Micro-CT experimental research of oil shale thermal cracking laws

Utilizing the μCT225kVFCB micro-CT experimental system (μm grade),which was newly co-designed by Taiyuan University of Technology and Applied Electronics Institute, Academy of Engineering Physics of China,a series of triaxial microscopic observation and analysis of oil shale thermal cracking under temperatures from 20 ℃ to 600 ℃ were carried out, It was demonstrated that the thermal cracking temperature threshold is 300 ℃ for the Fushun oil shale.Under 300 ℃,it was observed that a small quantity of micro-fissures formed in the specimen mainly along the raw original bedding and the border of hard mineral particles,the thermal fissure surfaces were basically parallel to the original bedding.After temperature exceeded 300 ℃,due to the influence of chemical reaction of the oil shale pyrolysis,the quantity, length,and width of the fissures increased rapidly,exhibiting the characteristics of widespread and bursting occurrence,original fissures developed and even connected to form larger fissures, and basically all fissure surfaces were still parallel with the surface of original bedding,this is a typical characteristic of oil shale thermal cracking.At the same time,a lot of micro-fissures formed perpendicular to the bedding direction,causing the connection between small fissures and large fissures,resulting in a huge connected network structure,which fundamentally improved the influent ability of the oil shale.