Measurements and Correlations of the Physical Properties of CO2-Heavy Crude Oil Mixtures

Abstract

Summary Viscosity reduction and swelling are the principal mechanisms contributed to the improvement of heavy-oil recovery by immiscible CO2 displacement. This paper presents the results of experimental measurements for the physical properties of heavy oils before and after CO2 saturation. Based on measured data, correlations were developed for the predictions of CO2 solubility, oil swelling factor, and viscosity change for CO2-saturated heavy oils. Introduction Recently, recovery of heavy oil by CO2 displacement methods has received more attention because of economic potential. This method is especially applicable in reservoirs where steamflooding is not applicable. Large-scale field tests, such as Lick Creek field in Arkansas and Wilmington field in California, have proved the applicability of CO2 immiscible displacement for heavy-oil recovery. Viscosities of heavy crude oils range from several hundred to 100,000 cp [100 Pa's]. Mobility of heavy oil under reservoir conditions is of major concern, and reducing oil viscosity is an important factor in recovery efficiency. Carbon dioxide is an effective agent in reducing oil viscosity. In addition, swelling of crude oil and solution gas drive are other possible mechanisms in CO2 immiscible displacement. Such physical properties as viscosity, density, and CO2 solubility in heavy oils are required to design and simulate a heavy-oil recovery process. The effects of CO2 on the physical properties of crude oils must be determined to design an effective immiscible displacement process. A predictive method for properties of heavy-oil/CO2 mixtures is useful for process design and screening.