In-Situ Wettability Distribution and Wetting Stability in Outcrop Chalk Aged in Crude Oil

摘要

This paper reports an investigation of in-situ wettability distribution and wetting stability of moderately-water-wet and nearly-neutral-wet outcrop chalk cores, aged in crude oil at elevated temperature. In this paper, in-situ wettability measurements by MRI tomography have shown to give Amott indices that agree well with the standard wettability indices based on average saturations. The in-situ method provides information concerning Amott index distribution radially and along the length direction of the core plugs. Applying multi-directional crude oil flooding during aging, uniform wettability distributions, both radially and axially, were obtained. Tests of wetting stability confirmed that stable wettability alterations for repeated waterfloods and Amott tests were established. The results showed that the core plugs may not be dried or cleaned, as this will render the core plugs strongly-water-wet. Stable wettability conditions were measured for cores subjected to storage in brine at 90℃.