煤炭地下气化作为一种煤炭原位化学采煤方法，被列为国家《能源技术革命创新行动计划(2016—2030年)》之煤炭无害化开采技术创新战略方向。从理论研究和技术开发2个方面，综述了煤炭地下气化技术的发展进程。系统阐述了煤层燃空区扩展规律及影响因素、热开采条件下煤层覆岩运移规律相关理论研究进展。以工艺路线为主线，概述了煤炭地下气化技术的发展历程，介绍了工艺路线特点、气化井连通方式、气化炉构型、气化炉运行模式以及典型工程案例。现代煤炭地下气化工艺路线是在可控后退注入点（CRIP）气化工艺基础上，集成现代钻井技术、先进的石油装备及井下测量技术而形成，其气化炉主要由长距离定向钻井构成，通过地面远程可控多介质集成注入装备及探测装备，实现煤层火区的精准控制，以及气化参数的实时调控。该工艺用于深部煤层原位开发具有显著优势，需在对示范项目综合评估的基础上，有序推进深部煤炭地下气化产业化进程。

As an in-situ chemical coal mining method,underground coal gasification(UCG) is listed as the strategic direction of innocuous coal mining technology in the Action Plan of the National Energy Technology Revolution & Innovation(from 2016 to 2030)in China.This paper summarizes the progress of UCG from two aspects of theoretical research and technological development.The researches related to UCG cavity growth and its influencing factors,and the movement of the coal seam overburden under the condition of thermal mining are systematically described.Taking the process route as the main line,this paper summarizes the development of UCG technology,introduces the characteristics of process route,connection of gasification wells,configuration of the gasifier,operation mode of gasifier and typical field test cases.The modern UCG is based on the controlled retraction injection point (CRIP) technology,which integrates modern drilling technology,advanced petroleum equipment and downhole measurement technology.The gasifier is mainly composed of long-distance directional boreholes.Through the remote controllable multi-phase integrated injection & measurement equipment,the precise control of coal seam fire face and the real-time control of operation parameters could be realized.This technology has obvious advantages in in-situ conversion of deep coal seams,however,it is necessary to promote the industrialization of deep UCG orderly based on the comprehensive evaluation of the pilot project.