High-pressure water burst and CO2 fracturing combined coal bed gas displacement extraction technology

Abstract

The invention discloses a high-pressure water burst and CO2 fracturing combined coal bed gas displacement extraction technology. The high-pressure water burst and CO2 fracturing combined coal bed gas displacement extraction technology comprises the following steps: ground stress state determination, hole sealing section drilling and sealing, hole drilling and slitting, charging, water injection hole sealing, high-pressure water burst crack starting, supercritical or liquid CO2 fracturing and gas extraction. A ceramsite proppant is mixed in the supercritical or liquid CO2, in a continuous fracturing process of the liquid CO2, extension conditions of burst cracks can be monitored in real time by a microseism monitoring instrument, and fracturing is stopped after an expected effect of extension in a set range is achieved. During guided slitting, slitting can be carried out step by step after holes are drilled according to the number of slits and a set distance between each two adjacent slits, and a mode of drilling holes and slitting alternately can also be adopted. The high-pressure water burst and CO2 fracturing combined coal bed gas displacement extraction technology has the advantages that the permeability of a low-permeability coal bed gas reservoir can be increased effectively, construction amount is reduced, and coal bed gas extraction efficiency is high.

Description

technical field [0001] The invention relates to the technical field of fracturing-displacement drainage of coalbed methane, in particular to a high-pressure water explosion and CO 2 CBM displacement and drainage technology combined with fracturing. Background technique [0002] Coal bed gas or gas (the main component is methane, chemical formula CH 4 ) is a kind of clean energy, and it is also an important factor causing gas accidents in coal mines. CBM drainage is an important measure to improve energy structure and reduce coal mine gas disasters. China's coalbed methane mining technology is dominated by hydraulic fracturing. Hydraulic fracturing is a fracturing technology widely used in fields such as oil and gas stimulation, geothermal resource development, and nuclear waste storage. Hydraulic fracturing is a method of fracturing and increasing permeability by injecting high-pressure water into the reservoir through a pump injection system to fracture the formation. ...

AI Technical Summary

Problems solved by technology

The main problems are as follows: 1) It consumes too much water and is unsustainable; 2) Hydraulic fracturing often produces only one main fracture that is symmetrically distributed along the fracturing borehole, perpendicular to the direction of the minimum principal stress, and expands and extends along the direction of the maximum principal stress , the anti-permeability effect is not very obvious, and the conductivity is unstable; 3) The water-based fracturing fluid system is easy to pollute the groundwater, which is not environmentally friendly; 4) The fracturing of underground coal and rock reservoirs rarely considers the influence of in-situ stress, which is unscientific

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