity surface complies with the law of conservation of mass;

[0085] The law of conservation of mass is that the total amount of material recovered in the denudation zone is equal to the total amount of material in the residual zone.

[0086] For the supplementary consideration of the integrity and availability of the seismic data volume, if the convergence surface is not complete due to the partial absence of deep seismic data or the limitation of seismic resolution, the tilt tendency of the strata control interface can be appropriately adjusted after the convergence surface is flattened. Since the denudation zone is a three-dimensional concept, it needs to comply with the law of conservation of mass, that is, the volume of the recovered denudation zone is equal to the volume of the residual strata.

[0087] The law of conservation of mass also includes that each two-dimensional profile in the 20m×20m high-density grid should comply with the law of conservation of mass during interpretation. The denudation amount is a numerical measurement in the two-dimensional profile, which can be obtained by calculating the difference between the denudation thickness of the top surface and the denudation thickness of the bottom surface of the strata in the trend extension part above the unconformity surface.

[0088] The purpose of setting the denudation subzone is to limit the conservation of mass on the volume of the sedimentary body within each denudation subzone. The area between the trend extension of the top surface and the bottom surface of the strata (two-dimensional profile) can be used as the basis for interpretation on the 20m×20m interpretation profile, and the subsequent extension to the entire recovery area in the work area forms a three-dimensional concept.

[0089] Based on the mechanism of isostatic thinning of the deep lithospheric layer, the marker interface reflecting magmatic uplift is identified, and the process of complex magmatic uplift is comprehensively analyzed, including its position and period of action, so as to realize the recovery of the real high point under magmatic action. The magmatic uplift recovery in the basin margin area is included in the control factors of paleogeomorphology recovery, which can expand the marker control layer interface used as the recovery reference, that is, not only the trend extension of the denuded residual strata is used for recovery, but also the deformation recovery of magmatic action is considered, so that the range of the recovered denudation zone is more accurate. In addition, as shown in the figure, the denudation subzone can more accurately and reasonably recover the paleogeomorphology, help to clarify the dynamic evolution process of the source area, and finely divide the source area catchment unit. Figure 5-6

[0090] Among them, Figure 5 The Chinese five sections refer to a section of the Wenchang Formation sedimentary strata formed by sedimentation during the Cenozoic rifting process of the basin. According to the interpretation of three-level sequence stratigraphy, the Wenchang Formation sedimentary strata can be vertically divided into six sections from bottom to top, namely, Wenchang six sections to Wenchang one section. Figure 6 ​The NWW-trending fault refers to a fault with a direction of approximately Northwest-West (NWW), and the NEE-trending fault refers to a fault with a direction of approximately Northeast-East (NEE).

[0091] The present application aims at the inapplicability of the existing prototype basin paleogeomorphology recovery method to the complex provenance uplift area in the magmatic uplift process, applies the identification of the magmatic uplift to the recovery of the denudation interface, realizes the improvement of the trend surface extension recovery method, makes the recovery result of the variable-source prototype basin paleogeomorphology caused by the magmatic uplift more reasonable, and thus effectively guides the research on the source-sink system evolution process of the oil and gas bearing basin.

[0092] Some embodiments of the present application disclose a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the paleogeomorphology recovery method of any one of the above embodiments, which will not be described here again.

[0093] It can be understood that the above embodiments only express some implementation manners of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application. It should be pointed out that, for the ordinary skilled in the art, the above embodiments or technical features can be freely combined without departing from the concept of the present application, and some modifications and improvements can be made, which all belong to the protection scope of the present application, i.e. the embodiments described in the "some embodiments" can be freely combined with any one of the above embodiments. Therefore, any equivalent transformation and modification within the scope of the claims of the present application should belong to the scope of the claims of the present application.

Claims

1. A method for ancient landform restoration, characterized in that, The method includes the following steps: S1: Obtain data on the top and bottom surfaces of the formation in the area to be restored; S2: Obtain the convergence surface and flatten it to obtain the data of the recovered top and bottom surfaces of the formation; S3: Determine the extent of the erosion zone based on the data from the restored top and bottom surfaces of the strata, and complete the paleomorphological restoration based on the extent of the erosion zone.

2. The paleomorphological restoration method according to claim 1, characterized in that, The procedure preceding step S1 also includes: S01: Select areas that meet the conditions for magma uplift as the areas to be restored; S02: Determine the geological period of the area to be restored; the geological period includes the Cenozoic era, and the top and bottom surfaces of the strata are the Cenozoic era interfaces. Step S1 includes: obtaining data on the top and bottom surfaces of the strata in the area to be restored based on geological periods.

3. The paleomorphological restoration method according to claim 2, characterized in that, Step S1 includes: Based on geological periods, a third-order sequence stratigraphic interpretation was performed on the area to be restored to obtain the interpretation depth of the top and bottom surfaces of the strata in the area to be restored.

4. The paleomorphological restoration method according to claim 3, characterized in that, Step S2 includes: S21: Interpret the pre-existing faults beneath the basal interface during the Cenozoic era to obtain the convergence surface; S22: Identify deep uplift reflections to determine fault morphology and flatten the convergence surface; S23: Based on the convergence surface after flattening, obtain the interpretation level and interpretation depth of the restored top and bottom surfaces of the strata.

5. The method for paleomorphological restoration according to claim 1, characterized in that, Step S3 includes: S31: Based on the data of the restored top and bottom surfaces of the strata, the trend of the restored top and bottom surfaces of the strata is extended, and the extent of the erosion zone is determined based on the endpoint of the trend extension; S32: Determine the ancient residual landforms and erosion thickness based on the extent of the erosion zone, and complete the ancient landform restoration based on the ancient residual landforms and erosion thickness.

6. The paleomorphological restoration method according to claim 5, characterized in that, Step S32 includes: S321: The difference between the depth of the top surface of the strata below the unconformity and the depth of the bottom surface of the strata is used to obtain the ancient residual landform. S322: The erosion thickness is obtained by subtracting the depth of the trend extension of the top and bottom surfaces of the strata above the unconformity. S323: Overlay the ancient residual landforms and erosion thickness with the unconformity as the reference to obtain the eroded strata superposition zone; S324: Perform depth numerical superposition of the residual area and the overlapping area of ​​eroded strata to complete the ancient landform restoration.

7. The paleogeographic restoration method according to claim 3 or 6, characterized in that, The residual zone is the difference between the interpretation depths of the top and bottom surfaces of the strata.

8. The method for paleomorphological restoration according to claim 1, characterized in that, The method further includes: The ridges of ancient landforms are identified as watersheds, and the areas between each watershed are designated as erosion zones. Ancient landform restoration is then completed for each erosion zone.

9. The paleomorphological restoration method according to claim 8, characterized in that, The process of flattening the convergence surface also includes: After flattening the convergence surface, the tilting tendency of the top and bottom surfaces of the strata is adjusted so that the volume difference between the extended portions of the top and bottom surfaces of the strata above the unconformity surface follows the law of conservation of mass. The law of conservation of mass states that the total amount of material recovered in the eroded zone is equal to the total amount of sediment in the residual zone.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the paleomorphological restoration method as described in any one of claims 1-9.

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