Key technologies and prospect for in-situ gasification mining of deep coal resources

China has rich reserves of deep coal resources, and underground coal gasification can transform coal into gas and transport it to the ground, which is an important way for in-situ fluidized mining of deep coal.This article introduces the development history and technical status of underground coal gasification technology (UCG), as well as typical cases of underground coal gasification in the middle and deep parts.Based on the modern underground coal gasification technology system, the key technologies and technical research directions of deep underground coal gasification was analyzed and the prospect of deep coal gasification mining with the goal of natural gas production was outlooked.The development trend of UCG is from the mine type to the drilling type, from shallow coal seams to deep coal seams, from single power generation to comprehensive utilization.The practice of UCG in the middle and deep coal seams has verified the technical feasibility.The key technologies of deep underground coal gasification mainly include geological evaluation and scientific site selection, gasifier construction, deep coal seam high-pressure ignition, controllable mobile injection and deep fire zone geophysical detection.Deep coal gasification to produce natural gas can not only realize the clean and efficient use of deep coal resources, but also solve the contradiction between supply and demand caused by the increase in natural gas consumption.