We perform single-phase and two-phase flooding on Edwards Brown rock samples. The single-phase injection was of seawater or CaCl₂ brine,at successive salinities 0.63,0.21,0.07,0.05,and 0 mol/L (distilled water). For CaCl₂ brine experimental run,no significant fines migration or permeability decrease is observed. For seawater experimental run,distilled water injection is found to bring about the highest concentration of produced fines and most of the permeability decrease,with the ultimate permeability decrease being 99.94%. Therefore,distilled water injection is used to stimulate fines migration in the following two-phase experimental runs. Two-phase experiments are performed on four Edwards Brown rock samples using seawater or CaCl₂ brine as the aqueous phase,and Soltrol? 130 or crude oil as the oleic phase. Rock samples are initially fully saturated with 0.63 mol/L of the selected aqueous solution. This is followed by injecting the selected oil at a constant rate for at least 20 pore volumes to displace brine. Next,selected brine is injected to displace oil,and finally distilled water. For CaCl₂ brine,distilled water injection is found to recover no additional oil of either type of oil. However,for seawater,the fines production observed during distilled water injection is found to reduce water relative permeability by two orders of magnitude when Soltrol? 130 is used and by three orders of magnitude when crude oil is used. The seawater experimental runs also brought about additional oil recovery during distilled water injection: 18% when Soltrol? 130 is used and 3.4% when crude oil is used. This last result can be attributed to the plugging of pores due to fines migration,which can divert further injected water into previously unswept pores.

This paper investigates the extent to which alcohol-treated carbon dioxide (CO₂), a mixture of alcohol and CO₂ equilibrated at experimental pressure and temperature, can lead to greater interfacial tension reduction and greater oil swelling than can pure CO₂. Experimental measurements of interfacial tension and swelling behavior are made using a high-pressure, high-temperature visual cell at 70 °C. Two sets of fluid pairs are used: pure CO₂ and oil, and alcohol-treated CO₂ and oil. Two types of oil are used: a mixture of 35% hexane and 65% decane (C ${}_6$-C ${}_{10}$ mixture), and pure decane (pure C ${}_{10}$). Ethanol and methanol are used to prepare alcohol-treated CO₂. Numerical simulations are used to estimate a reduction in the minimum miscibility pressure when using alcohol-treated CO₂. Interfacial tension between alcohol-treated CO₂ and oil is found to be 0.02 to 2.2 mN/m less than that between pure CO₂ and oil. Simulation results suggest that alcohol-treated CO₂ yields 0.2 to 1.2 MPa lower minimum miscibility pressure compared to pure CO₂. Alcohol-treated CO₂ also is found to cause 6% to 43% more swelling of oil than does pure CO₂. Interfacial tension and swelling results suggest that alcohol-treated CO₂ yields better miscibility with oil compared to pure CO₂.