Device and method for testing in-situ porosity of coal rock

Abstract

The invention discloses a coal rock in-situ porosity testing device and method, and the device comprises a support which is provided with a vertical slide rail; the sliding table is arranged on the sliding rail of the bracket in a sliding manner; the drilling barrel is rotationally connected to the lower portion of the sliding table; the inner pipe is rotationally connected into the drilling barrel, and an air inlet hole is formed in the side wall of the upper portion of the drilling barrel; the upper end of the inner pipe penetrates to the position above the drilling barrel, and an air outlet hole is formed in the side wall of the upper portion of the inner pipe. The driving motor is arranged on the sliding table and used for driving the drilling barrel to rotate; the vacuum pump is arranged at the bottom of the support, the gas inlet hole is connected to a gas supply device, and the gas supply device can provide calibration gas; the air outlet hole is connected to the vacuum pump; compared with the prior art, errors possibly introduced in the processes of sample collection, transportation and laboratory treatment are avoided, so that the test precision is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coal rock detection, and in particular to a coal rock in-situ porosity testing device and method. Background Art

[0002] Coal rock porosity refers to the percentage of pore volume in coal rock to the total volume, which reflects the development degree and distribution of pores inside coal rock. The measurement of porosity is crucial to understanding the gas storage capacity, permeability and migration law of fluids in coal rock. Porosity testing can provide a scientific basis for the exploration, development and utilization of coalbed methane, which helps to optimize mining plans, improve mining efficiency, reduce mining costs and reduce environmental impact. In the field of coal resource exploration and development, the measurement of coal rock porosity is one of the key parameters for evaluating coal reservoir characteristics, predicting coalbed methane mining potential and optimizing mining plans. Porosity, as an important physical property of coal rock reservoirs, is directly related to the permeability, gas storage capacity and mining efficiency of coal reservoirs. Therefore, accurate and efficient measurement of coal rock porosity is of great significance for the sustainable development and utilization of coal resources.

[0003] The testing principle of coal rock porosity is mainly based on Boyle's law and gas permeability principle. Boyle's law states that under constant temperature, the pressure of a certain amount of gas is inversely proportional to its volume. By measuring the changes in pressure and volume of coal rock samples before and after gas injection, the pore volume of coal rock can be calculated, and then the porosity can be obtained. The gas permeability principle indirectly reflects the porosity and permeability of coal rock by measuring the penetration rate of gas in coal rock samples.

[0004] Although laboratory tests are highly accurate, they are affected by errors that may be introduced during sample collection, transportation, and pretreatment, making it difficult to fully guarantee the accuracy of the test results. Field tests, due to limited conditions, often use indirect measurements or estimates, which can result in large errors. It is also difficult to test the porosity of coal rocks in situ, and cannot truly reflect the actual conditions of coal reservoirs.

[0005] Therefore, it is necessary to provide a coal rock in-situ porosity testing device and method to solve the problems raised in the above background technology. Summary of the invention

[0006] To achieve the above object, the present invention provides the following technical solution: a coal rock in-situ porosity testing device, comprising:

[0007] A bracket, wherein the bracket has a vertical slide rail;

[0008] A slide table, the slide table is slidably arranged on a slide rail of the bracket;

[0009] A drill tube, the drill tube is rotatably connected below the slide;

[0010] An inner tube, the inner tube is rotatably connected to the drill tube, wherein:

[0011] The side wall of the upper portion of the drill tube is provided with an air inlet hole;

[0012] The upper end of the inner tube passes through the top of the drill pipe, and the side wall of the upper part of the inner tube is provided with an air outlet;

[0013] A driving motor, the driving motor is arranged on the slide and is used to drive the drill tube to rotate;

[0014] A vacuum pump is disposed at the bottom of the bracket.

[0015] Wherein, the air inlet is connected to a gas supply device, which can provide calibration gas;

[0016] The gas outlet is connected to the vacuum pump.

[0017] Furthermore, a sensor for detecting the calibration gas is provided at the exhaust port of the vacuum pump;

[0018] The gas supply device comprises a gas storage tank for storing calibration gas and a flow controller for detecting gas flow.

[0019] Furthermore, a drill bit is connected to the bottom of the inner tube, and saw teeth are distributed on the side wall of the lower end of the drill tube.

[0020] Furthermore, a lower bevel gear is fixed to the upper end of the drill tube, an upper bevel gear is fixed to the upper end of the inner tube, a horizontal driving bevel gear is rotatably arranged in the slide, the lower bevel gear and the upper bevel gear are both meshed with the driving bevel gear, and the driving motor is used to drive the driving bevel gear to rotate.

[0021] Furthermore, a winch is provided at the bottom of the bracket, and the winch is connected to a pull rope, and the pull rope passes around the top of the bracket and is fixed to the slide.

[0022] Furthermore, the inner tube side wall is provided with multiple circles of air extraction holes at different heights;

[0023] A groove is also provided at each circle of the air extraction holes on the inner wall of the inner tube, a slip ring is slidably provided in the groove, and the height of the slip ring is greater than the diameter of the air extraction hole;

[0024] The inner wall of the groove is also provided with a plurality of vertical sliding grooves, and the slip ring is slidably connected to the sliding grooves, thereby limiting the rotation of the slip ring.

[0025] Furthermore, the slip ring is made of magnetic conductive material, and magnets are arranged above and below the groove.

[0026] Furthermore, the piston disc is provided with a plurality of vent holes which pass through from top to bottom so that air can pass through the piston disc.

[0027] Furthermore, a screw is rotated in the inner tube, a piston disc is slidably arranged in the inner tube, and the piston disc is threadedly connected to the screw;

[0028] The inner walls of the inner tube and the slip ring are provided with multiple sliding grooves;

[0029] The outer wall of the piston disc is provided with a plurality of convex strips and a plurality of rubber balls, the convex strips are embedded in the slide grooves, and the rubber balls can fit with the slide rings.

[0030] A method for using a coal rock in-situ porosity testing device, comprising:

[0031] S1. Select a suitable measurement position at the coal mine site, ensure that the measurement position is flat and stable, and ensure that the measurement position can represent the porosity characteristics of the entire coal layer, so that the drill tube and inner tube are gradually drilled into the coal layer;

[0032] S2, connect the pipeline of the air supply device to the air inlet, and connect the pipeline of the vacuum pump to the air outlet;

[0033] S3, turn on the gas supply device, inject calibration gas into the drill tube, start the vacuum pump, suck the gas in the drill tube through the inner tube, so that the calibration gas is extracted through the inner tube and the gas outlet, set a sensor at the exhaust port of the vacuum pump to monitor the gas composition in real time, and when the sensor detects the calibration gas, record the volume of the calibration gas output by the gas supply device;

[0034] S4. Calculate the volume of the coal rock layer in the drill barrel according to the diameter of the drill barrel and the drilling depth. Calculate the porosity of the coal rock layer according to the volume of the calibration gas and the volume of the coal rock layer. The porosity calculation formula is: Porosity = calibration gas volume / coal rock layer volume × 100%.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] In the present invention, by directly conducting in-situ testing at the coal mine site, errors that may be introduced during sample collection, transportation and laboratory processing are avoided, thereby improving the accuracy of the test. At the same time, the calibration gas supply system and vacuum suction system built into the device can ensure accurate injection and effective suction of gas during the test, further improving the accuracy of the test.

[0037] In the present invention, the reverse rotation design of the drill tube and the inner tube can ensure that the cutting force and torque when drilling into the coal and rock layers are moderate, thereby avoiding excessive damage to the coal and rock layers.

[0038] In the present invention, the piston disc and slip ring system built into the device can realize layered detection of coal rock layers at different depths without the need for destructive sampling of the entire coal rock layer, thereby protecting the original state of the coal rock, and can realize accurate measurement of the porosity of the coal rock at different depths, providing more detailed data support for coalbed methane extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of a coal rock in-situ porosity testing device;

[0040] Figure 2 It is a structural schematic diagram of the slide;

[0041] Figure 3 It is a schematic diagram of the structure inside the drill tube;

[0042] Figure 4 It is a schematic diagram of the structure inside the inner tube when the piston disc is located above the air extraction hole;

[0043] Figure 5 It is a schematic diagram of the structure inside the inner tube when the piston disc is located below the air extraction hole;

[0044] In the figure: 1. bracket; 2. slide; 3. drill tube; 31. air inlet; 32. sawtooth; 4. pull rope; 5. winch; 6. inner tube; 61. air outlet; 62. air extraction hole; 63. piston plate; 631. vent hole; 632. convex strip; 633. rubber ball; 64. drill bit; 65. groove; 66. slip ring; 7. screw; 8. vacuum pump; 9. driving bevel gear; 10. lower bevel gear; 11. upper bevel gear; 12. driving motor. DETAILED DESCRIPTION

[0045] See also Figure 1-Figure 5 In an embodiment of the present invention, a coal rock in-situ porosity testing device includes:

[0046] A bracket 1, wherein the bracket 1 has a vertical slide rail;

[0047] A slide 2, wherein the slide 2 is slidably disposed on a slide rail of the bracket 1;

[0048] A drill tube 3, wherein the drill tube 3 is rotatably connected to the bottom of the slide 2;

[0049] The inner tube 6 is rotatably connected to the drill tube 3, wherein:

[0050] The side wall of the upper portion of the drill tube 3 is provided with an air inlet hole 31;

[0051] The upper end of the inner tube 6 penetrates above the drill pipe 3, and the side wall of the upper part of the inner tube 6 is provided with an air outlet 61;

[0052] A driving motor 12, wherein the driving motor 12 is disposed on the slide 2 and is used to drive the drill tube 3 to rotate;

[0053] A vacuum pump 8 is provided at the bottom of the bracket 1.

[0054] Wherein, the air inlet 31 is connected to a gas supply device, which can provide calibration gas;

[0055] The air outlet 61 is connected to the vacuum pump 8 .

[0056] When the vacuum pump 8 is sucking, negative pressure is generated in the inner tube 6, causing the calibration gas to enter the drill barrel 3 through the air inlet 31 and be sucked by the vacuum pump 8 through the air outlet 61. When the sensor detects the calibration gas, it indicates that the coal rock in the drill barrel 3 has been infiltrated by the calibration gas. By calculating the volume of the calibration gas discharged from the gas supply device and the volume of the coal rock in the drill barrel 3, the porosity of the coal rock can be obtained.

[0057] In this embodiment, a sensor for detecting the calibration gas is provided at the exhaust port of the vacuum pump 8 .

[0058] In this embodiment, the gas supply device includes a gas storage tank for storing calibration gas and a flow controller for detecting gas flow.

[0059] In this embodiment, a drill bit 64 is connected to the bottom of the inner tube 6 .

[0060] In this embodiment, saw teeth 32 are distributed on the side wall of the lower end of the drill tube 3 .

[0061] In this embodiment, a lower bevel gear 10 is fixed to the upper end of the drill tube 3, an upper bevel gear 11 is fixed to the upper end of the inner tube 6, a horizontal driving bevel gear 9 is rotatably arranged in the slide 2, the lower bevel gear 10 and the upper bevel gear 11 are both engaged with the driving bevel gear 9, and the driving motor 12 is used to drive the driving bevel gear 9 to rotate.

[0062] That is to say, driving the bevel gear 9 to rotate can simultaneously drive the lower bevel gear 10 and the upper bevel gear 11 to rotate in the opposite direction, thereby causing the drill barrel 3 and the inner tube 6 to rotate in the opposite direction. The reverse rotation design of the drill barrel 3 and the inner tube 6 can increase the cutting force and torque when drilling into the coal and rock formations, so that the device can drill into the coal and rock formations more efficiently. During the drilling process, the reverse rotation of the drill barrel 3 and the inner tube 6 can ensure that the coal and rock formations in the drill barrel 3 are subjected to balanced forces, thereby avoiding damage to the original state of the coal and rock formations.

[0063] In this embodiment, a winch 5 is provided at the bottom of the bracket 1 , and the winch 5 is connected to a pull rope 4 . The pull rope 4 passes over the top of the bracket 1 and is fixed to the slide 2 .

[0064] The lifting and lowering of the slide 2 can be controlled by winding up the pull rope 4 with the winch 5 .

[0065] In this embodiment, the side wall of the inner tube 6 is provided with multiple circles of air extraction holes 62 at different heights;

[0066] A groove 65 is further provided at each circle of the air extraction holes 62 on the inner wall of the inner tube 6, and a slip ring 66 is slidably provided in the groove 65, and the height of the slip ring 66 is greater than the diameter of the air extraction holes 62;

[0067] The inner wall of the groove 65 is also provided with a plurality of vertical sliding grooves, and the slip ring 66 is slidably connected to the sliding grooves, thereby limiting the rotation of the slip ring 66.

[0068] That is to say, the circle of air extraction holes 62 can be opened or closed by sliding the slip ring 66 up and down, so that air can be extracted from the drill tube 3 at different depths to achieve the purpose of layered detection.

[0069] In this embodiment, the slip ring 66 is made of a magnetic conductive material, and magnets are disposed above and below the groove 65 .

[0070] That is to say, the slip ring 66 can be adsorbed above or below the groove 65 by the magnet.

[0071] In this embodiment, a plurality of vent holes 631 extending vertically through the piston disk 63 are formed in the piston disk 63 so that air can pass through the piston disk 63 .

[0072] In this embodiment, a screw rod 7 is rotated in the inner tube 6, a piston plate 63 is slidably arranged in the inner tube 6, and the piston plate 63 is threadedly connected to the screw rod 7;

[0073] The inner walls of the inner tube 6 and the slip ring 66 are provided with a plurality of slide grooves;

[0074] The outer wall of the piston plate 63 is distributed with a plurality of convex strips 632 and a plurality of rubber balls 633 . The convex strips 632 are embedded in the sliding grooves, and the rubber balls 633 can fit with the sliding ring 66 .

[0075] Since the convex strips 632 distributed on the outer wall of the piston disc 63 are embedded in the slide groove, the rotation of the piston disc 63 can be limited. The piston disc 63 can slide up and down in the inner tube 6 by rotating the screw rod 7. When the piston disc 63 passes through the slip ring 66 from top to bottom, the rubber ball 633 fits against the slip ring 66, and the friction force drives the slip ring 66 to slide down and adsorb the slip ring 66 to the magnet under the groove 65, thereby closing the circle of air extraction holes 62. Conversely, when the piston disc 63 passes through the slip ring 66 from bottom to top, the circle of air extraction holes 62 can be opened.

[0076] When the circle of exhaust holes 62 is opened and the sensor detects the calibration gas under the suction state of the vacuum pump 8, it indicates that the coal rock in the drill barrel 3 above that height has been infiltrated by the calibration gas. By closing each slip ring 66 from top to bottom in turn, the porosity of each layer of coal rock can be detected layer by layer from top to bottom.

[0077] A coal rock in-situ porosity testing method, comprising:

[0078] S1. Select a suitable measurement position at the coal mine site, ensure that the measurement position is flat and stable, and ensure that the measurement position can represent the porosity characteristics of the entire coal layer, so that the drill tube 3 and the inner tube 6 are gradually drilled into the coal layer;

[0079] S2, connecting the pipeline of the air supply device to the air inlet 31, and connecting the pipeline of the vacuum pump 8 to the air outlet 61;

[0080] S3, turn on the gas supply device, inject calibration gas into the drill tube 3, start the vacuum pump 8, suck the gas in the drill tube 3 through the inner tube 6, so that the calibration gas is extracted through the inner tube 6 and the gas outlet 61, and set a sensor at the exhaust port of the vacuum pump 8 to monitor the gas composition in real time. When the sensor detects the calibration gas, the volume of the calibration gas output by the gas supply device is recorded;

[0081] S4. Calculate the volume of the coal layer in the drill tube 3 according to the diameter of the drill tube 3 and the drilling depth. Calculate the porosity of the coal layer according to the volume of the calibration gas and the volume of the coal layer. The porosity calculation formula is: porosity = calibration gas volume / coal layer volume × 100%.

[0082] In this embodiment, the steps of using the piston disc 63 are also included:

[0083] When the drill tube 3 and the inner tube 6 are drilling into the coal and rock layer, the piston plate 63 slides to the bottom of the inner tube 6, and all the air extraction holes 62 are in a closed state to prevent stones from blocking the air extraction holes 62 and entering the inner tube 6;

[0084] Before the test begins, the piston plate 63 is slid to the top of the inner tube 6 by rotating the screw 7, so that all the air extraction holes 62 are in an open state;

[0085] When the inner tube 6 sucks the gas in the drill tube 3, when the sensor detects the calibration gas for the first time, the gas supply device stops outputting the calibration gas and records the volume of the calibration gas output before. According to the height of the first circle of gas extraction holes 62, the volume of the coal rock layer in the drill tube 3 above the height is obtained to obtain the porosity of the first coal rock layer.

[0086] The piston plate 63 is slid to a position below the first circle of air pumping holes 62 by rotating the screw rod 7, and the first circle of air pumping holes 62 is closed at this time;

[0087] Repeat the above detection arrangement, gradually close the exhaust holes 62 at different heights from top to bottom, record the volume of the calibration gas output at each circle of exhaust holes 62, and combine the height of each circle of exhaust holes 62 to achieve the purpose of layered detection.

[0088] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A coal rock in-situ porosity testing device, characterized in that: include: A bracket (1), wherein the bracket (1) has a vertical slide rail; A slide table (2), the slide table (2) being slidably arranged on a slide rail of the bracket (1); A drill tube (3), the drill tube (3) being rotatably connected to the bottom of the slide table (2); An inner tube (6), the inner tube (6) being rotatably connected to the drill tube (3), wherein: An air inlet hole (31) is provided on the side wall of the upper portion of the drill tube (3); The upper end of the inner tube (6) penetrates above the drill pipe (3), and the side wall of the upper portion of the inner tube (6) is provided with an air outlet hole (61); A drive motor (12), the drive motor (12) being arranged on the slide table (2) and used for driving the drill tube (3) to rotate; a vacuum pump (8), wherein the vacuum pump (8) is arranged at the bottom of the bracket (1), Wherein, the air inlet (31) is connected to a gas supply device, and the gas supply device is capable of providing calibration gas; The air outlet (61) is connected to the vacuum pump (8).

2. The coal rock in-situ porosity testing device according to claim 1, characterized in that: A sensor for detecting the calibration gas is provided at the exhaust port of the vacuum pump (8); The gas supply device comprises a gas storage tank for storing calibration gas and a flow controller for detecting gas flow.

3. The coal rock in-situ porosity testing device according to claim 1, characterized in that: The bottom of the inner tube (6) is connected to a drill bit (64), and the side wall of the lower end of the drill tube (3) is provided with saw teeth (32).

4. The coal rock in-situ porosity testing device according to claim 1, characterized in that: A lower bevel gear (10) is fixed to the upper end of the drill tube (3), an upper bevel gear (11) is fixed to the upper end of the inner tube (6), a horizontal driving bevel gear (9) is rotatably arranged in the slide (2), the lower bevel gear (10) and the upper bevel gear (11) are both meshed with the driving bevel gear (9), and the driving motor (12) is used to drive the driving bevel gear (9) to rotate.

5. The coal rock in-situ porosity testing device according to claim 1, characterized in that: A winch (5) is provided at the bottom of the bracket (1), and the winch (5) is connected to a pull rope (4). The pull rope (4) passes around the top of the bracket (1) and is fixed to the slide (2).

6. The coal rock in-situ porosity testing device according to claim 1, characterized in that: The side wall of the inner tube (6) is provided with a plurality of circles of air extraction holes (62) distributed at different heights; A groove (65) is further provided at each circle of the air extraction holes (62) on the inner wall of the inner tube (6), a slip ring (66) is slidably arranged in the groove (65), and the height of the slip ring (66) is greater than the diameter of the air extraction holes (62); The inner wall of the groove (65) is also provided with a plurality of vertical sliding grooves, and the slip ring (66) is slidably connected to the sliding grooves, thereby limiting the rotation of the slip ring (66).

7. The coal rock in-situ porosity testing device according to claim 6, characterized in that: The slip ring (66) is made of a magnetic conductive material, and magnets are arranged above and below the groove (65).

8. The coal rock in-situ porosity testing device according to claim 6, characterized in that: The piston disk (63) is provided with a plurality of vent holes (631) that penetrate vertically, so that air can pass through the piston disk (63).

9. The coal rock in-situ porosity testing device according to claim 6, characterized in that: A screw rod (7) is rotated in the inner tube (6), a piston plate (63) is slidably arranged in the inner tube (6), and the piston plate (63) is threadedly connected to the screw rod (7); The inner walls of the inner tube (6) and the slip ring (66) are provided with a plurality of sliding grooves; The outer wall of the piston disc (63) is provided with a plurality of convex strips (632) and a plurality of rubber balls (633); the convex strips (632) are embedded in the slide grooves; and the rubber balls (633) are capable of fitting with the slide ring (66).

10. A method for using a coal rock in-situ porosity testing device, using the coal rock in-situ porosity testing device according to any one of claim 1, characterized in that: include: S1. Select a suitable measurement position at the coal mine site, ensure that the measurement position is flat and stable, and ensure that the measurement position can represent the porosity characteristics of the entire coal layer, so that the drill tube (3) and the inner tube (6) are gradually drilled into the coal layer; S2, connecting the pipeline of the air supply device to the air inlet (31), and connecting the pipeline of the vacuum pump (8) to the air outlet (61); S3, turning on the gas supply device, injecting calibration gas into the drill tube (3), starting the vacuum pump (8), sucking the gas in the drill tube (3) through the inner tube (6), so that the calibration gas is drawn out through the inner tube (6) and the gas outlet (61), and arranging a sensor at the exhaust port of the vacuum pump (8) to monitor the gas composition in real time. When the sensor detects the calibration gas, the volume of the calibration gas output by the gas supply device is recorded; S4. The volume of the coal rock layer in the drill tube (3) is calculated based on the diameter of the drill tube (3) and the drilling depth. The porosity of the coal rock layer is calculated based on the volume of the calibration gas and the volume of the coal rock layer. The porosity calculation formula is: porosity = calibration gas volume / coal rock layer volume × 100%.

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