Print this pageGas Washing Pattern and Economics
in an Area of Continental Shelf, Offshore Louisiana
Steven Losh, Daniel Swart, and Andrew Dickinson
Department of Chemistry and Geology, FH 241, Minnesota State University, Mankato, Minnesota 56001
ABSTRACT
Crude oil from the continental shelf, offshore Louisiana, has been stripped of its light ends to variable extent by subsurface interaction with a mobile gas phase. Previous work showed that oils from fields nearest the present coastline suffered the greatest gas washing, and that the depletion diminishes southward along a transect across the shelf to nil at the Jolliet Field on the slope. New data from fields up to 50 mi (80 km) from the transect broadly supports this pattern, but shows that the extent of gas washing decreases in a southeastward direction in the study area, discordant with the east-west depositional strike of deep sands within depopods that are thought to be the sites of gas washing. Gas washing, by stripping more-valuable light ends, can substantially diminish oil quality. We estimate that the most-depleted oils may have lost up to 20% of their value (on a dollars per barrel basis) relative to unfractionated oils, although most crudes in our study were considerably less affected by gas washing.
Losh, S., D. Swart, and A. Dickinson , 2009, Gas washing pattern and economics in an area of continental shelf, offshore Louisiana: Gulf
Coast Association of Geological Societies Transactions, v. 59, p. 477-484.
AAPG Search and Discover Article #90093 © 2009 GCAGS 59th Annual Meeting, Shreveport, Louisiana