Method for interpreting carbonate rock karst fracture-cavity body structure by using ground penetrating radar data

Abstract

The invention discloses a method for interpreting a carbonate rock karst fracture-cave body structure by using ground penetrating radar data, which comprises the following steps of: surveying a similar outcrop on site, and acquiring a favorable acquisition area of the ground penetrating radar data; designing a ground penetrating radar survey line deployment and acquisition mode based on the favorable data acquisition area of the ground penetrating radar; processing the carbonate rock karst fracture-cave body data detected by the ground penetrating radar; establishing a ground penetrating radar interpretation standard based on an unmanned aerial vehicle scanning image; and performing three-dimensional interpretation on the ground penetrating radar data of the similar outcrops of the carbonate rock karst fracture-cavity body based on the ground penetrating radar interpretation standard. Therefore, the method can be widely applied to three-dimensional representation of the outcrop area carbonate rock karst fracture-cavity body structure, and a similar outcrop three-dimensional geological mode is provided for fine description of a deep buried hill oil and gas reservoir karst fracture-cavity type reservoir.

Description

Technical Field

[0001] The invention relates to a method for interpreting carbonate rock karst fracture-cavern structure using ground penetrating radar data, and relates to the technical field of oil and gas exploration and development. Background Art

[0002] Karst fracture-cave carbonate buried-hill oil and gas reservoirs are an important type of oil and gas reservoirs discovered recently. In many domestic oil and gas basins such as the Bohai Bay Basin and the Tarim Basin, karst fracture-cave buried-hill oil and gas reservoirs are widely developed, with great potential for oil and gas exploration and development. This type of reservoir forms a fault zone under the action of tectonic stress, undergoes multiple periods of atmospheric freshwater karstification, and is superimposed on deep hydrothermal dissolution and transformation to form a karst fracture-cave reservoir matrix with an extremely complex structure. It is difficult to accurately obtain reservoir structural characteristics with the help of three-dimensional seismic data for deep exploration. There are many geological outcrops of carbonate karst fracture-cave bodies controlled by NW-SE strike-slip faults on the western edge of the Tarim Basin. We selected similar outcrops with obvious fault-cave characteristics in the Xinneng Stone Field, mainly using ground penetrating radar, and combined with multi-source information to interpret the three-dimensional structure of karst fracture-cave bodies, which has guiding significance for seismic identification of fracture-cave bodies in carbonate rock areas and oil and gas exploration and development.

[0003] Ground penetrating radar is an important means of detecting the three-dimensional structure of similar outcrops in carbonate karst fractures and caves. Compared with collecting surface image information, it can obtain the internal structure information of the outcrop, thereby establishing the three-dimensional structure of the fractures and caves of similar outcrops. Ground penetrating radar is based on the reflection or diffraction characteristics formed by the difference in propagation and absorption rates in different media. The electromagnetic wave reflection information recorded by the ground penetrating radar antenna obtains the electromagnetic wave impedance difference characteristics of the detected object. The carbonate karst fracture-cave bodies are mainly composed of faults, cracks and dissolution holes. The surface cracks formed by strike-slip faults are steep and nearly vertical, and the electromagnetic wave signals of ground penetrating radar can hardly be reflected. The rock physical properties of the surrounding rocks of carbonate formations are stable, and the formation wave impedance is large. The fracture-cave bodies composed of faults, cracks and caves form a large wave impedance difference with the surrounding rocks, resulting in a strong diffraction phenomenon. After the migration converges, the electromagnetic wave reflection characteristics of the fracture-cave bodies are manifested as continuous strong amplitude characteristics in the longitudinal direction of the phase axis. This strong amplitude is an important basis for identifying and interpreting carbonate karst fracture-cave bodies, thereby establishing a three-dimensional geological model of similar outcrop karst fracture-cave bodies.

[0004] In the process of using 3D seismic data to identify deep karst fracture-cave carbonate reservoirs, the existing technology draws on the geological understanding and conceptual model based on the field exploration of outcrop profiles in Yijianfang and Shipianchang areas in the Tarim Basin, but does not use ground penetrating radar analysis to establish a similar outcrop 3D geological model suitable for 3D seismic interpretation in the study area. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, in response to the above problems, the present invention provides a method for interpreting carbonate karst fracture-cave structures using ground-penetrating radar data. On the basis of fine processing of ground-penetrating radar data, the method of calibrating radar profiles by scanning images of unmanned aerial vehicles is used to establish interpretation standards for the components of carbonate karst fracture-cave bodies. By fine positioning of multiple two-dimensional radar profiles, the three-dimensional data body construction and geological interpretation of the fracture-cave structure of the two-dimensional radar profiles are realized, and finally a method for interpreting carbonate karst fracture-cave structures using ground-penetrating radar data is formed, which provides accurate interpretation results for solving the three-dimensional characterization of carbonate karst fracture-cave structures in similar outcrop areas, and provides a prototype geological model guidance for the seismic fine characterization of karst fracture-cave structures in carbonate buried-hill oil and gas reservoirs.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: The present invention provides a method for interpreting carbonate karst fracture-cavity structure using ground penetrating radar data, comprising: Conduct field surveys of similar outcrops to obtain favorable areas for collecting ground penetrating radar data; Design the GPR survey line deployment and collection method based on the favorable GPR data collection area; Process the carbonate karst fracture-cavity data detected by ground penetrating radar; Establishing ground penetrating radar interpretation standards based on drone scanning images; Based on the ground penetrating radar interpretation standard, the ground penetrating radar data of similar outcrops in carbonate karst fractures and caves were interpreted in three dimensions.

[0007] In a possible embodiment, similar outcrops are surveyed on the spot to obtain favorable areas for collecting ground penetrating radar data, including: the ground penetrating radar needs to move forward relatively stably during actual operation to obtain the best detection results, and the target to be detected must have a relatively flat surface condition. At the same time, the target geological body is identified based on the characteristics of radar wave emission and diffraction waves, and it is necessary to establish an interpretation standard for radar data, requiring the selection of outcrops with clear geological phenomena as standard outcrop profiles.

[0008] In a possible embodiment, based on the favorable collection area of ​​ground penetrating radar data, the ground penetrating radar survey line deployment and collection method are designed, including: Design survey line deployment method for standard outcrop profile; Design similar outcrop three-dimensional interpretation and two-dimensional survey line deployment methods for data collection.

[0009] In a possible embodiment, the survey line deployment method of the standard outcrop profile is designed as follows: One side of the standard outcrop section of the stone field is high and steep, with many visible faults, cracks and caves. A two-dimensional survey line is deployed at the safest distance from the high and steep section to achieve three-dimensional detection of faults and caves.

[0010] In a possible embodiment, a two-dimensional survey line deployment method similar to the three-dimensional interpretation of outcrops is designed for data collection, including: adopting a horizontal and vertical survey line deployment method for the target geological body, deploying two horizontal survey lines perpendicular to the fault trend, and deploying four vertical survey lines approximately perpendicular to the horizontal survey lines to achieve three-dimensional detection of the target geological body.

[0011] In a possible embodiment, the carbonate karst fracture-cave data detected by ground penetrating radar are processed, including: Regularization of radar profiles according to acquisition parameters: Regularization of radar profiles acquired by ground penetrating radar includes two parts: horizontal distance normalization and surface elevation correction. Horizontal distance normalization is used to ensure the accuracy of the horizontal position of the detected target; surface elevation correction is used to adjust the surface elevation of the detected geological body and remove the error caused by ground undulation on the vertical position of the geological body; GPR data are processed by background noise removal, digital filtering, offset relocation, gain compensation or deconvolution to obtain high-resolution profile data; Target processing of the response characteristics of carbonate karst fractures and caves: The Kirchhoff migration method is used to perform migration and relocation processing on the SGY gather data collected by the ground penetrating radar, making the target response characteristics on the radar profile clearer and reducing the multiple solutions of the interpretation; Pseudo-seismic data processing is used to improve the resolution of radar profiles and assist in the interpretation of geological targets.

[0012] In one possible embodiment, a ground penetrating radar interpretation standard is established based on drone scanning images, including: Standard interpretation of drone scanned images; Comparative interpretation of ground penetrating radar profiles; Based on the standard interpretation of UAV scanning images and the comparative interpretation of GPR sections, the GPR interpretation standard for fracture-cave structures in similar outcrop areas is established.

[0013] In one possible embodiment, based on the standard interpretation of UAV scanning images and the comparative interpretation of GPR sections, the GPR interpretation standard for fracture-cave structures in similar outcrop areas is established, specifically: The fault occurrence and position observed in the UAV scanning image can be seen as a continuous strong amplitude feature in the longitudinal direction of the event axis at the corresponding position of the radar profile. This feature is defined as the response feature of the fault. Field surveys also revealed unfilled caves at the intersection of the faults at the bottom of the mountain. The radar profile bottom signal was weak, but the local amplitude anomaly characteristics could still be seen from the radar profile, which was interpreted as a cave. Based on the above interpretation, the interpretation standard of geological body in GPR profile is established.

[0014] In a possible embodiment, the specific process of performing three-dimensional stereoscopic interpretation of ground penetrating radar data of similar outcrops of carbonate karst fracture-cavity bodies based on the ground penetrating radar interpretation standard is as follows: The relative coordinate system of the ground penetrating radar profile is standardized and interpreted in three-dimensional stereoscopic form in the seismic interpretation software. According to the interpretation standard of the established geological body, the spatial distribution of faults, cracks and caves is interpreted to achieve three-dimensional expression of the fracture-cavity structure. Establish the structural model of carbonate karst fracture-cavity body based on the stereo interpretation results; The three-dimensional structural model is used to analyze the reservoir structure of deep karst fracture-cave carbonate buried-hill oil and gas reservoirs.

[0015] In a possible embodiment, a carbonate rock karst fracture-cave structure model is established based on the stereo interpretation results, including: Carry out interpretation of fault, crack and karst hole development zones in multiple radar profiles respectively; Based on the interpretation results of multiple two-dimensional profiles, the three-dimensional spatial layout of faults, cracks and caves is extracted, and the positional relationship between the three is analyzed, including the relationship between fault and crack density, the relationship between fault combination and cave size, etc. These relationships are used to guide the establishment of a three-dimensional structural model of carbonate karst fracture-caves.

[0016] The present invention adopts the above technical solution, and has the following characteristics: 1. Based on the exploration of similar outcrops of carbonate karst fracture-cave reservoirs, the present invention combines ground surveying and mapping methods with underground detection methods, and calibrates the ground-penetrating radar detection profile by scanning the outcrops with unmanned aerial vehicles, thus realizing the characterization of carbonate karst fracture-cave bodies in outcrop areas with multi-source information coordination and ground-underground integration, providing a new method for the interpretation of karst fracture-cave bodies in the field.

[0017] 2. The present invention breaks through the limitations of traditional outcrop two-dimensional geological exploration, converts multiple two-dimensional geological radar profile signals into pseudo-seismic data, applies them to commercial seismic interpretation software, constructs a three-dimensional data body of two-dimensional ground penetrating radar profiles, and performs three-dimensional interpretation of fracture-cavity structures, effectively improving the accuracy and reliability of karst fracture-cavity structure characterization, and providing a new method and new idea for the construction of three-dimensional geological models of karst fracture-cavity structures.

[0018] In summary, the present invention can be widely used in the three-dimensional characterization of the karst fracture-cave structure of carbonate rocks in outcrop areas, and provide a similar three-dimensional outcrop geological model for the detailed description of karst fracture-cave reservoirs in deep buried hill oil and gas reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Throughout the accompanying drawings, the same reference numerals are used to represent the same components. In the accompanying drawings: Figure 1 A schematic diagram of a method for interpreting carbonate rock karst fracture-cavity structure using ground penetrating radar data and its production application in an embodiment of the present invention; Figure 2 The theoretical model of detecting similar outcrops of karst fracture cave bodies by the detection radar of the embodiment of the present invention; Figure 3 The interpretation standard established based on the comparative interpretation of similar outcrop digital images and ground penetrating radar in the embodiment of the present invention, wherein (a) is the outcrop profile and interpretation corresponding to the radar survey line, (b) is the field environment and deployment position of the radar survey line, (c) is the ground penetrating radar profile and interpretation results, and (d) is the karst cave at the intersection of the outcrop fault; Figure 4 The three-dimensional interpretation and stereoscopic display of the two-dimensional radar survey line of the embodiment of the present invention, wherein (a) is the digital image of the GPR detection area and the fracture and cave characteristics, (b) is the digital image of the GPR detection area and the survey line layout, and (c) is the three-dimensional display and interpretation result of the GPR detection profile; Figure 5 The embodiment of the present invention implements radar profile interpretation in commercial interpretation software based on interpretation standards; Figure 6 The present invention adopts multiple processing methods to carry out target processing on the ground penetrating radar detection profile at various stages. The comparison diagram shows that (a) is the original radar profile; (b) is the radar profile after background noise removal; (c) is the radar profile after digital filtering, which controls the effective signal within a certain frequency band range and highlights the target response; (d) is the radar profile after offset, which realizes the offset return and diffraction wave convergence of the non-horizontal geological body; (e) is the radar profile after gain compensation, which realizes the consistency of the upper and lower signal capabilities; (f) is the radar profile after deconvolution, which broadens the frequency band and improves the vertical resolution through wavelet compression; (g) is the radar profile with dominant frequency band, which realizes the information interference outside the target geological body; (h) is the radar profile after structural guidance filtering, which realizes the reduction of the messy noise of the processed profile and makes the energy abnormal points (such as fault zone response) clearer.

[0020] Figure 7 The present invention is an embodiment of the present invention. The relative range of the outcrop profile ground penetrating radar survey line deployment is established and the three-dimensional display of the interpretation results is shown, wherein (a) is the satellite image shadow penetrating radar survey line deployment plan and relative coordinates, (b) is the three-dimensional interpretation plan of the ground penetrating radar data based on the relative coordinates, and (c) is the fault and layer interpretation results based on the three-dimensional space.

[0021] Figure 8 This is a three-dimensional model of a carbonate karst fracture-cave body established based on the ground penetrating radar interpretation result according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0023] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0024] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside", "outside", "inner side", "outer side", "below", "above", etc. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0025] Since the prior art does not use ground penetrating radar to analyze and establish a three-dimensional geological model of similar outcrops suitable for three-dimensional seismic interpretation in the study area, the present invention provides a method for interpreting carbonate karst fracture-cave structure using ground penetrating radar data, including: based on the exploration of similar outcrops of carbonate karst fracture-cave reservoirs, fully considering all aspects involved in ground penetrating radar interpretation of similar outcrops of carbonate karst fracture-cave bodies, and using industrial means such as drone scanning, ground penetrating radar detection and commercial software interpretation, from similar outcrop selection, radar survey line deployment, data processing, standard profile establishment, three-dimensional interpretation data regularization, two-dimensional radar profile interpretation and three-dimensional interpretation, etc., to achieve accurate three-dimensional interpretation of fracture-cave structure in an all-round and multi-information manner, thereby providing support for further realizing the detailed description of deep karst fracture-cave carbonate buried-hill oil and gas reservoirs.

[0026] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0027] With the increasing requirements for the fine characterization of the reservoir structure in the fault zone, the three-dimensional geological model of the karst fracture-cave structure is constructed by optimizing the processing of similar outcrop ground-penetrating radar data and establishing a three-dimensional interpretation method, which provides a more reliable interpretation scheme for the fine characterization of the karst fracture-cave reservoir structure in deep carbonate buried-hill oil and gas reservoirs. The outcrop surface images obtained by on-site photography and drone scanning during field surveys are the most direct evidence of the reliability of ground-penetrating radar interpretation. The relationship established between the two provides a standard for the ground-penetrating radar interpretation of carbonate karst fracture-cave outcrops. The positioning information in the acquisition process is an important parameter for the three-dimensional interpretation of the two-dimensional ground-penetrating radar profile. The regularization of sgy data by establishing a standard coordinate system for the survey line is the basis for the commercial seismic interpretation software to carry out three-dimensional ground-penetrating radar interpretation.

[0028] Based on the above concept, Figure 1 As shown, the method for interpreting carbonate karst fracture-cave structure using ground penetrating radar data provided in this embodiment includes: S1. Conduct field surveys of similar outcrops to obtain favorable areas for collecting ground penetrating radar data.

[0029] In this embodiment, since the characteristics of the fracture-cave bodies developed in the outcrop area on the northwest edge of the Tarim Basin are highly consistent with the structural characteristics of the karst fracture-cave reservoir formed near deep faults, the present invention can provide a prototype geological model for a detailed description of the deep karst fracture-cave reservoir structure through field surveys of similar outcrops. This is taken as an example and is not limited to this.

[0030] like Figure 2 As shown in the figure, the ground penetrating radar needs to move forward relatively stably in actual operation to obtain the best detection results. This requires that the detected target has a relatively flat surface condition. At the same time, in order to identify the target geological body based on the characteristics of radar wave emission and diffraction waves, it is necessary to establish the interpretation standard of radar data, which also requires the selection of outcrops with clear geological phenomena as standard outcrop profiles.

[0031] Furthermore, if Figure 3 As shown, this embodiment selects the outcrop of the fracture surface of the Xinneng Stone Field as the standard outcrop. The section on one side of the outcrop is high and steep, with many faults, cracks and caves developed. Although the top of the section is slightly undulating, the surface is regular. The detection environment of the ground penetrating radar instrument is good, and it is suitable as a standard outcrop section. It can realize comparative analysis of actual structural characteristics and radar response characteristics and establish interpretation standards.

[0032] Furthermore, if Figure 4 As shown in the figure, a carbonate rock outcrop of room-shaped fracture cave was selected as the research object. Since the detection area is located in the mountainous area on the northwest edge of the Tarim Basin, the surface structure is complex, and the mountain has formed irregular peaks due to weathering and erosion. It is difficult to deploy ground penetrating radar in most areas. It is necessary to deploy multiple two-dimensional survey lines at a position on the outcrop where the surface is relatively horizontal and the detection instrument can be moved to realize three-dimensional data collection of similar outcrops.

[0033] S2. Select the ground penetrating radar model.

[0034] In this embodiment, since the detection depth of the ground penetrating radar is related to the signal transmission frequency of the instrument, the higher the signal frequency, the smaller the detection depth. For the analysis of the standard profile and the target geological body, Figure 3 As shown, when the target geological body is about 10m away, according to the detection range of the ground penetrating radar, a 100MHz instrument can be selected for detection. This is an example and is not limited to this.

[0035] S3. Design the GPR survey line deployment and collection method.

[0036] In this embodiment, a two-dimensional survey line is deployed at a safe distance closest to the vertical profile for the standard profile to achieve three-dimensional detection of the total faults and karst caves on the vertical surface, including: S3.1. Design the survey line deployment method for the standard outcrop profile.

[0037] In this embodiment, Figure 3 As shown, one side of the standard outcrop section of the stone flake field has a high and steep section with many visible faults, cracks and caves. In order to obtain the closest radar response characteristics of these geological bodies, a two-dimensional survey line is deployed at the safest distance closest to the high and steep section to achieve three-dimensional detection of faults and caves in order to establish interpretation standards.

[0038] S3.2. Design a similar outcrop 3D interpretation and 2D survey line deployment method for data collection.

[0039] In this embodiment, Figure 4 As shown in Figure 1, the horizontal and vertical survey lines are deployed for the target geological body, and two horizontal survey lines are deployed perpendicular to the fault direction, such as Figure 5 As shown, four longitudinal survey lines are deployed approximately perpendicular to the horizontal survey lines to achieve three-dimensional detection of the target geological body.

[0040] S4. High-resolution processing of carbonate karst fracture-cave detection data.

[0041] In this embodiment, the electromagnetic waves generated by the ground penetrating radar and the seismic wave propagation characteristics used in earthquakes are very similar. Similarly, there are great similarities between the radar data profile and the seismic profile. In terms of data processing methods, the two are also very similar. This embodiment integrates the superior algorithms of the two in data processing and establishes a method that meets the response characteristics of the prominent carbonate rock karst fracture cave body for processing, including: S4.1. Regularize the radar profile according to the acquisition parameters.

[0042] In this embodiment, the regularization processing of the radar profile collected by the ground penetrating radar mainly includes two parts: horizontal distance normalization and surface elevation correction.

[0043] Furthermore, the main purpose of horizontal distance normalization is to ensure the accuracy of the horizontal position of the detection target. When collecting data in the field, such as Figure 2 As shown, you can choose to make marks directly on site, such as making a mark every meter, to help determine the location of the marked track; if some marks are not made on site in time and the acquisition instrument moves evenly, you can also use software to edit the data to add marks.

[0044] Furthermore, the purpose of surface elevation correction is to adjust the surface elevation of the detected geological body and remove the error caused by ground undulation on the vertical position of the geological body. The present invention uses a three-dimensional digital image established by drone scanning to obtain the surface elevation parameters of the outcrop, and adopts a method of gradually supplementing the single-channel sampling points of the radar profile to make the profile show the true position of the underground geology, and finally realize that the radar profile can reflect the accurate position of the detected target in the longitudinal and transverse directions.

[0045] S4.2. Processing ground penetrating radar data.

[0046] In this embodiment, noise is inevitable during the signal acquisition process. Its interference with the effective signal masks the true characteristics of the geological phenomenon. At the same time, low-frequency noise reduces the profile resolution, which is not conducive to the resolution of details. Figure 6As shown in (a)-(f), a series of methods such as background noise removal, digital filtering, offset relocation, gain compensation and deconvolution are used to complete a systematic processing flow, thereby obtaining high-resolution profile data to assist geological interpretation. This method can highlight the effective signals of carbonate karst fractures and caves and achieve high-resolution processing of the target geological body.

[0047] S4.3. Target processing of response characteristics of carbonate karst fractures and caves.

[0048] In this embodiment, the electromagnetic wave impedance of the rock in the fault-crack-hole combination area is significantly different from the wave impedance of the surrounding rock. The wavelength of the electromagnetic wave with a main frequency of 100 MHz in the limestone with a relative dielectric constant of 6 to 8 is about 1 m to 1.5 m, and the width of the detected fault zone varies from about 0.05 m to 1 m, which will cause a large number of diffraction phenomena. The Kirchhoff migration method is used to perform migration and relocation processing on the SGY gather data collected by the ground penetrating radar. As a result, the diffraction phenomenon near the response of the fault zone on the profile is eliminated, and the target response characteristics of the fault-hole combination on the radar profile are clearer, reducing the ambiguity of the interpretation.

[0049] S4.4. Use pseudo-seismic data processing to improve radar profile resolution and assist in interpreting geological targets.

[0050] In this embodiment, Figure 6 (g) and Figure 6 As shown in (h), in view of the diffraction characteristics of high-steep cracks and fracture-caves, a method combining conventional ground penetrating radar data processing with pseudo-seismic data processing is established, and the main frequency 100MHz electromagnetic wave is equivalent to 30Hz seismic data. Multi-wavelet transform is carried out to optimize the data frequency band and anisotropic diffusion edge-preserving filtering is carried out to improve the target resolution of carbonate karst fractures and caves.

[0051] S5. Establishment of interpretation standards for ground penetrating radar based on UAV scanning images.

[0052] In this embodiment, Figure 3 As shown in the figure, the vertical digital images collected by UAV on the standard outcrop profile of the stone flake field and the measurement results of fractures and caves obtained by field exploration are used to calibrate the response characteristics of the target processing results of the standard outcrop profile of the stone flake field, and establish the interpretation standards for geological bodies such as faults and caves in the ground penetrating radar profile, including: S5.1, Interpretation of drone scanning image standards; In this embodiment, Figure 3 As shown, the profile fracture features on one side of the small mountain next to the Shipianchang Fault are clear. 23 faults were interpreted through the digital images obtained by drone scanning. In order to correspond to them, a ground penetrating radar survey line was deployed on the top of the mountain near the profile.

[0053] S5.2, comparative interpretation of ground penetrating radar profiles; In this embodiment, Figure 3 As shown in the figure, the processed radar profile was interpreted, and the response characteristics of the radar processed profile were compared and analyzed with the image interpretation results. It was found that 21 of the 23 faults were consistent in their strike and position. Although the strike of the other two faults was inconsistent, they also had response characteristics on the geological radar profile, and the consistency between the two was more than 90%.

[0054] S5.3. Establish ground penetrating radar interpretation standards for fracture-cavity structures in similar outcrop areas.

[0055] In this embodiment, Figure 3 As shown in the figure, according to the position parameters of faults, cracks and caves obtained from digital images and field survey images, the corresponding calibrated ground penetrating radar target processing profiles are used. For example, the fault occurrence and position observed in the drone scanning image, the longitudinal continuous strong amplitude feature of the event axis can be seen at the corresponding position of the radar profile, and this feature is defined as the response feature of the fault; the field survey also found that there are unfilled caves at the intersection of the faults at the bottom of the mountain, and the signal at the bottom of the radar profile is weak, but the local amplitude abnormality feature can still be seen from the radar profile, which is interpreted as a cave. Based on this, the interpretation standard of geological bodies such as faults and caves in ground penetrating radar profiles is established.

[0056] S6. Three-dimensional interpretation of ground penetrating radar data of similar outcrops of carbonate karst fractures and caves.

[0057] In this embodiment, Figure 7 As shown, by collecting fixed-point marking information (see S4.1), and by editing the sgy trace header collected by the ground penetrating radar, accurate coordinate information is given to each data, so that multiple two-dimensional survey lines can be accurately positioned in three-dimensional space, and three-dimensional stereoscopic display is completed using commercial software. On this basis, according to the established interpretation standards, the spatial distribution of faults, cracks and caves is interpreted to achieve a three-dimensional expression of the fracture-cavity structure. Based on the three-dimensional interpretation results, a carbonate karst fracture-cavity structure model is established, and the three-dimensional structure model is used for the structural analysis of deep carbonate karst fracture-cavity reservoirs, including: S6.1. Standardize the relative coordinate system of the GPR profile and implement three-dimensional interpretation in the seismic interpretation software; In this embodiment, the ground penetrating radar profile after standardization is converted into sgy data through the ground penetrating radar professional processing software, such as Figure 7As shown in the figure, by combining the coordinate information of the calibrated points in the UAV scanning image and the acquisition process, the geographic information coordinates can be directly assigned to each data detected by the ground penetrating radar, and a relative coordinate system can also be established to achieve positioning by track. Under the premise of ensuring the accuracy of the relative coordinates of each track in the ground penetrating radar detection results, the radar profile is finally imported into the commercial software for seismic data interpretation, and the three-dimensional interpretation of fractures, cracks and caves in carbonate karst fractures and caves is realized according to the interpretation standards obtained above.

[0058] S6.2. Establish the structural model of carbonate karst fracture-cavern based on the stereo interpretation results; In this embodiment, Figure 3 As shown in the figure, the longitudinal continuous strong amplitude characteristics of the phase axis are interpreted as faults, and the local irregular circular or semicircular strong amplitude anomaly characteristics seen in the ground penetrating radar profile are interpreted as caves. Interpretations of the development areas of faults, cracks and karst holes in multiple radar profiles are carried out respectively. Based on the interpretation results of multiple two-dimensional profiles, the three-dimensional spatial layout of faults, cracks and caves is extracted, and the positional relationship between the three is analyzed, such as the relationship between fault and crack density, the relationship between fault combination and cave size, etc. These relationships are used to guide the establishment of a three-dimensional structural model of carbonate karst fracture-caves.

[0059] S6.3. The three-dimensional structural model is used for reservoir structure analysis of deep karst fracture-cave carbonate buried-hill oil and gas reservoirs.

[0060] In this embodiment, based on the three-dimensional interpretation results, the spatial stereoscopic characteristics of the geological body are analyzed. It can be seen that the main faults in similar outcrop areas are still developed in a nearly east-west direction, and only locally there are faults developed in a nearly north-south direction. The development locations of the filling holes are also mainly concentrated in the fracture development areas, and generally develop along the fault direction. On this basis, a three-dimensional development model of carbonate karst fracture-cavity bodies corresponding to similar outcrops is established. This method can be extended to multiple similar outcrops to establish fracture-cavity body models with different structures, and it can be used to guide the interpretation of reservoir structural characteristics of karst fracture-cavity type carbonate buried-hill oil and gas reservoirs to reduce the ambiguity of the interpretation results.

[0061] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In the description of this specification, the description of reference terms "a preferred embodiment", "further", "specifically", "in the present embodiment", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of this specification. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples without contradiction.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for interpreting carbonate rock karst fracture-cavity structure using ground penetrating radar data, characterized in that: include: Conduct field surveys of similar outcrops to obtain favorable areas for collecting ground penetrating radar data; Design the GPR survey line deployment and collection method based on the favorable GPR data collection area; Process the carbonate karst fracture-cavity data detected by ground penetrating radar; Establishing ground penetrating radar interpretation standards based on drone scanning images; Based on the ground penetrating radar interpretation standard, the ground penetrating radar data of similar outcrops in carbonate karst fractures and caves were interpreted in three dimensions.

2. The method for interpreting carbonate karst fracture-cavity structure using ground penetrating radar data according to claim 1, characterized in that: Field surveys of similar outcrops are conducted to obtain favorable areas for collecting ground-penetrating radar data, including: the ground-penetrating radar needs to move forward relatively stably during actual operation to obtain the best detection results, and the target to be detected must have a relatively flat surface condition. At the same time, the target geological body is identified based on the characteristics of radar wave emission and diffraction waves. It is necessary to establish radar data interpretation standards, and it is required to select outcrops with clear geological phenomena as standard outcrop profiles.

3. The method for interpreting carbonate karst fracture-cavity structure using ground penetrating radar data according to claim 1, characterized in that: Based on the favorable collection area of ​​GPR data, the GPR survey line deployment and collection method are designed, that is, for the standard profile, a two-dimensional survey line is deployed at the safest distance from the vertical profile to achieve three-dimensional detection of the total faults and caves on the vertical surface, including: Design survey line deployment method for standard outcrop profile; Design similar outcrop three-dimensional interpretation and two-dimensional survey line deployment methods for data collection.

4. The method for interpreting carbonate karst fracture-cavity structure using ground penetrating radar data according to claim 3 is characterized in that: Design the survey line deployment method of the standard outcrop profile, specifically: One side of the standard outcrop section of the stone field is high and steep, with many visible faults, cracks and caves. A two-dimensional survey line is deployed at the safest distance from the high and steep section to achieve three-dimensional detection of faults and caves.

5. The method for interpreting carbonate karst fracture-cavity structure using ground penetrating radar data according to claim 4, characterized in that: Design a two-dimensional survey line deployment method for three-dimensional interpretation of similar outcrops to collect data, including: adopting horizontal and vertical survey line deployment methods for the target geological body, deploying two horizontal survey lines perpendicular to the fault trend, and deploying four vertical survey lines approximately perpendicular to the horizontal survey lines to achieve three-dimensional detection of the target geological body.

6. The method for interpreting carbonate karst fracture-cavity structure using ground penetrating radar data according to claim 1, characterized in that: The carbonate karst fracture-cave data detected by ground penetrating radar are processed, including: The radar profile is processed according to the acquisition parameters, including horizontal distance normalization and surface elevation correction. Horizontal distance normalization is used to ensure the accuracy of the horizontal position of the detected target; surface elevation correction is used to adjust the surface elevation of the detected geological body and remove the error caused by ground undulation on the vertical position of the geological body; Processing the GPR data using background noise removal, digital filtering, offset relocation, gain compensation and / or deconvolution to obtain high-resolution profile data; Target processing of the response characteristics of carbonate karst fractures and caves: The Kirchhoff migration method is used to perform migration and relocation processing on the SGY gather data collected by the ground penetrating radar, making the target response characteristics on the radar profile clearer and reducing the multiple solutions of the interpretation; Pseudo-seismic data processing is used to improve the resolution of radar profiles and assist in the interpretation of geological targets.

7. The method for interpreting carbonate karst fracture-cavity structure using ground penetrating radar data according to claim 1, characterized in that: Establishing GPR interpretation standards based on UAV scanned images, including: Standard interpretation of drone scanned images; Comparative interpretation of ground penetrating radar profiles; Based on the standard interpretation of UAV scanning images and the comparative interpretation of GPR sections, the GPR interpretation standard for fracture-cave structures in similar outcrop areas is established.

8. The method for interpreting carbonate karst fracture-cavity structure using ground penetrating radar data according to claim 7, characterized in that: Based on the standard interpretation of UAV scanning images and the comparative interpretation of ground penetrating radar sections, the ground penetrating radar interpretation standard for fracture-cave structures in similar outcrop areas is established, specifically: According to the position parameters of faults, cracks and caves obtained from digital images and field survey images, the corresponding ground penetrating radar target processing profile is calibrated. Specifically, the fault occurrence and position observed in the UAV scanning image, the longitudinal continuous strong amplitude feature of the event axis can be seen at the corresponding position of the radar profile, and this feature is defined as the response feature of the fault; Field investigation revealed that there were unfilled caves at the intersection of faults at the bottom of the mountain. The signal at the bottom of the radar profile was weak, but the local amplitude anomaly characteristics could still be seen from the radar profile, which was interpreted as a cave. Based on the above interpretation, the interpretation standard of geological bodies in ground penetrating radar profiles was established.

9. The method for interpreting carbonate karst fracture-cavity structure using ground penetrating radar data according to claim 8, characterized in that: The specific process of three-dimensional interpretation of ground penetrating radar data of similar outcrops of carbonate karst fractures and caves based on the ground penetrating radar interpretation standard is as follows: The relative coordinate system of the ground penetrating radar profile is standardized and used to implement the three-dimensional interpretation in the seismic interpretation software, that is, according to the established interpretation standards of the geological body, the spatial distribution of faults, cracks and caves is interpreted to achieve the three-dimensional interpretation of the fracture-cavity structure; Establish the structural model of carbonate karst fracture-cavity body based on the stereo interpretation results; The three-dimensional structural model is used to analyze the reservoir structure of deep karst fracture-cave carbonate buried-hill oil and gas reservoirs.

10. The method for interpreting carbonate karst fracture-cavity structure using ground penetrating radar data according to claim 9, characterized in that: The structural model of carbonate karst fracture-cavity body is established based on the results of stereoscopic interpretation, including: Carry out interpretation of fault, crack and karst hole development zones in multiple radar profiles respectively; Based on the interpretation results of multiple two-dimensional profiles, the three-dimensional spatial layout of faults, cracks and caves is extracted, and the positional relationship between the three is analyzed, including the relationship between fault and crack density, the relationship between fault combination and cave size, etc. These relationships are used to guide the establishment of a three-dimensional structural model of carbonate karst fracture-caves.

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