Fracture development coal seam drill hole secondary hole sealing device
By designing a secondary sealing device for boreholes in fractured coal seams, the gaps in the grout are filled using primary and secondary grouting pipes, solving the problem of high gas leakage rate in traditional sealing methods and achieving efficient gas extraction and long-term sealing.
Patent Information
- Application Number
- CN202423206454.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2034-12-25
AI Technical Summary
Traditional sealing techniques result in high borehole leakage rates, low extraction concentrations, and rapid sealing decay in fractured coal seams, making it difficult to effectively prevent gas explosions and coal and gas outbursts.
A secondary sealing device for boreholes in fractured coal seams is adopted, which includes a primary grouting pipe, a secondary grouting pipe, and an extraction pipe. The pipe is inserted into the grouting section through a sealing component at the borehole opening. Grout is injected during the primary and secondary grouting processes, and the grout solidifies to fill the gaps, ensuring a tight seal.
It increased the gas extraction concentration, reduced the borehole leakage rate and shut-in rate, increased the extraction flow rate, and extended the sealing life.
Smart Images
Figure CN223594148U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of coal mine gas extraction technology, specifically to a secondary sealing device for boreholes in fractured coal seams. Background Technology
[0002] Coal mine gas is a toxic and harmful gas released during coal mining, posing a serious threat to the lives of miners and production operations. When the amount of gas emitted in a coal mine is large and cannot be diluted and removed by ventilation alone, it can easily lead to gas explosion accidents if it is not extracted and treated in time. Coal mine gas extraction involves drilling into the coal seam and gas accumulation area, connecting the borehole to a dedicated pipeline and sealing the borehole, and using extraction equipment to extract the gas from the coal seam and goaf to the surface. This is an important measure to reduce the amount of gas emitted during mining, prevent gas from exceeding limits and accumulating, and prevent gas explosions and coal and gas outburst accidents.
[0003] Coal mines have complex geological conditions, with well-developed primary faults and fissures in the coal (rock) strata. For example, in the Longmenxia Nan Coal Mine, when traditional grouting techniques are used for sealing boreholes, the cement grout shrinks and collapses after solidification, resulting in tiny gaps between the cement solids and the borehole wall. These gaps connect with the rock strata fissures, causing an increase in the gas leakage rate inside the borehole, a decrease in the extracted gas concentration, a reduction in the total concentration along the drill length (single group), an increase in the borehole shut-off rate, a decrease in the pure extraction flow rate, and a rapid decay of the sealing gas. Utility Model Content
[0004] This invention provides a secondary sealing device for boreholes in fractured coal seams, which can solve the above-mentioned technical problems.
[0005] This utility model is achieved through the following technical solution:
[0006] A secondary sealing device for boreholes in fractured coal seams includes a primary grouting pipe, a secondary grouting pipe, a extraction pipe, and a sealing component for sealing the borehole opening.
[0007] The bottom of the borehole is located diagonally above the opening of the borehole;
[0008] The sealing element is located between the orifice and the bottom of the orifice, and the area between the sealing element and the bottom of the orifice is a grouting section;
[0009] The extraction pipe, the primary grouting pipe, and the secondary grouting pipe are all inserted into the grouting section through the orifice and the sealing member. An extraction screen is provided at the end of the extraction pipe near the bottom of the orifice. The distance between the primary grouting pipe and the bottom of the orifice is greater than the distance between the secondary grouting pipe and the bottom of the orifice.
[0010] Furthermore, the length of the primary grouting pipe located within the grouting section is more than 1m.
[0011] Furthermore, the distance between the secondary grouting pipe and the extraction pipe is more than 4m, and the distance between the primary grouting pipe and the secondary grouting pipe is more than 8m.
[0012] Furthermore, the diameter of the extraction pipe is the same as the diameter of the extraction screen pipe.
[0013] Furthermore, the diameter of the extraction pipe can be 15mm to 150mm, and the diameters of the primary grouting pipe and the secondary grouting pipe can be 8mm to 80mm.
[0014] Furthermore, the primary grouting pipe and the secondary grouting pipe have the same diameter.
[0015] Furthermore, the diameter of the extraction pipe is 32mm, and the diameters of the primary grouting pipe and the secondary grouting pipe are both 16mm.
[0016] Furthermore, it also includes a binding device for binding the primary grouting pipe and the secondary grouting pipe to the extraction pipe.
[0017] Compared with the prior art, this utility model has the following advantages and beneficial effects:
[0018] A secondary sealing device for boreholes in fractured coal seams includes a primary grouting pipe, a secondary grouting pipe, an extraction pipe, and a sealing element for sealing the borehole opening. The extraction pipe, primary grouting pipe, and secondary grouting pipe are all inserted into the grouting section through the sealing element at the borehole opening. The sealing element seals the borehole opening. During the initial grouting, grout is injected into the grouting section through the primary grouting pipe. Grouting stops when grout returns from the secondary grouting pipe. After the initially injected grout solidifies, grout is injected a second time into the grouting section through the secondary grouting pipe. Grouting stops when grout returns from the extraction pipe. In the secondary sealing process, under the combined action of pressurized grouting and gravity, the grout enters and fills the gaps formed after the initial grouting solidifies, ensuring the tightness of the borehole sealing. The gas extraction concentration of a single borehole using the secondary sealing process can reach 65% to 73%, and the total concentration of the drilling site (single group) is increased by more than 48% to 57% compared with the original sealing process. The borehole shut-off rate is reduced by 53% to 59%, the borehole leakage rate is reduced by 12% to 17%, and the pure extraction flow rate is also improved compared with the original sealing process. The sealing decay rate is also slower. Attached Figure Description
[0019] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:
[0020] Figure 1 This is a schematic diagram of a secondary sealing device for drilling holes in fractured coal seams, according to an embodiment of this utility model.
[0021] The attached diagram shows the markings and corresponding component names:
[0022] 10-Drill hole, 11-Hole opening, 12-Hole bottom, 13-Primary grouting pipe, 14-Secondary grouting pipe, 15-Extraction pipe, 151-Extraction screen pipe, 16-Sealing component, 17-Binding component, 18-Coal seam. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.
[0024] Example
[0025] A secondary sealing device for boreholes in fractured coal seams includes a primary grouting pipe, a secondary grouting pipe, an extraction pipe, and a sealing element for sealing the borehole opening. For example, the sealing element includes AB sealing material and cotton cloth. Polyurethane AB components are mixed and then absorbed by the cotton cloth, which is then wrapped around the primary, secondary, and extraction pipes. Subsequently, the primary, secondary, and extraction pipes are inserted into the grouting section, where the AB sealing material expands due to a chemical reaction, sealing the borehole opening. Alternatively, the sealing element may include wooden wedges and yellow mud; wooden wedges of a certain length are interspersed with yellow mud (or kelp) for sealing. The yellow mud (or kelp) solidifies (expands) to provide a seal. For example, the primary grouting pipe, located within the grouting section, is at least 1 meter long to prevent the sealing material from clogging the grout outlet and preventing grout from flowing from the primary grouting pipe.
[0026] The bottom of the borehole is located diagonally above the borehole opening, and the sealing element is located between the borehole opening and the bottom of the borehole. The grouting section is located between the sealing element and the bottom of the borehole.
[0027] The extraction pipe, primary grouting pipe, and secondary grouting pipe are all inserted into the grouting section through a sealing fitting at the borehole opening. An extraction screen is installed at the end of the extraction pipe near the bottom of the borehole. The distance from the primary grouting pipe to the bottom of the borehole is greater than that of the secondary grouting pipe. According to the requirements of the gas drainage drilling construction process, the sealing length for boreholes drilled along the seam should not be less than 8m, and the sealing length for boreholes drilled across the seam should not be less than 5m. The distance between the primary and secondary grouting pipes should be more than 8m, meaning the initial sealing length is greater than 8m for better sealing effect. The sealing length can be increased based on factors such as the gas content and coal quality of the coal seam, and the drilling depth. For example, the distance between the grout outlet end of the primary grouting pipe and the grout outlet end of the secondary grouting pipe can be 9m or 10m. The present invention is not limited to 11m. For example, the distance between the secondary grouting pipe and the extraction pipe is more than 4m, that is, the length of the secondary sealing hole is greater than 4m. This distance can be increased according to factors such as the gas content of the coal seam, the coal quality, and the drilling depth. For example, the distance between the grout outlet end of the secondary grouting pipe and the end of the extraction pipe near the bottom of the hole can be 5m, 6m, or 7m. The present invention is not limited to this. For example, the ratio of the borehole sealing material is water: cement: gypsum powder = 10:8:1 (mass ratio). After starting the grouting pump and pressurizing the grouting section, the initial grouting volume is 125kg of cement, and the secondary grouting volume is 75kg of cement. The secondary grouting volume can effectively fill the gap formed after the primary grouting solidifies.
[0028] A secondary sealing device for boreholes in fractured coal seams includes a primary grouting pipe, a secondary grouting pipe, an extraction pipe, and a sealing element for sealing the borehole opening. The extraction pipe, primary grouting pipe, and secondary grouting pipe are all inserted into the grouting section through the sealing element at the borehole opening. The sealing element seals the borehole opening. During the initial grouting, grout is injected into the grouting section through the primary grouting pipe. Grouting stops when grout returns from the secondary grouting pipe. After the initially injected grout solidifies, grout is injected a second time into the grouting section through the secondary grouting pipe. Grouting stops when grout returns from the extraction pipe. In the secondary sealing process, under the combined action of pressurized grouting and gravity, the grout enters and fills the gaps formed after the initial grouting solidifies, ensuring the tightness of the borehole sealing. The gas extraction concentration of a single borehole using the secondary sealing process can reach 65% to 73%, and the total concentration of the drilling site (single group) is increased by more than 48% to 57% compared with the original sealing process. The borehole shut-off rate is reduced by 53% to 59%, the borehole leakage rate is reduced by 12% to 17%, and the pure extraction flow rate is also improved compared with the original sealing process. The sealing decay rate is also slower.
[0029] In another embodiment, the extraction pipe and the extraction screen pipe have the same diameter. The diameter of the extraction pipe can be 15mm to 150mm, and the diameters of the primary grouting pipe and the secondary grouting pipe can be 8mm to 80mm. For example, the diameters of the primary grouting pipe and the secondary grouting pipe are the same, and the secondary grouting can use the same grouting pressure equipment, which is convenient to operate. Preferably, the diameter of the extraction pipe is 32mm, and the diameters of the primary grouting pipe and the secondary grouting pipe are both 16mm. The diameter of the extraction pipe is 32mm, which can ensure the gas extraction efficiency and throughput. Different diameter extraction pipes can be used according to the actual situation of the coal mine. This utility model is not limited to this. The grouting pipe with a diameter of 16mm performs best in cement grouting, which can provide better slurry distribution and permeability, thereby ensuring the firmness and sealing of the hole. It should be noted that different diameter grouting pipes can be used according to the actual situation of the coal mine. This utility model is not limited to this.
[0030] In another embodiment, a binding device is also included to tie the primary grouting pipe and the secondary grouting pipe to the extraction pipe. The binding device can be a clamp for secure fixing or a cable tie for ease of use and low cost. By using the binding device to tie the primary grouting pipe, the secondary grouting pipe and the extraction pipe together before sending them into the borehole, it is easy to send them in. The pipes are less likely to shift in the borehole, and it is easy to control the depth of the primary grouting pipe, the secondary grouting pipe and the extraction pipe entering the borehole, thus ensuring the grouting distance.
[0031] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.
Claims
1. A secondary sealing device for boreholes in fractured coal seams, characterized in that, This includes primary grouting pipes, secondary grouting pipes, extraction pipes, and sealing components for plugging borehole openings. The bottom of the borehole is located diagonally above the opening of the borehole; The sealing element is located between the orifice and the bottom of the orifice, and the area between the sealing element and the bottom of the orifice is a grouting section; The extraction pipe, the primary grouting pipe, and the secondary grouting pipe are all inserted into the grouting section through the orifice and the sealing member. An extraction screen is provided at the end of the extraction pipe near the bottom of the orifice. The distance between the primary grouting pipe and the bottom of the orifice is greater than the distance between the secondary grouting pipe and the bottom of the orifice.
2. The secondary sealing device for boreholes in fractured coal seams according to claim 1, characterized in that, The length of the primary grouting pipe located within the grouting section is more than 1m.
3. The secondary sealing device for boreholes in fractured coal seams according to claim 2, characterized in that, The distance between the secondary grouting pipe and the extraction pipe is more than 4m, and the distance between the primary grouting pipe and the secondary grouting pipe is more than 8m.
4. The secondary sealing device for boreholes in fractured coal seams according to claim 1, characterized in that, The diameter of the extraction pipe is the same as the diameter of the extraction screen pipe.
5. A secondary sealing device for boreholes in fractured coal seams according to claim 4, characterized in that, The diameter of the extraction pipe can be 15mm to 150mm, and the diameters of the primary grouting pipe and the secondary grouting pipe can be 8mm to 80mm.
6. A secondary sealing device for boreholes in fractured coal seams according to claim 5, characterized in that, The primary grouting pipe and the secondary grouting pipe have the same diameter.
7. A secondary sealing device for boreholes in fractured coal seams according to claim 6, characterized in that, The diameter of the extraction pipe is 32mm, and the diameters of the primary grouting pipe and the secondary grouting pipe are both 16mm.
8. A secondary sealing device for boreholes in fractured coal seams according to any one of claims 1 to 7, characterized in that, It also includes a binding device for binding the primary grouting pipe and the secondary grouting pipe to the extraction pipe.