Segmented hydrostatic test device

Abstract

A segmented water pressure test device is arranged in a water injection drill hole 10 of an actually measured working face top plate two-zone and a bottom plate damage zone and comprises a first hole packer 20, a second hole packer 30 and an expansion connecting pipe 40, the expansion connecting pipe 40 is communicated with an expansion cavity of the first hole packer 20 and an expansion inner cavity of the second hole packer 30, the second hole packer is arranged on the side close to a hole opening 11 of the water injection drill hole 10, and the expansion inner cavity of the second hole packer 30 is communicated with the expansion inner cavity of the expansion connecting pipe 40. The interval space between the first hole packer and the second hole packer is a segmented hydrostatic test section S. The second hole packer 30 is connected with a test water injection pipeline 12 and an expansion pressure pipeline 13. The utility model has the beneficial effects that the double plugging devices are adopted to carry out segmented water pressure test on a single water injection drill hole, test data of the whole segment of the water injection drill hole can be obtained, test positions can be flexibly selected, the number of the water injection drill holes and test equipment are reduced, the test cost is obviously saved, the working efficiency and the equipment utilization rate are improved, and the production cost is reduced. And the test data is enriched.

Description

Technical Field

[0001] This utility model relates to the technical field of testing the "two zones" of the roof and the failure zone of the floor in coal mine working faces, and in particular to a segmented hydrostatic testing device. Background Technology

[0002] When aquifers, near-water bodies, or confined water exist above a coal seam being mined, and the mining process causes destructive effects that are transmitted to the roof and floor, the roof collapse zone, roof water-conducting fracture zone (commonly known as the "two roof zones"), and the floor mining-induced damage zone and geological structures can easily induce water inrushes into the mining space, posing a serious threat to safe coal mining operations. Therefore, coal mine safety measures require determining the development height of the roof "two roof zones" and the depth of the floor damage zone to provide fundamental data support for safety analysis and demonstration of modules, coal pillar placement, and other coal mine safety work.

[0003] Article 27 of the "Detailed Rules for Geological Work in Coal Mines" stipulates that in the general survey of water-conducting fracture zones, the height of the water-conducting fracture zone in the mining area should be determined by actual measurement methods, and the scope and extent of the impact should be predicted. Mines threatened by floor water should ascertain the depth of the floor water-conducting damage zone caused by mining.

[0004] The testing principles for the roof "two zones" and the floor failure zone are basically the same. Currently, the double-plug method is generally used, with equal-length leakage tests to determine the depth of the floor failure zone, combined with borehole inspection (breach television). Borehole construction can be carried out on the corresponding ground surface or near the roadway at the mining face.

[0005] Chinese utility model patent (patent number: CN201710196579) discloses a method for detecting the depth of the working face floor damage zone through drilling and water injection. This method involves drilling water injection holes at different depths in adjacent roadways, with most holes using casing, except for the end holes which are left uncased. Water is continuously injected and pressurized into the holes before and after mining, and the pressure and leakage changes are continuously observed. The depth of floor damage is determined based on the drilling pressure and leakage. This technical solution allows each hole to be used for water injection tests at a specific depth. For example, in the embodiment described in the patent document, six holes are set at one test point, with the final hole locations at 18m, 20m, 22m, 24m, 26m, and 30m below the working face floor, respectively. In this technical solution, multiple water injection boreholes need to be drilled at a single test point (drilling site), resulting in a large workload and high testing costs. Each water injection borehole can only collect water injection test data at a fixed point, and the pre-designed center hole position of each borehole prevents flexible testing at full depths and hinders the detection of newly developed fractures. As an improvement, a segmented test can be conducted on a single water injection borehole to obtain test data at multiple different depths. This technical solution requires a device to implement segmented testing. Utility Model Content

[0006] The purpose of this invention is to propose a segmented hydrostatic testing device to improve the efficiency of hydrostatic testing and obtain richer and more comprehensive test data.

[0007] To achieve the above objectives, the technical solution of this utility model is: a segmented hydrostatic test device, which is set in the water injection borehole (10) of the top plate "two zones" and the bottom plate failure zone of the actual working face, including a first sealing device (20), a second sealing device (30) and an expansion connecting pipe (40). The expansion connecting pipe (40) connects the expansion cavity of the first sealing device (20) and the expansion inner cavity of the second sealing device (30). The second sealing device is located on the side close to the orifice (11) of the water injection borehole (10). The space between the first sealing device (20) and the second sealing device (30) is the segmented hydrostatic test section (S). The second sealing device (30) connects the test water injection pipe (12) and the expansion pressure pipe (13). The test water injection pipe (12) connects the segmented hydrostatic test section (S).

[0008] Furthermore, a preferred sealing device structure is as follows: one end of the first sealing device (20) is provided with a first expansion pipe interface (21), one end of the second sealing device (30) is provided with a second expansion pipe interface (31) and a second water injection pipe interface (32), the other end of the second sealing device (30) is provided with a second expansion pipe string interface (33) and a second water injection pipe outlet (34), the second water injection pipe outlet (34) is connected from the second sealing device to the second water injection pipe interface (32), the first expansion pipe interface (21) and the second expansion pipe string interface (33) are connected through an expansion connecting pipe (40), the second expansion pipe interface (31) is connected to an expansion pressure pipe (13), the second water injection pipe interface (32) is connected to a test water injection pipe (12), and the second water injection pipe outlet (34) is connected to the segmented water pressure test section (S).

[0009] Furthermore, in order to facilitate the entry of the sealing device into the water injection borehole and to ensure the accurate length of the segmented water pressure test section, the expansion connecting pipe (40) is a rigid pipe.

[0010] Furthermore, in order to obtain test data, the test water injection pipe (12) and the expansion pressure pipe (13) are connected to a water injection pump (14), a pressure sensor (15) and a timer (16) are provided on the test water injection pipe (12), and control valves are provided on the test water injection pipe (12) and the expansion pressure pipe (13).

[0011] The beneficial effects of this utility model are: by using a double plugger to conduct segmented water pressure tests on a single water injection borehole, test data for the entire section of the water injection borehole can be obtained, and the test location can be flexibly selected, reducing the number of water injection boreholes and test equipment, significantly saving test costs, improving work efficiency and equipment utilization, and enriching test data.

[0012] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the water injection drilling system of this utility model;

[0014] Figure 2 This is a structural diagram of the dual-sealing device of this utility model, viewed from the top (second sealing device side);

[0015] Figure 3 yes Figure 2 The A-view is a structural diagram of the dual plugger, viewed from the bottom (first plugger side). Detailed Implementation

[0016] Example 1:

[0017] In the process of measuring the "two zones" of the roof and the failure zone of the floor in a coal mine working face, a corrosion prevention method of conducting segmented tests on a water injection borehole was adopted, which can obtain test data at multiple different depths. Such a technical solution requires a segmented test device.

[0018] like Figures 1 to 3 A segmented hydrostatic test device is installed in the water injection borehole 10 of the "two zones" of the top plate and the failure zone of the bottom plate of the actual working face, including a first sealing device 20, a second sealing device 30 and an expansion connecting pipe 40.

[0019] The first sealing device 20 and the second sealing device 30 are improvements on the currently common sealing device structure to adapt to the segmented hydrostatic testing of the top plate "two zones" and bottom plate failure zone of the working face.

[0020] The first sealing device 20 and the second sealing device 30 are cylindrical structures with an expansion cavity.

[0021] One end of the first sealing device 20 is provided with a first expansion pipe interface 21, which connects to the expansion cavity of the first sealing device. The other end of the first sealing device 20 is a closed end.

[0022] One end of the second sealing device 30 is provided with a second expansion pipe interface 31 and a second water injection pipe interface 32, and the other end of the second sealing device 30 is provided with a second expansion pipe serial interface 33 and a second water injection pipe outlet 34. The second expansion pipe interface 31 and the second expansion pipe serial interface 33 are connected to the expansion cavity of the second sealing device, and the second water injection pipe interface 32 is connected to the second water injection pipe outlet 34 through a pipe inside the second sealing device 30. The second water injection pipe interface 32 and the second water injection pipe outlet 34 are not connected to the expansion cavity of the second sealing device.

[0023] The expansion connecting pipe 40 is a rigid pipe. The first expansion pipe interface 21 and the second expansion pipe serial interface 33 are connected through the expansion connecting pipe 40, allowing the expansion cavities of the first and second sealing devices to communicate. The length of the expansion connecting pipe 40 corresponds to the length of the segmented hydrostatic test section S. The expansion connecting pipe 40 is made of rigid pipe, such as steel pipe.

[0024] The diameter of the first and second sealing devices is smaller than that of the water injection borehole 10 under normal pressure. When the expansion cavity is pressurized, the first and second sealing devices will expand and squeeze the inner wall of the water injection borehole 10 to seal the water injection borehole.

[0025] Inside the water injection borehole 10, a second sealing device is positioned near the borehole opening 11. The space between the first sealing device 20 and the second sealing device 30 is the segmented hydrostatic test section S. The length of the segmented hydrostatic test section S can be changed by replacing the expansion connecting pipe 40 with different lengths.

[0026] The second expansion pipe interface 31 connects to the expansion pressure pipe 13. For ease of access to and from the water injection borehole, the expansion pressure pipe 13 is made of steel. Water is injected and pressurized into the first sealing device 20 and the second sealing device 30 through the expansion pressure pipe 13, causing them to expand and seal the water injection borehole 10, forming a closed segmented water pressure test section S. After the expansion pressure pipe 13 is depressurized, the first sealing device 20 and the second sealing device 30 contract, allowing them to move within the water injection borehole. The expansion pressure pipe 13 is connected to the water injection pump 14, and a control valve 18 is installed on the expansion pressure pipe 13.

[0027] The second water injection pipe interface 32 connects to the test water injection pipe 12, and the test water injection pipe 12 connects to the segmented water pressure test section S through the second water injection pipe interface 32 and the second water injection pipe outlet 34. The test water injection pipe 12 is connected to the water injection pump 14, which can be a fracturing pump. A pressure sensor 15 and a timer 16 are installed on the test water injection pipe 12, and a control valve 17 is also installed on the test water injection pipe 12.

[0028] The segmented hydrostatic testing device in this embodiment creates a closed segmented hydrostatic testing section S for the water injection borehole 10, and the segmented hydrostatic testing section S can be moved to any position (depth) within the water injection borehole 10. Hydrostatic testing conditions are provided for the segmented hydrostatic testing section S through pressurization by a water injection pump and valve control. Hydrostatic test data are obtained through pressure sensors and timers.

[0029] Example 2:

[0030] A method for measuring the "two zones" of the roof and the failure zone of the floor in a working face is provided. The method uses the segmented water pressure test device described in Example 1. The process includes drilling water injection holes, conducting segmented water pressure tests on the water injection holes, obtaining segmented water pressure data in the water injection holes before and after mining, and comparing the development of rock fractures before and after mining.

[0031] The process of this method includes:

[0032] 1. Estimated Depth of Floor Failure Zone. The estimated depth of floor failure is calculated based on the "Specifications for Coal Pillar Retention and Coal Mining in Buildings, Water Bodies, Railways and Main Shafts", or existing measured data on floor failure depth in working faces nationwide, and empirical formulas for floor failure depth in working faces.

[0033] 2. Drilling Design and Construction. Water injection boreholes will be drilled based on the predicted depth of floor failure. The design of water injection boreholes will consist of two or more groups to facilitate comparative testing. These boreholes can be located in adjacent roadways or on the surface. The borehole design should conform to the KA / T4-2023 standard. The designed vertical depth of the borehole must be greater than the predicted depth of floor failure, and the borehole depth into the (viewed) longwall face must be greater than 20m. A borehole opening pipe will be installed at the borehole opening; the length of the opening pipe will be determined by the lithology and the degree of fracture development. After drilling, the borehole opening 11 needs to be reinforced. Reinforcement can be achieved using a borehole opening pipe, which should be made of steel pipe and fixed with cement.

[0034] To facilitate control experiments, multiple water injection boreholes can be drilled in the test mining area. The preferred option is to drill four water injection boreholes 10 in the test mining area. The four water injection boreholes are divided into two groups, with two water injection boreholes in each group. The interval between the two groups of water injection boreholes needs to be greater than the cycle pressure step distance. Usually, the interval between the two groups of water injection boreholes can be set to 100m.

[0035] 3. Conduct pre-mining observation of the water injection borehole. After the borehole and wellhead pipe are installed, perform repeated flushing. Before mining (at a distance greater than 20 meters from the mining face), use a borehole inspection instrument to inspect the water injection borehole. A borehole inspection instrument (breach television) with inclinometer and natural gamma sensor is preferred; if unavailable, core sampling is required. Use the inspection data to compile a borehole columnar section and compare fracture development before and after mining.

[0036] 4. Conduct pre-mining water injection tests on the water injection borehole. Before mining (at a distance greater than 20 meters from the mining face), conduct multiple segmented water pressure tests. During the segmented water pressure tests, insert the first sealing device 20 and the second sealing device 30 into the designated positions of the water injection borehole 10 to achieve a seal with the borehole. Then, use the water injection pump 13 to inject water into the segmented water pressure test section S. First, fill the segmented water pressure test section S with water to maintain a normal pressure (e.g., 0 MPa). Then, start injecting water into the segmented water pressure test section S and begin timing. When the water injection test pressure is reached, the timer records the pressurization time. The water injection test pressure should be determined according to the rock strata structure and set based on the regional rock strata compressive strength to avoid excessive pressure that could cause rock strata fracture. To obtain effective data, the test pressure of the water in the water injection borehole is usually not less than 1.0 MPa. For example, to conduct a water injection test pressure of 1.5 MPa, the water pressure in the segmented water pressure test section S can be increased to above 1.5 MPa, such as to 1.6 MPa. Then, pressurization is stopped, and control valve 16 is closed to cut off the influence of the tail equipment on the water pressure in the segmented water pressure test section S. Due to the voids and fissures in the rock strata, the water pressure in the segmented water pressure test section S will gradually decrease. Pressure sensor 14 detects the water pressure. When the water pressure is about to reach 1.5 MPa, timer 15 starts timing. When the water pressure drops to normal pressure (such as 0 MPa), timer 15 records the time, which is the time it takes for the water pressure in the water injection borehole to drop from the test pressure to normal pressure, called the depressurization time.

[0037] The sectional hydrostatic test is conducted in multiple steps, with each step involving a hydrostatic test of a section S. Several sections S can be selected as needed, or the tests can be performed sequentially to conduct a full-section hydrostatic test on the water injection borehole. The length of the sectional hydrostatic test section S can be set according to the test requirements, typically ranging from 0.8m to 2.0m.

[0038] Before mining, multiple segmented hydraulic pressure tests need to be conducted on the same segmented hydraulic pressure test section S. Comparing the results of the segmented hydraulic pressure tests before mining can determine the self-development of the rock strata, that is, the natural changes of the rock strata unaffected by mining. After tapping, at least one segmented hydraulic pressure test should be conducted, and the results of the segmented hydraulic pressure test after mining should be compared with the results of the segmented hydraulic pressure test before mining to determine the impact of the mining process on the development of the rock strata.

[0039] 5. Data Analysis. Data analysis focuses primarily on depressurization time, incorporating results from water injection borehole inspection. Pressure increase time, influenced by factors such as pump, operating valve assembly, and natural water pressure, is only considered as a reference value. In the depressurization data analysis, the average depressurization time is calculated for multiple segmented hydrostatic test sections S (or the entire section). This average depressurization time is compared to the depressurization time of each segmented hydrostatic test section S; a higher ratio indicates more developed primary fractures or higher porosity. As reference data, the average pressure increase time for multiple segmented hydrostatic test sections S is also calculated and compared to the pressure increase time of each segmented hydrostatic test section S.

[0040] After mining, the damage to the floor affects the rock structure, resulting in the development of fractures and an increase or decrease in porosity. When the impact of mining is greater than the impact of the original primary fracture development or high porosity before mining, the data before and after mining will show differences. When the impact of mining is less than the impact of the original primary fracture development or high porosity before mining, the data before and after mining will show the same trend. In sections unaffected by mining, the data before and after mining will show the same trend (the degree of impact is not determined by a ratio greater than or less than 1).

[0041] Therefore, analyzing and judging the impact of the failure zone of the roof and floor during mining provides data support for coal mine safety.

Claims

1. A segmented hydrostatic testing device, installed in water injection boreholes (10) in the "two zones" of the top plate and the failure zone of the bottom plate of the measured working face, characterized in that, It includes a first sealing device (20), a second sealing device (30), and an expansion connecting pipe (40). The expansion connecting pipe (40) connects the expansion cavity of the first sealing device (20) and the expansion inner cavity of the second sealing device (30). The second sealing device is located on the side close to the orifice (11) of the water injection borehole (10). The space between the first sealing device (20) and the second sealing device (30) is a segmented water pressure test section (S). The second sealing device (30) connects the test water injection pipe (12) and the expansion pressure pipe (13). The test water injection pipe (12) connects to the segmented water pressure test section (S).

2. The segmented hydrostatic testing device according to claim 1, characterized in that, One end of the first sealing device (20) is provided with a first expansion pipe interface (21), one end of the second sealing device (30) is provided with a second expansion pipe interface (31) and a second water injection pipe interface (32), the other end of the second sealing device (30) is provided with a second expansion pipe string interface (33) and a second water injection pipe outlet (34), the second water injection pipe outlet (34) is connected from the second sealing device to the second water injection pipe interface (32), the first expansion pipe interface (21) and the second expansion pipe string interface (33) are connected through an expansion connecting pipe (40), the second expansion pipe interface (31) is connected to an expansion pressure pipe (13), the second water injection pipe interface (32) is connected to a test water injection pipe (12), and the second water injection pipe outlet (34) is connected to the segmented water pressure test section (S).

3. The segmented hydrostatic testing device according to claim 1, characterized in that, The expansion connector (40) is a rigid pipe.

4. The segmented hydrostatic testing device according to claim 1, characterized in that, The test water injection pipe (12) and the expansion pressure pipe (13) are connected to the water injection pump (14). A pressure sensor (15) and a timer (16) are provided on the test water injection pipe (12). Control valves are provided on the test water injection pipe (12) and the expansion pressure pipe (13).

Images