Experimental study and numerical modeling of cryogenic fracturing process on laboratory-scale rock and concrete samples

Abstract

Cryogenic fracturing is a new fracturing concept that uses cryogenic fluids as fracturing fluids. Its mechanism rests on the effect of a thermal shock introduced by cryogen on the hot surface of reservoir rock. The thermo-mechanical properties of rock and failure criteria play very important roles during the cryogenic fracturing process. The objective of this research is to conduct cryogenic fracturing experiments on concrete and rock samples and build a simulation tool. For the experimental aspect, a tri-axial stress confining system with capability of injecting liquid nitrogen or other cryogenic fluid is built. It is capable of conducting cryogenic fracturing treatment on concrete and rock samples under tri-axial stresses. For modeling, the experimental process is simulated and matched with the actual experiment results. The simulation tool can also predict the distribution of artificial fractured samples. The influences of different confining stress, injection pressure and failure criteria are identified by comparing results from modeling and experiments. The experiment setup and modeling tool developed can also provide valuable guidance to field applications of cryogenic fracturing technology to select most efficient operation factors.