Enhancing Water Imbibition Rate and Oil Recovery by Carbonated Water in Carbonate and Sandstone Rocks

Abstract

Spontaneous imbibition is regarded as an important mechanism of oil recovery by waterflood, particularly in heterogeneous or fractured reservoirs where direct displacement of oil by water is usually poor. It has been shown that carbonated water injection (CWI) can improve recovery from oil reservoirs. It has also been reported that the dissolution of CO2 in water can alter water/oil contact angle, which is a direct indication of the wettability of a crude oil/water/rock/system. In this work, our main objective was to experimentally investigate the potential of carbonated water for improving the rate of spontaneous imbibition of water and, hence, the oil recovery from systems where spontaneous imbibition of water would be important. To achieve this objective, a special high-pressure imbibition cell has been designed, and six spontaneous imbibition experiments have been performed on two different types of rocks (carbonate rock and sandstone) at a pressure of 2500 psi and room temperature. Crude oil was used...