煤炭地下气化中的地质问题

煤炭地下气化是弥补我国天然气供需缺口的多元化途径之一。然而,该项技术历经80余年现场试验目前仍未产业化应用。煤炭地下气化炉的载体为地质体,煤矿床地质禀赋约束了特定地下气化项目的可行性,推进这一过程必须跨越地质风险瓶颈。立足于这一战略需求和基本认识,简要回顾历史并提出问题,从资源禀赋、选址评价、环境安全3个方面评述了国内外关于煤炭地下气化地质因素的认识与进展,提出了推进煤炭地下气化产业化的地质工作建议。分析认为,煤炭地下气化地质工作贯穿于规划布局、炉址选择、气化生产、燃后处理整个过程,系统性地质工作尚不到位是煤炭地下气化长期未能实现产业化的重要原因,需要从战略高度上充分理解我国煤炭资源禀赋对当前地下气化技术的适应性,国外严格的选址"标准"启示我们加大对难采、劣质、零散煤炭资源原位规模性气化技术研究探索的力度,高温因素与静态地质体叠加所潜在环境地质安全问题需要正视并积极应对。基于上述地质思考,建议对煤炭地下气化技术应持谨慎的乐观态度,不宜保守,更不宜盲目,鼓励选择适宜地质条件开展工业性试验探索。将煤炭地下气化作为一项保障国家长远能源安全的战略措施,围绕煤炭地下气化资源评价选区与战略规划、气化炉勘查与选址评价技术、高安全广适性地下气化工艺技术、生产地质动态监测预警技术、地下气化地质保障系列规范5个方面,推进并组织论证和实施"煤炭地下气化地质风险评价与预测关键技术"计划。其中,煤炭地下气化资源评价选区与战略规划是打破目前"难以产业化"僵局的基础,需要立足于我国煤炭资源特性及赋存条件实际,总结国内外地下气化工业性试验经验,建立全国统一的煤炭地下气化资源评价技术准则,评价全国或大区煤炭资源对当前地下气化技术的适应性程度。然后,提出可供分步实施的典型地质条件国家级先导性试验区建议。

Geological problems in underground coal gasification

Underground coal gasification (UCG) is one of the diversified ways to fill the gap between the supply and demand of natural gas in China.However,after more than 80 years of field tests,the technology has not yet been industrialized.The carrier of UCG gasifier is geological body and the geological endowment of coal deposit restricts the feasibility of specific UCG project.To promote this process,it is necessary to overcome the bottleneck of geological risk.Based on this strategic need and basic understanding,the authors in this paper briefly review the history of UCG,put forward relevant problems,review the understanding and progress on the geological control of UCG at home and abroad from three aspects of resource endowment,site selection and evaluation,and environmental safety,and put forward some suggestions for geological work to promote the UCG industrialization.It is considered that the geological work of UCG runs through the whole process of planning layout,site selection,gasification production and post combustion treatment.The lack of systematic geological work is an important reason for the long term failure to realize the UCG industrialization.It is necessary to fully understand the adaptability of China’s coal resource endowment to the current UCG technology from a strategic perspective,and the strict site selection “standards” abroad enlightens us to strengthen the research and exploration of in situ large scale gasification technology for difficult to extract,inferior and scattered coal resources.The potential environmental safety caused by the superimposition of high temperature factors and static geological bodies needs to be faced up to and actively dealt with.Based on the geological considerations above,it is suggested that the attitude toward the UCG technology should be cautiously optimistic,not conservative,not blindly,and the selection of appropriate geological conditions for industrial UCG test should be encouraged.The UCG should be regarded as a strategic measure to ensure the long term energy security of the country.It should focus on five aspects:the evaluation and area selection of UCG resources and strategic planning,the exploration and site evaluation technology of gasifier,the technology of UCG with high safety and wide applicability,the technology of dynamic monitoring and early warning of production geology,and the series of specifications for the UCG geological guarantee.The implementation of the “Key Technologies for Geological Risk Assessment and Prediction of UCG” plan should be promoted.Among them,the UCG resources evaluation,site selection and strategic planning are the key to break the current “difficult industrialization” deadlock.It is necessary to,based on the characteristics and occurrence of coal resources in China,summarize the industrial test experience of UCG at home and abroad,establish a national unified technical criterion for the UCG resources evaluation,and evaluate the adaptability of national or regional coal resources on current UCG technology.Then,the suggestions of national pilot test areas with typical geological conditions which can be implemented step by step should be put forward.