A method for seismic stratigraphic correlation of superimposed composite basins

Abstract

The application discloses a method for seismic geology layering of superimposed composite basins, and belongs to the technical field of oil exploration and development research. The method comprises the following steps: establishing a seismic framework network, selecting a standard well, comprehensively utilizing logging, well logging, seismic, outcrop, paleontology and analysis and test data, identifying regional unconformity surfaces and dividing structural layers for regions with marker beds and regions without marker beds, establishing a standard seismic geology interpretation profile and an isochronous stratigraphic framework, realizing accurate comparison of field outcrops, drilling and seismic strata, completing the update of a stratification data table of an exploration well, and improving the accuracy and precision of seismic geology layering of superimposed composite basins. The method uses paleontology data as a constraint and is based on the basic principles of sequence stratigraphy. Through the identification of unconformity surfaces and the division of structural layers, the isochronous stratigraphic framework is established, and the problem of seismic geology layering, i.e. the difficulty in connecting seismic geology horizons and the inconsistency of seismic geology horizons in the whole basin, is solved, which is caused by the fact that the lithology, color and electrical characteristics of strata are similar, and the seismic geology horizons are difficult to connect.

Description

Technical Field

[0001] This invention belongs to the field of petroleum exploration and development research technology, specifically relating to a seismic geological stratification method for superimposed composite basins. Background Technology

[0002] Seismic geological strata are fundamental to oil and gas exploration, constraining the systematic development of research on sedimentation, reservoirs, source rocks, and hydrocarbon accumulation. If the stratigraphic age of a sedimentary basin or region is unclear, drilling strata do not match seismic strata, and stratigraphic correlation is difficult to establish within the basin, it will directly impact oil and gas exploration and development. Superimposed and complex basins are characterized by complete stratigraphic development, alternating marine and terrestrial facies, multiple tectonic evolution stages, complex tectonic deformation, multi-stage and multi-level fault systems, and multiple reservoir-seal assemblages, posing significant challenges to seismic geological strata. Accurate seismic geological strata analysis of superimposed and complex basins, establishing interconnected seismic geological strata within the basin, is crucial for understanding the basin's tectonic evolution history, sedimentary infill history, paleogeomorphological features, and hydrocarbon accumulation patterns. It is also essential for conducting comprehensive basin studies and guiding multi-layered and multi-target oil and gas exploration and development within the basin.

[0003] Methods for seismic geological stratification mainly include lithological correlation, paleontological analysis, geophysical methods, and sequence stratigraphy. Lithological correlation typically utilizes similarities in lithological assemblage, color characteristics, thickness variations, grain size variations, and unique inclusions in strata for stratigraphic correlation and division, generally applicable to tectonically and sedimentarily stable localized areas. Paleontological analysis uses fossils and their assemblages within strata to correlate stratigraphic ages. Geophysical methods utilize geophysical characteristics of strata for stratigraphic correlation. Sequence stratigraphy uses unconformities as isochronous boundaries to correlate strata according to their isochronous arrangement. These methods have significant limitations for seismic geological stratification in superimposed complex basins; in practice, multiple methods are usually employed in combination to stratify seismic geological structures, depending on the specific geological conditions.

[0004] Dai Wanwei proposed a stratigraphic correlation method based on well-seismic cross-plots (Well Logging Technology, Vol. 41, No. 6, 2017). This method comprehensively utilizes well logging, seismic data, and other data, relying on the calibration of seismic synthetic records. It completes well-seismic stratigraphic correlation by establishing well-seismic cross-plots of standard well stratigraphic layers. However, this method does not utilize paleontological data or the principles of sequence stratigraphy to identify unconformities and define the isochronous framework for stratigraphic correlation. In superimposed composite basins, situations may arise where lithology, color, and electrical properties of strata are similar, but seismic geological strata are difficult to correlate, resulting in inconsistent seismic geological strata throughout the basin.

[0005] Yu Sihai et al. proposed a stratigraphic correlation method based on sequence stratigraphy for the marine-continental transition zone (Exploration and Development, No. 12, 2016). This method, combining regional sedimentary characteristics with sequence stratigraphic theory and incorporating seismic, well logging, and production dynamics features, breaks away from the previous approach of isochronous stratigraphic correlation, establishing an isochronous stratigraphic framework from the entire region to local areas. However, this method does not consider complex tectonic, seismic, and geological strata, and is prone to stratigraphic inconsistencies, leading to errors in stratigraphic correlation due to the presence of interlayer transgressions in both local and overall stratigraphic frameworks.

[0006] Patent application CN110320570A discloses a comprehensive stratigraphic correlation method under complex geological conditions. This method integrates well logging, well logging, seismic data, and analytical testing to identify local unconformities, determine the groups and sections of strata above and below the unconformities, and ultimately determine the stratigraphic levels through detailed stratigraphic correlation and cross-verification using well and seismic data. This method solves the problem of stratigraphic correlation in areas with complex geological conditions, uneven distribution of drilled wells, and high difficulty in stratigraphic correlation. However, this method does not consider stratigraphic correlation in complex tectonic sedimentary backgrounds of superimposed composite basins, where marker beds are lacking, and does not systematically address how to achieve accurate correlation of field outcrops, well drilling, and seismic strata. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention aims to provide a seismic geological stratification method for superimposed composite basins. This method addresses the challenges of complex tectonic deformation, rapid lateral changes in field strata, and the difficulty in interpreting seismic, drilling, and field outcrop geological stratification across the entire basin as oil and gas exploration progresses. It also addresses the inaccuracy and precision of stratigraphic correlation results. The invention aims to unify seismic, drilling, and field outcrop geological stratification, supporting the overall basin study, basin mapping, and oil and gas exploration in new areas and fields.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] This invention discloses a method for stratification of seismic geology in superimposed composite basins, comprising:

[0010] S1: Establish a seismic grid network, determine standard wells, and identify the regional unconformity in the study area; determine whether a marker layer exists in the study area;

[0011] S2: If marker layers exist, use standard well, paleontological, and seismic data to determine the stratigraphic layering of the study area; use standard wells to perform well-seismic calibration of the study area and determine the stratigraphic correlation and division scheme;

[0012] S3: If there is no marker layer and the earthquake can be traced and interpreted, then the seismic profile is segmented and flattened, an abnormal earthquake response form is established, and the seismic horizon is determined based on the abnormal earthquake response form;

[0013] S4: Interpret and classify the strata of the surface outcrops, establish the correspondence between the surface outcrop strata and the seismic horizon through geological caps, and achieve the unification of drilling, seismic, and outcrop stratification through seismic stratification.

[0014] S5: Based on the stratigraphic correlation and division scheme determined in S2 and the unification of drilling, seismic, and outcrop stratification achieved in S4, divide the structural layers;

[0015] S6: Establish a standard seismic geological stratigraphic interpretation profile based on the divided structural layers, and establish an isochronous stratigraphic framework based on the standard seismic geological stratigraphic interpretation profile;

[0016] S7: Based on the isochronous stratigraphic framework obtained in S6, and taking the principle of seismic energy connectivity as the basis, and relying on the stratigraphic correlation and division scheme of the standard wells obtained in S2, the seismic framework network is interpreted across the entire area. The stratification data of key exploration wells and appraisal wells in the study area are adjusted to obtain a seismic geological stratification data table.

[0017] Preferably, in S1, a seismic grid network for basin-level strata is established based on seismic data, and standard wells with complete and distinctive lithological, electrical, and paleontological data are selected based on regional geological data to serve as the basic database for basin-level strata.

[0018] Preferably, in S1, the regional unconformity is determined based on the reflection characteristics of the seismic wave group, and the regional unconformity is traced and interpreted to establish a basis for judging whether a marker layer exists in the study area.

[0019] Preferably, in S2, based on the paleontological data and index fossil data in the study area, the stratigraphic layers of the standard wells are compared with those of the standard wells to determine the stratigraphic layers. The stratigraphic layers of the standard wells include primary marker layers and secondary marker layers. Using the logging and well logging data of the standard wells, sonic synthesis records are produced for well-seismic calibration to determine the stratigraphic correlation and division scheme.

[0020] Preferably, in S3, for seismic profiles that do not have marker layers and whose earthquakes can be traced and interpreted, the small-angle unconformity is flattened layer by layer and segment by segment to establish an abnormal earthquake response form. Based on the abnormal earthquake response form, the seismic wave group reflection characteristics of each abnormal point are analyzed. If there is obvious erosion and the overlying strata are parallel to the flattened strata, they are judged to be the same unconformity, thereby determining the seismic strata of the unconformity.

[0021] Preferably, in S4, through detailed field outcrop investigation, a field stratigraphic lithology profile is drawn. Combined with the regional geological map, the strata of the surface outcrops are interpreted and divided. Through geological caps, the correspondence between the surface outcrop strata and the seismic horizon is established. Through seismic strata, the tracing is carried out from the surface outcrops into the basin interior, thus achieving the unification of drilling, seismic, and outcrop stratification.

[0022] Preferably, achieving unification of drilling, seismic, and outcrop stratification includes the following steps:

[0023] 1) Conduct detailed geological surveys of field outcrops, draw lithological profiles of the outcrops, and compare them with the lithology, color, lithofacies, and paleontology of the strata in standard wells to determine the stratification scheme of the field outcrops.

[0024] 2): For the stratification scheme of the exposed strata in the field, combined with regional geological data and regional geological maps, the surface outcrop stratification and seismic profile marking are carried out to complete the seismic geological capping and realize the unification of drilling, seismic and outcrop stratification.

[0025] Preferably, in S5, the division of tectonic layers is based on unconformities, combined with the alternation of marine and terrestrial sediments in different periods of superimposed composite basins and the tectonic evolution background, to divide tectonic layers and transitional layers.

[0026] Preferably, based on the established standard seismic geological stratigraphic interpretation profile, the seismic grid of the superimposed composite basin is interpreted by connecting and closing the seismic geological stratigraphic network across the entire region, and an isochronous stratigraphic grid is established.

[0027] Preferably, in S7, based on the principle of seismic energy connectivity, and relying on the stratigraphic correlation and division scheme of standard wells, the stratigraphic data of key exploration wells on the seismic grid are marked onto the seismic profile to verify whether the drilling stratigraphy and seismic stratigraphy are consistent. If they are inconsistent, the seismic stratigraphy is used as the main factor for adjustment to obtain a seismic geological stratigraphic data table; if they are consistent, no stratigraphic change is made.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This invention discloses a seismic geological stratigraphy method for superimposed composite basins. Through the establishment of a seismic framework, selection of standard wells, and comprehensive utilization of logging, well logging, seismic, outcrop, paleontological, and analytical data, it addresses the specific needs of areas with and without marker beds. It identifies regional unconformities, delineates structural layers, establishes standard seismic geological interpretation profiles, and builds an isochronous stratigraphic framework. This achieves precise comparison of field outcrops, wells, and seismic strata, and updates well stratification data tables, improving the accuracy and precision of seismic geological stratigraphy in superimposed composite basins. Utilizing paleontological data constraints and based on the fundamental principles of sequence stratigraphy, this invention solves the problem of inconsistent seismic geological stratigraphy across superimposed composite basins due to similar lithology, color, and electrical properties, but difficulty in establishing coherent seismic geological strata. By utilizing a grid network covering the entire region and based on standard wells, the system achieves a unified understanding of drilling strata and seismic strata. This allows for closed-loop interpretation of the grid network across the entire region and all stratigraphic systems, effectively addressing the problem of local and overall stratigraphic interleaving within the seismic geological strata of complex tectonic basins. For areas lacking marker beds, the system comprehensively utilizes segmented layer flattening, the establishment of seismic anomaly response forms, detailed field outcrop geological surveys, precise geological capping, and accurate seismic introductory layers. This unified stratigraphic correlation analysis technique, integrating drilling, seismic, and outcrop strata, systematically considers the stratigraphic development characteristics under complex tectonic sedimentary backgrounds, effectively resolving the difficulty in achieving effective unification of field outcrop strata, drilling strata, and seismic strata. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the process of the present invention;

[0031] Figure 2 A plan view showing the distribution of the seismic grid and standard and exploration wells in the study area;

[0032] Figure 3 The characteristics and distribution map of the marker layer in the study area;

[0033] Figure 4 Seismic interpretation profile of the unconformity in the study area;

[0034] Figure 5 This is a comprehensive columnar section of the B1 standard well.

[0035] Figure 6 The standard well B1 acoustic synthesis record and well-through seismic profile are shown.

[0036] Figure 7 For wells B1, B2, and T18, well seismic profiles of the lead-in layer are used for well seismic calibration.

[0037] Figure 8Comparison diagrams of lithology, electrical properties, and paleontology of strata from Paleozoic to Cenozoic in wells B1, B2, and T18;

[0038] Figure 9 To flatten the Neogene unconformity in the study area layer by layer, a comprehensive map of abnormal seismic response forms was established.

[0039] Figure 10 Interpretive diagram of the C1 Cenozoic lithological profile of the field outcrop section in the study area, coordinates of ground stratigraphic points and stratigraphic indices of the seismic profile;

[0040] Figure 11 A scheme for dividing the structural and transitional layers in the study area;

[0041] Figure 12 This is a north-south isochronous stratigraphic framework section of the study area;

[0042] Figure 13 A comparative table of seismic geological strata data for wells B1, B2, and T18. Detailed Implementation

[0043] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0044] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0045] The present invention will now be described in further detail with reference to the accompanying drawings:

[0046] A standard well is a vertical well that has systematic core analysis and logging data, complete formation development, complete logging data, and clear lithological and electrical characteristics of the marker layer.

[0047] A marker layer refers to a stratum that is stable in planar distribution, has clear lithological and electrical characteristics, and has clear seismic wave reflection characteristics that can be traced and interpreted (such as gypsum-salt rock, mudstone, standard limestone, coal seam, etc.).

[0048] The stratigraphic correlation scheme refers to the correspondence between seismic stratigraphy and well drilling stratigraphy.

[0049] A standard seismic geological stratigraphic interpretation profile refers to a profile in which the unconformity features are clear, the standard well stratigraphy matches the seismic stratigraphy, the tectonic sedimentary evolution features are clear, and the tectonic strata are reasonably divided.

[0050] See Figure 1 This invention discloses a method for stratifying the seismic geology of superimposed composite basins, comprising:

[0051] S1: Establish a seismic grid network for basin-level strata based on seismic data; select standard wells with complete and distinctive lithological, electrical, and paleontological data based on regional geological data to serve as the basic database for basin-level strata; determine regional unconformities based on seismic wave group reflection characteristics; and conduct follow-up interpretation of regional unconformities to establish a basis for determining whether a marker layer exists in the study area.

[0052] S2: If marker layers exist, compare them with standard wells based on paleontological and index fossil data in the study area to determine the stratigraphic layers of the standard wells. The stratigraphic layers of the standard wells include primary and secondary marker layers. Use the logging and well logging data of the standard wells to create sonic synthesis records for well-seismic calibration and determine the stratigraphic correlation and division scheme.

[0053] S3: If there is no marker layer and the earthquake can be traced and interpreted, then the seismic profile is flattened layer by layer and segment by segment to flatten the small-angle unconformity, and an abnormal earthquake response form is established. Based on the abnormal earthquake response form, the seismic wave group reflection characteristics of each abnormal point are analyzed. If there is obvious erosion and the overlying strata are parallel to the flattened strata, then it is judged to be the same unconformity, thereby determining the seismic strata of the unconformity.

[0054] S4: Through detailed field outcrop investigation, draw field stratigraphic and lithological profiles. Combined with regional geological maps, interpret and classify the strata of surface outcrops. Establish the correspondence between surface outcrop strata and seismic horizons using geological caps. Tracing from surface outcrops into the basin interior using seismic strata leader, achieve unification of drilling, seismic, and outcrop seismic stratification. This includes the following steps:

[0055] S1: Conduct detailed geological surveys of field outcrops, draw lithological profiles of field outcrops, compare them with the lithology, color, lithofacies and paleontology of standard well strata, and determine the stratification scheme of field outcrops.

[0056] S2: For the stratification scheme of the outcrop strata in the field, combined with regional geological data and regional geological maps, geological caps are set up to establish the correspondence between the surface outcrop strata and the seismic stratification. Through the seismic stratification guide, the stratification is traced from the surface outcrop to the interior of the basin to achieve the unification of drilling, seismic and outcrop stratification.

[0057] S5: Based on the stratigraphic correlation and division scheme determined in S2 and the unification of drilling, seismic, and outcrop seismic stratification achieved in S4, structural layers are divided. The structural layers are divided based on unconformities, combined with the alternation of marine and terrestrial sediments in different periods of superimposed composite basins and the tectonic evolution background, to divide structural layers and transitional layers.

[0058] S6: Based on the established standard seismic geological stratigraphic interpretation profile, the seismic grid network of the superimposed composite basin is interpreted by connecting and closing the seismic geological stratigraphic network throughout the region, and an isochronous stratigraphic grid is established.

[0059] S7: Based on the principle of seismic energy connectivity, the isochronous stratigraphic framework obtained in S6 is interpreted across the entire seismic grid network according to the stratigraphic correlation and division scheme of the standard wells obtained in S2. The stratification data of key exploration wells and appraisal wells in the study area are adjusted to obtain a seismic geological stratification data table.

[0060]

Example

[0061] like Figure 2 As shown, the study area is a superimposed complex basin with complete stratigraphic development (Paleozoic to Cenozoic), alternating marine and terrestrial sedimentary deposits, and multiple tectonic movements including the Tarim, Caledonian, Hercynian, Indosinian, Yanshanian, and Himalayan orogenies, forming the present-day three-high-four-depression tectonic pattern. The tectonic deformation is complex, exhibiting various structural styles such as basement involvement and caprock detachment, a multi-stage and multi-level thrust-strike-slip fault system, multiple tectonic unconformities along the longitudinal direction, and multiple reservoir-caprock assemblages.

[0062] Due to the complex tectonic basin evolution background, there are significant differences in lithology, color, and other characteristics between the strata surrounding the basin mountains and those within the basin. Previous studies on non-oil and gas exploration target strata such as the Cenozoic have been limited, and stratigraphic correlation remains highly controversial. Existing stratigraphic methods have not been based on a holistic study of seismic geological bodies, and paleontological data points are scattered, failing to fully connect seismic, drilling, and field outcrop data. The following are the steps for seismic geological stratigraphy of the Paleozoic-Cenozoic strata in the Tarim Basin using the superimposed composite basin seismic geological stratigraphy method of this invention:

[0063] (1) Evaluate the seismic data of the study area, select high-quality seismic data to establish a basin-level seismic grid, see [reference]. Figure 2Based on regional geological data, standard wells with complete lithological, electrical, and paleontological data and distinct characteristics are selected as the basic database for the stratigraphic sequence.

[0064] (2) Determine the characteristics and distribution of marker layers in the study area based on regional geological data;

[0065] The geological data of the study area were fully collected, summarized, and analyzed to clarify the stratigraphic characteristics of the study area and to establish a table of the characteristics and distribution of marker beds in the study area. (See [reference]). Figure 3 The study area has 6 main marker beds (Cambrian Yuertus Formation dark mudstone, Middle Cambrian gypsum-salt rock, Middle Ordovician top limestone, Carboniferous standard limestone, Permian igneous rocks, and Paleogene gypsum-salt rock) and 7 secondary marker beds (Silurian Kezhong Member mudstone, Carboniferous bioclastic limestone, Triassic Huangshanjie Formation lacustrine mudstone, Jurassic Yangxia Formation lacustrine mudstone, Jurassic Kizilnur Formation coal-bearing strata, Cretaceous Yageliemu Formation Chengqiang conglomerate, and Neogene bluish-gray mudstone).

[0066] Regional outcrop data, drilling data, and seismic data can reflect the development patterns and characteristics of strata, as well as seismic wave group reflection responses, such as paleontological characteristics, lithological assemblages, lithofacies variations, electrical characteristics, and seismic wave group reflection responses. This information can effectively guide the seismic geological strata of superimposed composite basins.

[0067] (3) Using seismic data, determine the regional unconformity of the study area;

[0068] like Figure 4 As shown, based on the seismic wave group reflection characteristics (erosion, overlay), the study area was identified as having nine major regional unconformities (Cambrian base, Upper Ordovician base, Silurian base, Devonian base, Triassic base, Jurassic base, Cretaceous base, Paleogene base, Neogene base), and the regional unconformities were traced and interpreted to establish the basis for sequence stratigraphy.

[0069] (4) Use standard well B1 for well seismic calibration to determine the stratigraphic division scheme;

[0070] Based on paleontological and index fossil data within the study area, and by comparison with standard well B1, the stratification of standard well B1 was determined. (See [reference needed]). Figure 5 Using logging and well logging data from standard well B1, sonic synthesis records were created for well-seismic calibration to determine the correspondence between seismic layers and drilling layers. (See [link to documentation]). Figure 6 ;

[0071] Standard well B1 is a vertical well with systematic core analysis and logging data, complete stratigraphic development, complete logging data, clear lithological and electrical characteristics of marker layers (Carboniferous standard limestone and Cambrian gypsum-salt rock), and clear seismic wave group reflection characteristics that can be traced and interpreted.

[0072] Seismic profiles from wells B1, T18, and B2 were selected. Based on marker beds and unconformities, well-to-well calibration seismic interpretation was performed to determine the seismic stratification scheme. (See [link to seismic profile]). Figure 7 ;

[0073] According to the seismic stratigraphic scheme, the lithology, electrical properties, and paleontological characteristics of the stratigraphic layers were compared between standard well B1 and wells T18 and B2. (See [link to seismic stratigraphic ... Figure 8 The stratification scheme was determined by cross-verification through well and seismic testing.

[0074] (5) Given the rapid changes in thickness, lithology, and lithofacies of the Cenozoic terrestrial strata in the southwestern basin orogenic belt of the study area, and the presence of numerous small unconformities in the seismic reflection wave groups, with no traceable stable marker layers, a layer-by-layer, segmented flattening of small-angle unconformities was employed to establish an anomalous seismic response table and determine the seismic horizon attribution of the unconformities. (See [reference needed]). Figure 9 ;

[0075] Based on the abnormal earthquake response form, the seismic wave group reflection characteristics of each abnormal point were analyzed. It was found that there was obvious erosion on the unconformity surface. The overlying strata were parallel to the flattened strata, which was then identified as the same stratigraphic interface.

[0076] (6) Based on the same stratigraphic reflection interface determined in step (5), the correspondence between the surface outcrop strata and the seismic horizon is established through the geological cap. Through the seismic guide layer, the tracing is carried out from the surface outcrop into the basin interior to achieve the unification of drilling, seismic, and outcrop stratification, including the following steps:

[0077] (a) A detailed geological survey was conducted on the outcrops in the southwest of the study area, and stratigraphic and lithological profiles of the outcrops were drawn. See [reference needed]. Figure 10 By comparing the lithology, color, lithofacies, and paleontology of the strata with those of standard well strata, a stratification scheme for the outcrops in the field can be determined.

[0078] (b) Combining regional geological data and maps, surface outcrop strata (N2a, N1p, N1a, N1k) were labeled with seismic data, completing seismic geological capping and resolving the inconsistency between well drilling, seismic data, and outcrop strata in the Cenozoic strata. See [link to relevant documentation]. Figure 10 .

[0079] (7) Divide the tectonic layers according to sedimentary cycles and sedimentary responses, establish standard seismic geological stratigraphic interpretation profiles, conduct seismic geological stratigraphic connection and closure interpretation of the whole region, and establish an isochronous stratigraphic framework;

[0080] Based on the nine major regional unconformities identified in step (3), and combined with the tectonic-sedimentary evolution characteristics of the study area from the Paleozoic to the Cenozoic, the study area was divided into tectonic layers and transitional layers. (See [reference]). Figure 11Establish an isochronous stratigraphic framework, see [reference]. Figure 12 And perform closed-loop tracking interpretation of the seismic grid;

[0081] (8) Based on the principle of seismic energy connectivity, and relying on the stratification of standard well B1, the stratification data of key exploration wells such as T18 and B2 on the seismic grid are mapped onto the seismic profile to verify whether the drilling stratification and seismic stratification are consistent. If they are not consistent, adjustments are made based on the seismic stratification to obtain a seismic geological stratification data table. (See [reference]) Figure 13 This solved the problem of unclear drilling, seismic, and outcrop stratification in superimposed composite basins.

[0082] The method of this invention comprehensively utilizes data from well logging, well logging, seismic data, outcrops, paleontology, and analytical testing. It targets areas with and without marker layers, identifies regional unconformities, delineates structural layers, establishes standard seismic geological interpretation profiles, and builds isochronous stratigraphic frameworks. This enables precise comparison of field outcrops, well drilling, and seismic strata, and completes the updating of well stratification data tables.

[0083] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for stratifying the seismic geology of superimposed composite basins, characterized in that, include: S1: Establish a seismic grid network, determine standard wells, identify regional unconformities based on seismic wave group reflection characteristics, and trace and interpret regional unconformities to establish a basis for determining whether a marker layer exists in the study area; determine whether a marker layer exists in the study area. S2: If a marker layer exists, determine the stratigraphic layering of the standard wells in the study area; use the standard wells to perform well-seismic calibration of the study area and determine the stratigraphic correlation and division scheme; S3: If no marker layer exists and the seismic energy can be traced and interpreted, the seismic profile is segmented and flattened, and an abnormal seismic response form is established. The seismic horizon is determined based on the abnormal seismic response form. Specifically, for seismic profiles without a marker layer and where the seismic energy can be traced and interpreted, the small-angle unconformity is flattened layer by layer and segment by segment, and an abnormal seismic response form is established. The seismic wave group reflection characteristics of each anomalous point are analyzed based on the abnormal seismic response form. If there is obvious erosion and the overlying strata are parallel to the flattened horizon, they are judged to be the same unconformity, thereby determining the seismic horizon of the unconformity. S4: Draw field stratigraphic and lithological profiles, and interpret and classify the strata of surface outcrops in conjunction with regional geological maps. By using geological caps, establish the correspondence between surface outcrop strata and seismic horizons. By using seismic strata, trace from surface outcrops into the basin interior to achieve the unification of drilling, seismic, and outcrop stratification. Achieving uniformity in drilling, seismic, and outcrop stratification includes the following steps: 1): Draw a lithological profile of the outcrops in the field, and compare it with the lithology, color, lithofacies and paleontology of the strata in the standard wells to determine the stratification scheme of the outcrops in the field; 2): For the stratification scheme of the outcrop strata in the field, combined with regional geological data and regional geological maps, the surface outcrop stratification and seismic profile marking are carried out to complete the seismic geological capping and realize the unification of drilling, seismic and outcrop stratification; S5: Based on the stratigraphic correlation and division scheme determined in S2 and the unification of drilling, seismic, and outcrop stratification achieved in S4, divide the structural layers; S6: Establish a standard seismic geological stratigraphic interpretation profile based on the divided structural layers, and establish an isochronous stratigraphic framework based on the standard seismic geological stratigraphic interpretation profile; S7: Based on the isochronous stratigraphic framework obtained in S6, and taking the principle of seismic energy connectivity as the basis, and relying on the stratigraphic correlation and division scheme of the standard wells obtained in S2, the seismic framework network is interpreted across the entire area. The stratification data of key exploration wells and appraisal wells in the study area are adjusted to obtain a seismic geological stratification data table.

2. The method for stratifying the seismic geology of superimposed composite basins according to claim 1, characterized in that, In S1, a seismic grid network for basin-level strata is established based on seismic data. Standard wells with complete lithological, electrical, and paleontological data and distinct characteristics are selected based on regional geological data to serve as the basic database for basin-level strata.

3. The method for stratifying seismic geology of superimposed composite basins according to claim 1, characterized in that, In S2, based on paleontological and index fossil data within the study area, comparisons were made with standard wells to determine the stratigraphic layers of the standard wells. The stratigraphic layers of the standard wells include primary and secondary marker layers. Using logging and well logging data from the standard wells, sonic synthesis records were created for well-seismic calibration to determine the stratigraphic correlation and division scheme.

4. The method for stratifying the seismic geology of superimposed composite basins according to claim 1, characterized in that, In S5, the tectonic layers are divided based on the unconformity surface, combined with the alternation of marine and terrestrial sediments in different periods of the superimposed composite basin, and the tectonic evolution background, to divide the tectonic layers and transitional layers.

5. The method for stratifying the seismic geology of superimposed composite basins according to claim 1, characterized in that, Based on the established standard seismic geological stratigraphic interpretation profile, the seismic grid network of the superimposed composite basin is interpreted by connecting and closing the seismic geological stratigraphic network across the entire region, and an isochronous stratigraphic grid is established.

6. The method for stratifying seismic geology of superimposed composite basins according to claim 1, characterized in that, In S7, based on the principle of seismic energy connectivity, and relying on the stratigraphic correlation and division scheme of standard wells, the stratigraphic data of key exploration wells on the seismic grid are marked onto the seismic profile to verify whether the drilling stratigraphy and seismic stratigraphy are consistent. If they are inconsistent, the seismic stratigraphy is used as the main factor for adjustment to obtain the seismic geological stratigraphic data table; if they are consistent, no stratigraphic changes are made.

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