Residual Fluid Blobs and Contact Angle Measurements from X-ray Images of Fluid Displacement

Over the past decade a growing number of high resolution, three-dimensional, X-ray computed tomography images of multiphase porous media systems have become available, as have the number of algorithms to analyze both the pore space and the fluid partitioning imaged within the voids. Here we consider the measurement of fluid-fluid and fluid-solid surfaces at residual fluid conditions in a Berea sandstone sample. 3D reconstructions of the residual fluid blobs show qualitative behaviour which is in agreeement with conventional wisdom. We consider the measurement of fluid-solid contact angle via such images. We elucidate the challenge in identifying triple points (points with three phases in contact) and describe an algorithm for contact angle measurement. Results from application of the contact angle algorithm indicate the ability to distinguish wetting and non-wetting fluid blobs and reveal satisfactory agreement with experimental wettability measurements.