Berea sandstone cores were contacted with six different crude oils to determine the effects of oil composition on mineral adsorption and wettability alteration. The crude oils employed in the study encompassed a wide range of chemical and physical properties. Three different types of Berea sandstone cores were contacted with each crude: dry, untreated cores; cores that contained an initial brine saturation prior to contact with oil; and cores that were treated with potassium hydroxide (KOH) for clay stabilization and contained an initial brine saturation prior to contact with oil. The Amott method was used to evaluate wettability alteration. Thin-sections, total organic carbon (TOC), and Rock-Eval analyses were performed to assess the extent and nature of adsorbed organics.

Positive correlations were noted between wettability alteration and oil resin and asphaltene content, and between the extent of adsorption and oil resin and base content. The extent of adsorption was also found to be inversely related to the oil saturate content. There was little correlation between extent of adsorption and wettability alteration.

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