When major maintenance, called a workover, is required on an oil and gas well, there are often a number of well service contractors involved. While the well was being prepared for its return to service after the workover activity was completed, an incorrectly positioned lock-screw was forcefully ejected from the wellhead. After reviewing the evidence, we opined on the incident cause and the responsibilities of the entities involved at the well site.

After an oil and/or gas production well has been operating for a while, major maintenance or remedial treatments must be performed to restore, prolong, or enhance the production of hydrocarbons. Owners/operators of the well typically rely on the skills of specialty contractors to perform these well workover services. Well service companies that specialize in these maintenance activities provide trained craftsmen and specific tools to perform the work.

A well service company was contracted to perform a well workover that entailed removing the production pipes from the well. One of the first steps in the process is to reduce wellhead pressure followed by removal of the tubing hanger. The tubing hanger suspends the production tubing and is kept in position over the wellhead with a set of adjustable lock-screws and gland-nuts.

Downhole well workover activities involving the efforts of multiple specialty well service contractors were completed over a three-week period. Then, in preparation to return the production tubing to service, the well service companies coordinated their activities to pump out the heavy well pressure control fluids. The gland-nut for the tubing hanger had not been correctly tightened, which allowed the lock-screw assembly to be forcefully ejected during the well control fluid pumping activity.

Baker & O'Brien was requested to opine on: 1) the incident cause; and 2) site responsibilities of the various entities and individuals associated with the well workover. Following our assessment, we developed an expert report, which was utilized to negotiate a settlement.