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Interim Report on Patterson Oklahoma Blowout
13 October 2018
After some comments on Linkedin regarding the Patterson Blowout that occurred in Oklahoma back in January this year, which stated that they were drilling the well underbalanced. I tracked down the interim report of the incident on the internet.

They indeed had an RCD installed and attempted to increase the hydrostatic pressure once the bit was in the vertical section of the well and then tripped out of the hole.

Have a read it makes for interesting reading.

Think well control barriers and procedures for monitoring the primary barrier.
What would you have done different
Documents uploaded by user:
3 answer(s)
Project Quality
Total Posts: 99
Join Date: 06/05/09

No, the investigation is still ongoing.  You may visit the site ( for details on the Pryor Trust blowout and all other incidents they are involved in.

Drilling and Workover Specialist
Kuwait Oil Company
Total Posts: 2
Join Date: 24/10/18
Is the investigation completed? If so please share the report with findings, root causes and recommendations.
Project Quality
Total Posts: 99
Join Date: 06/05/09
Very interesting read, establishes the basic facts without speculation.  It seems as if the rig crew 'did everything right' in the sense they were operating as a "team" ...  the two DSVs, the one DE, the Patterson drilling crew and RMO were obviously in comms with each other during tripping (and one would assume during other critical operations), and the use of a weighted slug as a temporary barrier is a long-accepted practice.

It seems somewhat coincidental that the string had to be wet-tripped just after pumping the slug.

Lots of unanswered questions.
Posted by

Steve Nas

Well Engineering Consultant and Instructor

Olango Consulting

Total Posts: 21
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