Loss of Well Control

Effective Date: 11/29/2004

U.S. Department of the Interior
Minerals Management Service
Gulf of Mexico OCS Region

Safety Alert No. 223
November 29, 2004

Contact: Frank Pausina
 (504) 736-2560

Loss of Well Control

Recently, during a workover operation, a well that had been shut-in for approximately 10 years began to flow as a sand bridge was removed by a nitrogen washing.  Gas flowed between the tubing string and a 7-inch casing and over the casing stub over which the tubing head was installed.  Because there was no seal assembly in the wellhead, the gas pressure was exerted on a structurally compromised wellhead injection port because of corrosion.  The port fitting failed and gas flowed through the port to the atmosphere, resulting in a minor condensate spill into the Gulf.  The well was shortly thereafter killed.

An MMS investigation of the incident concluded that the causes of the incident, in addition to the immediate structurally deficient equipment, were, in part, (1) failure to inspect and maintain equipment, (2) failure to conduct a Job Safety Analysis (JSA) for workover activities, (3) failure to provide clear and specific instructions to contracted personnel, and (4) failure to communicate with the contracted operator of the lease.

It is therefore recommended that:

  1. Lessees and Operators should review their well maintenance policies and activities.

  2. Lessees and Operators should communicate clearly and in writing what is expected of all of their field representatives.

  3. JSA’s should be performed for all tasks involving hazards.

For details of the accident, see OCS Report MMS 2004-075.  Copies of the report may be obtained from the MMS Public Information Office located at 1201 Elmwood Park Boulevard, New Orleans, Louisiana 70123 (1-800-200-GULF or local 736-2519).