干热岩压裂建造人工热储发展现状及建议

能源是经济社会长期稳定发展的有力保障。同时, 我国也进入了生态文明建设的关键时期。为实现此目标, 亟需建设清洁、低碳、高效、多元的现代能源体系。干热岩型地热作为一种新兴的环境友好型资源, 有望推进能源结构转型。开发干热岩需要建立增强型地热系统, 其核心是向储层钻井并压裂形成一定规模的裂缝网络, 构建井间循环回路来提取热能发电。20世纪70年代以来, 多个发达国家先后进行干热岩资源开发尝试, 然而受到人工热储建造和诱发地震防控等关键技术的限制, 成功运行的EGS工程屈指可数。近些年来, 干热岩资源的优越性和规模化开发可行性进一步得到国际社会的认可, 投入建设的EGS数量总体上不断增加。水力压裂是建造人工热储的核心技术手段之一, 水力裂缝的形态直接决定了换热体积和取热效率。本文在分析国内外典型EGS压裂案例的基础上, 总结了干热岩水力压裂的工艺特点。此外, 结合几种较为流行的理论模型和我国首例EGS工程——共和盆地恰卜恰干热岩试采工程的实际情况, 简要阐述了干热岩压裂与诱发地震之间的关系。最后从压裂工艺、智能化开发、微地震监测矩张量反演等方面为干热岩水力压裂向更深层次发展提出建议。 

Development status and suggestions of hot dry rock hydraulic fracturing for building geothermal reservoirs

Energy is a powerful guarantee for the long-term stable development of the economy and society. At the same time, China has also entered a critical period of ecological civilization construction. To achieve this goal, it is urgent to build a clean, low-carbon, efficient, and diversified modern energy system. As new environment-friendly energy, hot dry rock (HDR) is expected to promote the energy mix transition. The development of HDR requires the establishment of an enhanced geothermal system(EGS). It is to build an well circulation to extract thermal energy for power generation after drilling and hydraulic fracturing. Since the 1970s, many developed countries have tried to develop HDR successively. However, limited by key technologies, such as artificial heat storage construction and induced earthquake prevention, few EGS projects have been successfully operated. In recent years, as the advantages and the large-scale development feasibility of HDR are gradually recognized by the international society, the number of EGS is increasing generally. Hydraulic fracturing is one of the core technologies to build the geothermal reservoir, which directly determines the heat transfer volume and the heat transfer efficiency. Based on the analysis of typical EGS cases at home and abroad, the characteristics of HDR hydraulic fracturing are summarized. Moreover, combined with several popular theoretical models and the actual situation of the first EGS (Qiabuqia HDR) in China, the relationship between the HDR fracturing and the induced earthquake is briefly described. From the point of view of fracturing technology, intelligent development, and micro-seismic moment tensor inversion, the suggestions for further development of HDR fracturing are presented.