Multi-stage permeability increasing method for coal body containing gas

Abstract

The invention discloses a multi-stage permeability increasing method for a coal body containing gas. The multi-stage permeability increasing method for the coal body containing gas comprises the steps that firstly, the geological condition of the occurrence area of a coal seam, the metamorphism degree of coal, the type of the coal and gas parameters are determined; secondly, different schemes are adopted for achieving first-stage permeability increasing of the coal body containing gas according to the fact whether the coal seam is located in a fault or a fold part or not, the permeability increasing effect is checked, and if the permeability increasing effect reaches a preset effect, the scheme adopted for first-stage permeability increasing is used for permeability increasing of the whole coal seam; if the permeability increasing effect does not reach the preset effect, second-stage acidification permeability increasing is conducted on the coal body containing gas based on first-stage permeability increasing; and finally, after second-stage acidification permeability increasing is completed, gas extraction is conducted on the coal body containing gas. According to the multi-stage permeability increasing method for the coal body containing gas, different permeability increasing schemes are established according to the geological conditions of different occurrence areas of coal seams, and thus the multi-stage permeability increasing method is extremely targeted; and meanwhile, by adoption of multi-stage permeability increasing, the permeability of the coal seams is greatly improved, and the gas extraction rate is increased.

Description

technical field [0001] The invention relates to a gas-containing coal body anti-permeability method, in particular to a gas-containing coal body multi-stage anti-permeability method, which belongs to the technical field of anti-gas outburst safety management in coal mines. Background technique [0002] my country is the world's largest coal producer and consumer, and coal plays an important role in my country's energy structure. In recent years, my country's coal mines have invested heavily in safety, and have achieved good results. However, coal mine accidents do happen from time to time. Statistics show that mine gas accidents and roof accidents account for more than 80% of the total accidents, among which mine gas accidents become the first killer of coal mines because of their high degree of harm, high casualty rate, and large economic losses. It can be seen that mine gas control has become the fundamental point to reduce or even eliminate gas accidents. Low permeabil...

AI Technical Summary

Problems solved by technology

At present, the main technical methods of coal seam anti-reflection include hydraulic fracturing, high-pressure water jet reaming, hydraulic slotting, deep hole control pre-splitting blasting, etc. These methods have achieved positive results to a certain extent. However, there are also some defects, which are mainly reflected in two aspects: one is the defect in the technology itself, mainly manifested in: the persistence of pressure relief and anti-reflection effect is poor, which may lead to local stress concentration, increase the risk of protrusion, and even induce shock-protrusion composite The second is the adaptability to the coal seam, which is mainly manifested in: the gas-bearing coal body in the fold zone is characterized by high gas content, small coal particle size, low residual mechanical strength, low permeability, and strong water sensitivity. Water conservancy measures, especially hydraulic fracturing, have little effect and often fail to achieve the expected anti-permeability effect

[0004] Invention patent - a gas-liquid-solid three-phase coupled blasting method for weakening rock impact and increasing permeability (CN 103161493B), which is mainly to inject water into the blasting hole before blasting, so that the ordinary gas-solid two-phase blasting can be transformed into a gas-liquid-solid three-phase blasting method. Phase blasting, using water pressure blasting to generate water shock waves, jets, and secondary pressure waves to enhance the blasting effect, but this scheme has the disadvantages of slow water absorption speed of the coal seam, insufficient reduction of coal elastic energy, long water injection time and large engineering volume question

Invention patent - chemical reaction method for preventing and controlling coal seam rockburst (CN 103061766 B) injects the coal body with an alkaline solution, and uses the alkaline solution to dissolve the organic matter in the coal, thereby eliminating the impact tendency, but mainly for R o,max <0.6% low-rank coal seam, the applicability is restricted

Invention patent - a chemical plugging method for coalbed methane near the wellbore (CN 103541713 B) by injecting an appropriate amount of ethanol into the coal seam section near the wellbore of the coal reservoir to extract and extract the coal, so as to increase the pores of the coal reservoir for the purpose of high degree and permeability, but the cost of this option is high and the ability to use ethanol for coal extraction and extraction is limited

Images