A Laboratory Study of Wilmington Tar Zone CO2 Injection Project

Abstract

Summary We conducted a laboratory study of heavy-oil recovery by CO2 injection to support-the Wilmington, CA tar zone CO2 injection project operated by Long Beach Oil Development Co. The study comprised (1) phase behavior of Wilmington tar zone reservoir oil and CO2, and (2) phase behavior of the oil and the refinery gas used for the field project, (3) viscosity measurements of oil/gas mixtures, (4) reservoir- condition displacements of oil by CO2 and by refinery gas, (5) equation-of-state characterization of phase behavior, and (6) computer simulation of gas/oil displacements. Saturation pressures'and swelling factors were measured for oil/gas mixtures, which showed that N2 is substantially less soluble in oil than is CO2. Viscosity measurements show that the viscosity reduction is a function of pressure and of the total gas dissolved in the oil. Four reservoir-condition corefloods showed that the recovery efficiency of CO2 is higher than that of the refinery gas for continuous or low WAG injection, and the recovery efficiency of the refinery gas at 1:1 WAG is about twice that of continuous injection. The corefloods were modeled with a finite-difference compositional simulator. Predictions agree with the experimental results.