Vaporization of Crude Oil by Supercritical CO₂ at Different Temperatures and Pressures: Example from Gorm Field in the Danish North Sea

The effect of temperature on supercritical carbon dioxide (SC-CO₂) extraction of crude oil from the Gorm oil field of the North Sea was investigated at temperatures of 40-70 °C and pressures of 20-60 MPa. MALDI-TOF, GC-MS, and NMR analyses were conducted in order to characterize the oil. Generally, the total recovery and vapor recovery increased, while the liquid recovery decreased, when the temperature was increased from 40 to 70 °C. At lower temperatures (40 and 50 °C), the liquid recovery increased from a minimum of 10% at 30 MPa to a maximum of 60% at 60 MPa, whereas the vapor recovery was 16% on average over the entire pressure range. In contrast, at higher temperatures (60 and 70 °C), the liquid recovery was 20% on average at all pressures, while the vapor recovery increased from 20% at 30 MPa to 58% at 60 MPa on average. This sharp increase of vapor recovery at higher pressures signified retrograde vaporization. This observed phenomenon suggested that the extraction of some types of oil from high-pressure reservoirs could be achieved by vaporization using SC-CO₂.