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Use of OBM for drilling of 8.5" laterals, approx. 10000 ft length from Offshore Jackup rigs_Risk involved
26 October 2016

Dear All,

For the Jackup wells of approx. 22,000 ft MD (10,000 ft lateral length) (2D profile wells|) we are using Water based non damaging mud for many years and we didn't face much of issues in running the 6-5/8" lower completions to well TD, however on recent wells we are facing problems running liner to well TD due increased complexities of profile like 3D profile, High DLS etc. Liner got stuck or held up earlier on some occasions and spent a lot of time to recover stuck liner with unsuccessful attempts. Which is why it is directing us to use OBM instead of WBM to lower down friction factors and help us to successful liner runs.

High risks are involved  in case the losses are encountered while 8.5" hole drilling in supplying OBM continuously to jack up rig. Especially in bad weather and no boats are working, it would led to disaster in case of well control issues.  

I wish to know, worldwide how is the practice for jack up rigs in using OBM for laterals drilling. What are the risks involved ? What mitigations plans should be in place ?

Your responses are highly appreciated.

2 answer(s)
gsoden
Service Company Operations Manager
SPREADAssociates
Total Posts: 16
Join Date: 03/05/12
Have you thought about / are able to run a sacrificial mud motor and drill bit below the liner to get you to bottom? 
MBourne
Well Integrity Specialist
National Offshore Petroleum Safety and Environmental Management Authority
Total Posts: 4
Join Date: 24/11/14
Hi Bushan,
 
Using OBM may cause more problems than it would solve. I would be more inclined to stick with the WBM and try and mitigate the problems. Are you running lubricants in the mud? Are your hole cleaning techniques adequate? Are you rotating the liner? Also, have you looked at running the liner in 2 sections, linking them together with a PBR? Floating the liner in would also work, but would need good planning to mitigate for well control issues.
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