Method for accurately probing distribution position of goaf beside drill hole

Abstract

The invention discloses a method for accurately exploring the distribution position of a goaf beside a drilling hole and a system for accurately exploring the distribution position of the goaf beside the drilling hole. The method comprises the step of exploring and accurately positioning the distribution position of the goaf around the drilling hole by adopting drilling hole natural gamma, radar and transient electromagnetic methods in horizontal directional drilling. According to the method, the change of the rock stratum near the drill hole is explored through gamma, the drill hole track layer penetrating condition and the trend of coal seam roofs and floors are analyzed through a chart method, and a reliable basis is provided for radar result interpretation. Radar data are processed by adopting methods such as digital filtering, the radial position of the goaf around the drill hole is found out, and an initial model is provided for a transient electromagnetic positioning algorithm. A transient electromagnetic method magnetic field three-component positioning algorithm is adopted to determine the spatial distribution position of the goaf.

Description

Technical Field

[0001] The present invention belongs to the field of coal mine safety, and specifically designs a method for accurately exploring the distribution position of gob areas beside boreholes. Background Technique

[0003] For the detection of such gob areas, after years of exploration and summary, the exploration and treatment technology of gob areas has changed from early geophysical exploration + a small amount of drilling verification to comprehensive geophysical exploration + drilling exploration. However, there are still great risks in the exploration and treatment process, such as the risk of personnel and equipment falling caused by the collapse of large gob areas, and there are still some cavities left after exploration and treatment. During the stripping process, equipment tipping and falling often occur, and even large unfilled cavities are found, resulting in the lack of guarantee for safe production. In these previous gob area treatment schemes, the detection of gob areas cannot be 100% accurate, and there are missing gob areas. During the exploration and treatment process, in the links of geophysical exploration, drilling, blasting treatment, and sand injection filling, each link may operate above the hanging and uncollapsed gob area, and there is a great potential safety hazard of sudden collapse of the gob area during operation.

[0004] Gob areas have become the biggest safety hazard in domestic open-pit coal mines. The previous exploration and treatment methods have great risks. To ensure construction safety, a set of absolutely safe and reliable gob area treatment schemes need to be studied and explored for gob areas with soft coal and rock and extremely poor roof stability in open-pit coal mines. In recent years, with the development of new technologies at home and abroad, especially the development of horizontal directional drilling technology, horizontal hole transient electromagnetic method and radar and other technologies, new technical ideas have been provided for the exploration and treatment of gob areas in domestic open-pit coal mines. Summary of the Invention

[0005] Aiming at the problem of accurate exploration of gob areas in open-pit mines, the present invention proposes a method for accurately exploring the distribution position of gob areas beside boreholes, and realizes the accurate exploration of the distribution position of gob areas by combining directional drilling and borehole geophysical exploration in the open-pit mine slope area.

[0006] To achieve the above purpose, the present invention is realized by adopting the following technical solutions:

[0007] A method for accurately exploring the distribution position of gob areas beside boreholes includes collecting data of borehole geophysical exploration in horizontal boreholes, and the borehole geophysical exploration includes gamma, radar, and transient electromagnetic method;

[0008] S1: Gamma explores the changes of rock strata near the borehole, and uses the distance inversion chart method to analyze the cross-strata situation of the borehole trajectory and the trend of the coal seam roof and floor; according to the distance inversion chart method, identify key points near the interface and connect them into a smooth curve, and draw the interface distance result chart;

[0009] S2: Process the radar data, find out the radial position of the gob area around the borehole, and obtain the inferred gob area;

[0010] S3: Based on the achievements of radar data processing, establish an initial goaf model between the hole depth and the radial distance of the borehole, draw the curves of the transient electromagnetic method's magnetic tri - components in this area, use the transient electromagnetic method's tri - component spatial positioning algorithm to locate the goaf in space, and finally determine the spatial distribution position of the goaf around the borehole.

[0011] Optionally, in the above - mentioned S1, the distance inversion chart method is based on the attenuation law of gamma rays in the formation, and establishes the curves obtained by the fast forward algorithm of the gamma - ray - while - drilling instrument at different positions in the formation and different formation models.

[0012] Optionally, in the above - mentioned S2, according to the forward modeling results, the response characteristic of the goaf in the borehole radar result map is "arc - shaped". Combining with the interface distance result map in S1, eliminate the false "arc - shaped" caused by cross - layer, and obtain the inferred goaf.

[0013] Optionally, the above - mentioned S3 specifically includes:

[0014] Draw the response characteristics of the tri - components of the target body in each quadrant according to the forward simulation of the transient electromagnetic method's tri - components, and then use the clustering algorithm to obtain the response form classification; draw the curves of the transient electromagnetic method's tri - components in the area of the inferred goaf obtained in S2, and finally determine the position of the goaf according to the principle of the spatial positioning algorithm.

[0015] Optionally, it specifically includes:

[0016] Number the horizontal boreholes in sequence as Z1, Z2... Zn. First, conduct data acquisition of borehole geophysical exploration in the Z1 horizontal borehole: connect the borehole geophysical exploration equipment to the front end of the drilling rig, push the equipment into the hole, and collect data point by point. The point spacing for data acquisition is c = 1 - 6m until the bottom of the hole to complete the data acquisition;

[0017] Interpret the borehole geophysical exploration data of the Z1 borehole:

[0018] (1) First, interpret the data of borehole gamma: when the ratio C of the natural gamma of the coal seam roof layer and the coal seam is constant, use the distance inversion chart method to obtain the information of the coal seam roof and floor interfaces, get the distance d of the gamma instrument from the interface, and predict the trend of the coal seam roof and floor interfaces;

[0019] (2) Then, interpret the data of borehole radar: pre - process the data, according to the "arc - shaped" response characteristic of the goaf, combine with the borehole gamma interpretation results in step (1), eliminate the "false anomaly" characteristics caused by cross - layer, and obtain the inferred goaf between the borehole depths H1 - H2 and the radial distances E1 - E2 from the borehole radial direction;

[0020] (3) Finally, interpret the data of the borehole transient electromagnetic method to locate the spatial position of the goaf: According to the inferred goaf results in step (2), establish an initial goaf model between the borehole depths H1 - H2 and the radial distances E1 - E2 from the borehole, plot the curves of the three components of the transient electromagnetic method in this area, and use the three-component spatial positioning algorithm of the transient electromagnetic method to locate the goaf in space, and finally determine the spatial distribution position of the goaf around the borehole;

[0021] Perform the above processing in sequence for the boreholes Z2... Zn to form the distribution positions of the goafs on the side of each borehole.

[0022] Optionally, step (1) specifically includes:

[0023] Interpret the data of the borehole gamma: According to the borehole situation, the opening position of this borehole is in the rock stratum at the bottom of the coal seam. Based on the natural gamma logging response characteristics, with the horizontal coordinate being the borehole depth and the vertical coordinate being the natural gamma value, the natural gamma GR characteristic value can be obtained from the curve. Based on the attenuation law of gamma rays in the formation, a curve obtained by establishing a fast forward modeling algorithm for the gamma-with-logging instrument at different positions in the formation and different formation models is used to infer the borehole trend, including the borehole passing through the rock stratum into the coal seam, encountering a fault, pinch-out, and / or grouting area.

[0024] The advantages of the present invention are:

[0025] Innovative comprehensive gamma + radar + transient electromagnetic method collaborative detection. Gamma data provides information on the rock stratum interface and the trend of the top and bottom coal seams. Radar detects the radial position of the goaf, and the transient electromagnetic method performs three-dimensional spatial positioning. The three complement each other to form a systematic process of "data acquisition - interpretation - model construction - positioning verification". Non-invasive detection effectively reduces the collapse risk of traditional drilling, and at the same time reduces the number of verification boreholes, combining high efficiency and economy, providing an accurate and safe solution for the treatment of goafs in open-pit coal mines and greatly reducing operation hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings are used to provide a further understanding of the present disclosure and form a part of the specification, and are used together with the following specific embodiments to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0027] Figure 1 It is the plate showing the distance from the interface under different natural gamma contrasts between the roof layer and the coal seam in the first embodiment of the present invention;

[0028] Figure 2 It is the morphological characteristic diagram of the response of the three-component spatial positioning algorithm in the first embodiment of the present invention;

[0029] Figure 3This is a diagram showing the interpretation result of the drilling gamma plate method in the first embodiment of the present invention;

[0030] Figure 4 This is a diagram of the interpretation result of the borehole radar in the first embodiment of the present invention;

[0031] Figure 5 The three-component curve of the drilling transient electromagnetic method in the first embodiment of the present invention;

[0032] Figure 6 This is a diagram of the verification results in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation cases. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the appended claims of the application.

[0034] In the safe slope area of ​​the open-pit mine, horizontal directional drilling with equal spacing is carried out to explore the goaf. For the blind areas between the boreholes, borehole geophysical exploration technology is used to accurately explore the blind areas: radar has a good detection effect on the goaf, but when the rock properties of the boreholes change suddenly, it will cause "false anomalies", so gamma detection of the rock properties of the boreholes is required. At the same time, radar cannot spatially locate the goaf, and the transient electromagnetic method has a weak response to the goaf, so it is necessary to use radar detection results to constrain the transient electromagnetic method results, and then use the transient electromagnetic method three-component positioning algorithm to accurately locate the spatial position of the goaf.

[0035] The method for accurately detecting the distribution position of the goaf area beside the borehole of the present invention comprises data collection of borehole geophysical exploration in the horizontal borehole, and the borehole geophysical exploration comprises gamma, radar and transient electromagnetic methods;

[0036] S1: Gamma exploration of rock formation changes near the borehole, using the distance inversion plate method to analyze the penetration of the borehole trajectory and the trend of the coal seam roof and floor; According to the distance inversion plate method, identify the key points near the interface and connect them into a smooth curve, and draw the interface distance result map. The interface refers to the point from the coal seam to the rock layer. Normal boreholes are all in the coal seam, and the interface is the key point;

[0037] S2: Process the radar data to find out the radial position of the goaf around the borehole;

[0038] S3: Based on the results of radar data processing, establish an initial goaf model between the hole depth and the radial distance of the borehole, draw the curves of the transient electromagnetic method magnetic method three components in this area, use the transient electromagnetic method three-component space positioning algorithm to locate the goaf in space, and finally determine the spatial distribution position of the goaf around the borehole.

[0039] In the embodiment of the present disclosure, in S1, the distance inversion chart method is based on the attenuation law of gamma rays in the formation, and establishes the curves obtained by the fast forward algorithm of the gamma-ray while-drilling instrument located at different positions in the formation and different formation models; the curves are established through the forward algorithm. The gamma values of the coal seam and the rock stratum, as well as the distance between the instrument and the interface, are required. The forward algorithm refers to using some formulas and known model parameters and boundary conditions to calculate the theoretically observed data or response results through mathematical and physical methods.

[0040] In the embodiment of the present disclosure, in S2, according to the forward results, the response characteristic of the goaf in the borehole radar result chart is "arc-shaped". Combining with the borehole gamma interpretation results in S1, the false "arcs" (that is, the arcs caused by the interface judged in S1, not caused by the goaf) are removed to obtain the inferred goaf.

[0041] In the embodiment of the present disclosure, S3 specifically includes: drawing the response characteristics of the three components of the target body in each quadrant according to the forward simulation of the transient electromagnetic method three components, and then using the clustering algorithm to obtain the response form classification; drawing the transient electromagnetic method three-component curves of the inferred goaf area obtained in S2, and finally determining the position of the goaf according to the principle of the space positioning algorithm.

[0042] The specific scheme of the method for accurately exploring the distribution position of the goaf beside the borehole of the present invention includes:

[0043] Number the horizontal boreholes as Z1, Z2... Zn in sequence. First, collect the data of borehole geophysical exploration in the Z1 horizontal borehole: connect the borehole geophysical exploration equipment to the front end of the drilling rig, push the equipment into the hole, and collect data point by point. The point distance of data collection is c = 1-6m until the bottom of the hole to complete the data collection;

[0044] Interpret the borehole geophysical exploration data of the Z1 borehole:

[0045] (1) First, interpret the data of borehole gamma: When the natural gamma ratio C of the coal seam roof layer and the coal seam is constant, use the distance inversion chart method to obtain the information of the coal seam roof and floor interfaces, obtain the distance d between the gamma instrument and the interface, and predict the trend of the coal seam roof and floor interfaces;

[0046] (2) Then interpret the data of the borehole radar: Preprocess the data. According to the "arc-shaped" response characteristics of the goaf and combined with the interpretation results of borehole gamma in step (1), eliminate the "false anomaly" characteristics caused by cross-strata, and obtain the inferred goaf between the borehole depths H1 - H2 and between the radial distances E1 - E2 from the borehole in the radial direction.

[0047] (3) Finally, interpret the data of the borehole transient electromagnetic method to realize the spatial position positioning of the goaf: According to the inferred goaf results in step (2), establish an initial model of the goaf between the borehole depths H1 - H2 and between the radial distances E1 - E2 from the borehole, draw the curves of the three components of the transient electromagnetic method in this area, and use the three-component spatial positioning algorithm of the transient electromagnetic method to position the goaf in space, and finally determine the spatial distribution position of the goaf around the borehole.

[0048] Perform the above processing in sequence for the boreholes Z2... Zn to form the distribution positions of the goafs beside each borehole.

[0049] Step (1) specifically includes:

[0050] Interpret the data of borehole gamma: According to the borehole situation, the opening position of this borehole is in the coal seam floor rock formation. Based on the natural gamma logging response characteristics, with the horizontal coordinate being the borehole depth and the vertical coordinate being the natural gamma value, the natural gamma GR characteristic value can be obtained from the curve. Based on the attenuation law of gamma rays in the formation, a curve obtained by establishing a fast forward modeling algorithm of the gamma-with-logging instrument at different positions in the formation and different formation models is used to infer the borehole trend, including the borehole passing through the rock formation into the coal seam, encountering faults, pinch-outs, and / or grouting areas.

[0051] Example 1:

[0052] Combined with Figure 1-6 Make a specific description of the method of the present invention:

[0053] 1. Collect and analyze the results of engineering geology and hydrogeology work, as well as the drilling results of horizontal directional boreholes, and initially master the distribution law of goafs in the area.

[0054] 2. Number the horizontal boreholes sequentially as Z1, Z2... Zn.

[0055] 3. First, conduct data collection of borehole geophysical exploration (natural gamma, radar, and transient electromagnetic method) in the Z1 horizontal borehole: Connect the borehole geophysical exploration equipment to the front end of the drill rig, push the equipment into the hole, and collect data point by point. The point spacing for data collection is c = 1 - 6 m until the bottom of the hole to complete the data collection.

[0056] 4. Interpret the borehole geophysical exploration data of the Z1 borehole:

[0057] (1) First, interpret the data of borehole gamma: According to the borehole conditions, the opening position of this borehole is in the rock stratum at the bottom of the coal seam. Based on the natural gamma logging response characteristics, analyze Figure 3 The figure below: The abscissa is the borehole depth, and the ordinate is the natural gamma value. From the curve, it can be obtained that the characteristic value of natural gamma (GR) is about 36 cps for the borehole depth from 0 to 18 m, the GR value decreases between 18 and 123 m and stabilizes at about 4 cps, and the GR value rises to about 110 cps between 123 and 172 m. Therefore, it is inferred that the borehole first encounters the bottom layer with a natural gamma (GR) characteristic value of about 36 cps, and then encounters the coal seam with a GR value of about 4 cps.

[0058] According to the results of the chart method Figure 1 , combined with the on-site geological data to interpret the borehole gamma data, the C ratio of the coal seam floor to the coal seam in this area is 1:9, that is, the natural gamma (GR) of the coal seam is 4 - 5 cps, and the natural gamma (GR) of the rock stratum at the bottom of the coal seam is 36 - 45 cps. Then select Figure 1 The purple curve in the figure: GR measurement / GR coal seam is 9, that is, the abscissa in Figure 1 is 9; then, the intersection point of the two, which is the yellow star in the figure, gives the ordinate as the distance from the interface d ≈ 0.13 m; finally, according to the characteristics of the measured values, it can be known that the instrument is in the bottom layer and is 0.13 m away from the interface. Near the borehole depth of 123 m, a non-coal seam with a GR value of about 110 cps is encountered. According to the chart method, identify the key points near the interface, connect them into a smooth curve, and draw the interface distance result Figure 3 In the above figure, the final interpretation result is that at point A, the borehole penetrates the rock stratum and enters the coal seam, and at point B, an abnormal structure such as a fault / pinch-out / grouting area is encountered.

[0059] Chart method: The chart method is a commonly used method in engineering and scientific research. It displays and analyzes data in the form of charts, Figure 1 and is a curve obtained based on the attenuation law of gamma rays in the formation and establishing a fast forward modeling algorithm for the gamma-ray while-drilling instrument in different positions in the formation and different formation models.

[0060] (2) Then, interpret the data of borehole radar: Preprocess the data (DC elimination, direct wave elimination, band-pass filtering, digital gain) by including but not limited to these methods to obtain the interpretation results of borehole radar Figure 4 . According to the forward modeling results, the response characteristic of the goaf in the borehole radar result diagram is "arc-shaped", but a similar "arc-shaped" characteristic will also appear when crossing layers. Interpret according to the forward modeling results Figure 4Two abnormal zones were found. Combining with the interpretation results of borehole gamma (1), abnormal structures such as faults, pinch-outs, and grouting zones were encountered near a borehole depth of 120 m. This abnormality was caused by cross-strata, so it was defined as a "false abnormality". An abnormality was found between borehole depths of 50 - 73 m and at a radial distance of 4 - 6 m from the borehole, which was speculated to be a goaf.

[0061] (3) Finally, interpret the data of the borehole transient electromagnetic method to locate the spatial position of the goaf: According to the results of (2), establish an initial model of the goaf between borehole depths of 48 - 73 m and at a radial distance of 4 - 6 m from the borehole, and draw the curves of the three components of the transient electromagnetic method in this area. According to the forward simulation of the three components of the transient electromagnetic method, draw the response characteristics of the three components of the target body in each quadrant, and then use the clustering algorithm (a method that automatically divides a pile of unlabeled data into several categories) to obtain Figure 2 the classification of the response forms. Draw the curves of the three components of the transient electromagnetic method in the area interpreted in the results of (2) to obtain the curves Figure 5 , and according to the principle of the spatial positioning algorithm Figure 2 , finally determine that the goaf is in the fourth quadrant of the borehole, that is, the upper right of the borehole.

[0062] 5. According to the interpretation results of step 4, explore a goaf abnormal area between borehole depths of 48 - 73 m and at a radial distance of 4 - 6 m from the borehole Z1 in the fourth quadrant of the borehole azimuth. To verify the accuracy of the borehole geophysical exploration results, drill a hole at an upward inclination about 7 m to the right of the borehole. When drilling to 48 m, a goaf was found when the borehole was pushed empty, verifying the accuracy of the interpretation results of the present invention. See Figure 6 .

[0063] Successively complete steps 3, 4, and 5 in the regional boreholes Z2... Zn to form the distribution positions of the goafs beside each borehole.

[0064] The above are only specific embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for accurately detecting the distribution position of goaf areas beside a borehole, characterized in that: The method includes data collection for borehole geophysical exploration in a horizontal borehole, wherein the borehole geophysical exploration includes gamma, radar and transient electromagnetic methods; S1: Gamma-ray exploration of rock formation changes near the borehole, using the distance inversion plate method to analyze the penetration of the borehole trajectory and the trend of the coal seam roof and floor; according to the distance inversion plate method, key points near the interface are identified and connected into a smooth curve, and the interface distance result map is drawn; S2: Processing radar data to find out the radial position of the goaf around the borehole and obtain the estimated goaf; S3: Based on the results of radar data processing, an initial model of the goaf between the hole depth and the radial distance of the borehole is established, and the three-component curves of the transient electromagnetic method and magnetic method in the area are drawn. The three-component spatial positioning algorithm of the transient electromagnetic method is used to locate the goaf in space, and finally the spatial distribution position of the goaf around the borehole is determined.

2. The method for accurately detecting the distribution position of the goaf area beside the borehole according to claim 1, characterized in that: In S1, the distance inversion plate method is based on the attenuation law of gamma rays in the formation, and establishes the curve obtained by the fast forward algorithm of the while drilling gamma instrument located at different positions in the formation and in different formation models.

3. The method for accurately detecting the distribution position of goaf areas beside a borehole according to claim 1 or 2, characterized in that: In S2, according to the forward modeling results, the response characteristic of the goaf in the borehole radar result map is "arc-shaped". Combined with the interface distance result map in S1, the false "arc-shaped" caused by the penetration is eliminated to obtain the inferred goaf.

4. The method for accurately detecting the distribution position of goaf areas beside a borehole according to claim 1 or 2, characterized in that: The S3 specifically includes: According to the forward simulation of the three-component transient electromagnetic method, the response characteristics of the three-component target body in each quadrant are drawn, and then the clustering algorithm is used to obtain the response morphological classification; the three-component curve of the transient electromagnetic method of the inferred goaf area obtained by S2 is drawn, and the location of the goaf is finally determined according to the principle of the spatial positioning algorithm.

5. The method for accurately detecting the distribution position of goaf areas beside a borehole according to any one of claims 1 to 4, characterized in that: Specifically include: The horizontal boreholes are numbered Z1, Z2, ... Zn in sequence. First, the data collection of borehole geophysical exploration is carried out in the Z1 horizontal borehole: the borehole geophysical exploration equipment is connected to the front end of the drilling rig, and the equipment is pushed into the hole to collect data point by point. The point spacing of data collection is c = 1 ~ 6m until the bottom of the hole, and the data collection is completed; Interpretation of the geophysical data of the Z1 borehole: (1) First, interpret the borehole gamma data: when the ratio C of the coal seam roof layer and the coal seam natural gamma is constant, the distance inversion plate method is used to obtain the interface information of the coal seam roof and floor, and the distance d from the gamma instrument to the interface is obtained to predict the trend of the coal seam roof and floor interface; (2) Then interpret the borehole radar data: pre-process the data, based on the "arc-shaped" response characteristics of the goaf area, combined with the borehole gamma interpretation results of step (1), eliminate the "false abnormality" caused by the penetration, and obtain the estimated goaf area between the borehole depth H1-H2 and the radial distance E1-E2 from the borehole; (3) Finally, the data of the borehole transient electromagnetic method is interpreted to realize the spatial location of the goaf: based on the estimated goaf results of step (2), an initial model of the goaf between the hole depth H1-H2 and the radial distance E1-E2 from the borehole is established, and the three-component curve of the transient electromagnetic method magnetic method in the area is drawn. The three-component spatial positioning algorithm of the transient electromagnetic method is used to spatially locate the goaf, and finally the spatial distribution position of the goaf around the borehole is determined; The above processing is completed in boreholes Z2...Zn in sequence to form the distribution position of the goaf area beside each borehole.

6. The method for accurately detecting the distribution position of goaf areas beside a borehole according to claim 5, characterized in that: The step (1) specifically comprises: Interpretation of borehole gamma data: According to the drilling situation, the borehole opening is located in the rock layer at the bottom of the coal seam. According to the natural gamma logging response characteristics, the horizontal axis is the borehole depth and the vertical axis is the natural gamma value. The natural gamma GR characteristic value can be obtained from the curve. Based on the attenuation law of gamma rays in the formation, a curve obtained by the fast forward algorithm of the while-drilling gamma instrument located at different positions in the formation and in different formation models is established to infer the direction of the borehole, including the borehole passing through the rock layer into the coal seam, drilling into faults, pinch-outs and / or grouting areas.

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