Coal bed gas-liquid CO2 and active water collaborative fracturing technique method

Abstract

The invention provides a coal bed gas-liquid CO2 and active water collaborative fracturing technique method. The coal bed gas-liquid CO2 and active water collaborative fracturing technique method includes the following steps that (1) nitrogen is injected into a sleeve, thus liquid in the annulus of the oil sleeve is displaced, and the pressure in the oil sleeve annulus is maintained; (2) nitrogenis injected into an oil pipe to clean a fracturing pipeline; (3) liquid CO2 is injected into the oil pipe, and fracturing is conducted; (4) nitrogen is injected into the oil pipe to clean the fracturing pipeline; (5) an active water fracturing fluid A is injected into the oil pipe, and fracturing is conducted; and (6) an active water fracturing fluid B is injected into the oil pipe, and fracturingis conducted. According to the coal bed gas-liquid CO2 and active water collaborative fracturing technique method, the liquid CO2 and the active water are successively injected to fracture, advantages of two fracturing methods are provided, and the fracturing transformation effect of a coal reservoir is enhanced.

Description

technical field [0001] The invention relates to a fracturing technology for unconventional reservoirs, in particular to a coal bed gas liquid CO 2 The invention relates to a cooperative fracturing process method with active water, which belongs to the research field of reservoir reconstruction technology. Background technique [0002] Coal bed methane (CBM), also known as coal bed methane, is a kind of unconventional natural gas that is formed during coal formation and occurs in coal seams. Coalbed methane, with methane as the main component, occurs in coal seams in three ways: adsorbed on the coal surface, free in coal pores, and dissolved in coal seam water, most of which (70% to 95%) are adsorbed on the inner surface of coal rock pores superior. Coalbed methane is a very potential unconventional oil and gas resource. Its exploration and development can not only alleviate the national energy shortage, but also help reduce coal mine gas accidents, which has extremely impo...

AI Technical Summary

Problems solved by technology

[0004] Although the active water fracturing technology commonly used in coalbed methane has the advantages of low cost, safety, strong operability, and wide application range, it has outstanding disadvantages such as high damage to the reservoir, difficult flowback, and single fracture creation. Make reservoir stimulation less effective

Compared with active water fracturing, liquid carbon dioxide fracturing has many advantages such as high rock-breaking efficiency, complex fracture network, less reservoir damage, easy flowback, and the ability to replace methane in coal seams. Disadvantages such as low pressure in the fracture, small width of the reconstructed fracture, difficulty in carrying and laying proppant, and high cost

If liquid carbon dioxide fracturing is used in the whole process, the construction cost will be increased and the construction risk will be increased

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