Revisiting the role of fluid imbibition in the hydrocarbon recovery processes from shale reservoirs

Spontaneous imbibition has recently received a great deal of research attention for improving hydrocarbon recovery from shale gas and oil reservoirs. It is highly desirable to know the true significance and the role of fluid imbibition in the recovery process. Using a Krüss Drop Shape Analyzer 100S with Krüss’ Advance software, water imbibition depth was measured in this study on dry cores from four shale gas/oil reservoirs namely Tuscaloosa Marine Shale, Eagle Fort Shale, Marcellus Shale, and Green River Shale. The initial water-contact angles on the Tuscaloosa Marine Shale, Eagle Fort Shale, Marcellus Shale and Green River Shale core surfaces were measured to be 36.62◦, 66.68◦, 52.78◦ and 84.73◦, respectively. The contact angle and thus volume of liquid droplet changed due to fluid imbibition into the core samples and evaporation. The change in droplet volume, together with the contact area and shale porosity, was used to calculate the imbibition depth. An analytical imbibition model was derived and tuned to upscale the tested fluid imbibition data to field level. The result of time-upscaling using the tuned imbibition models shows that the 1-month water imbibition depths for the Tuscaloosa Marine Shale, Eagle Fort Shale, Marcellus Shale and Green River Shale are 2.61, 1.59, 0.89 and 0.16 cm, respectively. These low values suggest that the direct effect of water imbibition into shale matrix on hydrocarbon recovery in shale reservoirs is insignificant in the practical scales of space and time. However, the imbibition-induced shale cracks can increase shale permeability significantly for mass transfer during the hydrocarbon recovery process. Water imbibition in the cracks should be investigated in future studies. Document Type: Original article Cited as: Guo, B., Wortman, P. Revisiting the role of fluid imbibition in the hydrocarbon recovery processes from shale reservoirs. Capillarity, 2025, 15(2): 25-32. https://doi.org/10.46690/capi.2025.05.01