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Recovery of ABB Vetco Gray SG5 wellhead from template
06 November 2015
We are planning to decommission some North Sea platform wells drilled around 1995/96.  The wells have a subsea ABB Vetco Gray SG5 wellhead landed into the template.  The wellhead has a locking mechanism allowing the 30” wellhead housing to pass into the subsea template but stopping it from being pulled from the subsea template.  It is our understanding that it may be possible to over-pull shear pins to allow the 30” wellhead housing to be pulled free of the subsea template.  We were wondering if anyone has any idea of what sort of overpull may be required and if anyone has successfully recovered from a cut below the seabed with this type of wellhead after a significant amount of time installed.
Documents uploaded by user:
Wellhead.jpg
9 answer(s)
yousaf70
Sr. Advisor, Well Engineering specialist Deepwater, ERD, HPHT & Special Projects
Chevron Corporation
Total Posts: 4
Join Date: 07/11/15
It is very difficult to shear the wellhead. 
Much easier to use an abrasive cutter below seabed, and then recover the wellhead.
The modern abrasive cutters will cut thru all the casing strings in one pass easily.
JohnDrummond
Business Development Manager
SPEX GROUP
Total Posts: 4
Join Date: 04/06/15

Post #4 has a good point,

SPEX offer a good Wellhead Severance Package That will remove the wellhead and cut all the conductors below the sea bed in one operation


Documents uploaded by user:
Wellhead Abandonment Severance 030315.pdf
clydebuilt
Drilling Services Consultant
Clyde Drilling
Total Posts: 10
Join Date: 05/11/14
It is very difficult to shear the wellhead. 
Much easier to use an abrasive cutter below seabed, and then recover the wellhead. The modern abrasive cutters will cut thru all the casing strings in one pass.
Augusto
Consultant [retired Shell staff]
SPREADAssociates
Total Posts: 226
Join Date: 02/09/05
The SG5 system has no shear pins but a 360 degrees shear ring - indeed a 3 x 120 degrees segments - which makes shear practically impossible.
barrychapman
Operations Director
SPEX GROUP
Total Posts: 2
Join Date: 07/10/14
All the wells on the Hutton TLP were recovered using explosives and cut 15ft below seabed, the template was also cut up using explosive shaped charges as part of the same program.  
BrianPlumb
SPREADAssociates
Total Posts: 1
Join Date: 11/09/08
Hi Doug,
Long time no chat.
I de-commed the wells on the Hutton TLP, same situation. We abandoned all the wells on the template from the Hutton TLP. After discussions with ABB Vetco if I remember correctly the answer was you need more than 3million pounds to shear the 30" out of the template? Needless to say the wellheads were left as part of the subsea removal workscope.
Regards
Brian
CasingCutter
Well Abandonment Manager
Schlumberger
Total Posts: 8
Join Date: 30/09/13

Are you planning on attempting to pull the 18 3/4" wellhead out of the 30" wellhead - or cutting together? The 18 3/4" HP wellhead housing may also be locked into the 30" LP wellhead

Garry has a good point about the template and removing the 30" subsea wellhead(s) during the structural decommissioning stage.

I remember from my past days of evaluating abrasive water cutting technology to cut out 30" wellheads away from a template in order to leave just the template down, recover all conductors and / or or wellheads and bury the template with a derogation process.

Garskel1
Consultant
SPREADAssociates
Total Posts: 3
Join Date: 06/11/15
the answer is 1 million foot pounds would be required to shear these pins. You could consider a compensated jacking table but it would be easier to remove the 30" housing at a later date when the template is recovered. I think this is the Armada platform 
Garskel1
Consultant
SPREADAssociates
Total Posts: 3
Join Date: 06/11/15
the answer is 1 million foot pounds would be required to shear these pins. You could consider a compensated jacking table but it would be easier to remove the 30" housing at a later date when the template is recovered. I think this is the Armada platform 
Posted by

Douglas Noble

Contractor P&A SDE

Marathon Oil

Total Posts: 9
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