Unconventional natural gas well horizontal staged methane multi-stage pulse blasting fracturing enhanced extraction method

Abstract

The invention discloses an unconventional natural gas well horizontal staged methane multi-stage pulse blasting fracturing enhanced extraction method. The method is suitable for efficient extraction of shale gas, coal bed gas and gas of a tight gas well. Firstly, the whole section of a horizontal well is perforated to form a guide slot; then oxygen is injected into the sealed section and premixed with methane to form mixed gas with a certain concentration; methane is detonated, first-stage pulse blasting fracturing is conducted, and a reservoir around the slot is fractured; meanwhile, methane desorption of the reservoir is promoted by high temperature; when it is monitored that the temperature and the carbon monoxide concentration exceed alarm threshold values, nitrogen is injected into the section, and the spontaneous combustion risk of the reservoir is eliminated; after methane is fully desorbed, secondary and other multi-stage pulse blasting fracturing is repeatedly conducted, and a three-dimensional fracture network is formed; after fracturing of the section is completed, the next section continues to be subjected to blasting fracturing until fracturing of all sections of the horizontal well is completed; and finally, methane extraction is conducted. According to the method, in-situ desorption of methane in the horizontal well is used for inducing blasting, the three-dimensional fracture network is constructed, and the extraction efficiency of the unconventional natural gas well is improved.

Description

technical field [0001] The invention relates to a horizontal segmented methane multi-stage pulse explosion fracturing enhanced drainage method for unconventional natural gas wells, and is especially suitable for efficient methane extraction of low-permeability unconventional natural gas reservoirs. Background technique [0002] With the increase of my country's energy demand, the exploitation of unconventional natural gas is developing rapidly. The traditional unconventional natural gas exploitation method is vertical well drainage and depressurization exploitation, which has low single well production and poor economic benefits. The commonly used stimulation measure is horizontal well hydraulic fracturing, but this measure consumes a lot of water resources, the fracturing fluid is easy to pollute the groundwater, the fracturing fracture network has a single shape, and it is easy to form a water lock effect on the reservoir. Therefore, there is an urgent need to develop eco...

AI Technical Summary

Problems solved by technology

The traditional unconventional natural gas exploitation method is vertical well drainage and depressurization exploitation, the single well production is low, and the economic benefit is poor

The commonly used stimulation measure is horizontal well hydraulic fracturing, but this measure consumes a lot of water resources, the fracturing fluid is easy to pollute the groundwater, the fracturing fracture network has a single shape, and it is easy to form a water lock effect on the reservoir

Images