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Oil platforms

Oil platforms are the man-made structures, which are used to house the workers and equipment used to drill for oil offshore. These mammoth structures may be either floating or anchored and are typically located on the continental shelf. As technology and the capability of engineering increases, though, drilling and production in deeper waters is not only possible but also economically feasible.

Large oil platforms may have many well heads to allow for drilling at different depths as well as directional drilling for work in progress as much as five miles distant. Some oil platforms have remote wellheads attached by umbilical cords.

At one time, these structures contained, men, equipment, wellheads and limited processing equipment, but occasional serious incidents with loss of life have made separate, self-contained housing and living accommodations more common for the sake of safety.

The oil platforms are normally self-sufficient as far as energy and water production is concerned. They house generators, desalination plants and needed processing equipment for delivery the crude oil either to pipelines or to oil tankers. Other needs are supplied by provisioning ships. In addition, search and rescue vehicles are available nearby, as well as larger ships suitable to towing platforms to a new location should it be needed.

Oil platforms come in many different types, but the major categorization is between fixed platforms and floating platforms. Fixed platforms have their legs firmly embedded into the sea floor. The base is concrete and the legs are made of steel or concrete. The legs support a deck or platform on which are located all the amenities of the offshore city. The platform supports all the equipment, tools, living accommodations and supplies which go into the work of the site. Because of the permanence of the building and anchoring, these oil platforms, such as the Hibernia Platform located in the North Atlantic. The Hibernia Platform at 37,000 tons above the water and a 600,000 ton gravity base is the largest of the world's oil platforms.

These fixed platforms often have built in storage compartments below the waterline which help to stabilize the structure. Oil platforms of this type are suitable for placement in water up to about 1700 feet in depth.

Compliant towers are used where there is severe incidence of side winds. This type of platform consists of tall flexible towers and a piled foundation which supports the traditional deck.

Semi-submersible oil platforms are created in such a way that the legs keep the structure buoyant due to their flotation, while the weight keeps the structure upright. These oil platforms can be towed from place to place. Jack-up platforms are designed in such a way that they can be towed into place and then the legs lowered to hold them solidly in position. Tension leg platforms perform much the same function with the floating unit tethered to the ocean floor with the tensioning units on the legs preventing unwanted sideways movement. The tension-leg platform can be used in water depths up to 6,000 feet. Smaller ‘mini' TLP's are sometimes used for preliminary drilling platforms or exploratory work.