CN-117189115-B - Coal seam anti-reflection device and method for variable-temperature jet flow of coal seam with low permeability in coal mine

Abstract

The invention belongs to the technical field of coal seam anti-reflection in underground coal mine drilling, and provides a coal seam anti-reflection device and an anti-reflection method for variable-temperature jet flow of a coal seam with low permeability in the coal mine, wherein the device comprises a jet nozzle arranged at an outlet of a high-pressure water pipe, an inlet of the high-pressure water pipe is connected with a high-pressure water pump, and the high-pressure water pump is connected with a rapid heater; the jet flow spray head is also connected with a liquid nitrogen generator through a vacuum heat insulation pipe, the inlet end of the liquid nitrogen generator is connected with the nitrogen generator, the outlet end of the liquid nitrogen generator is connected with the inlet end of a liquid nitrogen storage tank, the outlet of the liquid nitrogen storage tank is connected with a liquid nitrogen tank group, the outlet end of the liquid nitrogen tank group is connected with a low-temperature pump, and the outlet of the low-temperature pump is led into the jet flow spray head through the vacuum heat insulation pipe; the device effectively increases the size of the cracks of the drilled holes, so that the permeability of the coal seam is increased, and the gas yield is improved. Meanwhile, the liquid nitrogen production device is adopted to directly produce liquid nitrogen, so that the cost is low and the liquid nitrogen can be reused. The method is simple and convenient to operate, can effectively solve the loss of liquid nitrogen in the transportation process, improves the effect of the liquid nitrogen on the coal body, and improves the permeability improvement effect of the coal bed.

Inventors

• GAO YABIN
• ZHANG SHAOQI
• LIU GUOQIANG
• CAO JING
• LI MENGBO
• ZHANG WEIHAO

Assignees

• 太原理工大学

Dates

Publication Date

20260508

Application Date

20230913

Claims (5)

1. 1. The method for permeability improvement of the coal seam anti-reflection device by adopting coal seam variable-temperature jet flow of the coal seam under the coal mine comprises a jet flow nozzle (1) arranged at the outlet of a high-pressure water pipe (12), wherein the inlet of the high-pressure water pipe (12) is connected with a high-pressure water pump (9), and the high-pressure water pump (9) is connected with a rapid heater (10); the jet flow spray head (1) is also connected with the liquid nitrogen generator (5) through the vacuum heat insulation pipe (2), the inlet end of the liquid nitrogen generator (5) is connected with the nitrogen generator (4), the outlet end of the liquid nitrogen generator is connected with the inlet end of the liquid nitrogen storage tank (6), the outlet of the liquid nitrogen storage tank (6) is connected with the liquid nitrogen tank group (11), the outlet end of the liquid nitrogen tank group (11) is connected with the low-temperature pump (7), and the outlet of the low-temperature pump (7) is led into the jet flow spray head (1) through the vacuum heat insulation pipe (2); The rapid heater (10), the high-pressure water pump (9), the low-temperature pump (7), the liquid nitrogen storage tank (6), the liquid nitrogen generator (5) and the nitrogen generator (4) are respectively connected with the PLC control system (8); the outer wall of the vacuum heat insulation pipe (2) is provided with a pressure sensor which is connected with a PLC control system; The method is characterized by comprising the following steps: (1) Determining construction process parameters of hydraulic drilling holes and monitoring drilling holes according to underground coal seam occurrence conditions, physical parameters, working pressure of water jet equipment and site requirements, wherein the hydraulic drilling holes are 80-170mm in size and 42-75mm in size, the monitoring drilling holes are respectively arranged in a mode of being parallel or perpendicular to the hydraulic drilling holes, and the hole arrangement mode of 1 hydraulic drilling hole and 6 or 7 monitoring drilling holes is adopted, wherein the hole arrangement intervals of the monitoring drilling holes and the hydraulic drilling holes are respectively L 1 = 1.2-1.6m monitoring holes, L 2 = 2.0-2.2m monitoring holes 1-2, L 3 = 2.6-3.00m monitoring holes 2, and L 4 = 3.2-3.6m monitoring holes 2; (2) Selecting a high-pressure water jet nozzle with the size of 1.8-2.6mm according to the mechanical parameters of the coal seam and the requirements of field application, controlling the water jet pressure to be 80-120MPa, and controlling the water temperature to be 0-90 ℃; (3) The method comprises the steps of utilizing 80-120MPa high-pressure water jet to impact a coal bed in a hydraulic drilling hole, heating water is not needed when the water jet is used for punching for the first time, controlling the water temperature to be 15-30 ℃, utilizing the high-speed water jet to impact the coal bed to break the coal bed, forming a punched hole, and meanwhile, setting a waterproof range finder to transmit back punching hole area parameters and guaranteeing the water jet punching effect at the middle position on a drill rod near a connecting jet nozzle, and properly adjusting the water jet impact parameters according to punching data transmitted by the range finder according to the condition of gangue or weak surfaces in the coal bed, so that a large-range uniform damage area is formed in the hydraulic drilling hole; (4) The coal cinder and the residual water in the hydraulic drilling hole are transported to the outside of the hydraulic drilling hole by using a spiral drill rod, and secondary separation and recycling are respectively carried out on the coal cinder and the residual water in the pit; (5) The method comprises the steps of carrying out local sectional hole sealing on a water jet punching area by utilizing a sectional temperature-resistant pressure-resistant hole sealing device, injecting normal-temperature nitrogen into the hole sealing area, controlling injection pressure P Normal nitrogen =nP Gas burner of the normal-temperature nitrogen, wherein P Gas burner is gas pressure in the coal seam, n is a pressure coefficient, n=4-7, utilizing the injected normal-temperature nitrogen to extrude water in the coal seam, enabling the water to enter the deep part of the coal seam, and simultaneously providing a channel for liquid nitrogen to enter the coal seam; (6) The freezing temperature of the water medium is often lower than the freezing temperature of pure water under the influence of partial inorganic salt components in the underground stratum water medium, so that the freezing capacity of the coal bed is basically lost when the temperature in the segmented hole sealing area is increased to be within the range of-7 ℃ to-13 ℃, and the liquid nitrogen treatment is completed; secondly, impacting the area by using a high-temperature high-pressure water jet with the pressure of 90-130MPa, and forming a damage area with a larger range on the frozen drilling coal bed again; (7) And (3) repeating the steps (5) and (6), sequentially injecting normal-temperature nitrogen and low-temperature liquid nitrogen into the area again, and repeatedly impacting the area by using high-temperature water jet flows with different pressures and temperatures.
2. 2. The method of claim 1, wherein the outlet end of the high-pressure water pump is provided with a water injection valve, and the outlet end of the low-temperature pump is provided with a nitrogen injection valve.
3. 3. The method according to claim 1, wherein the jet nozzle (1) is arranged in a coal seam, a sealing plug (3) is arranged between the end parts of the high-pressure water pipe (12) and the vacuum insulation pipe (2) and the coal seam, and the jet nozzle (1) is connected with the high-pressure water pipe (12) and the vacuum insulation pipe (2) respectively by flanges.
4. 4. The method of claim 1, wherein the jet head penetrates into the coal seam to a depth of 1-2m for coal seam anti-reflection, and the variable-temperature jet flow anti-reflection is continued at a distance of 1.5-6.5 m.
5. 5. The method according to claim 1, wherein the water jet impact is that the flow rate of water is 1-2.5m3/min, the injection time is 5-35min, the first time is a high-temperature water jet with the pressure of 80-120MPa, the second time is a high-temperature water jet with the temperature of 75-85 ℃ and the pressure of the water medium exceeding the first time of 10-20MPa, the water temperature in the high-temperature high-pressure water jet is reduced by 5-20 ℃ each time, the pressure is kept constant, the amount of low-temperature liquid nitrogen injected each time is reduced by 10-30% in sequence, the flow rate of liquid nitrogen which is just started is 1.5-3.5m3/min, the injection time is 10-30min, and the temperature of the liquid nitrogen is controlled between-200 ℃ and-205 ℃.

Description

Coal seam anti-reflection device and method for variable-temperature jet flow of coal seam with low permeability in coal mine Technical Field The invention belongs to the technical field of coal seam anti-reflection in underground coal mine drilling, and particularly relates to a coal seam anti-reflection device and an anti-reflection method for variable-temperature jet flow of a coal seam with low permeability in the underground coal mine. Background The geological conditions and structural characteristics of different coal beds have large differences, and the occurrence characteristics of the coal bed gas are controlled by various geological factors such as construction conditions, hydrologic conditions, coal bed burial depth, coal reservoir pressure, coal bed thickness and the like, so that the gas distribution is extremely complex. The conventional drilling gas extraction mode at present is poor in effect, the extraction period is long, and the underground exploitation progress is influenced. The measures for mining the protective layer are limited by the occurrence condition of the coal seam and face great limitation. In this context, a series of hydraulically powered measures have been developed, such as hydraulic punching, hydraulic slotting, hydraulic slitting, etc. However, as the mining depth increases, coal seams continuously emerge under complex conditions such as low permeability, high gas pressure, high ground stress and the like, single hydrodynamic permeability-increasing measures and permeability-increasing effects face the subsequent debilitation condition as well, and a set of efficient underground coal seam permeability-increasing method is needed to improve the gas extraction rate aiming at the existing low permeability coal seam. The hydraulic punching is one of the methods commonly used in gas exploitation at present, the coal body around the hole wall is destroyed by high-pressure water jet, small-sized protrusions are induced in the drill hole, the space generated by flushing the coal body by water jet is utilized, so that the stress of the coal body is released, the permeability of the coal bed is improved, the yield of gas is improved, but the complexity of the coal bed is gradually increased along with the deepening of the exploitation depth, the exploitation effect of single-factor hydraulic punching measures is affected, and the subsequent requirements are difficult to continue to be met, so that the existing hydraulic punching measures are required to be improved, and the punching effect is jointly improved through the interaction of multiple factors. Disclosure of Invention Aiming at the problems, the invention provides the coal seam anti-reflection device and the coal seam anti-reflection method for the variable-temperature jet flow of the coal seam with low permeability in the coal mine. Meanwhile, the liquid nitrogen production device is adopted to directly produce liquid nitrogen, so that the cost is low and the liquid nitrogen can be reused. The vacuum heat insulation pipeline can be adopted in the transportation process of liquid nitrogen, so that the loss of the liquid nitrogen in the transportation process is reduced, and the effect of the liquid nitrogen in the punching process is improved. The method is simple and convenient to operate, can effectively solve the loss of liquid nitrogen in the transportation process, improves the effect of the liquid nitrogen on the coal body, and improves the permeability improvement effect of the coal bed. The coal seam permeability increasing device comprises a jet nozzle arranged at the outlet of a high-pressure water pipe, wherein the inlet of the high-pressure water pipe is connected with a high-pressure water pump, the high-pressure water pump is connected with a rapid heater, the jet nozzle is also connected with a liquid nitrogen generator through a vacuum heat insulation pipe, the inlet end of the liquid nitrogen generator is connected with a nitrogen generator, the outlet end of the liquid nitrogen generator is connected with the inlet end of a liquid nitrogen storage tank, the outlet of the liquid nitrogen storage tank is connected with a liquid nitrogen tank group, the outlet end of the liquid nitrogen tank group is connected with a low-temperature pump, and the outlet of the low-temperature pump is led into the jet nozzle through a vacuum heat insulation pipe; the rapid heater, the high-pressure water pump, the low-temperature pump, the liquid nitrogen storage tank, the liquid nitrogen generator and the nitrogen generator are respectively connected with the PLC control system; the outer wall of the vacuum heat insulation pipe (2) is provided with a pressure sensor for monitoring the pressure condition in the drilled hole. And the outlet end of the high-pressure water pump is provided with a water injection valve, and the outlet end of the low-temperature pump is provided with a nitrogen injection valve. The jet nozzle i