F. Shi, Y. Duan, Y. Soong, M. Gray
National Energy Technology Laboratory,
Keywords: oil, recovery, spill, separation
Summary:Preventing oil spills is a top priority for the oil and gas industry, and the ability to avert and respond to oil spills is essential for obtaining an operating license. Oil spill response is a challenging effort under any conditions, but responding to spills in Arctic waters—with their subzero temperatures, ice-covered waters, strong ocean currents, and dangerous operating conditions—presents unique challenges. Current mechanical methods, including booms and skimmers, are not optimized for oil spill recovery in the harsh environment of Artic regions. Flotation is an aqueous, efficient, inexpensive, easy to operate, and well-developed commercial technology which has been widely applied in various industrial processes, including mineral processing and wastewater treatments. Researchers from the National Energy Technology Laboratory (NETL) have successfully demonstrated proof-of-concept for a new oil spill recovery flotation process  under simulated Arctic conditions. The work  is being conducted under a grant awarded to NETL by the U.S. Department of the Interior’s Bureau of Safety and Environment Enforcement, which manages the nation’s natural gas, oil, and other mineral resources on the outer continental shelf. NETL’s new process uses a froth flotation process to separate crude oils from cold sea water, even from crushed sea ice and water. Laboratory-scale testing focused on the efficiency of crude oil separation using different surfactants, temperatures, and ice conditions under both batch and continuous operation scenarios. NETL’s flotation process has not only been used for the recovery of Arctic crude, i.e., North Star crude and ANS crude, but also been successfully demonstrated with crude oils from Pacific and Gulf of Mexico (Ewing Bank and Harmony crude oils) at varied sea water conditions. Results demonstrated high oil-recovery rates and a high oil-to-water final product, which significantly reduces waste water volume. The NETL system is capable of generating a water stream with residual oil below 5.0 ppm, meeting the Environmental Protection Agency’s requirement of less than 15 ppm of residual oil and allowing direct discharge into the sea. NETL’s novel on-board flotation system will be perfect as a primary or secondary method for spilled oil recovery for varied oil spill situations.