Coal seam ground stress measuring device

Abstract

The utility model relates to a coal seam crustal stress measuring device which comprises a bag, a pressure sensor, a reading meter and a long plastic pipe, and the bag is arranged in a drill hole of a coal seam crustal stress area to be measured. The interior of the bag is filled with expansion particles, and the expansion particles are attached to the inner wall of the drill hole after being completely expanded; a pressure sensor is arranged at the top of the bag, the pressure sensor is connected with a reading meter, and the pressure sensor is used for measuring parameters of pressure borne by the surface of the bag and transmitting the parameters to the reading meter; one end of the bag is connected with a long plastic pipe, and the other end of the long plastic pipe extends out of the drill hole. Measurement of stress parameters of a to-be-measured coal seam ground stress area and real-time monitoring of stress change conditions are achieved, and a large amount of time and manpower and material resource cost are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of geological measurement, in particular to a coal seam ground stress measuring device. Background Art

[0002] Geostress is the fundamental force that causes the crustal rock mass to form geological structures such as folds, fractures, and joints. In the design and construction of oil and gas exploration, drilling, and oil production projects, the geostress data of coal seams is an indispensable basic parameter. It plays a vital role in judging the stability of the well wall and the fracture force of the formation. The geostress data of coal seams can be used for the design and control of the borehole trajectory of directional and horizontal wells, and is the prerequisite for achieving scientific well layout. Therefore, it is very necessary to measure the geostress of coal seams.

[0003] Some mines in my country have entered the deep mining stage. With the increase of coal seam burial depth, ground stress is also increasing. Coal and gas outburst is a special dynamic phenomenon in which broken coal and gas are suddenly ejected from the coal body into the mining space under the action of ground stress and gas pressure. It is the most frequent and most harmful type of accident in coal mines. In order to prevent accidents, regional gas control measures such as mining protective layers and pre-extraction of coal seam gas are often adopted.

[0004] Coal seam ground stress parameters are an important indicator for formulating regional gas control plans and testing the effectiveness of regional outburst prevention measures. Therefore, accurate determination of coal seam ground stress parameters is an important link in the prevention and control of coal and gas outbursts.

[0005] At present, oil pillow type borehole stress gauges are mostly used to measure coal seam geostress, which convert the changes in coal seam geostress into electrical signals for reading. However, oil pillow type borehole stress gauges can only measure the relative changes in geostress and it is difficult to measure its absolute value. In addition, the cost of use is high, the installation steps are relatively cumbersome, and it is easy to be disturbed, resulting in a decrease in measurement accuracy. Utility Model Content

[0006] The purpose of the utility model is to overcome the above-mentioned shortcomings and provide a coal seam ground stress measuring device to achieve rapid and accurate measurement of coal seam ground stress, provide guidance for the adoption of coal and gas outburst prevention and control measures, and eliminate the danger of coal seam outburst.

[0007] The purpose of the utility model is achieved in this way:

[0008] A coal seam ground stress measuring device comprises a bag, a pressure sensor, an indicator and a long plastic tube, wherein the bag is arranged in a borehole in a coal seam ground stress measuring area; the bag is filled with expansion particles, and the expansion particles are fitted with the inner wall of the borehole after being fully expanded; a pressure sensor is arranged on the top of the bag, and the pressure sensor is connected to the indicator, and the pressure sensor transmits the pressure parameters on the surface of the bag to the indicator; one end of the bag is connected to the long plastic tube, and the other end of the long plastic tube extends out of the borehole; the indicator and the pressure sensor are connected in a wired or wireless manner, and the parameters given by the pressure sensor can be processed and displayed for real-time reading, and the connecting line between the indicator and the pressure sensor can be led out from the long plastic tube.

[0009] Furthermore, after the expanded particles in the pouch are fully expanded, the pouch is cylindrical in shape, with a length of 20 to 50 cm and a diameter of 4 to 10 cm.

[0010] Furthermore, the pouch is made of fiber materials with certain strength and elasticity, such as natural fibers such as cotton and linen, or artificial synthetic fibers.

[0011] Furthermore, the expansion particles are made of slowly expandable materials, such as polymer water-absorbing expansion agents, concrete expansion agents or controllable expansion plugging agents.

[0012] Furthermore, in the absence of external force, the fully expanded particles exert a pressure of 10-20 MPa on the outer wall of the pouch.

[0013] Compared with the prior art, the beneficial effects of the utility model are:

[0014] The utility model provides a coal seam ground stress measuring device, which uses expansion particles to allow the bag to quickly fit the inner wall of the borehole, overcoming the shortcomings of the slow expansion speed and low efficiency of the oil pillow type borehole stress gauge using the oil injection pump; and uses the force balance method to measure the absolute ground stress of the coal seam, overcoming the shortcomings of the oil pillow type borehole stress gauge that can only measure the relative change of ground stress. The method of the utility model is simple, has low time and labor costs and good effects, and has wide applicability in the technical field. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the measuring device of the utility model.

[0016] in:

[0017] Bag 1, expansion particles 2, pressure sensor 3, indicator 4, coal seam ground stress test area 5, drill hole 6, long plastic pipe 7. DETAILED DESCRIPTION

[0018] In order to better understand the technical solution of the present invention, the following will be described in detail in conjunction with the relevant illustrations. It should be understood that the following specific embodiments are not intended to limit the specific implementation of the technical solution of the present invention, and are only implementations that can be adopted by the technical solution of the present invention. It should be noted that the description of the positional relationship of each component in this article, such as component A being located above component B, is based on the description of the relative positions of the components in the illustration, and is not intended to limit the actual positional relationship of the components. Example 1

[0019] See also Figure 1 , Figure 1 A schematic diagram of the structure of the coal seam ground stress measuring device of this embodiment 1 is drawn. As shown in the figure, a coal seam ground stress measuring device of the utility model comprises a bag 1, a pressure sensor 3, an indicator 4 and a long plastic tube 7, wherein the bag 1 is arranged in a borehole 6 of a coal seam ground stress measuring area 5.

[0020] The bag 1 is filled with expandable particles 2. After full expansion, the bag 1 is cylindrical, about 30 cm long and 5 cm in diameter. The expandable particles 2 will fully expand after about 15 minutes of filling, fit with the inner wall of the borehole 6, and fill the aperture of the borehole 6; in the absence of external force, the fully expanded expandable particles 2 can apply a pressure of up to 10-15 MPa to the outer wall of the bag 1.

[0021] A pressure sensor 3 is arranged on the top of the bag 1, and the pressure sensor 3 is connected to a display gauge 4. The pressure sensor 3 can accurately and quickly measure the pressure parameters on the surface of the bag 1 and transmit the parameters to the display gauge 4. The display gauge 4 is connected to the pressure sensor 3 in a wired or wireless manner, and the parameters given by the pressure sensor 3 can be processed and displayed for real-time reading.

[0022] One end of the bag 1 is connected to a long plastic tube 7 , and the other end of the long plastic tube 7 extends out of a borehole 6 . The connecting line between the indicator 4 and the pressure sensor 3 can be led out from the long plastic tube 7 .

[0023] The bag 1 can be made of natural fibers such as cotton and linen or artificial synthetic fibers with certain strength and elasticity; the expansion particles 2 can be made of slowly expandable materials such as polymer water-absorbing expansion agents, concrete expansion agents or controllable expansion plugging agents.

[0024] The utility model discloses a method for measuring coal seam ground stress, comprising the following steps:

[0025] Step 1: Drilling

[0026] A borehole 6 is constructed along the layer in the area 5 to be tested for coal seam ground stress. The diameter of the borehole 6 is about 5 cm and the depth is 7-15 m.

[0027] Step 2: Install the pouch

[0028] Fill the expanded particles 2 into the bag 1 and seal it, and use the long plastic tube 7 to quickly deliver the bag 1 to the designed position in the drill hole 6;

[0029] Step 3: Determine pressure parameters

[0030] The bladder 1 begins to expand under the action of the expansion particles 2, and gradually fits with the inner wall of the borehole 6. The pressure sensor 3 installed on the outer wall of the bladder 1 contacts the inner wall of the borehole 6. The pressure sensor 3 begins to generate pressure parameters and transmits the pressure parameters to the indicator 4.

[0031] Step 4: Read the pressure parameters

[0032] Observe the reading of the indicator 4. When the reading is stable, it means that the outer wall of the bag 1 and the inner wall of the borehole 6 are completely attached to each other, and the bag 1 is in a force balance state. At this time, the pressure on the pressure sensor 3 is the ground stress of the coal seam ground stress test area 5, which can be directly read by the indicator 4;

[0033] Step 5: Monitor changes in ground stress

[0034] With the implementation of coal and gas outburst prevention and control measures, if the ground stress in the coal seam ground stress test area 5 changes, the pressure on the pressure sensor 3 will also change accordingly, and the ground stress change can be monitored in real time through the indicator meter 4.

[0035] Working principle:

[0036] The utility model discloses a coal seam geostress measuring device. After expansion particles are filled into a bag, the bag is sent into a coal seam geostress measuring area along a borehole. After the expansion particles expand, the outer wall of the bag quickly fits with the inner wall of the borehole. The geostress is accurately measured using a pressure sensor installed on the outer wall of the bag. The utility model realizes the measurement of stress parameters in the coal seam geostress measuring area and real-time monitoring of stress changes, thereby reducing a lot of time and manpower and material costs.

[0037] The above are only specific application examples of the utility model, and do not constitute any limitation on the protection scope of the utility model. Any technical solution formed by equivalent transformation or equivalent replacement shall fall within the protection scope of the utility model.

Claims

1. A coal seam ground stress measuring device, characterized in that: The invention comprises a bag (1), a pressure sensor (3), an indicator (4) and a long plastic tube (7). The bag (1) is arranged in a borehole (6) of a coal seam ground stress test area (5). The bag (1) is filled with expansion particles (2). After the expansion particles (2) are fully expanded, they are in contact with the inner wall of the borehole (6). A pressure sensor (3) is arranged on the top of the bag (1). The pressure sensor (3) is connected to the indicator (4). The pressure sensor (3) transmits the pressure parameter measured on the surface of the bag (1) to the indicator (4). One end of the bag (1) is connected to the long plastic tube (7). The other end of the long plastic tube (7) extends out of the borehole (6). The indicator (4) and the pressure sensor (3) are connected in a wired or wireless manner. The parameters given by the pressure sensor (3) are processed and displayed. The connecting line between the indicator (4) and the pressure sensor (3) can be led out from the long plastic tube (7).

2. A coal seam ground stress measuring device according to claim 1, characterized in that: After the expanded particles (2) in the pouch (1) are fully expanded, the pouch (1) is cylindrical in shape, with a length of 20 to 50 cm and a diameter of 4 to 10 cm.

3. A coal seam ground stress measuring device according to claim 1, characterized in that: The bag (1) is made of natural fiber or artificial synthetic fiber fiber material with strength and elasticity.

4. A coal seam ground stress measuring device according to claim 1, characterized in that: The expansion particles (2) are made of a material that can slowly expand.

5. The device for measuring coal seam ground stress according to claim 1, characterized in that: In the absence of external force, the fully expanded particles (2) exert a pressure of 10-20 MPa on the outer wall of the pouch (1).

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