Analysis method for maze cluster karst fracture-cavity type structure of secondary fault zone

Abstract

The invention provides an analysis method for a maze cluster karst fracture-cave type structure of a secondary fault zone, and aims at solving the problem of a maze cluster type corrosion fracture network control and storage mechanism of the secondary fault zone of a Tahe oil field, a floor type control and storage and three-dimensional oil-gas migration method is constructed to guide three-dimensional development of maze cluster oil reservoirs. According to the method, a karst hydrological framework comprising a cave layer and a water-resisting layer is perfected by constructing a semi-open pressure-bearing karst fracture-cavity karst water circulation mode, and a floor-shaped plane structure of a labyrinth cluster fracture-cavity type structure is graded and classified by utilizing comprehensive interpretation, characterization and recognition of logging and earthquakes of a karst layer system. And multi-layer three-dimensional fine development of the secondary fault zone is realized.

Description

Technical Field

[0001] The present invention relates to the field of seismic exploration and development, and particularly to an analysis method for a karst fissure-cavern structure in a secondary fault zone. Background Art

[0002] After nearly 10 years of development practice of the paleo-karst fissure-cavern reservoir in Tahe Oilfield, it has been confirmed that the main strike-slip faults and associated faults in Tahe Oilfield are strongly active, fault-related karst is very developed, the reservoir material basis is good, the reservoir-forming scale is large, and high cumulative production zones have been formed; at the same time, it has also been confirmed that the main strike-slip faults are developed with reservoir control, reservoir formation control, and accumulation control laws dominated by fragmentation and karst water solution expansion.

[0003] With the deepening of development practice and technical research, the development target of Tahe Oilfield gradually transitions from the large-scale main fault dissolution zone to the maze cluster type dissolution fracture network of lower order of 3-4 levels. Accordingly, the developed fissure-cavern scale is smaller, and its enrichment law is more complex. Currently, the maze cluster type dissolution fracture network between the main faults has become the main development target, and the reservoir control mechanism of the maze cluster type dissolution fracture network in the secondary fault zone has become an urgent problem to be solved, specifically reflected in: the karst formation and aquitard in the secondary fault area need to be further subdivided, the longitudinal hydrodynamic relationship between the cave layers is unclear, there are also certain differences in the discharge paths of the karst water cycle, and the development mode of the karst fissure-cavern structure is not clear.

[0004] Currently, there are mainly two analysis methods for the maze cluster type dissolution fracture network structure in the secondary fault zone:

[0005] Firstly, the deep and slow-flow karst circulation analysis method, which establishes a karst water cycle system based on the karst water flow trend of the paleo-topography, primary dissolution bedding, and fracture system, and believes the significance of unconformity surface in karst water conduction for the development process of interlayer karst fissure-cavern bodies. This method ignores the influence of the overall karst hydrogeological system in Tahe Oilfield on the floor-by-floor dissolution structure of the secondary fault fracture network.

[0006] Secondly, the shallow circulation and bedding circulation analysis method, which focuses on the bedding karst and vertical layered dissolution phenomena of fissures and caverns controlled by fractures in different directions, and emphasizes that confined karst water takes the deeply incised valleys and faults as discharge channels. This method does not analyze the corresponding relationship between the deeply incised valleys and the floor-by-floor dissolution structure, and fails to establish the key typical maze cluster karst fissure-cavern structure in the confined area.

[0007] In addition, development practice has confirmed that the maze cluster reservoir has the characteristics of a floor-like fissure-cavern structure and compound reservoir formation. Its fissure-cavern structure and reservoir formation are three-dimensional. The above two methods are relatively simple karst water circulation models and have not been able to construct a multi-layer reservoir control method to guide the three-dimensional development of the maze cluster reservoir. Summary of the Invention

[0008] To solve the problem that the existing technology cannot clearly recognize the karst fracture-cavity structure of the "labyrinth cluster" in the secondary fracture zone, and thus conduct reservoir development by constructing a multi-layer controlled reservoir for the labyrinth cluster, the present invention provides an analysis method for the karst fracture-cavity structure of the "labyrinth cluster" in the secondary fracture zone, and constructs a method of floor-type controlled reservoir and three-dimensional oil and gas migration to guide the three-dimensional development of the labyrinth cluster reservoir.

[0009] To solve the above technical problems, the technical solution of the present invention is as follows:

[0010] An analysis method for the karst fracture-cavity structure of the "labyrinth cluster" in the secondary fracture zone includes the following steps:

[0011] S1. Analyze the karst water circulation pattern of semi-open confined karst fracture-cavities: Combine the geological karst conditions of the target area, and construct the karst groundwater circulation system of the target area based on the information of paleogeomorphic restoration and paleo-water system restoration;

[0012] S2. Analyze the karst hydrogeological framework of the cave layer and the aquitard layer: Determine the karst hydrogeological framework and composition structure of the cave layer and the aquitard layer according to the seismic data and well logging data of the area;

[0013] S3. Seismic characterization and identification of the cave layer and the aquitard layer, extract the amplitude and coherence attributes of the cave layer and the aquitard layer in the target area described in S2 to characterize the fracture-cavity structure of the cave layer and the aquitard layer and the karst connection points between the upper and lower cave layers;

[0014] S4. Classification and grading of the floor-shaped labyrinth cluster fracture-cavity structure: Extract the coherence attributes of the one-room group and the upper section of the Ying Mountain Formation in the cave layer to form deep and shallow dissolution fracture networks representing geological significance; Perform contour extraction on the instantaneous amplitude of the T7 5 interface, and its instantaneous amplitude contour map represents the karst water connection points between the two layers of caves; Finally, superimpose the geological fracture network and the distribution map of dissolution connection points of the cave layer on the plane to obtain the distribution map of the labyrinth cluster group in the target well area;

[0015] S5: Construct a labyrinth cluster atlas under semi-open confined conditions: According to the recharge-runoff-discharge path of karst groundwater, the genetic-association relationship between the labyrinth cluster and the main fractures in different directions, and the complexity of the fracture dissolution space network, subdivide the structure of the labyrinth cluster group and the labyrinth cluster, and further construct a labyrinth cluster atlas under semi-open confined conditions.

[0016] Preferably, the steps of analyzing the karst water circulation pattern of semi-open confined karst fracture-cavities in S1 are as follows:

[0017] S11. Geological survey and karst feature analysis: Conduct a detailed geological survey of the target area to understand the basic geological conditions of the strata, structures, and lithologies; Identify karst features, including karst caves, fractures, and groundwater levels;

[0018] S12: Paleogeomorphic restoration: Based on stratigraphic, tectonic, and geomorphic features, attempt to restore the paleogeomorphology to understand the morphology of the past surface and the distribution of river channels; consider past climate conditions and their possible impacts on karst processes and the hydrological cycle.

[0019] S13: Paleo-water system restoration: Restore the paleo-water system through geomorphological methods and seismic attribute interpretation means, including the trend of ancient rivers; consider the drainage direction of the paleo-water system and the main runoff paths.

[0020] S14: Establish a karst hydrogeological model: Use geological and hydrogeological information to establish a karst hydrogeological model, which includes determining the positions of impermeable layers and permeable layers, identifying main karst channels, fissures, and caves; defining hydrogeological parameters.

[0021] S15: Construct a water cycle model: According to the hydrogeological model, construct a semi-open confined karst fissure-cave water cycle model, considering the recharge sources, runoff pipelines, and discharge areas of groundwater under semi-open confined karst conditions; simulate the formation process of ancient karst groundwater circulation controlling caves and fissure-caves.

[0022] S16: Model verification: Use the dynamic production data of existing oilfield development wells to verify the accuracy of the established water cycle model; conduct a comparative analysis to see if the model can better explain the actual observed inter-well fissure-cave connectivity relationship.

[0023] In step S1 of analyzing the semi-open confined karst fissure-cave water cycle model, for semi-open confined karst, consider the confined conditions of karst water bodies underground and the impact of confinement on hydrological processes, and analyze the impact of confined groundwater flow on the dissolution and enlargement of fissures and caves.

[0024] The steps of S2 for analyzing the karst hydrogeological framework of the cave layer and the aquitard layer are as follows:

[0025] S21: Investigate the ancient karst geological conditions, including stratigraphic, tectonic, and lithologic information; identify possible karst caves, fissures, and aquitard layer characteristics and understand their spatial distributions.

[0026] S22: Seismic data analysis: Analyze seismic data, including seismic reflection tomography, to identify the tectonic characteristics of underground rock layers, fault zones, and possible cave layers; use the characteristics of seismic profiles and seismic facies of reflected waves to indicate cave layers or aquitard layers.

[0027] S23: Log data analysis: Use log data to obtain formation parameters such as density, acoustic velocity, and resistivity; identify changes in possible cave layers and aquitard layers, including different lithologies, porosities, and permeabilities.

[0028] S24: Seismic-logging joint interpretation: Combine seismic data and logging data for joint interpretation. By comparing the changes in seismic reflection interfaces and logging curves, identify possible cave layers and aquitards; correlate the seismic stratigraphic reflection characteristics with logging data to identify possible caves or fractures and possible aquitards.

[0029] S25: Groundwater dynamics analysis: Based on the cave layers and aquitards determined from seismic and logging data, establish a hydrogeological model; analyze the changes and spatial distribution of hydrogeological parameters to determine the migration law of paleokarst groundwater and the hydraulic connection and isolation of cave layers.

[0030] S26: Construct a karst hydrogeological framework: Combine the determined cave layers and aquitards with geological characteristics for induction and division to construct a karst hydrogeological framework; the composition structure of the karst hydrogeological framework includes descriptions of karst cave layers, fracture systems, aquitards, and other strata.

[0031] Preferably, in step S3, the method for depicting the fracture-cave structure is as follows:

[0032] Depict the fracture-cave structure of the cave layer of the Yijianfang Formation by extracting the average absolute amplitude and coherent attribute overlay map of the cave layer of the Yijianfang Formation. Depict the fracture-cave structure of the upper part of the Ying Mountain Formation of the cave layer by extracting the average absolute amplitude and coherent attribute overlay map of the upper part of the Ying Mountain Formation of the cave layer.

[0033] Extract the upper part of the Ying Mountain Formation of the cave layer Depict the fracture-cave structure of the upper part of the Ying Mountain Formation of the cave layer by extracting the average absolute amplitude and coherent attribute overlay map of the upper part of the Ying Mountain Formation of the cave layer.

[0034] Preferably, in step S3, the method for depicting the karst connection point is as follows: Extract the instantaneous amplitude of the top surface of the Ying Mountain Formation ( interface) to depict the fracture-cave structure of the aquitard and analyze the karst connection points between the upper and lower cave layers of the Yijianfang Formation and the upper part of the Ying Mountain Formation.

[0035] Preferably, in step S4, use the coherent attributes of the two cave layers of the Yijianfang Formation and the upper part of the Ying Mountain Formation to determine the shape and boundary of the cave layer by using an edge detection algorithm, divide the cave layer into deep and shallow layers, and then generate deep and shallow dissolution fracture networks.

[0036] Preferably, conduct a first-level classification of the maze clusters and mazes, dividing them into maze clusters dominated by three directions: northeast, northwest, and east-west.

[0037] Preferably, conduct a second-level classification of the maze clusters and mazes, dividing them into complex grid maze clusters, sparse grid maze clusters, and single-branch maze clusters.

[0038] Beneficial effects: The present invention provides an analysis method for the maze cluster karst fissure-cave type structure of the secondary fault zone, and provides a method applicable to characterizing and identifying the floor-shaped maze type fissure-cave oil reservoir in the secondary fault zone. By constructing a semi-open confined karst fissure-cave karst water circulation model, improving the karst hydrogeological framework including the cave layer and the aquitard layer, and using the comprehensive interpretation, characterization and identification of logging and seismic data of the karst strata series, a typical karst model of the maze cluster fissure-cave type structure is established, and the floor-shaped planar structure of the maze cluster fissure-cave type structure is classified hierarchically to achieve the multi-layered three-dimensional fine development of the secondary fault zone. This method fills the gap in detecting and evaluating the karst fissure-cave bodies in the low-order fault zones, provides a technical method that can characterize the vertical superposition law and the interlayer groundwater dynamic connection of the upper and lower cave systems of the Yijianfang Formation and the upper section of the Ying Mountain Formation, and further classifies and divides multiple self-contained maze cluster networks with production connection relationships, realizing the multi-layered three-dimensional fine development of the maze cluster fissure-cave oil reservoir in the secondary fault zone.

[0039] The present invention uses the paleogeomorphic analysis method, the seismic attribute extraction method and the geological body contour extraction and analysis method to more accurately characterize the carbonate rock low-order fault maze cluster karst fissure-cave reservoir. Through the comprehensive interpretation of logging, seismic and floor karst fissure-cave structures under the constraint of the karst geological model, the karst fissure-cave structure in the confined karst area is constructed to achieve the comprehensive identification of small-scale maze cluster fissure-cave bodies. This method can effectively predict the small-scale fissure-cave reservoirs in the secondary fault zones between the main fault zones, strongly support the efficient development of heavy oil reservoirs and the tapping of remaining oil, and can be popularized and applied in the same type of oil reservoirs, with broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is the technical flow chart established according to the embodiment of the present invention;

[0041] Figure 2 is the plane distribution of the early Hercynian karst paleogeomorphology and ancient surface water systems in the target area;

[0042] Figure 3 The development mode of the early Hercynian karst caves in the shallow covered area of the Tahe Oilfield;

[0043] Figure 4 is the seismic profile of the Ordovician karst hydrogeological framework in the target area;

[0044] Figure 5 is the distribution map of the maze-type karst caves in the target well area;

[0045] Figure 6 is the distribution map of the maze cluster groups in the target well area;

[0046] Figure 7 is the hierarchical classification atlas of the maze clusters in the target well area. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The following will elaborate on the implementation mode of the present invention in combination with the attached drawings and embodiments, so that the implementation personnel of the present invention can fully understand how to apply technical means to solve practical problems and achieve technical effects.

[0048] As Figure 1 shown, a method for analyzing the karst fracture-cavity type structure of the "maze cluster" of secondary fracture zones includes the following steps:

[0049] S1. Analyze the karst water circulation mode of semi-open confined karst fractures and cavities: Combine the geological karst conditions of the target area, and construct the karst groundwater circulation system of the target area based on the information of paleogeomorphic restoration and paleo-water system restoration;

[0050] S2. Analyze the karst hydrogeological framework of the cave layer and the aquitard layer: Determine the karst hydrogeological framework and composition structure of the cave layer and the aquitard layer according to the seismic data and logging data of this area;

[0051] S3. Seismic characterization and identification of the cave layer and the aquitard layer, extract the amplitude and coherence attributes of the cave layer and the aquitard layer in the target area described in S2 to characterize the fracture-cavity structure of the cave layer and the aquitard layer and the karst connection points between the upper and lower cave layers;

[0052] S4. Classification and grading of the floor-like maze cluster fracture-cavity type structure: Extract the contour of the coherence attributes of the "one-room group" in the cave layer and the upper part of the Yingshan Formation to form deep and shallow dissolution fracture networks representing geological significance; Perform contour extraction on the instantaneous amplitude of the T7 5 interface, and its instantaneous amplitude contour map represents the karst water connection points between the two layers of caves; Finally, overlay the geological fracture network and the distribution map of dissolution connection points of the cave layer on a plane to obtain the distribution map of the maze cluster group in the target well area;

[0053] S5: Construct a maze cluster atlas under semi-open confined conditions: According to the recharge-runoff-discharge path of karst groundwater, the genetic-associative relationship between the maze cluster and the main fractures in different directions, and the complexity of the fracture dissolution space network, subdivide the structure of the maze cluster group and the maze cluster, and further construct a maze cluster atlas under semi-open confined conditions.

[0054] Preferably, the steps of analyzing the karst water circulation mode of semi-open confined karst fractures and cavities in S1 are:

[0055] S11: Geological survey and karst feature analysis: Conduct a detailed geological survey on the target area to understand the basic geological conditions of the strata, structures, and lithologies; Identify karst features, including karst caves, fractures, and groundwater levels;

[0056] S12: Paleogeomorphic restoration: Based on stratigraphic, tectonic, and geomorphic features, attempt to restore the paleogeomorphology to understand the past surface morphology and river channel distribution; consider past climate conditions and their possible impacts on karst processes and the hydrological cycle.

[0057] S13: Paleo-water system restoration: Restore the paleo-water system through geomorphological methods and seismic attribute interpretation, including the trend of ancient rivers; consider the drainage direction and main runoff paths of the paleo-water system.

[0058] S14: Establish a karst hydrogeological model: Utilize geological and hydrogeological information to establish a karst hydrogeological model, which includes determining the positions of impermeable and permeable layers, identifying major karst channels, fissures, and caves; defining hydrogeological parameters.

[0059] S15: Construct a water cycle model: According to the hydrogeological model, construct a semi-open confined karst fissure-cave water cycle model, considering the recharge sources, runoff pipelines, and discharge areas of groundwater under semi-open confined karst conditions; simulate the formation process of ancient karst groundwater circulation controlling caves and fissure-caves.

[0060] S16: Model verification: Use the dynamic production data of existing oilfield development wells to verify the accuracy of the established water cycle model; conduct comparative analysis to see whether the model can better explain the observed inter-well fissure-cave connectivity relationship.

[0061] In step S1 of analyzing the semi-open confined karst fissure-cave water cycle model, for semi-open confined karst, consider the confined conditions of karst water bodies underground and the impact of confinement on hydrological processes, and analyze the impact of confined groundwater flow on the dissolution and enlargement of fractures and caves.

[0062] The steps for analyzing the karst hydrogeological framework of the cave layer and the aquitard in S2 are as follows:

[0063] S21: Investigate the ancient karst geological conditions, including stratigraphic, tectonic, and lithological information; identify possible karst cave, fracture, and aquitard characteristics and understand their spatial distribution.

[0064] S22: Seismic data analysis: Analyze seismic data, including seismic reflection tomography, to identify the tectonic characteristics, fault zones, and possible cave layers of underground rock formations; use the characteristics of seismic profiles and seismic facies of reflected waves to indicate cave layers or aquitards.

[0065] S23: Well logging data analysis: Use well logging data to obtain formation parameters such as density, acoustic velocity, and resistivity; identify the variations of possible cave layers and aquitards, including different lithologies, porosities, and permeabilities.

[0066] S24: Seismic-logging joint interpretation: Combine seismic data and logging data for joint interpretation. By comparing the changes in seismic reflection interfaces and logging curves, identify possible cave layers and aquitards; correlate the seismic stratigraphic reflection characteristics with logging data to identify possible caves or fractures and possible aquitards.

[0067] S25: Groundwater dynamics analysis: Based on the cave layers and aquitards determined from seismic and logging data, establish a hydrogeological model; analyze the changes and spatial distribution of hydrogeological parameters to determine the migration law of paleokarst groundwater, and determine the hydraulic connection and isolation of cave layers.

[0068] S26: Construct a karst hydrogeological framework: Combine the determined cave layers and aquitards, summarize and classify them according to geological characteristics, and construct a karst hydrogeological framework; the composition structure of the karst hydrogeological framework includes descriptions of karst cave layers, fracture systems, aquitards, and other strata.

[0069] Preferably, in step S3, the method for depicting the fracture-cave structure is as follows:

[0070] By extracting the average absolute amplitude and coherent attribute overlay map of the Yijianfang Formation in the cave layer to depict the fracture-cave structure of the Yijianfang Formation cave layer.

[0071] Extract the average absolute amplitude and coherent attribute overlay map of the upper part of the Ying Mountain Formation in the cave layer to depict the fracture-cave structure of the upper part of the Ying Mountain Formation.

[0072] Preferably, in step S3, the method for depicting the karst connection point is as follows: Extract the instantaneous amplitude of the top surface of the Ying Mountain Formation interface) to depict the fracture-cave structure of the aquitard and analyze the karst connection points between the upper and lower cave layers of the Yijianfang Formation and the upper part of the Ying Mountain Formation.

[0073] Preferably, in step S4, use the coherent attributes of the two cave layers of the Yijianfang Formation and the upper part of the Ying Mountain Formation, adopt an edge detection algorithm to determine the shape and boundary of the cave layer, divide the cave layer into deep and shallow layers, and then generate deep and shallow dissolution fracture networks.

[0074] Preferably, conduct a first-level classification of the maze cluster groups and mazes, and divide them into maze cluster groups dominated by three directions: northeast, northwest, and east-west.

[0075] Preferably, conduct a second-level classification of the maze cluster groups and mazes, and divide them into complex grid maze clusters, sparse grid maze clusters, and single-branch maze clusters.

[0076] Example 2 selects a piece of data from the Ordovician oil reservoir in Tahe Oilfield across the coverage area of the Upper Ordovician Lianglitage Formation as an application example, and the specific implementation method is as follows:

[0077] 1. Analysis of the karst water circulation pattern in semi-open confined karst fissure-cave systems. Combining the regional geological karst conditions, through the restoration of paleogeomorphology and paleo-water systems ( Figure 2 ), the target area generally belongs to a semi-open confined karst groundwater system. The recharge of karst water comes from the precipitation in the northern karst outcrop area. The northern karst outcrop area is located at the high part of the ancient terrain, and the large elevation difference provides a large hydraulic head difference, driving groundwater to enter the Upper Ordovician covered area along fractures and faults from the northern outcrop area ( Figure 3 ).

[0078] 2. Analysis of the karst hydrogeological framework including cave layers and aquitards. Relying on high-precision seismic and logging data, it is determined that there are three main karst aquitards and two cave layers developed in the early Hercynian in the target area. The aquitards are the Lianglitag Formation - Qerbake Formation, the lower member of the Yingshan Formation, and the inter-formational aquitard of the Upper Ordovician, and the cave layers are the Yijianfang Formation and the upper member of the Yingshan Formation ( Figure 4 ). Combining the karst hydrogeological framework and the confined karst background, it is analyzed that the dolomitic limestone section of the lower member of the Yingshan Formation is the regional aquitard floor, and the upper member of the Yingshan Formation and the Yijianfang Formation develop the two main cave layers. The fractures and cracks in the upper member of the Yingshan Formation and the Yijianfang Formation are preferentially dissolved and developed into the shape of karst caves.

[0079] 3. Seismic characterization and identification of cave layers and aquitards. The main seismic response of large karst caves is manifested as bead-shaped reflections, and strong seismic amplitude anomalies can be used to well identify karst caves. By extracting the average absolute amplitude and coherence attribute overlay map of the Yijianfang Formation (T7 4 - T7 5 ) to depict the fracture-cave structure of the cave layer of the Yijianfang Formation ( Figure 5 a), extracting the average absolute amplitude and coherence attribute overlay map of the upper member of the Yingshan Formation (T7 4 - T7 5 ) to depict the fracture-cave structure of the cave layer of the upper member of the Yingshan Formation ( Figure 5 b), and extracting the instantaneous amplitude of the T7 5 interface to depict the fracture-cave structure of the aquitard to reflect the karst connection point between the upper and lower cave layers ( Figure 5 c).

[0080] 4. Classification and grading of the floor-like maze cluster fracture-cave type structure. Using the contour tracing function of the coreldraw software to extract the coherence attributes of the two cave layers of the Yijianfang Formation and the upper member of the Yingshan Formation, forming deep and shallow karst dissolution fracture networks representing geological significance; similarly, performing contour extraction on the instantaneous amplitude of the T7 5 interface, and its instantaneous amplitude contour map represents the karst water connection point between the two cave layers; finally, overlaying the two-layer cave geological fracture network and the distribution map of karst dissolution connection points on the plane to obtain the maze cluster group distribution map of the target well area ( Figure 6 ).

[0081] 5. According to the recharge-runoff-discharge path of karst groundwater, the genetic-associative relationship between maze clusters and main faults in different directions, and the complexity of the fracture dissolution space network, the maze cluster groups and maze clusters are structurally subdivided, and a maze cluster atlas under semi-open confined conditions is further constructed Figure 7 ): The first-level classification can be divided into maze cluster groups dominated by three directions: northeast, northwest, and east-west, and the second-level classification can be further subdivided into complex grid maze clusters, sparse grid maze clusters, and single-branch maze clusters.

[0082] It should be noted that the above specific implementation manners can enable those skilled in the art to understand the present invention and creation more comprehensively, but do not limit the present invention and creation in any way. Therefore, although this specification has described the present invention and creation in detail with reference to the drawings and embodiments, those skilled in the art should understand that the present invention and creation can still be modified or equivalently replaced. In short, all technical solutions and their improvements that do not depart from the spirit and scope of the present invention and creation should be covered by the protection scope of the patent of the present invention and creation.

Claims

1. An analysis method for the karst fissure-cave type structure of the "maze cluster" in a secondary fracture zone, characterized in that, It includes the following steps: S1. Analyze the karst water circulation pattern of semi-open confined karst fissure-cave: Combine the geological karst conditions of the target area and construct the karst groundwater circulation system of the target area based on the information of paleogeomorphic restoration and paleo-water system restoration; S2. Analyze the karst hydrogeological framework of the cave layer and the aquitard layer: Determine the karst hydrogeological framework and composition structure of the cave layer and the aquitard layer according to the seismic data and logging data of this area; S3. Seismic characterization and identification of the cave layer and the aquitard layer, extract the amplitude and coherence attributes of the cave layer and the aquitard layer in the target area described in S2 to characterize the fissure-cave structure of the cave layer and the aquitard layer and the karst connection points between the upper and lower cave layers; S4. Classification and Grading of the Floor-like Maze Cluster Fracture-vug Structure: Extract the contours of the coherent attributes of a room group in the cave layer and the upper part of the Yingshan Formation to form deep and shallow dissolution fracture networks representing geological significance; perform contour extraction on the instantaneous amplitude of the top surface (T7 5 interface) of the Yingshan Formation, and its instantaneous amplitude contour map represents the karst water connection points between the two layers of caves; finally, overlay the geological fracture network and the distribution map of dissolution connection points in the cave layer on a plane to obtain the distribution map of the maze cluster group in the target well area; S5: Construct a maze cluster atlas under semi-open confined conditions: According to the recharge-runoff-discharge path of karst groundwater, the genetic-associative relationship between the maze cluster and the main faults in different directions, and the complexity of the fracture dissolution space network, subdivide the structure of the maze cluster group and the maze cluster, and further construct a maze cluster atlas under semi-open confined conditions.

2. The analysis method of the karst fissure-cave type structure of the "maze cluster" of the secondary fracture zone according to claim 1, characterized in that, The steps for analyzing the karst water circulation pattern of semi-open confined karst fissure-cave in S1 are as follows: S11: Geological investigation and karst feature analysis: Conduct a detailed geological investigation on the target area to understand the basic geological conditions of the strata, structures, and lithologies; Identify karst features, including karst caves, fractures, and groundwater levels; S12: Paleogeomorphic restoration: Based on the strata, structures, and geomorphic features, attempt to restore the paleogeomorphology, understand the morphology of the past surface, river channel distribution, and lake conditions; Consider the past climate conditions and their possible impacts on karst processes and hydrological cycles; S13: Paleo-water system restoration: Restore the paleo-water system through geomorphology methods and seismic attribute interpretation means, including the trend of ancient rivers; Consider the drainage direction of the paleo-water system and the main runoff paths; S14: Establish a karst hydrogeological model: Use geological and hydrogeological information to establish a karst hydrogeological model, and the model includes determining the positions of impermeable layers and permeable layers, identifying the main karst channels, fissures, and caves; Defining hydrogeological parameters; S15: Water circulation pattern construction: According to the hydrogeological model, construct a karst water circulation pattern of semi-open confined karst fissure-cave, considering the recharge sources, runoff pipelines, and discharge areas of groundwater under semi-open confined karst conditions; Simulate the formation process of ancient karst groundwater circulation controlling karst caves and fissure-caves; S16: Model verification: Use the dynamic production data of existing oilfield development wells to verify the accuracy of the established water circulation model; Conduct a comparative analysis to see whether the model can better explain the actual observed inter-well fissure-cave connection relationship.

3. The analysis method of the karst fissure-cave type structure of the "maze cluster" in the secondary fracture zone according to claim 1, wherein, In the steps of analyzing the karst water circulation pattern of semi-open confined karst fissure-cave in S1, for semi-open confined karst, consider the confined conditions of karst water bodies underground and the influence of confinement on hydrological processes, and analyze the influence of the expansion and contraction of karst fractures and caves on groundwater flow.

4. The analysis method of the karst fissure-cave type structure of the "maze cluster" in the secondary fracture zone according to claim 1, characterized in that, The steps for analyzing the karst hydrogeological framework of the cave layer and the aquitard layer in S2 are as follows: S21: Investigate the ancient karst geological conditions, including strata, structure, and lithology information; Identify possible karst cave, fracture, and aquitard layer features and understand their spatial distributions; S22: Seismic data analysis: Analyze seismic data, including seismic reflection tomography, to identify the structural features, fault zones, and possible cave layers of underground rock formations; use the characteristics of seismic profiles and seismic reflection facies to indicate cave layers or aquitards. S23: Well logging data analysis: Use well logging data to obtain formation parameters such as density, acoustic velocity, and resistivity; identify the variations of possible cave layers and aquitards, including different lithologies, porosities, and permeabilities. S24: Seismic-well logging joint interpretation: Combine seismic data and well logging data for joint interpretation. By comparing the variations of seismic reflection interfaces and well logging curves, find possible cave layers and aquitards; correlate seismic stratigraphic reflection characteristics and well logging data to identify possible caves or fractures and possible aquitards. S25: Groundwater dynamics analysis: Based on the cave layers and aquitards determined from seismic and well logging data, establish a hydrogeological model; analyze the variations and spatial distributions of hydrogeological parameters to determine the migration law of groundwater, and determine the hydraulic connection and isolation of cave layers. S26: Construct a karst hydrogeological framework: Summarize and classify the determined cave layers and aquitards in combination with geological characteristics to construct a karst hydrogeological framework; the composition structure of the karst hydrogeological framework includes descriptions of karst cave layers, fracture systems, aquitards, and other strata.

5. The analysis method of the karst fissure-cave type structure of the "maze cluster" in the secondary fracture zone according to claim 1, characterized in that The S2 step also includes: Hydrogeological model verification and adjustment. Use the dynamic production data of oilfield development wells to verify the accuracy of the constructed karst hydrogeological framework model.

6. The analysis method of the karst fissure-cave type structure of the "maze cluster" in the secondary fracture zone according to claim 1, characterized in that In the S3 step, the method for characterizing the fracture-cave structure is as follows: By extracting the superimposed map of the average absolute amplitude and coherence attributes of a room group in the cave layer to characterize the fracture-cave structure of the cave layer of a room group; Extract the upper member of the Yingshan Formation in the cave layer Use the superposition map of the average absolute amplitude and coherence attributes to characterize the fracture-cave structure of the upper member of the Yingshan Formation 7. The analysis method of the karst fissure-cave type structure of the "maze cluster" in the secondary fracture zone according to claim 1, characterized in that, In step S3, the method for depicting the karst connection point is as follows: extract the instantaneous amplitude of the top surface of the Yingmountain Formation ( interface) to depict the fracture-vug structure of the aquitard, and analyze the karst connection point between the upper and lower cave layers, i.e., between the Yijianfang Formation and the upper part of the Yingmountain Formation.

8. The analysis method of the karst fracture-cave type structure of the "maze cluster" in the secondary fracture zone according to claim 1, characterized in that, In the S4 step, use the coherence attributes of the two cave layers of the Yijianfang Formation and the upper member of the Ying Mountain Formation to determine the shape and boundary of the cave layer by using an edge detection algorithm, divide the cave layer into deep and shallow layers, and then generate deep and shallow dissolution fracture networks.

9. The analysis method of the karst fissure-cave type structure of the "maze cluster" in the secondary fracture zone according to claim 1, characterized in that Perform primary classification on maze clusters and mazes, and divide them into maze clusters dominated by three directions: northeast, northwest, and east-west.

10. The analysis method of the karst fissure-cavern type structure of the "maze cluster" in the secondary fracture zone according to claim 1, characterized in that, Perform secondary classification on maze clusters and mazes, and divide them into complex grid maze clusters, sparse grid maze clusters, and single-branch maze clusters.

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