Ground cold exchange injection system and coal reservoir phase change reconstructing method

摘要

Abstract The present invention provides a ground cold exchange injection system and a coal reservoir phase change reconstructing method, belonging to the technical field of reconstructing coal reservoir. In the present invention, spacer liquid, phase change liquid, 5 spacer liquid and coolant liquid are injected successively into oillets in the coal reservoir, so that the coolant liquid conducts the cold energy to the phase change liquid to produce the phase change and volumetric expansion, therefore netshaped crack is formed on the coal reservoir around the oillets under a swelling stress due to low temperature and phase change liquid, the netshaped crack has many branches, which increases mining passages 10 for the coal bed gas and thus better helps mining of the coal bed gas absorbed in the coal reservoir; moreover, the method causes the coal reservoir to be expanded from the oillets to produce the crack and to be free from washing by external objects, thereby reducing coal powder generated by coal rock and thus avoiding blocking of the crack, so that the crack formed by the present invention has a strong flow conductivity, which helps the drainage 15 works after the coal reservoir phase change reconstruction and improves mining efficiency of the coal bed gas. 7240430_1 (GHMatters) P101851.AU LYNT 3,/"t 14 15 8 9 10 180- 11 14 15 18 I T, _Fig 4 '4 142 1 01 0 113 17l Fig. 4