Extraction of Hydrocarbons and Minimizing Organic Deposits from Crude Oil Using Carbon Dioxide

Supercritical fluid extraction (SFE) technology is a new and powerful separation process, which has several applications in environmental and petroleum industry fields. Supercritical carbon dioxide (SC CO2) extraction process can be applied as a remediation technique for sediments contaminated with crude oil. On the other hand, SC CO2 can be applied as an Enhanced Oil Recovery (EOR) technique in the petroleum industry to increase the ultimate recovery factor of crude oil from reservoirs. Therefore, utilization of SC CO2 for the extraction applications can result both in environmental and economic benefits. In this study, SC CO2 was used for the extraction of petroleum hydrocarbons from sediments partly saturated with crude oil from Bu Hasa oil field of UAE. The effect of CO2 flow rate (1 and 4 ml/min), temperature (80 and 160°C), pressure (250 and 350 bar) and addition of 5% (v/v) organic solvent (heptane or toluene) in the SC CO2 extraction was investigated. The highest extraction of hydrocarbons (up to 92%) was obtained at 80°C and 350 bar using modified SC CO2 with 5% of (v/v) heptane. The residual hydrocarbon profile for the sediment, after the extraction process, shows that SC CO2 is an excellent remediation technique, where up to 93% of Total Petroleum Hydrocarbon (TPH) in the contaminated sediment was removed. In addition, a significant reduction in levels of some Polycyclic Aromatic Hydrocarbons (PAHs) was observed. Moreover, the SC CO2 extraction of petroleum hydrocarbons from sediment and limestone particles spiked with crude oil was conducted at the reservoir conditions (300 bar, 120°C)