The MMS identifies decommissioning as the process of ending oil, gas, or sulphur operations and returning the lease or pipeline right-of-way to a condition specified by regulatory requirements. The MMS works to ensure that obsolete structures and components are cleared from the site to prevent use conflicts. To avoid release of hydrocarbons to the environment, wells are plugged and cut below the mudline and pipelines removed or internally cleaned and prepared for abandonment in place.

Approximately 3,700 active platforms exist in the OCS. With more than 40% of these facilities over 25 years old and in sight of their designed service life, industry has averaged more than 130 platforms removals per year over the past decade, exceeding the number of new installations. In most cases the topsides that contain the operational components are taken to shore for recycling or re-use. The substructure is generally severed below the mudline, removed, cleaned, and brought to shore to sell as scrap for recycling or refurbished for installation at another location. A small number of platforms meeting stringent requirements may be towed for use at an approved artificial reef site using the criteria in the National Artificial Reef Plan as permitted by U.S. Federal agencies. State government agencies responsible for managing marine fisheries resources administer the program.

The MMS supports and encourages the reuse of obsolete offshore petroleum structures as artificial reefs in US waters as long as the structure does not pose an unreasonable impediment to future mineral development and other OCS use. Reuse must comply with the artificial reef permitting requirements of the Corps of Engineers and the criteria in the National Artificial Reef Plan. The state agency responsible for managing marine fisheries resources must accept liability for the structure before MMS will release the Federal lessee from lease obligations. Challenges lie ahead for platform removal from the OCS, particularly for large platforms (> 10,000 tons) in deeper waters. MMS continues to support research to meet these and other challenges.