Contact Angle Measurements Using Sessile Drop and Micro-CT Data from Six Sandstones

Numerous sessile drop and micro-computed tomography (micro-CT) studies have been conducted to quantify geologic carbon storage formation wettability by measuring static contact angles (theta); however, the influence of pore geometry remains unknown. In this work, six sandstones (Bandera Brown, Berea, Bentheimer, Mt. Simon, Navajo, and Nugget) are used to measure theta using the two aforementioned experimental methods at identical testing conditions (45 degrees C and 12.41 MPa). The range of theta measured at in situ conditions (micro-CT) exceeds the range at ex situ (sessile drop method) conditions for all sandstones. However, when droplets with more representative in situ diameters are analyzed, theta averages show ex situ theta exceed those of in situ theta. Pore geometry does influence local theta, but the size of ex situ droplets relative to pore size appears to influence theta. This is important to consider for future sessile drop studies used for analysis of CO2 behavior in carbon storage reservoirs.