An experimental study analyzing effects of cryogenic treatments on porosity, permeability, and dynamic elastic properties of marcellus formation core samples

Cryogenic treatment involves injecting cryogenic fluids such as liquid nitrogen (LN2) into a formation to initiate and propagate fractures and to connect existing natural fracture networks. In this research, seven core samples from Marcellus formation were placed in a core holder, hosted in an oven, and heated up to the reservoir temperature of 66°C. LN₂ (-177°C) was then injected into the core samples at approximately 0.14 MPa. Six core samples were pressurized using nitrogen (N2) at 1.38 and 2.76 MPa, while the seventh core sample was not pressurized. Real-time pressure and temperature were recorded using a cryogenic pressure transducer and a T-type thermocouple during each experiment. CT-scan, porosity, permeability, and ultrasonic velocity tests were conducted on the core samples prior to and after conducting each experiment to investigate the effects of cryogenic treatments on the porosity, permeability, and elastic properties. The results of CT-scan, porosity, permeability, and elastic properties revealed that implementing the cryogenic treatment resulted in creating cracks in the core samples, and higher treatment pressures resulted in creating more cracks. The results also revealed that the cryogenic treatment could be potentially implemented in shale oil and shale gas fields to increase hydrocarbon production rates from these reservoirs.