Deep coal bed gas and heat co-extraction method

Abstract

The invention discloses a deep coal bed gas and heat co-extraction method. The method comprises the steps that 1, a first vertical drilling well is constructed, a heat-preserving casing pipe is adopted for carrying out gas sealing and heat isolating protection for a well hole; 2, construction of a layering horizontal well is carried out according to the thickness of a coal bed, the layering numberK is determined according to the coal bed real thickness M and the gas drainage radius R, and K is equal to M / 2R; 3, a second vertical drilling well is constructed; 4, circumferential dispersing holes of the horizontal well are constructed, and then first extraction of gas is carried out; 5, hydraulic fracturing is carried out on all the drilled holes, a three-dimensional fracture mesh is formed,and then second extraction of the gas is carried out; 6, the first vertical drilling well serves as a water injecting well, the second vertical drilling well serves as a steam output well, the wateris injected into the deep coal bed, the principle of heat transfer is utilized for transferring geothermal energy into the water steam, and the water steam is extracted and utilized. According to themethod, gas extraction and geothermal energy exploitation can be carried out for the deep coal bed which is 1500-3000 meters, the geothermal extraction efficiency is improved, energy is saved, emission is reduced, and the geological environment problems of water and soil pollution, thermal pollution and the like are prevented.

Description

technical field [0001] The invention belongs to the field of geothermal and coal-bed methane exploitation, and specifically proposes a method for deep coal-bed methane thermal co-exploitation. Background technique [0002] The total amount of coalbed methane resources shallower than 3,000 meters in my country is about 55 trillion cubic meters, and the national coalbed methane resources of shallower than 3,000 meters are about 55 trillion cubic meters, of which coalbed methane resources with a coal seam buried depth of 1,500-3,000 meters account for 54.5%. At present, most of underground coal mining and coal bed methane development and mining are coal seams and coal bed methane shallower than 1500 meters, and there are great technical difficulties in the mining of deep coal bed methane. In addition, deep coal seams are subjected to high in-situ stress and low coal seam permeability, which seriously restricts the efficiency of coalbed methane extraction. [0003] Geothermal r...

AI Technical Summary

Problems solved by technology

The disadvantage of the second-generation technology is that the connectivity between production and irrigation wells is not easy to determine, and the recharge efficiency is low, and it will also pollute groundwater to varying degrees. However, compared with the first generation of direct discharge, only mining without irrigation, etc. partial advantage

[0005] Existing geothermal resources mining technologies are only limited to geothermal mining, and there is no relevant technical data on coalbed methane and geothermal mining in deep coal seams, and high drilling costs are a major factor restricting geothermal mining

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