Developing a high capacity axis translation apparatus for gas shale testing

Gas shales are usually partially saturated due to hydrocarbon generation and often have a low in-situ degree of saturation less than 40 %. During stimulation, substantial fluid imbibition into the formation occurs due to high suction. Recent research on these shales showed that changes in saturation strongly affect the strength and elastic properties, as well as their hysteretic behavior. To date, most experimental methodologies were based on total suction control by the vapor equilibrium technique. We postulate that the more representative in-situ conditions can be reproduced by capillary pressure control using the axis translation technique. The main challenge, however, is that the capillary pressure range is limited and far from sufficient to bring gas shales to partially saturated conditions. This paper introduces our recent progress in developing a high capacity axis translation apparatus for gas shales testing. Four high air entry value (HAEV) filter candidates were tested and evaluated for their performances and suitability.