Deep coal bed gas and dry hot rock type terrestrial heat combined mining method

Abstract

The invention discloses a deep coal bed gas and dry hot rock type terrestrial heat combined mining method, and belongs to the technical field of geological new energy development. A CO2 injection well is a single-branch horizontal well, a horizontal well section is located in a hot dry rock geothermal reservoir, and 8-10 geothermal exploitation vertical wells are constructed on the ground on the two sides of the horizontal well section; and the CO2 injection well horizontal well section is subjected to staged fracturing and is synchronously fractured with the geothermal exploitation vertical well, so that an artificial fracture channel is formed between the CO2 injection well and the geothermal exploitation well. Lateral drilling of a branch horizontal well is carried out on a straight well section of the CO2 injection well, the lateral drilling horizontal well section is located in the deep coal reservoir, and after drilling is completed, a screen pipe is put down for well completion; and 8-10 coalbed methane mining vertical wells are constructed on the ground on the two sides of the lateral drilling horizontal well section, and a deep coal reservoir is transformed in a fracturing mode after perforation well completion. CO2 is injected into a well for continuous gas injection, the recovery ratio of deep coal bed gas is increased through the replacement and displacement effects of CO2 on CH4, meanwhile, the geothermal energy in the hot dry rock is extracted with supercritical CO2 as a circulating working medium, and the geothermal energy is converted into electric energy through a supercritical CO2 generator.

Description

technical field [0001] The invention relates to a method for the joint exploitation of deep coalbed methane and dry hot rock type geothermal energy, especially a method suitable for continuously injecting CO2 from a single-branched horizontal well. 2 , using CO 2 to CH 4 The displacement and displacement effect of CO can improve the recovery rate of coalbed methane resources in deep coal reservoirs, and at the same time, supercritical CO 2 (scCO 2 ) is a method for extracting geothermal energy in hot dry rock geothermal reservoirs with circulating working fluid, and belongs to the technical field of deep geological new energy development. Background technique [0002] my country is rich in deep coalbed methane resources, and the amount of coalbed methane resources at a burial depth of 1000-1500m is about 21×10 12 m 3 , 1500~3000m coalbed methane resources are about 30×10 12 m 3 , accounting for 38.2% and 54.5% of the total resources of coalbed methane shallower than 3...

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Problems solved by technology

[0005] Technical problem: The purpose of this invention is to overcome the low gas production rate, low resource recovery rate, and poor economy of deep coalbed methane development under the traditional drainage and pressure reduction mining method, as well as the low heat extraction efficiency of water circulation in hot dry rock type geothermal mining, and large environmental impacts, etc. problem, to provide a continuous injection of CO through horizontal wells 2 Combined mining method of deep coalbed methane and hot dry rock type geothermal

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