Statistical and Analytical Review of Worldwide CO₂ Immiscible Field Applications

CO ₂ immiscible flooding is an important enhanced oil recovery (EOR) technology that has demonstrated great potential under varying reservoir and fluid conditions. This paper provides a comprehensive review of worldwide CO ₂ immiscible experiences by collecting and analyzing data of 41 field applications from more than 60 publications, including books, DOE reports, AAPG databases, Oil and Gas Journal surveys, field reports, and SPE publications. About 100 papers have been reviewed. Two major parts are included in this paper. The first part explores where CO ₂ immiscible could be applied, in which screening guidelines have been established and updated by applying statistical methods. Boxplots and histograms were used to detect special cases and to interpret the main distributions of reservoir/fluid properties. The second part discusses the influences of operation to the productions, the performances of each field, and the existing operational problems by using analytical methods, which include injection strategies, gas injection compositions, CO ₂ utilization, CO ₂ injection efficiency, incremental oil recovery, and incremental oil production rate per well. Results show that CO ₂ immiscible flooding could produce an additional 4.7%-12.5% of oil with 10.07 Mscf/stb average CO ₂ injection efficiency.