Belmont Island Decommissioning Project

May, 2002

In 1948, Marine Exploration Company drilled the discovery well for the Belmont Field under a tide and submerged lands permit PRC 186 from the California State Lands Commission (CSLC) from a site one-half mile inland from the coast. Marine Exploration realized that it would need to build an offshore drilling and production island to adequately develop the oil and gas field. Monterey, the successor to Marine Exploration began construction of the island in 1952 on a site located about one and a half miles offshore from the City of Seal Beach (latitude 33° 43' 18.19"N and longitude 118° 07' 28.77"W) in approximately 42 feet of water. Monterey, with Texaco as its partner, completed Monterey Island (later renamed Belmont Island) in 1954. Designed to allow the drilling of 70 wells, the 75-foot diameter circular island, had an outer rim (caisson) of interlocking sheet steel piling driven into the ocean floor about 15 feet. It was filled with small rock and sand and topped with a concrete drilling deck. The wood pile and concrete North Wharf and the South Span that connected the steel South Tower to the island finished the original island. Submerged pipelines were laid on the ocean floor to carry production to an onshore production terminal.

The first well on the Island was started (spudded) in May 1954 and was completed in September of that year. It was the first offshore well drilled from an offshore platform or island in California and produced 300 barrels of oil per day (BOPD). To enhance development capabilities, the East Wharf, shop, drilling fluid (mud) tank, crane pedestal, and mezzanine deck were added in 1958. Before the end of the decade, 41 wells had been drilled and over five million barrels of oil had been piped ashore. In 1960 an electrical sub-sea cable laid and the island was converted to shore power. Humble Oil Company (Exxon) purchased Monterey in 1961 and acquired the operating interest in the Belmont Field.

After severe storm damage suffered in 1983, Exxon installed a tubular steel strut support system to stabilize the North Wharf, a tubular steel boat landing jacket on the north side, and added new deck sections, crew change room, and electrical switchgear module and transformers to the South Tower.

During the 40-year life of the Island, the wells produced approximately 28 million barrels of oil and 24 million cubic feet of natural gas. The state received over $40 million revenue. Production terminated in 1994, and the oil wells were plugged with cement and abandoned in 1996 to prevent any leak of oil or gas into the environment in compliance with State regulatory requirements. The buried oil and gas pipelines to shore were purged and flushed to remove residual oil and gas.

Exxon and State Lands representatives participated in pre-abandonment meetings with a number of agencies responsible for issuing permits or for resource protection. These meetings included representatives from CSLC staff, the California Coastal Commission (CCC), the U.S. Army Corps of Engineers (USACE), the California Department of Fish & Wildlife (CDF&W), and the Regional Water Quality Control Board (RWQCB). Initially, an on site artificial reef concept was considered as an alternative to the total deconstruction of the Island.

At the June 14, 1999 CSLC hearing, several interested groups recommended leaving some or all of the Island in place as an artificial reef. Because of that interest, the Commission withheld action on the calendar item pending more review on the potential of leaving material at the site for sport fishing and other recreational uses.

The main drawbacks were lack of sufficient water depth at the site, proximity to the local harbors and marinas, poor water clarity and liability issues. The consensus among the public agencies consulted was that this site was not suitable due to water depth and clarity issues. The CDF&W agreed to have the rock materials transported and used to enhance the artificial reef offshore Bolsa Chica (in federal waters off Huntington Beach) and Exxon elected to propose that option. The Commission subsequently approved the abandonment project on December 3, 1999.

The CSLC staff oversaw the project to ensure that decommissioning of the island was done in accordance with and adherence to all mitigation measures, the approved work and contingency plans, the lease terms, and all applicable rules and regulations of the Commission and other permit stipulations.