煤炭地下气化及对中国天然气发展的战略意义

Underground coal gasification and its strategic significance to the development of natural gas industry in China

基于国内外煤炭地下气化技术发展现状与趋势,提出了煤炭地下气化基本概念、机理与模式,指出目前面临的挑战、发展潜力与发展路径。煤炭地下气化这一革命性技术能够实现"人工制气",且符合煤炭清洁利用方向,在新能源达到规模化供应之前,可开辟中国特色的有效供甲烷与氢气战略新途径。中国含油气盆地煤系发育,仅超出煤炭企业井工开采深度、埋深1 000～3 000 m的煤炭资源量即为3.77×10^(12) t,初步预计可气化煤炭折合天然气资源量为(272～332)×10^(12)m^3,是常规天然气资源量的3倍,与非常规天然气资源量的总和基本相当。根据煤炭地下气化反应机理和产物组分的差别,初步将煤炭地下气化分为"浅层富氢、中深层富甲烷、深层超临界极富氢"3种开发模式。石油石化企业可在煤炭企业井工开采范围之外,发挥自身技术、管道、市场等一体化优势,根据不同需求和相应技术成熟度,优选路径发展煤炭地下气化业务,可将大量煤炭资源进行有效清洁开发利用,缓解天然气供应紧张局面,还可结合产出氢气就近利用以及在邻近油区开展CO_2驱油与埋存,打造石油石化循环经济净零排放示范区,为"氢经济"时代到来储备资源和技术,更为中国"清洁、低碳、安全、高效"的现代能源体系建设开辟新的途径。

Based on the present situation and trend of underground coal gasification in China and overseas, this article puts forward the basic concept, mechanism and mode of underground coal gasification, and presents the challenges, development potential and development path now faced. In China, underground coal gasification which is in accord with the clean utilization of coal can produce 'artificial gas', which provides a new strategic approach to supply methane and hydrogen with Chinese characteristics before new energy sources offer large-scale supply. Coal measure strata in oil-bearing basins are developed in China, with 3.77 trillion tons coal reserves for the buried depth of 1 000-3 000 m. It is initially expected that the amount of natural gas resources from underground coal gasification to be 272-332 trillion cubic meters, which are about triple the sum of conventional natural gas, or equivalent to the total unconventional natural gas resources. According to the differences of coal reaction mechanism and product composition of underground coal gasification,the underground coal gasification can be divided into three development modes, hydrogen-rich in shallow, methane-rich in medium and deep, supercritical hydrogen-rich in deep. Beyond the scope of underground mining of coal enterprises, petroleum and petrochemical enterprises can take their own integration advantages of technologies, pipeline, market and so on, to develop underground coal gasification business based on their different needs and technical maturity, to effectively exploit a large amount of coal resources cleanly and to alleviate the tight supply of natural gas. It can also be combined with using the produced hydrogen in nearby area and the CO2 flooding and storage in adjacent oil areas to create a demonstration zone for net zero emissions of petroleum and petrochemical recycling economy. It is significant for reserving resources and technologies for the coming 'hydrogen economy' era, and opening up a new path for China’s 'clean, safe and efficient' modern energy system construction.