An experimental investigation of interactions between supercritical CO ₂, aspheltenic crude oil, and reservoir brine in carbonate cores

Asphaltene precipitation and rock dissolution can significantly hinder the success of carbon dioxide flooding of asphaltenic crude in carbonate formation. It is essential during CO₂ flooding when both processes exist to study separately the effect of each phenomenon on the flooding process. Core flooding experiments under high pressure and temperature conditions (250°F, and 4000 psia) were conducted to evaluate each phenomenon separately. Actual cores representing different areas of carbonate oil field and actual fluids, (crude oil and brine) were used to evaluate the interaction between CO ₂, rock and fluids. Asphaltene content of the produced crude oil, water and mineralogical rock analysis, and pores micro-photos were performed to evaluate the effect of SC CO₂ flood on the petrophysical characteristics of the limestone cores. Results indicate that the amount of damage depends on the fabric of the rocks, salinity of the brine, core permeability and damage is due to interaction between CO₂ and rock. Fluids assessment should be conducted to different areas of the field.