A coalbed methane mining method for liquid nitrogen freeze-thaw cracking coal seam permeability enhancement

A mining method and coalbed methane technology, which is applied in the fields of mining fluid, earthwork drilling, wellbore/well components, etc., can solve the problems of complex technical process, difficulty in feeding medicine, high technical cost, etc., and achieve changes in physical mechanics performance, expanding the range of freeze-thaw cracking, and increasing the effect of wetting range

Active Publication Date: 2017-10-24
CCTEG CHINA COAL RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The hydraulic anti-reflection technology has the advantages of simple operation and low technical cost, but it usually requires the conditions to protect the coal and rock pillars on site, which is easy to induce injection holes and cause the gas in the roadway to exceed the limit, which affects the safety of construction operations
The technology of high-energy gas fracturing and anti-permeability technology is complicated, the technology cost is high, and it is difficult to feed and lower the tube during the construction of low-permeability broken soft coal seams. Due to the anisotropy of the coal body and the limitation of the amount of charge, the blasting range is small, The directionality of crack growth is poor, and at the same time, due to the existence of methane in the coal seam, the risk of gas explosion and outburst in the hole is increased during the blasting process
Directional long-hole drilling technology has the advantages of large drilling length and directional drilling, but it is difficult to take advantage of the drainage effect in low-permeability broken soft coal seams
With the development of coalbed methane into deep mining, the characteristics of high stress and low permeability of reservoirs become more and more obvious, and the existing methods of coalbed gas permeability enhancement can no longer meet the requirements of coalbed methane drainage
[0003] In summary, the existing technology cannot fully adapt to the characteristics of coal seams under deep mining, and there is a lack of coal bed methane mining methods that can effectively increase the output rate of coal bed methane

Method used

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  • A coalbed methane mining method for liquid nitrogen freeze-thaw cracking coal seam permeability enhancement

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] The coalbed methane exploitation method of liquid nitrogen freeze-thaw cracking coal seam anti-permeability is characterized in that: comprising the following steps:

[0038] a) drilling a drainage borehole 2 into the coalbed methane mining coal seam 1 in the underground roadway, and cutting out a number of slots 3 in the drainage borehole 2;

[0039] b) in the coalbed methane mining coal seam 1, drill a monitoring borehole 4 at a position 4m away from the extraction borehole 2;

[0040] c) arrange the drainage pipeline 5, extend one end of the drainage pipeline 5 into the drainage borehole 2, and communicate with the drainage equipment at the other end, install a drainage pipeline on the drainage pipeline 5 Stop valve 6;

[0041] d) Arrange the injection pipeline 7, extend one end of the injection pipeline 7 into the extraction borehole 2, and communicate with the liquid nitrogen injection pump 8 at the other end, install liquid nitrogen injection on the injection pip...

Embodiment 2

[0055] Compared with Embodiment 1, this embodiment also includes step d1) after step d) and before step i): connecting the water injection pump 13 with the injection pipeline 7, and installing a water injection shut-off valve on the connecting pipeline 14. Determine that the water injection shut-off valve 14 is in a closed state; after step d1) and before step i), step i1): open the water injection shut-off valve 14, start the water injection pump 13, and perform the water injection operation, The water injection speed is 80I / min. After water injection for 3 hours, close the water injection pump 13 and the water injection stop valve 14 to complete the water injection operation.

[0056] In this embodiment, a pulse water injection controller 15 is connected between the water injection pump 13 and the water injection shut-off valve 14 to form a pulsed water flow and adjust the water injection pressure to keep the water injection pressure at 4MPa.

[0057] This embodiment is the ...

Embodiment 3

[0059] Compared with Embodiment 2, this embodiment is all the same except for the following differences:

[0060] In this embodiment, the drainage borehole 2 has a length of 50 m and a diameter of 95 mm.

[0061] In this embodiment, the depth of the cut groove 3 is 45 cm, the distance between two adjacent cut grooves 3 is 1.8 m, and the angle between the cut groove surface of the cut groove 3 and the direction of the maximum principal stress of the coal seam is 90°.

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Abstract

A coalbed methane mining method for liquid nitrogen freeze-thaw cracking coal seam permeability enhancement, including drilling drainage boreholes; drilling monitoring boreholes; arranging drainage pipelines; arranging injection pipelines; installing temperature monitoring devices; starting coalbed methane pumping Extraction operation; start liquid nitrogen injection operation; repeat liquid nitrogen injection operation; start extraction operation and other steps. The invention fully adapts to the physical and mechanical characteristics of the coal seam under deep mining conditions, can effectively improve the permeability of the coal seam, and further significantly increase the output rate of coal seam gas.

Description

technical field [0001] The invention relates to a coal bed gas mining method, in particular to a coal bed gas mining method for liquid nitrogen freeze-thaw cracking coal seam permeability enhancement. Background technique [0002] my country's coal reservoirs have the characteristics of "three lows and one high" (low permeability, low saturation, low pressure and high gas content), resulting in high input costs for CBM mining and low output rates, making it difficult to develop and utilize CBM in coal mining areas. At present, coal mine enterprises mainly increase the production of coalbed methane through coal seam anti-permeability, that is, the method of enhancing the permeability of coal seam. Coal seam anti-permeability methods mainly include hydraulic anti-permeability, high-energy gas fracturing and anti-reflection drainage technology of directional long drilling, etc. . The hydraulic anti-reflection technology has the advantages of simple operation and low technical ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/00E21B43/26
Inventor 沈春明张浪汪东郭建行高旭张慧杰侯金玲姜黎明
Owner CCTEG CHINA COAL RES INST
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