Pressure Wave and Acoustic Properties Generated by the Explosive Removal of Offshore Structures in the Gulf of Mexico.

摘要

Oil and gas operations on the Federal Outer Continental Shelf (OCS) result in the placement of structures, equipment, and moorings into and onto the seafloor. The companies are obligated to decommission the offshore infrastructure when their activities are completed and remove the components from the OCS, as mandated under regulatory and lease requirements. Decommissioning is the process of ending the operations, removing the equipment and facilities, and returning the seafloor to its pre-lease condition. Under the OCS Lands Act (OCSLA), the U.S. Department of the Interior’s Bureau of Ocean Energy Management (BOEM) establishes decommissioning obligations to which an operator must commit when they sign an offshore lease; these includes the requirement to apply for and obtain a permit for subsequent removal of wells and facilities. The U.S Department of the Interior’s Bureau of Safety and Environmental Enforcement (BSEE) is responsible for regulating the decommissioning of OCS facilities in accordance with 30 CFR 250 Subpart Q. The regulations and lease agreements typically require the operator to remove all structures within one year of lease termination or before termination of the lease if either the operator or BSEE deems the structure unsafe, obsolete, or no longer useful for operations. The OCSLA regulatory and lease requirements for decommissioning offshore platforms are designed to minimize the environmental and safety risks inherent in leaving unused structures in the ocean. Decommissioning an offshore platform generally entails plugging all wells supported by the platform, severing the well casings 15 feet below the mudline (BML), and removing the platform from its foundation by severing all bottom-founded components at least 15 ft BML. Additionally, the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) published the Notice to Lessees and Operators (NTL) No. 2010-G05, “Decommissioning Guidance for Wells and Platforms,” for lease holders in the Gulf of Mexico OCS Region (GOMR) to provide clarification and interpretation of Subpart Q requirements. The policy informs lease holders and operators of their responsibilities and provides definitions and timelines for decommissioning idle wells and associated platforms. Decommissioning idle wells and inactive platforms in a timely manner reduces potential environmental and navigational risks on the OCS. Based on the most recent available data from BSEE (January 2016) (USDOI, BSEE, 2016), there are more than 2,325 existing structures the GOM OCS (Figure 1 has locations as of December 2015). The four main types of structures found on the GOM OCS are multi-leg platforms (67%), caissons (23%), well protectors (8%), and floating facilities (2%), which includes spars, tension leg platforms (TLPs), and mobile offshore production units (MOPUs). The majority of structures are located off the coast of Louisiana in less than 300 ft of water.