A semi-quantitative identification method of fracture-cavity separation based on karst transformation

Abstract

The present invention discloses a method for semi-quantitatively distinguishing the segregation of fractures and caves based on karst transformation. The key point of its technical solution is to take the internal structure of ancient karst fractures and caves as the research target. It is the first to semi-quantitatively distinguish the development degree of fracture cutting transformation, filling transformation, and collapse transformation based on karst transformation. It comprehensively analyzes the influence of the three types of karst transformation on fractures and caves, compares the results of karst transformation, and comprehensively establishes two types of models: fracture cutting and filling can lead to a separation model within the system, and fracture cutting and collapse lead to a blocking model within the system. The present invention solves the previous problems of disconnection between geophysical engraving and karst geological analysis, and the high accuracy of the analysis of the internal structure of fractures and caves by single research on filling and collapse. It effectively solves the problems of insufficient geophysical interpretation accuracy and inaccurate single factor analysis, and improves the accuracy of fracture and cave internal analysis.

Description

Technical Field

[0001] The present invention relates to the field of description of the internal structure of ancient karst fractures and caves, and more specifically, to a semi-quantitative identification method of fracture-cavity separation based on karst transformation. Background Art

[0002] The Ordovician reservoirs in the Tahe Oilfield are carbonate fracture-vuggy reservoirs formed through multiple phases of tectonic movement and paleokarstification. The reservoir's reservoirs are primarily composed of structural fractures generated by tectonic deformation and pores, caves, and fractures formed by karstification. Large caves are the primary reservoir spaces, and fractures serve as both the primary reservoir space and the primary connecting pathways. The carbonate matrix has little reservoir-permeability significance. The reservoir spaces are diverse in shape, size, and distribution, and exhibit strong heterogeneity. Fracture-vuggy characterization is challenging, making reservoir prediction and remaining oil potential extremely challenging.

[0003] The journal article "Study on Fracture-Vuggy Compartmentality in Carbonate Reservoirs in the Tahe Oilfield" proposes that within the same fracture-vuggy aggregate, due to differences in fracture-vuggy structure, there may be fracture-vuggy bodies that are not directly connected laterally or have relatively independent oil-water relationships. It also proposes the concept of compartmentalization for such fracture-vuggy bodies. Currently, the main methods for describing fracture-vuggy compartmentality include geophysical identification, geological prediction, and production performance verification. The specific descriptions are as follows:

[0004] Geophysical techniques characterize fracture-cavity structures: Karst fracture-cavity reservoir spaces are classified, and different seismic attributes are used to characterize different reservoir spaces. These are then integrated to form a composite karst fracture-cavity reservoir space. Furthermore, high-frequency attributes are used to finely identify differences in the internal structure of the fractures and caves. Multi-attribute predictions are used to predict collapse, filling, and other characteristics, determining the internal structural characteristics of the fractures and caves and forming a composite karst fracture-cavity structure prediction volume. The different targeted nature of each attribute leads to inconsistent analysis results, and each geophysical attribute has a high degree of ambiguity, making it difficult to accurately reflect the true and reliable fracture-cavity structure.

[0005] Comprehensive geological description of a single karst transformation: Use static data such as well logging and mud logging to identify the filling properties of a single point. Use geological attribute predictions and comparisons with actual drilling characteristics of a single well to clarify the filling characteristics around the well. Use geophysical predictions and structural morphological changes to predict the collapse characteristics of the well area. By predicting a single filling or collapse property, the impact of a single action on the internal structure of fractures and caves can be determined. The fracture-cavity separation of the well area can be determined based on a single karst transformation. However, the internal structure of fractures and caves is the result of the combined effects of multiple transformation processes, and single-factor analysis is prone to significant deviations.

[0006] Production dynamics validates karst transformation results: This method primarily uses inter-well production characteristics, energy characteristics, water-rise characteristics, and inter-well production interference, among other production dynamics, to comprehensively analyze the differences in the internal structure of karst fractures and caves. This determines the separation and connectivity characteristics of these fractures and caves, as well as the differences in the internal structure of large fractures and caves and the main connecting matrix characteristics between them. This validates the predicted results of fracture-cavity separation and connectivity. However, production dynamics validation also suffers from multiple solutions and significant human interference.

[0007] Based on the problems existing in the above three methods, the present invention aims to analyze the internal structure of fractures and holes from the perspective of controlling the causes of the fractures and holes, and propose a semi-quantitative judgment standard for fracture and hole separation, so as to improve the accuracy of fracture and hole separation research. Summary of the Invention

[0008] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a semi-quantitative identification method for fracture-cavity separation based on karst transformation. It takes the internal structure of ancient karst fractures and caves as the research target, and pioneers a semi-quantitative identification of the development degree of fault cutting transformation, filling transformation, and collapse transformation based on karst transformation. It comprehensively considers the influence of the three types of karst transformation on fractures and caves, compares the results of karst transformation identification, and establishes the separation and blocking patterns of the internal fractures and caves formed by different combinations of karst transformation types. It effectively solves the problems of insufficient geophysical interpretation accuracy and inaccurate single factor analysis, and improves the accuracy of fracture and cave interior analysis.

[0009] To achieve the above object, the present invention provides the following technical solution: a semi-quantitative identification method of fracture-cavity separation based on karst transformation, comprising the following steps:

[0010] S1. Semi-quantitative characterization of fracture cutting, filling and collapse of fracture-cavity system:

[0011] The characterization parameters of fault cutting and transformation include fault strike, disconnected layer, active period and fault type.

[0012] Filling and transformation characterization parameters include filling type, slug characteristics, karst element location, and structural location.

[0013] The collapse transformation characterization parameters include reflection morphology, seismic profile characteristics, and wave impedance.

[0014] S2. Based on the results of S1, determine the impact of fracture cutting, filling, and collapse on the fracture-cavity system. The criteria are as follows:

[0015] The fracture-cavity system transformed by fault cutting meets the following requirements: the principal stress direction in the area where the fracture-cavity system is located intersects with the fault trend of the fracture-cavity system, the fault was formed in the middle Caledonian to early Hercynian period, the fault continued to be active in the late Hercynian period, and the fault type is compression or translation.

[0016] The fracture-cavity system transformed by filling meets the following requirements: the filling type in the fracture-cavity system is mud, the fracture-cavity system presents a slug-like characteristic, the fault cutting structure is concentrated at the water inlet position of the local karst, and the fracture-cavity system is located at the horizontal cutting part of the Ming River.

[0017] The fracture-hole system to be reconstructed by the collapse meets the following requirements: The fracture-hole system is in T7 4 The reflection morphology below the layer shows a concave event axis and a phase deformation of at least one phase. The diffraction wave reflection characteristics in the seismic profile are chaotic and discontinuous, and the wave impedance profile is chaotic and discontinuous.

[0018] S3. Based on the results of S2, the fracture-cavity system transformed by fault cutting and filling is determined to be a separated type. The dynamic characteristics of the separated type are an independent pressure system, energy and fluid are not connected, and there is no interference between water injection and gas injection wells. The fracture-cavity system transformed by fault cutting and collapse is determined to be a blocking type. The dynamic characteristics of the blocking type are the same pressure system as the reservoir, fluid is not connected, and there may be pressure response or oil increase between water injection and gas injection wells.

[0019] The present invention is further configured as follows: the judgment criteria for the fracture direction of the fracture-hole system in S2 that is transformed by fracture cutting are refined to the angle between the principal stress direction of the area where the fracture-hole system is located and the fracture direction of the fracture-hole system being greater than 40°.

[0020] The present invention further provides that: the judgment criteria of the fracture-cavity system in S2 that is transformed by the fracture cutting in terms of the fracture disconnection layer are refined to the fracture from T7 4 The horizon continues to be dislocated to T5 0 Stratum.

[0021] The present invention further provides that: the judgment criteria of the fracture-cavity system in S2 that is transformed by the fracture cutting in terms of the fracture disconnection layer are refined to the fracture from T7 6 The horizon continues to be dislocated to T5 0 Stratum.

[0022] The present invention is further configured as follows: the characterization parameter of the fracture cutting transformation in S1 also includes a vertical fault distance; and the judgment criterion for the vertical fault distance of the fracture-hole system transformed by the fracture cutting in S2 is that the vertical fault distance of the fracture is greater than 30m.

[0023] The present invention is further provided as follows: the criteria for judging the activity period of the fracture-cavity system in S2 that is transformed by fault cutting are refined to the fact that the fracture-cavity system is mainly a fault that was continuously active in the middle to late period of Hercynian.

[0024] The present invention is further configured as follows: in the judgment criteria for the position of karst elements in the fracture-cavity system transformed by filling in S2, the karst elements at the deformation site of the fracture-cavity system have the characteristics of planar extension, that is, obvious deformation or continuous faulting occurs at the deformation site of the fracture-cavity system.

[0025] The present invention is further configured as follows: in the judgment criteria for the slug-type characteristics of the fracture-cavity system transformed by filling in S2, the slug-type characteristics are determined based on the porosity inversion result.

[0026] The present invention is further configured as follows: in the judgment criteria for the slug-like characteristics of the fracture-cavity system transformed by filling in S2, the slug-like characteristics are manifested as a low-porosity section with a porosity inversion result lower than 5% and a lateral continuous section greater than 10m.

[0027] The present invention is further configured as follows: the collapse transformation characterization parameters in S1 also include karst location, and the judgment criteria for the karst location of the fracture-cavity system affected by collapse transformation in S2 is that the karst location of the fracture-cavity system is located in a fault or a fault-intensive development area that crosses the underground river, and the fault cutting is obvious.

[0028] In summary, the present invention has the following beneficial effects compared with the prior art: the present invention changes the previous problems of disconnection between geophysical carving and karst geological analysis, and the high accuracy of analysis of the internal structure of fractures and caves by single research on filling and collapse. The internal structure of ancient karst fractures and caves is taken as the research target, and it is the first to semi-quantitatively judge the development degree of fault cutting, filling and collapse based on karst transformation. The influence of the three types of karst transformation on fractures and caves is comprehensively analyzed, and the results of karst transformation are compared to establish two types of models, namely: fault cutting and filling can lead to separation mode within the system, and fault cutting and collapse lead to blocking mode within the system. The mechanism of separation and blocking of the internal fractures and caves is further verified and explained, which effectively solves the problems of insufficient geophysical interpretation accuracy and inaccurate single factor analysis, and improves the accuracy of fracture and cave internal analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the process of an embodiment;

[0030] Figure 2 This is a schematic diagram of the multi-attribute plane superposition of the TK446CH2 well area;

[0031] Figure 3 This is a schematic diagram of the seismic section of the TK446CH2 belt;

[0032] Figure 4 Schematic diagram of the fracture of TK446CH2 band;

[0033] Figure 5These are three types of residual oil distribution patterns. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the invention.

[0035] Example

[0036] like Figure 1 FIG. 1 is a flow chart of a preferred embodiment of the present invention, which is a semi-quantitative method for determining the separability of fractures and caves based on karst transformation, and includes the following steps:

[0037] S1. Semi-quantitative characterization of fracture cutting, filling, and collapse of the fracture-cavity system.

[0038] (1) Characterization of fault cutting and transformation: The karstification in the main area of ​​Tahe mainly occurred in the early Hercynian period. Therefore, the faults formed in the middle Caledonian to early Hercynian period are conducive to the occurrence of karstification. This type of fault mainly plays a constructive role in karstification, and has a weak effect on the separation and transformation of karst. It mainly controls the main development direction of karst and the formation of various karst elements. This type of fault is mainly manifested as a main large fault and a major secondary fault. This type of secondary fault is generally characterized by a deep incision depth and a large plane distribution range.

[0039] On this basis, the characterization parameters of fault cutting and reconstruction are established, including disconnection layer, vertical fault throw, activity period, fault type and fault strike. The descriptions of each parameter are as follows:

[0040] Disconnected layer, if the fault continues to break to T5 0 , indicating that the probability of the fault being continuously active during the burial period is higher, and the reformation effect on the fracture cavity is also stronger. 4 The horizon continues to be dislocated to T5 0 Layer or fracture from T7 6 The horizon continues to be dislocated to T5 0 Horizontal position is one of the criteria for judging fault cutting and reconstruction.

[0041] Vertical throw: The vertical throw of a fault. A larger throw indicates a greater offset distance to the karst, indicating a greater likelihood that the fault formed within a karst fracture or cave, leading to persistent offset to the fracture or cave and increasing the probability of a septal fracture. In this example, a vertical throw greater than 30m is used as one of the criteria for determining fracture cutting and reconstruction.

[0042] As for the activity period, the main karst period in the main area was in the early Haixi period. The faults that were continuously active in the middle and late Haixi periods must have been continuously active during the burial period, and the main effect on the fractures and caves was transformation.

[0043] As for the fault type, compression and translation are more likely to cause a higher degree of fault closure due to compression stress, which leads to an enhanced separation of the fracture-cavity system by the fault.

[0044] Fault strike: An angle greater than 40° between the principal stress direction in the region where the fracture-cavity system is located and the fault strike in the fracture-cavity system is more likely to cause fracture closure under a compressive stress background, increasing the probability of separation. In this example, the principal stress direction in Tahe is north-south, so high-angle faults with an east-west strike are more likely to increase the probability of separation.

[0045] (2) Characterization of filling and transformation: Domestic and foreign scholars have studied the classification of fracture-cavity fillings, but the classification schemes are different. Based on the outcrop survey in Tabei and the observation of downhole cores, and after integrating the classification scheme of modern karst fillings by Zhang Meiliang, Zhu Xuewen, etc., it is proposed to divide the Ordovician carbonate rock fracture-cavity fillings into four categories according to the material composition, sedimentary accumulation environment, and morphological combination of the fracture-cavity fillings: mechanical sediments, chemical sediments, colluvial fillings, and their weathering residuals. The fillings in the Tahe area are mainly divided into chemical sediments and mechanical sediments. The effect of chemical filling on fracture-cavity transformation is relatively weak. Therefore, the semi-quantitative analysis of fillings mainly focuses on mechanical sediments.

[0046] On this basis, filling transformation characterization parameters are established, including filling material type, slug characteristics, karst element location and structural location. The descriptions of each parameter are as follows:

[0047] As for filling type, the sandy filling still has a certain permeability and a relatively weak separation effect, while the muddy filling of the Bachu Formation has extremely low permeability and a relatively strong separation effect. Comprehensively judging, the separation effect of muddy filling is stronger than that of sandy filling.

[0048] For slug-like characteristics, lower porosity inversion parameters indicate a strong shale filling pattern and a slug-like characteristic; lower porosity parameters indicate a weak slug-like characteristic. When the porosity of the sandy sludge filling is less than 5%, it lacks lateral flow capacity. Experiments have shown that low-porosity sections with a lateral length greater than 10 meters have a strong lateral obstruction. Therefore, a slug-like characteristic is manifested by a low-porosity section with a porosity inversion result less than 5% and a lateral continuity greater than 10 meters.

[0049] Regarding the location of karst elements, when dissolution stops and the mud of the Bachu Formation begins to be deposited, mud filling is likely to occur at the water inlet and sinkhole, and the probability of mud filling is higher at the water inlet.

[0050] At the structural location, where the plane deformation of the karst fracture-cavity system is close to the karst location, the hydrodynamic force is sharply weakened, which easily leads to filling. Some karst conduits cross the surface valley. In other words, the fracture-cavity system is located at the horizontal cutting point of the Ming River. At this time, sand and mud under the valley easily seep down and fill the interior of the karst fracture-cavity system. Furthermore, if the karst elements at the fracture-cavity system deformation site have the characteristics of plane extension, that is, the fracture-cavity system deformation site shows obvious deformation or continuous faulting, then sand and mud are more likely to seep down and fill the interior of the karst fracture-cavity system.

[0051] (3) Collapse transformation characteristics: Collapse will change the contour morphology and internal structure of the fracture and cave, and it occurs during both the karst period and the burial period. During the karst period, under the action of gravity, the cave roof and cave wall will form a stress dome or maximum shear zone, which may cause the cave roof to collapse and form brecciated rock at the cave bottom. In addition, the transition section of the fault or the intersection of the fault will also cause the collapse of the periphery of the large cave. The impact of the collapse, after entering the burial period, mechanical compaction begins to appear. This compaction usually causes the overall collapse of the cave, the effective space of the fracture and cave to become smaller, and the internal separation is enhanced.

[0052] On this basis, collapse transformation characterization parameters are established, including karst location, reflection morphology, seismic profile characteristics and wave impedance. The specific descriptions of each parameter are as follows:

[0053] Karst location: When the karst location is in a fault that crosses an underground river or in an area with densely developed faults, the fault cutting is obvious, which can easily lead to the collapse of the periphery of a large cave.

[0054] Reflection form, at T7 4 Below the surface, when the phase axis is concave and the deformation exceeds one phase, the probability of large-scale fracture-cavity body deformation is high, which can be used to determine the collapse location.

[0055] The seismic profile characteristics show that the diffraction wave reflection profile is messy and discontinuous due to the complex fracture-cavity structure inside the collapse of the large fracture-cavity body.

[0056] Wave impedance: Since the interior of the large fracture-cavity collapse is characterized by a complex fracture-cavity structure, the wave impedance profile presents a chaotic and discontinuous feature.

[0057] S2. Based on the results of S1, determine the impact of fracture cutting, filling and collapse on the fracture-cavity system. Take the TK476-T403-TK446CH2 well group as an example. Figure 2-4 As shown, this well group is located in a fracture-cavity system controlled by a northwest-trending fault. Originally, there were only two wells, TK476 and T403, in this system, both of which were in the high water-cut stage. By identifying the compartmentalization within the fractures and cavities, the TK446CH2 well was deployed more densely, achieving high water-free production, reaching 46 tons of oil per day. The specific identification process is as follows:

[0058] Table 1 Identification table of fracture cutting and transformation effect in TK446CH2 well area

[0059] Serial number Main indicators Separation qualitative and semi-quantitative indicators Fracture No. 1 Fracture No. 2 Fracture No. 3 Fracture No. 4 1 Vertical fault distance ＞30m 26m 23m 28m 49m 2 Disconnect layer <![CDATA[T7 6 —T5 0 or T7 4 Insider - T5 0 ]]> <![CDATA[T7 6 —T5 0 ]]> <![CDATA[T7 6 —T5 0 ]]> Weak continuity <![CDATA[T76—T5 0 ]]> 3 Activity Period Continuous activity in the middle and late stages of Haixi Haixi Evening Haixi Evening Haixi mid-late Haixi Evening 4 Fracture type Squeeze or translate Pan extrusion extrusion Pan 5 Fault direction ＞40° 71° 79° 88° 41°

[0060] The karst fracture-cavity system was identified through fault-cutting reconstruction. As shown in Table 1, the faults in this fracture-cavity system formed during the Middle Caledonian period and are late-stage reconstruction faults formed under a compressional setting. The overall longitudinal ductility of the faults is strong and continuous, interrupting the T74-T76 horizons. The faults have similar incision depths to those of the northwest-trending karst-stage faults, with the southern fault throw significantly greater than the northern fault throw. This fracture-cavity system is primarily a continuously active fault from the Middle and Late Hercynian period. Fault stresses are primarily compressional and translational. From a fault perspective, the fractures are primarily near-east-west trending, with a large angle to the fracture-cavity system and significant misalignment of the fracture-cavity system's cutting points. A comparison of comprehensive parameters reveals that all four faults have been significantly reconstructed by fault-cutting reconstruction.

[0061] Table 2 Identification table of filling and transformation effects in TK446CH2 well area

[0062]

[0063]

[0064] The filling and transformation of this karst fracture-cavity system was assessed, as shown in Table 2. Actual drilling revealed that each segment within this fracture-cavity system is fully filled with gray-green mud from the Bachu Formation. Porosity inversion results indicate that localized intervals exist in 1, 2, 3, and 4, 5, indicating porosity inversion results below 5%. Faults are located at the water inlet of the local karst, and morphological dislocations are observed along the plane of the fractures. All 1, 2, 3, and 4, 5, were incised by the Ming River. Therefore, a comprehensive semi-quantitative assessment indicates that this system has undergone significant filling and transformation.

[0065] Table 3. Discrimination table of collapse transformation effect in TK446CH2 well area

[0066]

[0067] Collapse analysis of this karst fracture-cavity system, as shown in Table 3, reveals that faulting occurs throughout the entire fracture-cavity system. While segments ①, ②, and ③ in the north lack significant concavity, segments ④ and ⑤ in the south exhibit more pronounced concavity. Seismic and wave impedance reflection profiles show continuous reflections in segments ①, ②, and ③ in the north, and chaotic reflections in segments ④ and ⑤ in the south. Therefore, a comprehensive, semi-quantitative analysis indicates that the collapse probability of segments ①, ②, and ③ in the north is low, while the southern segments ④ and ⑤ may have a certain degree of collapse.

[0068] S3. Analyze the internal structural pattern of fractures and caves based on karst transformation and determine the type of remaining oil.

[0069] like Figure 5 As shown, this embodiment conducts a separation investigation on the main fractures and caves in the study area based on the characterization parameters described in S1, and divides the patterns with obvious residual reserves into three categories according to production dynamic characteristics, namely separation type, blocking type, and attic oil. Among them, the presence of pressure dissimilarity, the main consideration in the initial stage of production is the original pressure of the reservoir, and the production dynamic characteristics are completely different from those of adjacent wells are judged as separation; the manifestation of the same pressure system, the fluid is not connected, and there may be pressure response or oil increase between water injection and gas injection wells is judged as blocking type; within the same reservoir, there is a clear unified pressure system with adjacent wells, and the performance is relatively similar to the production dynamics, and the water flooding characteristics show a clear correlation with the structural characteristics, which is defined as attic oil type.

[0070] Table 4 Analysis standard table of fracture cutting transformation effect

[0071]

[0072] Semi-quantitative calibration of residual oil patterns was performed at 48 sample points, as shown in Table 4. Eleven of these points exhibited compartmentalization, primarily characterized by fracture cutting and filling; 16 points exhibited containment, primarily characterized by fracture cutting and collapse reformation; and 21 points exhibited attic oil, with no apparent combination of reformation characteristics. Based on this preliminary conclusion, fracture cutting and filling can lead to compartmentalization within the system, while fracture cutting and collapse can lead to containment within the system.

[0073] Based on the S2 results and comprehensive geological analysis, it is determined that Fault No. 4 in the southern part of the fracture-cavity system where TK476-T403 is located is a late-stage reformed fault formed under a compressional setting. Its incision depth is similar to that of the northwest-trending karst-period faults. Formed in the Middle Caledonian period, the fault cuts through an underground river, with a minimum throw of 44 meters and an angle greater than 45 degrees, separating the T74-T76 horizons. Fault incision led to the subsequent continuous influx of Bachu Formation sediments along the fault, primarily forming large-scale separation points at the transverse incision sites of the fault. This results in the overall "fault incision + filling" pattern in the fifth segment, and a "separation-type" residual oil pattern. Therefore, despite the overall high water cut, the TK446CH2 well deployed in the southern part achieved high production.

[0074] In summary, this first example addresses the previous disconnect between geophysical engraving and karst geological analysis, and the high accuracy of fracture-cavity internal structure analysis based solely on filling and collapse. Focusing on the internal structure of paleokarst fractures and caves, this study pioneered a semi-quantitative method for determining the development of fracture-cutting, filling, and collapse-based alterations based on karst alteration. By integrating the impacts of these three types of karst alteration on fractures and caves and comparing the results of karst alteration identification, two comprehensive models were established: one in which fracture cutting and filling can lead to internal separation, and the other in which fracture cutting and collapse can lead to internal blocking. This method further validates and explains the mechanisms of internal separation and blocking within fractures and caves, effectively addressing the issues of insufficient geophysical interpretation precision and inaccurate single-factor analysis, and improving the accuracy of fracture-cavity internal analysis. Ultimately, despite the overall high water content, the deployment achieved high yields.

[0075] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A semi-quantitative identification method of fracture-cavity separation based on karst transformation, characterized by: The steps include: S1. Semi-quantitative characterization of fracture cutting, filling and collapse of fracture-cavity system: Characterization parameters of fault cutting and transformation include fault strike, disconnected layer, active period and fault type; Fill transformation characterization parameters include fill type, slug characteristics, karst element location, and structural location; The collapse transformation characterization parameters include reflection morphology, seismic profile characteristics, and wave impedance; S2. Based on the results of S1, determine the impact of fracture cutting, filling, and collapse on the fracture-cavity system. The criteria are as follows: The fracture-cavity system modified by fault cutting meets the following requirements: the principal stress direction in the area where the fracture-cavity system is located intersects with the fault trend of the fracture-cavity system, the fault was formed in the middle Caledonian to early Hercynian period, the fault was continuously active in the late Hercynian period, and the fault type was compression or translation; The fracture-cavity system to be transformed by filling meets the following requirements: the filling type in the fracture-cavity system is muddy, the fracture-cavity system presents slug-type characteristics, the fault-cutting structure is concentrated at the water inlet of the local karst, and the fracture-cavity system is located at the horizontal cutting part of the Ming River; The fracture-hole system to be reconstructed by the collapse meets the following requirements: The fracture-hole system is in T7 4 The reflection morphology below the horizon shows a concave event axis and a phase deformation of at least one phase. The diffraction wave reflection characteristics in the seismic section are chaotic and discontinuous, and the wave impedance section is chaotic and discontinuous. S3. Based on the results of S2, the fracture-cavity system transformed by fault cutting and filling is determined to be a separated type. The dynamic characteristics of the separated type are an independent pressure system, energy and fluid are not connected, and there is no interference between water injection and gas injection wells. The fracture-cavity system transformed by fault cutting and collapse is determined to be a blocking type. The dynamic characteristics of the blocking type are the same pressure system as the reservoir, fluid is not connected, and there is pressure response or oil increase between water injection and gas injection wells.

2. A semi-quantitative identification method of fracture-cavity separation based on karst transformation according to claim 1, characterized in that: The judgment criteria for the fracture-cavity system in S2, which is modified by fault cutting, in terms of fault strike direction is refined to the angle between the principal stress direction in the area where the fracture-cavity system is located and the fault strike of the fracture-cavity system being greater than 40°.

3. The semi-quantitative identification method of fracture-cavity separation based on karst transformation according to claim 1 is characterized by: The judgment criteria of the fracture-cavity system in S2, which was transformed by the fault cutting, in terms of the fault disconnection layer, are refined to the fault from T7. 4 The horizon continues to be dislocated to T5 0 Stratum.

4. A semi-quantitative identification method of fracture-cavity separation based on karst transformation according to claim 3, characterized in that: The judgment criteria of the fracture-cavity system in S2, which was transformed by the fault cutting, in terms of the fault disconnection layer, are refined to the fault from T7. 6 The horizon continues to be dislocated to T5 0 Stratum.

5. The semi-quantitative identification method of fracture-cavity separation based on karst transformation according to claim 3 is characterized by: The characterization parameters of fault cutting transformation in S1 also include vertical fault throw. The vertical fault throw judgment standard for the fracture-cavity system transformed by fault cutting in S2 is that the vertical fault throw is greater than 30m.

6. The semi-quantitative identification method of fracture-cavity separation based on karst transformation according to claim 1 is characterized by: The criteria for judging the activity period of the fracture-cavity system in S2 that was modified by fault cutting are mainly faults that were continuously active in the middle to late Hercynian period.

7. The semi-quantitative identification method of fracture-cavity separation based on karst transformation according to claim 1 is characterized by: In the judgment criteria for the location of karst elements in the fracture-cavity system transformed by filling in S2, the karst elements at the deformation site of the fracture-cavity system have the characteristics of planar extension, that is, obvious deformation or continuous faulting occurs at the deformation site of the fracture-cavity system.

8. The semi-quantitative identification method of fracture-cavity separation based on karst transformation according to claim 1 is characterized by: In the judgment criteria of the slug-like characteristics of the fracture-cavity system transformed by filling in S2, the slug-like characteristics are determined based on the porosity inversion results.

9. A semi-quantitative identification method of fracture-cavity separation based on karst transformation according to claim 8, characterized in that: The slug-like characteristics of the fracture-cavity system transformed by filling in S2 are judged by the following criteria: the slug-like characteristics are manifested by a low-porosity section with a porosity inversion result lower than 5% and a lateral continuity greater than 10 m.

10. The semi-quantitative identification method of fracture-cavity separation based on karst transformation according to claim 1 is characterized by: The collapse transformation characterization parameters in S1 also include karst location. The judgment criteria for the karst location of the fracture-cavity system affected by collapse in S2 are that the karst location of the fracture-cavity system is located in the fault or the area with dense development of faults that cross the underground river, and the fault cutting is obvious.

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