Retrieval of Back-Pressure Valve Results in Loss of Well Control
Effective Date: 6/17/1996
 | Minerals Management Service Gulf of Mexico OCS Region |
Notice No. 167
June 17, 1996
Retrieval of Back-Pressure Valve Results
in Loss of Well Control
In the process of retrieving a back-pressure valve during a workover operation, a loss of well control occurred as pressure was released from the wellbore. The release of pressure expelled fluids from the wellbore and also caused the rotary bushing inserts to be blown onto the drill floor. The accident resulted in one fatality and two injuries.
A subsequent inspection of the back-pressure valve found that the relief groove, which is designed to detect pressure below the valve and allow communication between the wellbore and the tubing hanger, was full of debris. The inspection also revealed that the poppet, which forms the pressure seal between the wellbore and the tubing hanger, was free to move. Subsequent testing of the surface-controlled subsurface safety valve indicated a minor leakage rate.
Therefore, from this information the following are recommended:
1. Lessees, drilling contractors, and all appropriate service personnel should ensure that:
a. A well is killed before initiating the installation and removal of a back-pressure valve.
b. All equipment is functioning properly before initiating installation of a back-pressure valve.
c. The rotary bushings inserts are locked down when inserted in the rotary table.
2. Lessees, drilling contractors, and all appropriate service personnel should attempt to determine if pressure is trapped below a back-pressure valve prior to initiating the removal of the valve.
MMS is the Federal Agency that manages the Nation's natural gas, oil and other mineral resources on the Outer Continental Shelf, and collects, accounts for, and disburses about $4 billion yearly in revenues from mineral leases on Federal and Indian lands.
-MMS-GOMR-
http://www.gomr.boemre.gov/