“双碳”目标下煤炭开采扰动空间CO2地下封存途径与技术难题探索

Underground CO2 storage and technical problems in coal mining area under the “dual carbon” target

  • 摘要: 煤炭作为我国主体能源地位短期内难以改变,但煤炭工业发展面临着“碳达峰,碳中和”目标的新挑战,积极推动煤炭资源绿色开采与低碳利用,充分发挥煤炭安全供给的兜底作用,是保障国家能源安全的重大现实需求。而CO2排放是煤炭工业可持续发展面临的最大制约,探索大规模、低成本CO2封存技术是煤炭资源低碳化利用必须面对及破解的难题。在对煤层自然封存CO2和CO2气藏赋存地质条件研究基础上,探讨和展望利用煤炭开采、地下气化及原位热解等形成的扰动空间进行CO2地下封存的技术途径,并明确了实现CO2地下高效封存的必备条件:① 煤层上部存在不受开采扰动影响的地质密闭层是实现煤矿扰动空间CO2封存的先决要求;② 构建功能性充填空间是实现CO2地下封存的核心工作;③ 由功能性充填体围限的碎裂岩体、气化煤灰及热解半焦等封存载体物性特征是影响CO2封存量及封存效果的重要因素。据此,剖析了进行CO2地下封存亟待解决的技术难题:① 实现CO2地下封存的地质条件及评价方法;② 构建CO2封存空间的材料与工程技术;③ 煤炭开采、气化及热解扰动范围探测与CO2封存潜力评价;④ CO2充注与封存效果监测及评估。在此基础上,针对煤炭开采、地下气化及原位热解过程中形成的扰动空间特点,分别提出了煤层采空区碎裂岩体、煤地下气化灰渣及碎裂岩体、煤原位热解半焦进行CO2地下封存的实现途径。

     

    Abstract: As the main energy source in China, the status of coal is difficult to change in the short term, but the development of coal industry is facing a new challenge in meeting the goal of“carbon peaking and carbon neutrality”. Actively promoting the green mining and low-carbon utilization of coal resources and fully playing the bottom role of coal security supply are major practical needs to ensure national energy security. Among them, the CO2 emission is the biggest constraint for the sustainable development of the coal industry. The development of large scale and low-cost CO2 storage technology is a problem that must be faced and solved in the low-carbon utilization of coal resources. Based on the study of natural CO2 storage in coal seams and geological conditions for CO2 gas reservoir storage, this paper discusses and prospects the technical methods of CO2 underground storage using the disturbedareaformed by coal mining, underground gasification and in situ pyrolysis.Also,it clarifies the necessary conditions for the CO2 underground efficient storage: ① the existence of a geologically confined layer in the upper part of the coal seam that is not affected by mining disturbances is a prerequisite for achieving CO2 storage in the disturbed space of the coal mine. ② Building functional filling space is the core work of CO2 underground storage.③ The physical characteristics of storage carriers such as fractured rock mass, gasification coal ash and pyrolysis semi coke confined by functional filling body are important factors affecting CO2 storage capacity and storage effect. Accordingly, the technical problems to be solved for the CO2 underground storage are analyzedincluding ① geological conditions and evaluation methods of the CO2 underground storage; ② materials and engineering technology for constructing CO2 storage space;③ detection of disturbance range of coal mining, gasification and pyrolysis and evaluation of CO2 storage potential; and ④ monitoring and evaluation of CO2 filling and storage effect. On this basis, according to the characteristics of disturbance space formed in the process of coal mining, underground gasification and in situ pyrolysis, the realization ways of CO2 underground storage in coal mined out area, coal underground gasification ash and crushed rock, and coal in situ pyrolysis char are proposed respectively.

     

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