The huge tonnages of waste steel from decommissioned offshore oil and gas structures represents a serious problem for operators looking to recoup losses and avoid environmental harm. A way to calculate the weight of the problem has been developed by US researchers and described in the International Journal of Oil, Gas and Coal Technology.
Oil and gas operations over water were first carried out at Summerland, California in 1896 with wells drilled from piers extending from the shore. By 1937, at Ferry Lake, Louisiana, wooden decks were erected on platforms. Exploration then moved into the swamp lands of South Louisiana using timber structures, and by the mid-1940s, the open seas of the Gulf of Mexico were being drilled. In open water, drilling structures are susceptible to the lateral forces of tidal currents, wind and waves, which means wooden frames are no longer adequate, and strong and robust steel structures became necessary. After World War II, the growth of offshore drilling in the Gulf of Mexico and elsewhere intensified and the amount of steel dispatched to sea grew enormously.
Two grades of steel are commonly used for offshore construction work. Low-carbon steel is used for structural elements such as jackets, decks, railings, walkways, and deck plating; high-strength, low-alloy steel is used for critical components and extreme climate conditions, such as tubular joint and spanning nodes.
At the end of its useful life, when an operator determines that a facility will be decommissioned, disposal and reuse options are made as part of the overall assessment. Decisions as to whether to refurbish, reuse, recycle, or remove for landfill are determined by economic, technological, and regulatory conditions.
According to Mark Kaiser of the Center for Energy Studies, Louisiana State University, "The weight of an offshore structure is an important factor in design and is closely linked to its fabrication, installation, a
|Contact: Mark J. Kaiser|