1 SCA2003-02: THE EFFECT OF DIFFERENT CRUDE OIL/BRINE/ROCK COMBINATIONS ON WETTABILITY THROUGH SPONTANEOUS IMBIBITION

Wettability depends on crude oil/brine/rock interactions. The presence of initial water saturation can determine the areas of rock pore surface where such interactions result in adsorption of polar components from crude oil to give a condition described as mixed wettability (MXW). If crude oil is removed to leave an organic film (F) on the rock surface, the condition is referred to as MXW-F. MXW and MXW-F wetting states are compared through spontaneous imbibition measurements for crude oil/brine/rock combinations that include one sandstone and one limestone with each rock type exposed to an asphaltic and a moderately asphaltic crude oil. The solvency of the crude oils for the asphaltenes was decreased by addition of n-decane with volumetric ratio ranging from 14 % to 30%. The limestone exhibited greater sensitivity to crude oil solvency than the sandstone. Whatever the crude oil or its composition, rates of recovery of refined oil by spontaneous imbibition from MXW-F cores were slower than for the corresponding MXW cores