Macro/microbehavior of shale rock under the dynamic impingement of a high-pressure supercritical carbon dioxide jet

Abstract

This paper focuses on the damage of shale rock impacted by a high-pressure supercritical carbon dioxide (SC-CO₂) jet. A well-designed apparatus was used to conduct experiments with a high-pressure SC-CO₂ jet impacting shale core plugs. The damage, including the macrofailure and the microchanges of shale samples, was analyzed. The results show that the shale cores develop grid-like fractures on the top surface, while many layered fractures were observed inside the shale cores by means of computed tomography scan. The maximum broken depth of the shale core plugs is dependent upon the combined actions of jet pressure, jet temperature and target distance. The scanning electron microscope images along with the X-ray diffraction results indicate that the shale samples are eroded by the SC-CO₂ jet. This erosion may further lead to the macrodamage of shale samples by reducing their mechanical strength.