Wettability of Rocks
Wettability of reservoir rock Wettability is defined as the tendency of one fluid to spread on or adhere to a solid surface in the presence of other immiscible fluids. The concept of wettability is illustrated in Figure 8.1 . Figure 8.1 illustration of wettability If a drop of water is allowed to fall on a clean plate of glass, the water spreads. The water is wet. If a droplet of mercury is allowed to fall on a clean plate of glass, the mercury remains in spherical form. If a drop of oil is placed on a clean glass plate, the oil droplet develops an approximately hemispherical shape. When the rock is water-wet, there is a tendency for water to occupy the small pores and to contact the majority of the rock surface. Figure 8.1 In an oil-wet system, the location of the two fluids is reversed, and oil will occupy the small pores and contact the majority of the rock surface. Depending on the specific interaction of rock, oil, and brine, the wettability of a...