The attributes of Conventional Tankers were displayed in a previous Section 2b. In terms of usage for an FPSO they are often limiting. For this reason other Floating Designs incorporate deck stiffening to remove these short comings and can take more concentrated load supports, Section 4 elaborates this fact in Module design. The limitations of this type of support, Fixed Towers is water depth. In very deep water (2000m) a Self Supporting Tower would be immense due to the large sectional size of the structual support members. Tower designs with some floatation capability mitigate this, but in terms of economy the floating solution is preferred in Deep Water. It is the cost of Deep Water Solutions for the Support of Platforms that has enabled the consideration of Sub Sea Solutions to be an alternative to the platform. Its the Application which governs the Solution in terms of practicality and cost.
1, Inshore Shear Leg Lift
2, Offshore, Twin Crane Thiulf wijh Pipe Line Stinger
3, Offshore Sleipner, 2 x 10,000te Cranes
One of the most common types of Fixed Installation is a Jacket. They are usually manufactured, and constructed in the horizontal and installed in the vertical, see 1.
The last example concerns the substantial Condeep Type Platforms constructed in concrete. These have appeal for a number of reasons. Firstly the platform is located in an area that favours making things in concrete as opposed to steel which requires more skilled constrution labour. They are self floating and can be moved by towing vessel to site. At site they are self installing requiring no lifting. They have storage capacity for crude. Finally they may be removed by deballasting to become buoyant
Inevitably to use a fixed support design we need to considor that once the Jacket is installed Modules or Topsides must be installed. There are now a series of floating cranes of varying deigns which can do this type of work. Inshore, where any lifting is more simplistic then shear leg type floating barges are used. Offshore things are more complex and to simplify things larger lifts are undertaken
Supports Fixed Towers Button
An alternative to a) is b) launch off of the stern of a barge over rockers (pads that tilt as the jacket skids off). using ballast and flotation they are landed, feet piled and the Topside Platform lifted on, see 4.
Once off of transport they are rotated using a controlled lift, floatation and ballast. When on location they are landed, feet piled and the Topside Platform lifted on, see 3.
Floaters is a broad reference to Hulls that Float, some are ship shape, some are other shapes such as cylindrical, semi sub, submerged pontoon.
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Index, Section 2 Supports,
a general understanding of Modules
Jackets are installed in a number of ways. They first are loaded out onto marine transport and taken to location. Installation can be undertaken by heavy lift and firstly a) lifted off of the transport, see 2
Over All Schemes,
Typical, Jacket Installation
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1, Installation Concept for a Jacket
2, Jacket Load Out, Transfer to Location
3, Jacket Rotation into Position
4, Jacket Launched Off of Barge at Site
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