Wetting behavior of porous structures: Three-dimensional determination of the contact angle after filter cake dewatering using X-ray microscopy

The wetting behavior of remaining isolated liquid bridges between particle interfaces determines the efficiency of filter cake dewatering. Micro-processes during and after dewatering can be traced by means of direct X-ray microtomography (ZEISS Xradia 510 Versa) providing insights into the filter cake structure. We measure the local contact angle between the immiscible phases on the pore scale after in-situ filter cake dewatering. By tracing the three-phase contact line and the two perpendicular vectors belonging to the solid and liquid surface, the contact angle is obtained from their scalar product at every mesh-node. The range of the resulting distribution and curvature increases with the degree of roughness, becoming more obvious for larger contact angles. The occurring roughness causes a naturally water-repellent surface and leads to low liquid saturations. The resulting angular distribution serves for a more accurate prediction of multiphase flow in pore networks as input for further pore model enhancement.