Intelligent high-precision three-dimensional seismic exploration method and device in weak seismic response area

Abstract

The invention discloses an intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area, and the method comprises the steps: carrying out the preliminary ground surface structure exploration of an exploration area, determining the optimal excitation well depth according to the preliminary ground surface structure exploration result, carrying out the sealing of a hole through slurry, water and soil, enabling the hole to generate concentrated downward explosive force, so as to increase the high-frequency excitation energy, and achieving the high-precision seismic exploration. Through static correction, gather consistency processing, velocity field establishment and pre-stack depth migration processing, the resolution and the signal-to-noise ratio are improved, and a more accurate three-dimensional seismic exploration data volume is obtained. The invention further provides three-dimensional seismic exploration equipment applying the method.

Description

Technical Field

[0001] The present invention relates to the field of geological prospecting technology, and in particular to an intelligent high-precision three-dimensional seismic prospecting method and equipment in a weak seismic response area. Background Art

[0002] 3D seismic exploration can identify the structural development in coal mining areas, and high-density 3D seismic can effectively identify faults with a drop of 5 meters or more. However, due to the differences in shallow and medium-deep geological conditions, the accuracy of 3D seismic exploration is ultimately affected.

[0003] The Jiangzhuang Coal Mine exploration area in Tengxian Coalfield, Shandong Province, belongs to the weak seismic response area. The near-surface loose layer is developed, with quicksand and sandstone, which is not conducive to the excitation of effective waves; at the same time, the development of medium-deep clay rocks is also not conducive to the propagation of waves; moreover, the target layer of structural development is shallow, which belongs to the complex seismic exploration area.

[0004] Because the soil layer near the surface is loose, it absorbs and attenuates seismic waves, affecting their propagation, weakening the multiple waves and resonance in the records, and the recorded signal-to-noise ratio is relatively low. More importantly, it is easy to produce strong interference, affecting the accuracy of three-dimensional seismic exploration.

[0005] In order to solve the above problems, the prior art generally considers the excitation method, such as increasing the excitation energy by increasing the well depth, increasing the amount of explosives, etc., so as to achieve the purpose of improving the quality of seismic reflection waves.

[0006] For example, in the literature “Application of Downhole Detectors in the Loess Area of ​​the Ordos Basin”, downhole excitation and downhole reception are used to improve the accuracy of collected signals. However, the above application is only tested on points, and there is a lack of further in-depth research on high-density three-dimensional seismic exploration.

[0007] As an improvement, Chinese invention patent CN114935784A discloses a high-density three-dimensional seismic exploration method for extremely thick loess plateaus. The method utilizes a common well for blasting and detection to effectively avoid the energy attenuation of shallow dry and loose loess. Several node instruments are arranged at detection points as seismic data acquisition equipment, and blasting is performed in sequence. The seismic waves are received by the detectors, which effectively improves the signal-to-noise ratio of seismic records and the signal-to-noise ratio of seismic exploration results.

[0008] For example, Chinese invention patent CN104459799A provides a method and system for designing the depth of a well for seismic source excitation. Based on the acquired micro-well logging data, the well depth corresponding to the excitation with large amplitude, wide bandwidth and good waveform consistency in the seismic data is selected as the optimal excitation section. This provides a reliable, accurate and effective method for designing the depth of a well for seismic source excitation in complex surface areas that are insensitive to velocity, especially in exploration areas of igneous rock development areas.

[0009] The above method improves the quality of seismic reflection waves and the accuracy of seismic data to a certain extent by determining the optimal excitation well depth according to the terrain. However, it requires the micro-well to obtain the nearest excitation well depth position of the seismic source at the location of each micro-well, and then fits the seismic source excitation elevation plane of the entire exploration area according to the designed optimal excitation well depth position of each seismic source. Due to the huge workload and limited micro-well density, more comprehensive data can only be obtained through fitting in the later stage, resulting in room for improvement in its accuracy.

[0010] And although the above method determines the optimal excitation well depth, especially compared with the existing fixed-depth excitation well depth, its larger excitation energy can ensure that the transmitted wave is transmitted to the detector to the greatest extent, but the difference in excitation well depth will inevitably lead to differences in the length of the transmission path of the transmitted wave, which will also increase the difficulty of subsequent processing and interpretation of seismic data. Summary of the invention

[0011] In view of the above defects or deficiencies in the prior art, this solution proposes a solution and equipment for implementing three-dimensional seismic exploration to achieve accurate exploration under geological conditions such as shallow quicksand layers and sand ginger stones, which is specifically implemented as follows: An intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area, the method comprising: S1. Conduct preliminary surface structure survey of the exploration area, divide the surface structure into a first surface layer with a loose structure and poor excitation effect, and a second surface layer with a good excitation effect, and obtain the first surface height H1 and the second surface height H2 of each seismic excitation point, where H1 and H2 are a set of series, and the number of series corresponds to the number M of seismic excitation points; S2. Set the excitation well depth to D, and the initial value of the excitation well depth of each seismic excitation point is the same. Use the following method to adjust the excitation well depth D of each seismic excitation point: The initial D value range is {H1 min , H2 min}, obtain the number N of corresponding seismic excitation points of each value point D within the second surface range at certain intervals, among which the value D1 corresponding to the largest N is determined as the optimal excitation well depth. For the seismic excitation point D1 that does not fall within the second surface range, if D1 (H1+H2), then D1=H1+H2-α;<h1> The value of δ should be greater than the length of the explosive column; the value of α is generally not less than 1m, so as to ensure that the shock wave generated by the explosive column has sufficient length to be located in the second surface layer with good excitation effect when propagating; S3, according to the optimal excitation well depth D1 of each seismic excitation point determined in the above steps, construction is carried out, and explosive columns are placed in the wells of the seismic excitation points; the excitation shot points are excited to obtain data; S4, forming a high-density three-dimensional seismic exploration data volume according to the later seismic data processing; Furthermore, in step S1, a non-seismic method is used to conduct a surface structure survey.

[0012] Furthermore, the non-seismic methods include but are not limited to gravity, magnetism, mechanical drilling and other exploration methods, and their measurement point density is higher than that of micro-well logging, which can greatly improve the point density and reduce the construction difficulty.

[0013] Furthermore, in step S3, mud, water, and soil are used to seal the hole, so as to generate a concentrated downward explosive force to increase high-frequency excitation energy; Furthermore, in the processing of step S4, through static correction, gather consistency processing, velocity field establishment, and prestack depth migration processing, the resolution and signal-to-noise ratio are improved, and a more accurate three-dimensional seismic exploration data volume is obtained.

[0014] On the other hand, an embodiment of the present application provides an intelligent high-precision three-dimensional seismic exploration equipment in a weak seismic response area, including a computer and an acquisition system for collecting seismic exploration data, the acquisition system including detectors and a data link that connects the detectors in series to form a digital channel structure, and the computer is used to analyze and process the received data.

[0015] Furthermore, the detector is a digital detector, and the track spacing between the digital detectors is 15-40m; Furthermore, the acquisition system also includes a plurality of seismic receiving lines arranged at equal intervals in the transverse direction, and each seismic receiving channel on the seismic receiving lines is provided with the detector.

[0016] Furthermore, a plurality of shot points arranged in a line perpendicular to the address receiving lines are arranged at the center of the setting area of ​​the plurality of seismic receiving lines.

[0017] Furthermore, the distance between two adjacent shot points is at least 40m.

[0018] In the process of exploration, the present invention uses a mechanical drill to penetrate the quicksand layer to ensure the excitation effect. Mud, water and soil are used to seal the hole to generate a concentrated downward explosive force to increase the high-frequency excitation energy and reduce the intensity of the excitation interference. Deep well excitation is adopted to penetrate the quicksand layer and the sand ginger stone layer, and good results are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1The embodiment of the present application shows an implementation framework of an intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area. DETAILED DESCRIPTION

[0020] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0021] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] The specific implementation environment of the intelligent high-precision three-dimensional seismic exploration method in weak seismic response areas proposed in this application can be found in Figure 1 . Figure 1 The embodiment of the present application shows an implementation architecture diagram of an intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area.

[0023] An intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area, the method comprising: S1. Conduct preliminary surface structure survey of the exploration area, divide the surface structure into a first surface layer with a loose structure and poor excitation effect, and a second surface layer with a good excitation effect, and obtain the first surface height H1 and the second surface height H2 of each seismic excitation point, where H1 and H2 are a set of series, and the number of series corresponds to the number M of seismic excitation points; S2, setting the excitation well depth to D, and the initial values ​​of the excitation well depths of the seismic excitation points are the same, and selecting the excitation well depth with the most seismic excitation points located in the second surface layer as the optimal excitation well depth. At this time, if the seismic excitation points corresponding to the optimal excitation well depth are located in the first surface layer, the optimal excitation well depth is increased so as to enter the second surface layer; if the seismic excitation points corresponding to the optimal excitation well depth are located below the second surface layer, the optimal excitation well depth is reduced so as to enter the second surface layer; S3, according to the optimal excitation well depth D1 of each seismic excitation point determined in the above steps, construction is carried out, and explosive columns are placed in the wells of the seismic excitation points; the excitation shot points are excited to obtain data; S4, forming a high-density three-dimensional seismic exploration data volume according to the later seismic data processing; The optimal excitation well depth determined in the above manner ensures to the greatest extent that the waves generated by the excitation point take roughly the same path to reach the detector after propagating underground, reducing the interference and noise caused by propagation of different lengths of paths, reducing the difficulty of subsequent seismic data processing and interpretation and improving accuracy.

[0024] In a specific embodiment of the present invention, considering that the exploration method of the present invention is mainly aimed at the Jiangzhuang coal mine exploration area of ​​Tengxian Coalfield in Shandong Province, which belongs to a weak seismic response area, in step S1, a non-seismic method is used to conduct a surface structure survey.

[0025] The main reason is that the area has a loose layer near the surface, with quicksand and sandstone, which makes it difficult to achieve high-density micro-logging exploration; At present, there are two main methods for preliminary exploration of surface structure. One is to adopt micro-logging exploration method, which uses seismic method on the surface or shallow ground. However, for the weak seismic response area with loose shallow soil, on the one hand, the measurement density is difficult to increase and the points need to be spaced at a large distance. On the other hand, the operation is cumbersome and the cost is high. The other is non-seismic exploration method, which can effectively conduct preliminary surface structure exploration in Jiangzhuang Coal Mine Exploration Area of ​​Tengxian Coalfield in Shandong Province.

[0026] As a further improvement of the technical solution of the present invention, the non-seismic method includes but is not limited to gravity, magnetism, mechanical drilling and other exploration methods. Its measurement point density is higher than the micro-well logging density, which can greatly improve the point density and reduce the construction difficulty.

[0027] In another specific embodiment of the present invention, in step S3, mud, water, and soil are used to seal the hole, so that it generates a concentrated downward explosive force to increase the high-frequency excitation energy; Finally, in order to further improve the accuracy, in the processing of step S4, static correction, consistency processing of gathers, velocity field establishment, prestack depth migration processing are performed to improve the resolution and signal-to-noise ratio, thereby obtaining a more accurate 3D seismic exploration data volume.

[0028] In another specific implementation of the present invention, steps S1, S3, and S4 are the same, and only step S3 is further limited. The specific method is as follows: The following method is used to adjust the excitation well depth D of each seismic excitation point: The initial D value range is {H1 min , H2 min}, obtain the number N of corresponding seismic excitation points of each value point D within the second surface range at certain intervals, among which the value D1 corresponding to the largest N is determined as the optimal excitation well depth. For the seismic excitation point D1 that does not fall within the second surface range, if D1 (H1+H2), then D1=H1+H2.<h1>

[0029] In actual practice, it is found that for the seismic excitation point corresponding to the optimal excitation well depth located in the first surface layer, the excitation well depth needs to be increased to allow it to enter the second surface layer. However, if the excitation well depth is equal to H1, since the explosive column occupies a certain height, after the explosive column is inserted into the excitation point, only a part of the column enters the second surface layer. The absorption and attenuation of the seismic wave by the first surface layer affects its propagation, causing the multiple waves and resonance in the record to weaken, and the recorded signal-to-noise ratio is relatively low, which needs to be adjusted. In another specific embodiment of the present invention, a method for intelligent high-precision three-dimensional seismic exploration in a weak seismic response area is provided, the method comprising: S1. Conduct preliminary surface structure survey of the exploration area, divide the surface structure into a first surface layer with a loose structure and poor excitation effect, and a second surface layer with a good excitation effect, and obtain the first surface height H1 and the second surface height H2 of each seismic excitation point, where H1 and H2 are a set of series, and the number of series corresponds to the number M of seismic excitation points; S2. Set the excitation well depth to D, and the initial value of the excitation well depth of each seismic excitation point is the same. Use the following method to adjust the excitation well depth D of each seismic excitation point: The initial D value range is {H1 min , H2 min}, obtain the number N of corresponding seismic excitation points of each value point D within the second surface range at certain intervals, among which the value D1 corresponding to the largest N is determined as the optimal excitation well depth. For the seismic excitation point D1 that does not fall within the second surface range, if D1 The value of δ should be greater than the length of the explosive column; S3, according to the optimal excitation well depth D1 of each seismic excitation point determined in the above steps, construction is carried out, and explosive columns are placed in the wells of the seismic excitation points; the excitation shot points are excited to obtain data; S4. Form a high-density three-dimensional seismic exploration data volume based on the later seismic data processing.

[0030] For the optimal excitation well depths of different depths determined for different terrains, the value of δ should be determined through repeated experiments on the premise that it is greater than the length of the explosive column. For example, for the Jiangzhuang coal mine exploration area of ​​the Tengxian Coalfield in Shandong Province in the present invention, the near-surface soil is relatively loose, so the value of δ is preferably greater than 4 times the length of the explosive column to reduce the significant changes in the structure of the upper soil caused by the vibration wave during blasting, thereby affecting the data accuracy; at the same time, it should not be too large, so as to avoid excessive differences in different excitation well depths, thereby affecting the data accuracy.

[0031] ​At the same time, it is also necessary to consider the soil conditions of the second surface layer and adjust the value of δ according to the amount of explosives. The above method can be obtained by technicians in this field through limited experiments based on records, and will not be repeated here.

[0032] As a further improvement to the technical solution of the present invention, when the seismic excitation point corresponding to the optimal excitation well depth is located below the second surface layer, the excitation well depth should not be close to the bottom of the second surface layer, so as to avoid changes in the soil quality below the second surface layer, which is not conducive to wave propagation and affects data acquisition.

[0033] In another specific embodiment of the present invention, a method for intelligent high-precision three-dimensional seismic exploration in a weak seismic response area is provided, the method comprising: S1. Conduct preliminary surface structure survey of the exploration area, divide the surface structure into a first surface layer with a loose structure and poor excitation effect, and a second surface layer with a good excitation effect, and obtain the first surface height H1 and the second surface height H2 of each seismic excitation point, where H1 and H2 are a set of series, and the number of series corresponds to the number M of seismic excitation points; S2. Set the excitation well depth to D, and the initial value of the excitation well depth of each seismic excitation point is the same. Use the following method to adjust the excitation well depth D of each seismic excitation point: The initial D value range is {H1 min , H2 min}, obtain the number N of corresponding seismic excitation points of each value point D within the second surface range at certain intervals, where the value D1 corresponding to the largest N is determined as the optimal excitation well depth, for seismic excitation points whose D1 does not fall within the second surface range, for seismic excitation points whose D1 does not fall within the second surface range, D1>(H1+H2), then D1= H1+H2-α; The value of α is generally not less than 4m, so as to ensure that the shock wave generated by the explosive column has sufficient length to be located in the second surface layer with good excitation effect; S3, according to the optimal excitation well depth D1 of each seismic excitation point determined in the above steps, construction is carried out, and explosive columns are placed in the wells of the seismic excitation points; the excitation shot points are excited to obtain data; S4. Form a high-density three-dimensional seismic exploration data volume based on the later seismic data processing.

[0034] After experiments, it was determined that the excitation effect is best when the excitation well depth is 4-6 meters above the second surface. If it is greater than 6 meters, the noise interference is large due to the large difference in excitation well depth with other seismic excitation points. If it is less than 4 meters, the wave propagation is insufficient and the recording signal-to-noise ratio is relatively low.

[0035] It should be noted that the confirmation of the above-mentioned values ​​varies greatly depending on the different address conditions. The values ​​obtained by the present invention are only for the address of the Jiangzhuang Coal Mine exploration area in the Teng County Coalfield in Shandong Province and are not universal. However, those skilled in the art can easily obtain a more appropriate range through effective tests according to the method described in the present invention, and the specific experimental process will not be repeated here.

[0036] Finally, based on the above experiments, another specific embodiment of the present application is as follows: An intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area, the method comprising: S1. Conduct preliminary surface structure survey of the exploration area, divide the surface structure into a first surface layer with a loose structure and poor excitation effect, and a second surface layer with a good excitation effect, and obtain the first surface height H1 and the second surface height H2 of each seismic excitation point, where H1 and H2 are a set of series, and the number of series corresponds to the number M of seismic excitation points; S2. Set the excitation well depth to D, and the initial value of the excitation well depth of each seismic excitation point is the same. Use the following method to adjust the excitation well depth D of each seismic excitation point: The initial D value range is {H1 min , H2 min}, obtain the number N of corresponding seismic excitation points of each value point D located within the second surface layer at certain intervals, wherein the value D1 corresponding to the largest N is determined as the optimal excitation well depth; For the earthquake excitation point where D1 does not fall within the second surface layer, if D1 (H1+H2), then D1= H1+H2-α;<h1> The value of δ should be greater than the length of the explosive column; the value of α is generally not less than 4m, to ensure that the shock wave generated by the explosive column has sufficient length to be located in the second surface layer with good excitation effect when propagating; S3, according to the optimal excitation well depth D1 of each seismic excitation point determined in the above steps, construction is carried out, and explosive columns are placed in the wells of the seismic excitation points; the excitation shot points are excited to obtain data; S4. Form a high-density three-dimensional seismic exploration data volume based on the later seismic data processing.

[0037] On the other hand, an embodiment of the present application provides an intelligent high-precision three-dimensional seismic exploration equipment in a weak seismic response area, including a computer and an acquisition system for collecting seismic exploration data, the acquisition system including detectors and a data link that connects the detectors in series to form a digital channel structure, and the computer is used to analyze and process the received data.

[0038] As an improvement, the detector is a digital detector, and the track spacing between the digital detectors is 15-40m; As a further improvement, the acquisition system further comprises a plurality of seismic receiving lines arranged at equal intervals in the transverse direction, and the detector is arranged on each seismic receiving channel of the seismic receiving lines.

[0039] As a further improvement, a plurality of shot points connected in a line perpendicular to the address receiving lines are arranged at the center of the arrangement area of ​​the plurality of seismic receiving lines.

[0040] As a further improvement, the distance between two adjacent shot points is at least 40m.

[0041] Although the embodiments of the present application provide the method operation steps shown in the following embodiments or drawings, more or fewer operation steps may be included in the method based on routine or no creative labor. In the steps where there is no necessary causal relationship logically, the execution order of these steps is not limited to the execution order provided in the embodiments of the present application. The method may be executed in the order of the method shown in the embodiments or drawings or in parallel during the actual processing process or when the device is executed.

[0042] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the aforementioned disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) by each other to form a technical solution.

Claims

1. An intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area, characterized in that The method includes the following steps: S1. Conduct a preliminary surface structure survey on the exploration area, divide the surface structure into a first surface layer with poor excitation effect of loose structure and a second surface layer with good excitation effect, and obtain the height H1 of the first surface layer and the height H2 of the second surface layer at each seismic excitation point, where H1 and H2 are respectively a set of sequences, and the number of sequences corresponds to the number M of seismic excitation points; S2. Set the excitation well depth as D, and the initial values of the excitation well depths at each seismic excitation point are the same. The following method is adopted to adjust the excitation well depth D at each seismic excitation point: The initial D value range is {H1 min , H2 min }, obtain the number N of corresponding seismic excitation points of each value point D located within the second surface layer at certain intervals, wherein the value D1 corresponding to the largest N is determined as the optimal excitation well depth; For the seismic excitation point where D1 does not fall within the range of the second surface layer, if D1 < H1 at this time, then D1 = H1 + δ; if D1 > (H1 + H2), then D1 = H1 + H2 - α; The value of δ should be greater than the length of the explosive charge column; the value of α is not less than 1m to ensure that the shock wave generated by the explosive charge column has enough length to be located within the second surface layer with good excitation effect during propagation; S3. Construction is carried out according to the optimal excitation well depth D1 determined for each seismic excitation point in the above steps. Place the explosive charge column into the well at the seismic excitation point; the shot point acquires data; S4. Form a high-density three-dimensional seismic exploration data volume based on the subsequent seismic data processing.

2. The intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area according to claim 1, characterized in that: In step S1, a non-seismic method is used for surface structure investigation.

3. The intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area according to claim 2, characterized in that: The non-seismic method includes gravity, magnetic, and mechanical drilling exploration methods, and the measurement point density is higher than the micro-logging density.

4. The intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area according to claim 3, characterized in that: In step S3, a mechanical drill is used to drill a well through the quicksand layer to ensure the excitation effect. After drilling, mud, water, and soil are used to seal the hole to generate a concentrated downward explosive force to increase the high-frequency excitation energy.

5. The intelligent high-precision three-dimensional seismic exploration method in a weak seismic response area according to claim 1, characterized in that: In the process of step S4 processing, through static correction, common receiver gather consistency processing, velocity field establishment, and prestack depth migration processing, the resolution and signal-to-noise ratio are improved to obtain a three-dimensional seismic exploration data volume.

6. An intelligent high-precision three-dimensional seismic exploration equipment in a weak seismic response area, including a computer and a collection system for collecting seismic exploration data. The collection system includes geophones and a data link that connects the geophones in series to form a digital trace structure. The computer is used to analyze and process the received data, and the acquisition of the data adopts the intelligent high-precision three-dimensional seismic exploration method in the weak seismic response area as described in any one of claims 1-5.

7. The intelligent high-precision three-dimensional seismic exploration equipment in a weak seismic response area according to claim 6, characterized in that: The geophones are digital geophones, and the trace interval between digital geophones is 15-40m.

8. The intelligent high-precision three-dimensional seismic exploration equipment in a weak seismic response area according to claim 6, characterized in that: The collection system further includes multiple seismic receiving lines arranged at equal intervals horizontally. Each seismic receiving trace on the seismic receiving line is provided with the above-mentioned geophones.

9. The intelligent high-precision three-dimensional seismic exploration equipment in a weak seismic response area according to claim 8, characterized in that: At the central position of the area where the multiple seismic receiving lines are arranged, a plurality of shot points connected in a line perpendicular to the address receiving line are provided.

10. The intelligent high-precision three-dimensional seismic exploration equipment in a weak seismic response area according to claim 9, characterized in that: The distance interval between adjacent two shot points is at least 40m.

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