Subsea Templates and Manifolds
A subsea template is a large steel structure which is used as a base for various subsea structures such as wells and subsea trees and manifolds. The image below shows a number of wellheads on a subsea template:
The wellheads can be seen with their guidebases (4 x white rods) pertruding from each corner, which are used to locate other equipment, i.e. trees.
The size of a template is dependant on the number of structures attached to it. Many will have protective structures covering them, as does the template pictured right. This helps prevent damage from fishing activities and also improves fishing safety by reducing the likelihood of nets becoming snagged on the equipment.
|Subsea template supporting wellheads
and protective structure
A subsea manifold is a large metal peice of equipment, made up of pipes and valves and designed to transfer oil / gas from wellheads into a pipeline. Manifolds are usually mounted on a template and often have a protective structure covering them - as with the image below right.
|Subsea manifold||Subsea manifold within a protection structure|
Manifolds vary greatly in size and shape, though can be huge structures reaching heights of 30 metres. The image below demonstrates just how large these structures can be, when compared to the cars placed alongside the manifold.
|Scaled model of a subsea manifold
and protection structure
Although this equipment often has a protective structure surrounding it, there is still a serious risk of fishing gear becomming snagged on the protruding elements or within inner cavities.
Most subsea templates / manifolds will be protected by a 500 metre safety zone centered on one position. However, other equipment may also be clustered within the same area, justifying the need to have a 500 metre safety zone.
The image to the right shows how associated seabed structures may extend more than 100 metres from the central location of the safety zone. This demonstrates just how important it is that a 500 metre safety zone is recognised by all seabed users.
|Cluster of subsea equipment around a manifold|