Case History: Decommissioning, Reefing, and Reuse of Gulf of Mexico Platform Complex

Abstract

Abstract During the creation of the Galveston 189 platform complex artificial reef several firsts were achieved: a permanent shallow water, low profile reef; a permanent reef site with easy access for the general public; and the largest diamond wire cut made in the Gulf of Mexico. In addition to these firsts, the procedures required during the decommissioning of an offshore platform, the severing techniques used and the variety of disposal options available for obsolete offshore oil and gas structures are reviewed. Introduction One requirement in every offshore oil and gas lease, in State or Federal waters, is the removal of the structure at the end of its useful life. In the best case, the end of life for a platform is defined as 15 months after production activities on that lease cease. The removal of an offshore facility is a multi-phase process. The first activities are the planning and permitting. Generally the planning and permitting phases will take a couple of weeks; in special cases, such as offshore California, they will require years of regulatory activities. Once the permits are received, the bid packages evaluated, and contracts in place the work onsite starts. The wells are permanently plugged. The pipelines are then cleaned and capped, and sometimes even removed. The production equipment is flushed and made gas free. The structure is removed. And finally the site is trawled with a shrimp net to prove the site is clear of objects on the seafloor. The reefing of oil and gas platforms in the Gulf of Mexico is considered a win-win solution for the operator, regulators and the environment. When a platform is installed offshore an artificial reef is automatically created. By providing a method to maintain the hard bottom strata created by the platform the existing marine life around the platform stays virtually intact. The regulatory agencies involved are the Minerals Management Service (MMS), Army Corps of Engineers (COE), United States Coast Guard (USCG) and State Wildlife Departments. These regulators have control over the location, placement and materials that are reefed. The operators have the opportunity to reduce removal costs and liability. Upon acceptance of the created reef the ownership of the reefed materials transfers to the local State agency. To assist in the maintenance of the reef sites and outreach programs the operators typically donate one-half of the cost savings to the Artificial Reef Program in the State that they are working with. For the GA 189 platform complex the reef donation amount was $300,000. Background The Galveston 189 platform complex standing in 60' of water approximately 12 miles off Galveston, Texas was installed in 1981. The complex consisted of a four-pile main production platform, GA 189 B, set up to produce 10 mmcf/d and 2,000 bo/d. The production platform was bridge connected to two satellite structures, GA 189 C and GA 189 D. The GA 189 C platform was a four pile well protector with a minimal deck.