Jackup platforms

Typical types of cyclic loadings in the marine environment, (a) Jackup platform leg (1-way) (b) earthquake loading (2-way) (c) ocean wave loading (2-way). (From Chaney, R.C., and Fang, H.Y., Liquefaction in the coastal environment An analysis of case histories, Marine Geotechnology, Vol. 10,343-370,1991. Reprinted with permission. Copyright ASTM.)... 

Fixed platforms are built of concrete and steel and are firmly anchored to the sea bed for long-term production drilling. A semisubmersible platform has hollow legs that can be used as displacement tanks to raise, lower, or stabilize the platform. This type of platform is movable and typically is anchored to the sea floor by cables. Jackup platforms have movable legs that can be raised or... 

Bottom-supported vessels consist of drilling platforms, jackup rigs, and drilling barges. A drilling platform is not employed until reserves warranting field development is indicated. Platforms are currently being set in water depths up to 1,000 ft, and also serve as permanent production facilities. 

Floating exploration and production facilities are sometimes provided on jackup rigs, semi-submersible vessels or ex-crude oil shipping tankers converted to production treatment vessels. These facilities are essentially the same as fixed offshore platform or installations except they are moored in place or provided with a temporary support structure instead of provided with fixed supports to the seabed. The major process fire and explosion risks are identical to the risks produced on offshore platforms. They have one addition major facility risk, that is the maintenance of buoyancy of the installation. Should fire or explosion effects cause a loss of buoyancy (or even stability) the entire facility is at risk of submergence. Adequate compartimization and integrity assurances must be implemented in these instances. 

It has been estimated that more than 4,000 offshore production facilities exist on the outer continental shelf (OCS). These exploration wells can be drilled to depths of around 10,000 feet. Most production systems are designed to operate at depths of 6,000 feet. Oil and gas product pipeline networks extend well off the continental slope. Offshore production rigs and drilling and production platforms can be classified as onshore platforms, fixed platforms, jackup rigs, semisubmersibles, drill ships, and tension-leg platforms. 

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