Research progress of fracture development during in-situ cracking of oil shale

Low heat transfer coefficient is a massive problem in the in-situ exploitation of oil shale. Meanwhile, the formation of a fracture network is of great engineering significance to the distribution of thermal fluid, the improvement of heat conduction efficiency, and the smooth migration channel of pyrolysis oil and gas. It is essential to find out the expansion and development law of fracture networks in oil shale exploitation. At present, no one has summarized and expounded the direction of fracture network expansion and development in the in-situ exploitation of oil shale. In this paper, based on the growth and expansion of fractures during in-situ cracking of oil shale, Its mechanism is elaborated from heating mode, natural fracture interference and different temperature and pressure conditions. The influence of temperature, pressure, bedding structure, rock properties and heating time on the expansion and development of crack network during in-situ cracking of oil shale is reviewed. This paper discusses the current shale in-situ separations on extending the research direction of the development of focus, puts forward another research direction. The design is to provide some ideas for in-situ exploitation of oil shale.