ESTABLISHING MIXED WET CONDITIONS IN CHALK - EMPHASIS ON WETTABILITY ALTERATION AND OIL RECOVERY

摘要

Oil/brine/rock systems at various wettabilities were prepared using different crude oils, synthetic formation brine and Portland outcrop chalk.Various mixed wettability conditions were achieved and quantified by the Amott test for 75 core plugs.Several trends were observed.The established wettability conditions varied from neutral wet to strongly water-wet.Endpoint water saturation after spontaneous imbibition(S_(wsp)) increased with increase in initial water saturation(S_(wi)).For some selected core plugs, repeated Amott tests were conducted and showed good reproducibility and proved stable wetting conditions.Maximum oil recovery after forced imbibition(S_(orw)) occurred at slightly water-wet conditions.