Relationship Between the Archie Saturation Exponent and Wettability

Summary The calculation of in-situ water saturations from resistivity well logs relies on the saturation exponent of Archie's equation, where n =2 for clean, consolidated, water-wet sandstones. The saturation exponent, however, is a function of the water/oil/rock wettability and was found to range from <2 to 8. The relationship between wettability and the saturation exponent is linear, and the slopes of the lines at low and high temperature are identical for a given sandstone.