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Conductor spacing on a platform.
21 March 2016

During a Platform well design review, questions were raised with regards to the planned conductor spacing. Although the current spacing (5.7ft) between the conductors is adequate for both the wellhead and the X'mas tree installation, there is no clear detail on what the spacing was based on as we have lost a lot of key personnel.

Does anyone know of any industry standard that gives a clear definition of what the minimum spacing between conductors on an offshore platform should be?

1 answer(s)
Head of Well Engineering
State Supervision of Mines
Total Posts: 13
Join Date: 09/11/15
There are no industry standards for conductor spacing. The things to consider (which could be 'conflicting') are:
  • Cost - wider spacing = higher cost
  • wellhead and tree / flowline design - can i get the trees in, how are the flow lines routed, is there enough space for instrumentation
  • Conductor subsidence and Wellhead growth - During the well lifetime the conductors often drop somewhat and the trees will move up & down with the well temperature changes. Sufficient space for this is required
  • Operating area - you will need safe to walk areas around the wellheads for drilling/workover/production crews to work in and on the trees/wellheads
  • Are the trees on one deck or on two decks? - with two tree decks you get a lot more space around the trees for your pipework
  • Collision - the closer the wellhead spacing is, the more issues there will be with collision avoidance while drilling the well top hole sections
  • Soil hardness - in very soft top sediments the above issue is worse and many slots in the North Sea for instance have been lost as conductors were hammered down and collided with neighboring ones
  • Are the conductors pre-installed with the jacket, or hammered in afterwards? in the 2nd case you would like a bit wider space.
  • Are the conductor guides vertical all the way or are they tapering out? - the surface separation is smaller then sea-bed separation
  • ...
5.7ft to me seems like one of the tighter spacings I have seen, but not impossible. I am quite sure though that the tree deck (if only one) will be difficult to walk through once the wells are in position.

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