煤炭地下气化腔CO2埋存的研究进展及发展趋势

CO₂捕集与埋存(CCS)可助力碳达峰、碳中和战略目标实现,是解决温室效应的重要手段.在众多地质埋存空间中,煤炭地下气化(UCG)后的气化腔近年来成为埋存研究的热点,但与传统埋存方式相比,相关工作仍处于理论探索阶段,缺乏现场实施案例.为推动该埋存方式的发展,文章从以下3方面开展工作.(1)介绍UCG和CO₂气化腔埋存的国内外研究进展,并将后者的发展划分为概念提出阶段、潜力评价和可行性分析阶段以及机理分析阶段,目前尚处于理论探索阶段.(2)从注入性、密闭性、经济性、储容量和CO₂埋存机理等多个角度出发,通过与其他埋存方式对比,分析了气化腔埋存的特点与优势:注入性良好;密闭性与未开发煤层类似,但更为复杂;显著节约CO₂运输成本;埋存潜力巨大;埋存机理非常复杂,需要考虑气化腔形态、边壁性质以及超临界CO₂与气化腔流体间复杂相互作用对注入和长期埋存过程的影响.(3)阐明CO₂气化腔埋存所涉及的关键科学问题和工程问题,并指出未来发展趋势.在以上工作的基础上,建议国家...

CO2 SEQUESTRATION IN UCG CAVITIES: RESEARCH PROGRESS AND FUTURE DEVELOPMENT TRENDS

Carbon capture and storage (CCS) could help a lot to achieve carbon peaking and carbon neutrality goals and is an effective way to deal with the Greenhouse effect. Among the geologic sequestration formations, the cavities resulting from deep underground coal gasification (UCG) become a hot topic in the research area of geologic CO₂ sequestration. However, compared with conventional sequestration methods, the related work is still in the theoretical exploration stage and lack of trial tests. To promote the development of UCG cavity sequestration, we have done the work as follows. First, we introduce the research progress of UCG and post UCG cavity sequestration, and divide the development of the latter one into three stages including the early stage of conception, stage of quantitative assessment and feasibility analysis, and stage of mechanism analysis. Currently, it is still in a stage of theory exploration. Second, we compare the UCG cavity sequestration with the conventional sequestration options in detail from the perspective of injectivity, sealing capacity, economy, storage capacity, and trapping mechanism. The results show that the UCG cavity sequestration holds an excellent injectivity, has a similar sealing capacity to the unmined coal seams but more complex, is capable to reduce transport cost a lot, has a great potential in storage capacity, and has complex trapping mechanisms, owing to the additional effects of cavity morphology, wall properties, and interactions between supercritical CO₂ and in-situ fluid on the injection and storage processes. Third, we point out the key scientific and engineering issues, and basic future development trends of the UCG cavity sequestration. Based on the above work, we suggest that the government introduces some policies to encourage and support the development of UCG and post cavity sequestration which could enrich the CCS family and promote the clean and low-carbon utilization of coal resources.