Effect of Viscous Forces and Initial Water Saturation on Water Injection in Water-Wet and Mixed-Wet Fractured Porous Media

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA systematic study of the effect of wettability and initial water saturation on water injection and imbibition was made in Kansas outcrop chalk samples. Water injection tests were conducted at different rates and at different pressure gradients to study the effect of viscous forces. Based on a large number of carefully conducted tests, the following conclusions are drawn. 1. Initial water saturation has a very pronounced effect on water injection in an intermediate-wet chalk. This effect is much less pronounced for a strongly water-wet chalk. The effects are also in opposite directions. Viscous forces have a very strong effect on water injection performance on intermediate-wet chalks.Our interpretation of the above experiments lead to the conclusion that the performance of the chalk reservoirs may be nearly independent of wettability state. The results from the experiments also reveal that there is no relation between laboratory measurements of spontaneous imbibition and field performance even when wettability state is perfectly restored in the laboratory.