High Island A-343 "A" and "B": A Case History of Offshore Platform Abandonment and Artificial Reef Planning

Abstract

Abstract Two obsolete offshore platforms were removed from the sea floor using explosives, towed from Texas OCS waters, and toppled in West Cameron 616, offshore Louisiana, creating an artificial reef and fish habitat to benefit recreational and commercial fishermen. The paper describes the planning, engineering, permitting and operational activities for the first structures donated to the Louisiana Artificial Reef Program from outside one of their reef planning areas and among the first structures abandoned under the limitations of the "Generic Consultation" issued by the National Marine Fisheries Service under the Endangered Species Act. Introduction The High Island A-343 "A" and High Island A-342 "B" platforms were abandoned and the jackets, weighing platforms were abandoned and the jackets, weighing a total of over 5200 tons, were placed in an artificial reef site during the 4th quarter of 1988. The "A" platform was a 24 slot, three-level drilling/production platform located in 237' water depth. The "B" platform was a 10 slot, two-level drilling/production platform located in 236' water depth. Both platforms were installed in 1977 and had produced a total of over 300 GCF prior to being shut-in in 1987. Removal operations began at the "A" platform on October 28, 1988 and at the "B" platform on November 24, 1988. The derrick barge phase was completed in 39 days (including 13 weather and mechanical downtime days) without an OSHA recordable accident using over 60,000 construction man-hours. The decks, conductors, main piles and platform appurtenances were transported to shore. The jackets were towed 30 miles to West Cameron 616, 110 miles off the coast of Louisiana, and toppled at the Louisiana Artificial Reef Program (LARP) permitted reef site located in 308' water depth. permitted reef site located in 308' water depth. Operations were conducted in compliance with the terms and conditions identified in the Incidental Take Statement (ITS) issued by the National Marine Fisheries Service (NMFS) included in the Minerals Management Service (MMS) approved application for the use of explosives. NMFS observers were onboard prior to and during all explosive operations. The prior to and during all explosive operations. The explosive plan required detonation of 63 bulk charges to sever piles below the mudline and resulted in no delays to comply with the MMS/NMFS stipulations. Background Requirements for Abandonment: Abandonment of offshore structures is regulated by the MMS on the Outer Continental Shelf (OCS) and by the U.S. Army Corps of Engineers (COE) in state waters. The MMS requirements for structure abandonment are to remove all structures from a lease within one year after surrender, to sever all well conductors and pilings at least 15' below the mudline (BML) and to pilings at least 15' below the mudline (BML) and to verify the location is clear of any bottom obstructions after completion of the abandonment. Since 1986, the MMS has also required a review and approval of all proposed abandonments with a focus on the use of explosives. Endangered Species Act Issues: Through a series of events in 1986, offshore structure abandonment changed from one of the least to one of the most regulated phases of offshore operations. Following the abandonment of several structures using explosives offshore Galveston, Texas, in March 1986, a circumstantial correlation between these abandonments and an apparent increase in sea turtle (particularly the Kemp's ridley sea turtle) and porpoise strandings was noted. In August 1986, in porpoise strandings was noted. In August 1986, in response to a request from the Center for Marine Conservation (CMC), then the Center for Environmental Education, Exxon Company U.S.A. voluntarily suspended abandonment operations on the Grand Isle 18 "A" structure located in the offshore state waters of Louisiana. The basis of the request was concern over the potential impacts of explosives on threatened and endangered species of sea turtles, especially the Kemp's ridley sea turtle. P. 91