TITLE:
An Efficient Method for Measuring Shale Permeability Using Optical-Imaging Spontaneous Imbibition Data
AUTHORS:
Boyun Guo, Philip Wortman
KEYWORDS:
Unconventional Reservoirs, Shale Formations, Permeability Measurement, Spontaneous Imbibition, Optical Imaging
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.16 No.9,
September
23,
2026
ABSTRACT: Shale permeability is difficult to measure due to shale’s nature of ultra-low transmissibility. It is highly desirable to develop an efficient method for measuring shale permeability. This study proposes a new method for measuring shale permeability based on optical-imaging spontaneous imbibition. The Krüss Drop Shape Analyzer initially developed for measuring the configuration of sessile drop was used for measuring the dynamic spontaneous imbibition in shale cores. The measured dynamic sessile drop contact angle, sessile drop height, and sessile drop wet diameter were used to calculate the dynamic volume and dynamic surface area of the sessile drop. The dynamic surface area data were used for calculating the dynamic fluid evaporation volume. After correction for fluid evaporation, the change in the dynamic volume of the sessile drop was translated into the time dependent depth of spontaneous imbibition based on material balance. A closed form analytical equation was derived in this study to describe the time-dependent depth of spontaneous imbibition. The trend of the spontaneous imbibition profile predicted by this equation is very consistent with the trend of the measured spontaneous imbibition profile with an R-value between 0.9426 and 0.9885 for four US shales. Matching the spontaneous imbibition profile given by the analytical equation to the measured spontaneous imbibition profile allowed for determination of shale permeability. The time required for determining shale permeability depends on the time of imbibition measurement, typically a few hours, mostly for humidity control. This is considered as an efficient method for measuring shale permeability.