The effect of rock surface characteristics on reservoir wettability

Significant strides have been made in recent years in gaining a better understanding of the role of fluid compositions on reservoir wettability. However, our knowledge of the effects that the solid surface characteristics have on establishing and altering wettability is quite limited. This study examines the effect of rock mineralogy and surface roughness on wettability in rock-brine-hydrocarbon systems. The wettability is characterized by using two different techniques. The Wilhelmy plate technique has been used to obtain dynamic (advancing and receding) contact angles averaged over the surface area of the solid substrate used. These results are compared with point-values of dynamic contact angles measured using the dual-drop dual-crystal (DDDC) technique for both smooth and rough solid surfaces of different mineralogy and roughness. The surfaces have been characterized using an Optical Profilometer and a Scanning Electron Microscope. Fluids from the Yates reservoir in West Texas have been used. While the Wilhelmy Plate Technique displayed insensitivity, the DDDC Technique showed significant effects of mineralogy and roughness on dynamic contact angles and hysteresis.