Current understanding of shale wettability: A review on contact angle measurements

What makes the shale wettability more interesting and in some way adds to its complexity is the effect of state variables such as ionic strength, pressure, temperature, pH, clay content, and organic matter content on contact angle. This review further discusses various studies that have up to now attempted to characterize the effect of these state variables on wettability based on contact angle measurements for different shales around the world.