CN114545498A - Comprehensive depicting method for ancient karst fracture-cave structure - Google Patents
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Abstract
The invention discloses a comprehensive depicting method of an ancient karst slot structure. The method is based on geophysical carving and comprehensive karst geological research, and is used for comprehensively judging the background and conditions of the formation of various karst caves, dividing the karst cave type control area of a well region and determining the development rule and control factors of the karst caves. Different geophysical attributes are adopted to describe each karst fissure cave type; the method is characterized in that a final paleo-karst fracture-cave structure is formed by combination on the basis of classification and identification, the distribution position and the control factor of main halls in a well area are analyzed, the utilization condition of reserves is dynamically analyzed by combining production, the distribution position of the residual reserves is finally determined, and a geological foundation is laid for efficient development of an oil field. The method has the characteristic of multidisciplinary integration, provides the method and the process for describing the paleo-karst fracture-vug for the first time, and has extremely important guiding significance for the development of the oil reservoirs.
Description
Technical Field
The invention belongs to the technical field of oil and gas reservoir exploration and development, relates to karst geological analysis, three-dimensional geological carving, a fracture-cave description technology, fracture-cave communication and separation relation analysis and other technologies, and particularly relates to a comprehensive carving method for an ancient karst fracture-cave structure.
Background
Researchers at home and abroad develop researches in multiple angles such as geophysical, karst geology, geochemistry, karst dynamics and the like aiming at ancient karst fracture and cave description, and determine the main generation period of karst. The Tahe oil field Ordovician system is subjected to I, II and III curtains in the middle of California and early karst in the west of sea in sequence, and finally forms the current slot structure through later-stage burying. The Tahe area can be divided into a middle-upper Ordovician denudation area and a coverage area, the karst effect of the denudation area is mainly in the Haisist period, the karst effect of the coverage area is mainly in the Calitong period, and the karst effects of the two periods are superposed in a transition area with thinner middle-upper Ordovician coverage; therefore, the seam holes in the denudation area are mainly represented by relatively complex seam hole combinations such as a dark river type pipeline, a vertical karst cave for fracture control, a small-scale seam hole body and the like; the fracture-cavity of the covering area is mainly characterized in that a fracture is taken as a core, and a fracture-cavity combination body is formed along the fracture, erosion and expansion, and is single in form; both transition zones exist, but the erosion fracture-cavity body controlled by fracture is taken as the main part, and the types of the fracture-cavities such as the dark river type and the like are reduced. In the longitudinal direction, the underground rivers and pipelines in the denudation area are mainly horizontal runoff, have obvious karst dissolution stopping layers, are relatively stable in the bottom boundary of the fracture and have strong structure control effect; the coverage area is broken, the solution is mainly dissolved and expanded along the longitudinal direction of the fracture, horizontal runoff is locally developed, a unified karst bottom surface is not formed on the whole, and the structure control effect is weak.
At present, the research on karst fissure caverns only stays in macroscopic regularity understanding, the research on influence and control factors of specific fissure cavern bodies is lacked, and the description of the correlation between the inner curtain structure of the fissure cavern and the fissure cavern mainly depends on single geophysical attributes for carving. For example, the amplitude-like attributes are mainly used for three-dimensional space carving of the space distribution characteristics of the large-scale slot-hole body; relevant attributes such as wave impedance inversion and the like are mainly used for positioning the core depth of the fracture-cavity body in the longitudinal direction; comprehensively identifying the distribution characteristics and the filling characteristics of the shale content in the region by GR inversion, porosity inversion and the like; the non-continuity attributes such as coherence, tensor, ant tracking, AFE and the like are mainly used for identifying the fracture of different levels and scales; edge detection, maximum non-similarity, chaos and other non-continuous detection attributes are used for identifying small-scale fracture-hole bodies and the like. The concrete single geophysical carving technology is relatively complete.
For example, chinese patent application CN102681013A discloses a method and an apparatus for establishing a carbonate reservoir space model, the method comprising: acquiring a seismic longitudinal wave transmission signal; correcting, amplitude preserving and pre-stack time migration processing are carried out on the seismic longitudinal wave transmission signals; determining a seismic wave reflection abnormal area of a target layer section according to the processed seismic longitudinal wave transmission signal; determining an approximate position of reservoir development according to the seismic wave reflection abnormal area of the target interval; determining the type and development characteristics of a reservoir near the well of the target interval according to the combined logging information and the logging curve characteristics; determining the type and development characteristics of a far well reservoir of a target interval according to the pressure recovery well testing data, the pressure of the pressure recovery well testing and the characteristics of a pressure reciprocal log curve; and constructing a space model of the reservoir according to the approximate position of the reservoir development, the type and the development characteristics of the reservoir of the near well of the target interval and the type and the development characteristics of the reservoir of the far well of the target interval. The method adopts seismic waves which are single geophysical attributes, and has weak pertinence and low accuracy.
For example, chinese patent application CN102465699A discloses a carbonate reservoir prediction method, which proposes a carbonate reservoir prediction method for calculating the amplitude change rate by testing the seismic reflection wave amplitude of a fracture-cave, and predicting the development scale of the fracture-cave body according to the strength standard and the amplitude change rate. The method comprises the following steps: acquiring the amplitude of seismic reflection waves of a test object; calculating an amplitude change rate according to the amplitude of the reflected wave; and reservoir prediction is carried out on the test object according to the strength standard and the amplitude change rate. The prediction method is applied to a main body area in the early stage of the tower river and a current peripheral area, the amplitude change rate technology is always a key technology for well location deployment, and statistics on well drilling in the tower river area shows that the success rate of predicting the carbonate karst fracture-cave type reservoir stratum by using the seismic amplitude change rate technology reaches over 90 percent. However, the prediction method is single in means and not strong in applicability, and cannot accurately describe different types of seams and holes by adopting different methods.
For another example, chinese patent application CN109425889A discloses a method for depicting an ancient karst underground river, which uses seismic waveform classification analysis technology to finely classify seismic waveforms in the spreading range of the ancient karst underground river, and explains reservoir body characteristics in combination with well points, so as to realize the characterization of reservoir body development characteristics in the curtain of the underground river. The seismic waveform classification analysis method can be completely operated without supervision or provided with wells to participate in operation in the actual seismic data interpretation process, classification is completely carried out based on waveform differences of adjacent seismic traces, calibration of well point interpretation results can be realized, geological interpretation basis is provided for the classification results, and oil field fine development is further guided. However, the method only uses a single geophysical attribute to draw the seam hole, and the applicability and the accuracy of the method need to be improved.
The description of the ancient karst fracture-cave system in the prior art has the following problems:
1) carbonate rock fracture-cave oil is hidden in the aspect of fracture-cave description, no effective research thought can be used for reference at home and abroad at present, modern karst research mainly stays in the stage of surface hydrogeology research, the research on the association relation between the ancient karst cave inner curtain structure and the fracture-cave is only limited in the aspect of macroscopic nature, and a technical method for accurately describing the ancient karst fracture-cave is urgently needed, so that a basis is provided for the accurate development of an oil reservoir.
2) The three-dimensional carving accuracy of the single geophysical attributes is low, the existing attributes are complex, the pertinence of each attribute is different, the analysis results are inconsistent, the multi-solution of each geophysical attribute is strong, the actual and reliable fracture-hole body cannot be accurately reflected, a multi-attribute fused system carving technology is not formed, the effective fracture-hole body cannot be directly carved, and the scale of the fracture-hole body can be judged.
Disclosure of Invention
The invention aims to solve the problems in the prior art, and aims to provide a comprehensive description technology for an ancient karst fracture-cave. The technology changes the phenomenon that the karst geology is disjointed with the fracture-cave carving in advance, so that the karst geology basic analysis is more precise, the geophysical carving is more accurate, and a more reliable basis is provided for oil field development.
In order to achieve the aim, the invention provides a comprehensive carving method of an ancient karst slot structure, which comprises the following steps:
(1) distinguishing types of ancient karst cracks according to comprehensive research results of karst geology, wherein the types of the karst cracks comprise a dark river type, an interrupted control type and a surface layer type;
(2) identifying the type of the underground river karst fissure cavern by using the amplitude seismic attributes, and analyzing the formation mechanism of a large-scale hall cave in the karst fissure cavern and the internal filling, communication and separation characteristics of the karst fissure cavern;
(3) identifying the type of the disconnected and controlled karst fissure cavern by using tensor seismic attributes, and analyzing the formation mechanism of a large-scale hall cave in the karst fissure cavern and the internal filling, communication and separation characteristics of the karst fissure cavern;
(4) identifying the type of the surface layer leaching fracture-cave by utilizing the maximum likelihood attribute, and analyzing the filling, communicating and separating characteristics in the fracture-cave body;
(5) and (4) three karst slot type spaces identified in the steps (1) to (4) are overlapped in a three-dimensional mode to obtain the overall structure of the ancient karst slot.
Preferably, the said karst caves of dark river type in the step (1) above are caves of horizontal runoff feature that are controlled by the underground river-pipeline to develop comprehensively, mainly develop horizontal caves, easy to fill, locally develop water inlets such as water falling caves, etc., develop large-scale caves; the developing area of the underground river type slot cave is characterized in that the amplitude change rate attribute is distributed in a continuous or discontinuous strip shape, the correlation with the coherence or tensor attribute is poor, the pipeline concentrated flow characteristic of the underground river is arranged on the plane, and the section is in a continuous strong reflection characteristic.
Preferably, the fracture-control karst caves in the step (1) are caves mainly based on the vertical direction of development with fractures as cores, the surface layers are separated, the deep development runoff characteristics are partially fractured, and large-scale development is realized; the fracture control type slot hole development area is characterized in that the correlation between the amplitude change rate layer attribute and the coherence and tensor attributes is strong, the plane is in a local point-like and integral linear distribution characteristic, and the section is in a vertical discontinuous strong reflection and disordered reflection characteristic.
Preferably, the surface karst caves in the step (1) are small-scale erosion caves which only develop on the surface layer, the distribution is within 0-20ms of the surface layer in all areas, and all areas are surface control areas.
Preferably, the structure of the dark river karst caves in the step (2) has obvious directionality, the combination of the karst caves and the pipelines is in a curved slug shape on the plane, the ancient karst water mainly takes the concentrated flow of continuous underground pipelines, mainly develops the horizontal runoff characteristic and has a more uniform karst datum plane. The main body of the underground river type karst caves is a horizontally-developed karst cave accompanied with a plurality of vertically-developed water falling caves, the impedance of the developing parts of the underground river and the local water falling caves is lower than that of surrounding rocks, the underground river and the local water falling caves are characterized by low impedance and strong amplitude, the underground river main body is characterized by continuous low impedance and strong amplitude and is in transverse bead-shaped strong reflection or disordered strong reflection, and the water falling caves are locally developed on the upper part of the continuous strong-amplitude underground river and go up to the top surface of a target layer and then go down to the underground river.
Preferably, the amplitude attribute in the step (2) may reflect the wave impedance difference, the height of the main body of the slot hole is the largest, the amplitude attribute reaction is the strongest, and the amplitude attribute reaction is weaker due to the smaller height of the slot hole flank, so the amplitude attribute may better reflect the distribution of the caverns such as the river, the overboard and the like.
Preferably, the common amplitude-class attributes in the step (2) are root mean square, instantaneous energy, absolute amplitude, amplitude gradient, etc.
More preferably, it is said in the above step (2)The taw generally adopts instantaneous energy attribute to identify the type of the underground river slot, and the function formula is as follows:
where f is the original seismic trace sample and g is the Hilbert transform.
Karst water is gathered into the underground river from the ground surface through the water falling cave, the underground river section with the water falling cave developing more intensively has strong karst capability, and large-scale hall caves are easy to develop. Based on the method, the development position of the hall hole can be judged by combining the development characteristics of the water falling hole with the shape of the underground river.
And predicting the filling characteristics of the karst fissure cavern by adopting a argillaceous content inversion technology. Specifically, the openings of the dark river type are filled to different degrees, resulting in the transverse separation of the interior of the dark river. On the basis of underground river slot and cave type identification, filling performance is predicted by adopting a mud content inversion technology, a nonlinear mapping relation between seismic frequency division attributes and logging data is established, mud content is inverted, filling performance is predicted, and a function formula is as follows: k (x, x)j)＝[(x·xj)+1]dWherein K (x, x)j) Is a kernel function, x.xjIs inner product operation, d is polynomial classifier.
Preferably, the fracture-control karst caves in the step (3) are formed by infiltration and corrosion of atmospheric fresh water along the fracture surface, and as the corrosion action is strengthened, a larger cave develops from the initial corrosion seams, and the corrosion seams, the corrosion holes, the caves and the pipelines can develop. The fracture control karst caves mainly develop vertical karst caves, horizontal runoff characteristics are not obvious, locally-developed karst reference surfaces and the caves are mainly communicated by means of fracture, so that shallow connectivity among the caves is poor.
The whole fracture-control karst caves are linearly distributed, the discontinuity is enhanced mainly along a certain fixed direction, and the discontinuity is gradually weakened in the direction transverse to the caves. Judging the trend of the earthquake homophase axis by using the earthquake tensor attribute, and judging the occurrence of the earthquake homophase axis by adopting a potential energy change judging method, thereby effectively identifying the fracture-cavity abnormal body in the broken control range; therefore, the tensor attribute can better carve the fracture control karst slot type, and the tensor attribute is established as follows:
the tensor calculation is not affected by a coordinate system, and can be generally represented by a three-dimensional matrix, the gradient vector of each point is composed of 3 elements, and represents the directions of x, y and t respectively, and at the position point (x, y and t), the three-dimensional gradient vector describing the dip angle and the azimuth angle of the seismic event can be represented as:
in the formula: μ represents three-dimensional seismic data;
to calculate the gradient; the superscript "T" denotes the transpose of the matrix. In order to reduce the noise interference influence in the seismic data, a structure tensor method is adopted to smooth the gradient vector, and the seismic data structure tensor is expressed as the product relation between the gradient vector and the transpose thereof:
the mean gradient structure tensor S is a 3 × 3 semi-positive definite symmetric matrix with eigenvalues greater than or equal to 0, and satisfies the following relation:
the characteristic vector and the characteristic value (lambda) can be conveniently calculated by using a characteristic value decomposition method1,λ2,λ3) And the eigenvector corresponding to the maximum eigenvalue is vertical to the reflection interface and indicates the normal direction of the seismic event.
aλ3+bλ2+cλ+d＝0(ab≠0)
For the curved laminar texture unit, λ 1 ≧ λ 2 ≧ λ 3 ═ 0 is generally satisfied, all eigenvalues are sorted from large to small, and different structural attributes can be constructed by the eigenvalues or the types of the image texture unit can be identified or distinguished according to the relationship of the relative sizes of the above 3 eigenvalues.
The development plane of the fracture-control strong erosion part is extended and large-scale slot body with large longitudinal depth, and the development plane of the weak erosion fracture is distributed in a point-like manner and small-scale hole body with small longitudinal depth. The secondary fracture intersection part, the deeper part of the main trunk fracture undercut and the deeper secondary fracture part of the undercut scale have strong corrosion action, and are easy to develop large-scale hall holes. Based on the method, the development position of the hall hole can be judged by combining the fractured structural characteristics with the carving body.
The fracture control karst caves mainly develop vertical karst caves, and the caves are mainly communicated by means of fracture, so that the direct communication in the caves is poor, and therefore, the communication and transformation effects of the filling effect on the fracture control karst caves are low, and only the local reservoir space is influenced.
Preferably, the superficial karst fissure cavern in the step (4) develops between 0 and 20ms below the top surface of the weathering crust and is a product of shallow karst water cycle corrosion. The plane distribution is obviously controlled by the micro landform of the ancient karst, and is frequently cultivated in the high platform area and the low-angle gentle slope zone. The surface karst caves mainly comprise a caves aggregate below meter level, and the field outcrop is expressed as erosion seams, erosion holes and small-sized caves; macroscopically, the crack system ditch passes through the longitudinal (vertical solution expansion) crack of the surface layer and the transverse (structural crack network). The cracks are mostly formed at the initial stage of exposure and denudation or the later stage of long-term weathering and denudation, the foreign matter filling degree is high, and the effective space ratio per unit volume is low.
The seismic reflection characteristic of the surface layer leaching fracture-cave type is disordered weak reflection, and because part of well zones are influenced on a strong reflection interface on the top surface of a target layer, the maximum likelihood attribute needs to be obtained after a strong axis removing technology is adopted, and the plane distribution characteristic of the maximum likelihood attribute is predicted. The maximum likelihood attribute is to calculate the non-similarity through the similarity coefficient and highlight the difference of the impedance, and the maximum likelihood attribute function formula is as follows: like (x, y, τ) ═ 1-C (x, y, τ)nWherein C (x, y, tau) is a similarity coefficient of an analysis point, the index n enlarges a similarity system, and the larger the value is, the larger the probability of small-scale slot hole development is.
Preferably, in the step (5), the three karst fracture-cavity types are spatially overlapped to form a complete ancient karst fracture-cavity structure, and under different landforms and different structural backgrounds, the ancient karst fracture-cavity structure presents different up-down stacking and plane configuration relations, resulting in different fracture-cavity structure development characteristics:
the ancient karst high-land hillock is formed by combining a surface layer type and a river type in an up-and-down superposed manner, a small-scale slot hole is formed in the surface layer of a slot hole structure, a water falling hole is locally developed, horizontal slots with different levels are developed in the middle and deep parts, a large-scale hall hole is easily developed in the higher part of the structure, and the lower part of the structure is easily filled, so that the connectivity among hillocks is poor;
secondly, the ancient karst area is represented by a combination of a fracture control type and a river type, small seam caves on the surface layer are low in development degree, a horizontal karst cave is developed in a river control area, a vertical karst cave is developed in a water falling cave, a hall cave is developed in a water falling cave concentrated area, and the diameter-reduced part of the local karst cave is easy to fill and is in a slug-shaped characteristic; vertical karst caves are developed in the fault control area and are distributed in a horizontal dotted strip manner, hall caves are developed at the fracture intersection part, the filling degree of the fault control area is low, and the connectivity is represented by shallow layer communication difference deep layer communication;
thirdly, the paleo-karst slow slope area is represented by a combination of a surface layer type, a fracture control type and a river type, a small-scale surface layer slotted cavern body develops at a local high position of the structure, the middle and deep part fractures, and the river comprehensively controls the development of various types of slotted caverns, so that the development law of the middle and deep part slotted caverns is similar to that of a platform area;
and fourthly, the annular concave land in the ancient karst basin area is represented by a configuration combination of a river type and a fracture control type plane, the surface layer slot cave type development degree is low, the surface layer slot cave type is filled with normal sand and mud, and the middle and deep karst cave structure is similar to that of the platform area but is easier to fill, so that the effective space development degree is low.
Compared with the prior art, the invention has the following beneficial effects:
(1) the method comprehensively describes the structure of the paleo-karst fracture-cave by integrating the karst geological theory and the geophysical carving, improves the precision of the description of the carbonate fracture-cave, defines the cause mechanism distribution characteristics of the fracture-cave, establishes comprehensive characterization technical methods of different types of paleo-karst fracture-cave structures, reduces the multi-resolution of the geophysical carving, enhances the applicability of different attribute combination application, determines the space position and the transverse separation characteristic of a main karst reservoir body, and guides the efficient development of the fracture-cave type oil reservoir;
(2) the method is applied to the field of comprehensive description of the ancient karst fissure caverns, adopts different geophysical attributes to carve different karst fissure cavern types, and determines the distribution characteristics of effective karst cavern bodies. The method changes the phenomenon of disjointing of karst geology and fracture cave carving before, initiates a technical method for fusing most seismic attributes by using the karst geology as a guide, can be used for reservoir management of the whole production period of oil fields such as ancient karst fracture cave identification and description, reserve calculation, well location deployment, well pattern planning and the like, and has wider application and popularization prospects.
Drawings
FIGS. 1-3 are schematic views of TK440 well zone, underground river karst caves type partitions: wherein, FIG. 1 is a carving body diagram of a underground river karst slot, FIG. 2 is a filling diagram of sand and mud by inversion prediction of mud content, and FIG. 3 is a type plane diagram of the underground river karst slot;
FIGS. 4-6 are plan views of TK440 well zone, underground river karst caves type: wherein, fig. 4 is a carving body diagram of a subsurface river karst cave, fig. 5 is a filling diagram of sand and argillaceous content inversion prediction, and fig. 6 is a type plane diagram of the subsurface river karst cave;
FIGS. 7-9 are plan views of TK440 well discontinuity control karst caves type: wherein, fig. 7 is a tensor attribute engraver + tensor layer attribute diagram, fig. 8 is a tensor attribute engraver + coherent layer attribute diagram, and fig. 9 is a discontinuity control karst slot type plan diagram;
FIGS. 10-11 are plan views of TK440 well discontinuity control karst caves type: wherein, fig. 10 is a maximum likelihood attribute carving diagram, and fig. 11 is a maximum likelihood attribute karst type + T74 top surface construction diagram;
FIG. 12 is a plan view of a karst fracture hole of a TK440 well region;
FIG. 13 is a sectional view of a TK440 well karst fracture hole.
Detailed Description
The present invention will be further explained with reference to specific examples in order to make the technical means, the technical features, the technical objectives and the effects of the present invention easier to understand, but the following examples are only preferred embodiments of the present invention, and not all embodiments of the present invention. Based on the embodiments in the implementation, other embodiments obtained by those skilled in the art without any creative efforts belong to the protection scope of the present invention.
The experimental methods in the following examples are conventional methods unless otherwise specified, and materials, reagents and the like used in the following examples are commercially available unless otherwise specified.
Examples
The TK440 well region in the four regions of the Tahe has the comprehensive water content of 85 percent, the water channeling among wells is serious, the well control degree is high, and a new well is not deployed in nearly ten years. Later analysis shows that the residual oil is mainly distributed in large-scale halls, the residual reserve in small-scale fracture holes at local parts among wells is low, and the halls are mainly separated by filling, so that the ancient karst fracture hole description work of the well region is carried out.
Comparing the attributes of the carved body of the fracture and the coherence and tensor, analyzing the matching relation between the fracture body and the fracture, and according to the coincidence degree of the planar distribution form and the fracture of the fracture body, the energy bodies in the north and the middle are distributed in a strip shape, the characteristics of the underground river are obvious, the energy bodies in the south are distributed in a punctiform linear mode along the coherence and tensor, so that the karst fracture type of the underground river mainly developing in the north and the middle can be judged, and the karst fracture type of the karst fracture controlling in the south can be judged, as shown in figures 1-3.
In a developing area of a type of a karst cave of the underground river at the middle and north parts, the shape of the underground river cave is carved by adopting instantaneous energy attributes, the whole underground river develops from the west east to the south, the west, and the developing position of the hall cave is judged by combining the developing position of the water cave and the description width of the underground river, the water cave mainly develops in the north and south sections, the plane scale of the underground river is wide, the filling degree is low, the underground river cave in the east and west sections does not develop, the plane scale of the underground river is narrow, the filling degree is high, the probability of judging the north developing hall cave is high, the scale of a reservoir is large, and the plane distribution of the types of the caves is shown in figures 4-6.
In the fracture-control karst fracture-cave type development area, the basic form of fracture is judged according to tensor and coherence attributes, a TK440 well area is located at the tail end of the north part of the northeast-oriented trunk fracture, the size of the fracture of the trunk along the northeast-oriented fracture-cave body is large, a small-scale secondary fracture mainly develops in the west part, a large-scale hall cave develops at the intersection of a plurality of secondary fractures, and the fracture-cave type plane distribution is shown in fig. 7-9.
The TK440 well region adopts maximum likelihood attribute to carve a small-scale seam hole body on the surface layer with 0-20ms, the type of the karst seam hole on the surface layer is controlled by the structure and mainly distributed on the high part of the structure, the karst seam hole is distributed in a sheet shape on the top of a residual hill, and the karst seam hole is distributed in a strip shape on the shaft part of the ridge of the structure, as shown in figures 10-11.
Reservoir body spaces of different karst transfer types are respectively described in a partitioning, layering and seismic attribute dividing mode, the surface layer is mainly of a surface karst slot type, the middle and deep parts are of a plane combination of a underground river karst slot type and a broken control karst slot type, and finally a complete ancient karst slot structure is formed, as shown in figure 12.
Comprehensive analysis of the structure of the ancient karst fissure in the well region shows that large-scale halls are mainly concentrated in the type of underground river fissure in the well region, the scale of a reservoir body is large, the 3 new wells are deployed together through analysis of the utilization condition of the halls, the type of the surface karst fissure in the middle-depth underground river halls is considered, and the utilization degree of the reserve is improved to the greatest extent, as shown in fig. 13.
Wherein, the new well TK495X is produced for 2 years, the accumulated oil is produced to 3.1 ten thousand tons, and 40t is produced daily at present without water; TK4116X well, oil production is carried out every day for 35t, and water production is not carried out; another 1 well is being drilled.
Finally, it should be noted that the above-mentioned contents are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, and that the simple modifications or equivalent substitutions of the technical solutions of the present invention by those of ordinary skill in the art can be made without departing from the spirit and scope of the technical solutions of the present invention.
Claims (10)
1. A comprehensive depicting method of an ancient karst fracture-cave structure is characterized by comprising the following steps:
(1) distinguishing types of ancient karst cracks according to comprehensive research results of karst geology, wherein the types of the karst cracks comprise a dark river type, an interrupted control type and a surface layer type;
(2) identifying the type of the underground river karst fissure cavern by using the amplitude seismic attributes, and analyzing the formation mechanism of a large-scale hall cave in the karst fissure cavern and the internal filling, communication and separation characteristics of the karst fissure cavern;
(3) identifying the type of the disconnected and controlled karst fissure cavern by using tensor seismic attributes, and analyzing the formation mechanism of a large-scale hall cave in the karst fissure cavern and the internal filling, communication and separation characteristics of the karst fissure cavern;
(4) identifying the type of the surface layer leaching fracture-cave by utilizing the maximum likelihood attribute, and analyzing the filling, communicating and separating characteristics in the fracture-cave body;
(5) and (5) three karst fracture hole type spaces identified in the steps (1) to (4) are overlapped in a three-dimensional mode to obtain an integral structure of the ancient karst fracture hole.
2. The method for comprehensively depicting an ancient karst caved structure according to claim 1, wherein the amplitude-like seismic attributes in the step (2) are selected from one or more of root mean square, instantaneous energy, absolute amplitude and amplitude gradient.
3. The comprehensive depiction method of an ancient karst cave structure according to claim 1, wherein when the formation mechanism of a large-scale hall cave in the karst cave is analyzed in the step (2), the development position of the hall cave is judged by combining the development characteristics of a water falling cave and the shape of a river.
4. The comprehensive depiction method of an ancient karst fracture-cave structure, as claimed in claim 1, wherein in step (2), when the characteristics of filling, communication and separation inside the fracture-cave body are judged, a mud content inversion technique is adopted to establish a nonlinear mapping relation between seismic frequency division attributes and logging data, invert mud content and predict filling performance.
5. The method for comprehensively depicting an ancient karst caves structure according to claim 1, wherein in the step (3), when the formation mechanism of a large-scale hall cave in the karst caves is analyzed, the development position of the hall cave is judged by combining the fractured structural characteristics with the carving body.
6. The comprehensive depiction method of an ancient karst fissure-cavern structure according to claim 1, wherein when the characteristics of filling, communication and separation in the karst fissure-cavern body are judged in the step (3), the direct communication in the karst fissure-cavern body is poor in the control-breaking karst fissure-cavern type, so that the communication transformation effect of the filling effect on the control-breaking karst fissure-cavern type is judged to be low, and only the local reservoir space is influenced.
7. The comprehensive depiction method of an ancient karst fracture-cavern structure as claimed in claim 1, wherein in the step (4), when the characteristics of filling, communication and separation in the fracture-cavern body are judged, the filling degree of foreign matters in the surface leaching fracture-cavern type is high, and the effective space ratio per unit volume can be judged to be low.
8. The method for comprehensively depicting an ancient karst caves structure according to claim 1, wherein the space in step (5) is three-dimensionally stacked in a top-bottom stacking combination of a surface layer type and a river type, and the whole structure of the ancient karst caves is an ancient karst highland dune.
9. The method for comprehensively depicting an ancient karst caves structure according to claim 1, wherein the space in the step (5) is three-dimensionally stacked into a combination of an interrupted control type and a river type stacking, and the whole structure of the ancient karst caves is an ancient karst platform.
10. The method for comprehensively depicting an ancient karst caves structure according to claim 1, wherein the space in the step (5) is three-dimensionally superposed into a combination of a surface layer type, a breaking control type and a river type, and the whole structure of the ancient karst caves is an ancient karst gradual slope region; the space is three-dimensionally superposed into a plane configuration combination of a dark river type and a broken control type, and the whole structure corresponding to the paleo-karst fracture cavern is an annular concave land of a paleo-karst basin area.
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