--> ABSTRACT: Impact Assessment of Offshore Sulfur-Mining Subsidence on Oil and Gas Infrastructure, by Jesse L. Hunt, Jr.; #91030 (2010)

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Impact Assessment of Offshore Sulfur-Mining Subsidence on Oil and Gas Infrastructure

Jesse L. Hunt, Jr.

Since the Frasch process was discovered in the early 20th century and used in mining sulfur from salt dome cap rocks in coastal Louisiana and Texas, varying degrees of subsidence have been observed. Review of both historic and recent aerial photographs over certain mine sites situated in marshy coastal areas reveals substantial subsidence. Since production began in 1960 at the Grand Isle Sulphur Mine located in state waters about 7 mi offshore of Grand Isle, Louisiana, approximately 70 ft of subsidence has occurred. The production platforms at the mine had to be raised or relocated due to the subsidence.

No adverse impacts to existing offshore oil and gas pipelines and platforms resulting from subsidence associated with sulfur mining have been documented to date. Many of the salt domes nominated for inclusion in a sulfur and salt lease sale in federal waters offshore Louisiana, proposed for 1988, have a well-developed oil and gas infrastructure; thus the potential for subsidence-related impact does exist. Therefore, an analysis of the potential impacts to oil and gas infrastructure resulting from subsidence was done as part of the environmental assessment for the proposed lease sale.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.