Method for monitoring development height of coal seam roof fracture by using micro-seismic

Abstract

The invention discloses a method for monitoring the fracture development height of a coal seam roof through microseism. The method comprises the following steps that ground surface microseism monitoring points, underground roadway microseism monitoring points and in-hole microseism monitoring points are arranged at the design positions of the ground surface, an underground roadway and exploration drill holes respectively; the to-be-observed coal seam roof area is located in an area defined by the micro-seismic monitoring points; determining a spatial three-dimensional position of the micro-seismic event by adopting a Direct operation method; the defect of inaccurate positioning caused by the fact that a sensor is only arranged on the ground or underground in traditional micro-seismic monitoring is overcome, a well-ground-hole combined micro-seismic monitoring technology is used, micro-seismic signals generated in the coal seam roof fracture development process are observed in an all-dimensional mode, and therefore micro-seismic events generated by coal seam roof fractures are positioned, and the monitoring accuracy is improved. Compared with pure ground micro-seismic monitoring, the method effectively avoids the defects of few micro-seismic events, low signal-to-noise ratio, poor inversion reliability and the like in data obtained by ground or underground monitoring due to stratum absorption, propagation paths and the like.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining monitoring, and in particular to a method for monitoring the height of coal seam roof crack development by using microseismic monitoring. Background Art

[0002] Microseismic monitoring technology is a set of geophysical technologies based on acoustic detection and seismology. It evaluates the damage and safety status of the monitored object by monitoring the vibrations generated by rock mass fractures or other objects, thereby providing a basis for disaster prediction and control. This technology is widely used in the positioning and monitoring of rock mass fractures in mines. It is an effective tool for predicting and forecasting roof collapse, mine water inrush, coal and gas outbursts, rock bursts, etc. It can also determine important parameters such as the height of the water-conducting fracture zone, the upper limit of mining, and the reasonable location of the tunnel based on the scope and degree of the monitored rock mass fractures.

[0003] At present, there is limited research on methods for predicting the height of coal seam roof fracture development using microseismic monitoring results, and there are the following problems: compared with simple ground microseismic monitoring, it is unavoidable that the data obtained from ground or underground monitoring have the disadvantages of few microseismic events, low signal-to-noise ratio, and poor inversion reliability due to reasons such as formation absorption and propagation path. Summary of the invention

[0004] The purpose of the present invention is to provide a method for monitoring the height of coal seam roof crack development using microseismic monitoring, which solves the shortcomings of the data obtained from ground or underground monitoring due to formation absorption, propagation path, etc., such as few microseismic events, low signal-to-noise ratio, and poor inversion reliability.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for monitoring the height of coal seam roof cracks using microseismic monitoring, characterized by comprising the following steps:

[0007] Surface microseismic monitoring points, underground tunnel microseismic monitoring points and in-hole microseismic monitoring points are arranged at the designed positions on the surface, underground tunnels and exploration boreholes;

[0008] The roof area to be observed is located within the monitoring range formed by the surface microseismic monitoring points, the underground tunnel microseismic monitoring points and the microseismic monitoring points in the hole;

[0009] The Direct calculation method is used to determine the spatial position of the microseismic event, obtain the point cloud of the microseismic event, and obtain the height of the crack development in the coal seam roof.

[0010] Preferably, the spatial stereoscopic position of the microseismic event is determined by three directions: X, Y, and Z.

[0011] Preferably, microseismic sensors are provided at the surface microseismic monitoring points, the underground tunnel microseismic monitoring points and the in-hole microseismic monitoring points.

[0012] Preferably, the surface microseismic monitoring points, underground tunnel microseismic monitoring points and in-hole microseismic monitoring points are arranged with equal radius around the center of the roof area to be observed.

[0013] Preferably, the radius of the surface microseismic monitoring points, the underground tunnel microseismic monitoring points and the in-hole microseismic monitoring points from the center of the coal seam roof area to be observed is no more than 100 meters.

[0014] Preferably, the Direct operation method selects a subdivision super-rectangle algorithm.

[0015] Preferably, the surface microseismic monitoring points are arranged in an array at designed positions on the surface.

[0016] Preferably, the microseismic monitoring points in the hole are arranged at equal intervals on the side wall of the drilling hole.

[0017] Preferably, the tunnel microseismic monitoring points are arranged in an array at designed positions on the ground surface.

[0018] Compared with the prior art, the present invention has achieved the following technical effects:

[0019] 1. The present invention improves the shortcoming of traditional microseismic monitoring that sensors are only placed on the ground or underground, resulting in inaccurate positioning. The present invention uses the "well-ground-hole" combined microseismic monitoring technology to comprehensively observe the microseismic signals generated during the development of coal seam roof cracks, thereby locating the microseismic events generated by the coal seam roof cracks. Compared with simple ground microseismic monitoring, it effectively avoids the shortcomings of few microseismic events, low signal-to-noise ratio, and poor inversion reliability in the data obtained from ground or underground monitoring due to formation absorption, propagation path, etc.

[0020] 2. The traditional microseismic location algorithm based on grid search is an "exhaustive method" whose location accuracy depends on the size of the grid division. The computational efficiency decreases as the grid is refined. For large-scale microseismic location, the computational efficiency is quite low. This project introduced the Direct algorithm and developed a microseismic monitoring stereo location algorithm based on the Direct algorithm, which has fast calculation speed and high positioning accuracy. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The purpose of the present invention is to provide a method for monitoring the height of coal seam roof crack development using microseismic monitoring, which solves the shortcomings of the data obtained from ground or underground monitoring due to formation absorption, propagation path, etc., such as few microseismic events, low signal-to-noise ratio, and poor inversion reliability.

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with specific implementation methods.

[0024] A method for monitoring the height of coal seam roof crack development by using microseismic monitoring comprises the following steps: arranging surface microseismic monitoring points, underground roadway microseismic monitoring points and in-hole microseismic monitoring points at designed positions on the surface, underground roadway and in-hole respectively; the roof area to be observed is located in the encirclement formed by the surface microseismic monitoring points, underground roadway microseismic monitoring points and in-hole microseismic monitoring points; using the Direct operation method, determining the spatial stereoscopic position of the microseismic event, and obtaining the microseismic event point cloud to obtain the height of coal seam roof crack development; the present invention improves the disadvantage of traditional microseismic monitoring that the sensor is only arranged on the ground or underground, resulting in inaccurate positioning, and uses the "well-ground-hole" combined microseismic monitoring technology to observe the microseismic signals generated in the process of coal seam roof crack development in all directions, so as to locate the microseismic events generated by the coal seam roof cracks. Compared with simple ground microseismic monitoring, it effectively avoids the disadvantages of less microseismic events, low signal-to-noise ratio, poor inversion reliability and the like in the data obtained by ground or underground monitoring due to formation absorption, propagation path and the like.

[0025] Furthermore, the spatial position of the microseismic event is determined by three directions: X, Y, and Z.

[0026] Furthermore, microseismic sensors are provided at the surface microseismic monitoring points, the underground tunnel microseismic monitoring points and the microseismic monitoring points in the hole.

[0027] Furthermore, the surface microseismic monitoring points, underground tunnel microseismic monitoring points and in-hole microseismic monitoring points are arranged with equal radius around the center of the roof area to be observed.

[0028] Furthermore, the radius of the surface microseismic monitoring points, the underground tunnel microseismic monitoring points and the in-hole microseismic monitoring points from the center of the coal seam roof area to be observed is no more than 100 meters.

[0029] Furthermore, the Direct operation method selects a subdivision super-rectangle algorithm.

[0030] Furthermore, the surface microseismic monitoring points are arranged in an array at designed positions on the surface.

[0031] Furthermore, the microseismic monitoring points in the hole are arranged at equal intervals on the side wall of the drilling hole.

[0032] Furthermore, the tunnel microseismic monitoring points are arranged in an array at designed positions on the ground surface.

[0033] Furthermore, the Direct operation method selects the subdivided hyperrectangle algorithm; the traditional microseismic positioning algorithm based on grid search is an "exhaustive method", and its positioning accuracy depends on the size of the grid division. The calculation efficiency decreases with the refinement of the grid. For large-scale microseismic positioning, the calculation efficiency is quite low. The present invention introduces the Direct algorithm and develops a microseismic monitoring stereo positioning algorithm based on the Direct algorithm, which has fast calculation speed and high positioning accuracy.

[0034] The present invention is based on the research on the height of the water-conducting fracture zone of the coal mine roof based on the well-ground combined microseismic monitoring technology. It innovatively adopts the well-ground combined microseismic monitoring method to carry out long-term monitoring of the height of the coal seam roof fracture during the mining process of the coal mine working face. According to the positioning results of the microseismic events, the height of the coal seam roof fracture development of the coal mine is determined, which provides a scientific basis for the prevention and control of coal mine roof water damage. The technology has high precision and simple construction, and can dynamically display the rupture process of the coal mine roof. The technology adopts the well-ground combined monitoring method. Compared with the monitoring only in the well or on the ground, it can greatly improve the positioning accuracy of the microseismic events and meet the prevention and control requirements of most mine roof water damage; compared with the traditional drilling observation method, the technology can easily obtain the dynamic changes of the roof during the mining process of the working face. It has obtained considerable economic benefits and good social benefits. At the same time, it is of great promotion value to mines with similar conditions in my country, especially the vast mines in the west that are affected by roof water damage.

[0035] In addition, the present invention adopts the method of "well-ground-hole" joint arrangement of seismic pickups and conducts a full surround method for the target working face, effectively obtaining microseismic events caused by rock formation damage during the working face recovery process, and through advanced Direct calculation methods, quickly and accurately determining the X, Y, and Z spatial positions of microseismic events, and obtaining microseismic event point clouds, effectively analyzing the development law of the "two zones". It replaces the traditional drilling exploration of the "two zones" development method, and has the advantages of high efficiency, energy saving, and science.

[0036] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for monitoring the height of crack development in coal seam roof using microseismic data, characterized in that: The following steps are involved: Surface microseismic monitoring points, underground tunnel microseismic monitoring points and in-hole microseismic monitoring points are arranged at the designed positions on the surface, underground tunnels and exploration boreholes; The roof area to be observed is located within the monitoring range formed by the surface microseismic monitoring points, the underground tunnel microseismic monitoring points and the microseismic monitoring points in the hole; The Direct calculation method is used to determine the spatial position of the microseismic event, obtain the point cloud of the microseismic event, and obtain the height of the crack development in the coal seam roof.

2. The method for monitoring the height of coal seam roof cracks using microseismic monitoring according to claim 1 is characterized in that: The spatial stereoscopic position of the microseismic event is determined by three directions: X, Y, and Z.

3. The method for monitoring the height of coal seam roof cracks by using microseismic data according to claim 1, characterized in that: Microseismic sensors are arranged at the surface microseismic monitoring points, the underground tunnel microseismic monitoring points and the microseismic monitoring points in the hole.

4. The method for monitoring the height of coal seam roof cracks by using microseismic data according to claim 1, characterized in that: The surface microseismic monitoring points, underground tunnel microseismic monitoring points and in-hole microseismic monitoring points are arranged with equal radius around the center of the top plate area to be observed.

5. The method for monitoring the height of crack development in coal seam roof by using microseismic data according to claim 4, characterized in that: The radius of the surface microseismic monitoring points, the underground tunnel microseismic monitoring points and the in-hole microseismic monitoring points from the center of the coal seam roof area to be observed is no more than 100 meters.

6. The method for monitoring the height of coal seam roof cracks by using microseismic data according to claim 1, characterized in that: The Direct operation method selects the subdivision super-rectangle algorithm.

7. The method for monitoring the height of coal seam roof cracks by using microseismic data according to claim 1, characterized in that: The surface microseismic monitoring points are arranged in an array at designed positions on the surface.

8. The method for monitoring the height of crack development in coal seam roof by microseismic detection according to claim 1, characterized in that: The microseismic monitoring points in the hole are arranged at equal intervals on the side wall of the drilling hole.

9. The method for monitoring the height of crack development in coal seam roof by using microseismic data according to claim 1, characterized in that: The tunnel microseismic monitoring points are arranged in an array at designed positions on the ground surface.