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:
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Lessees and Operators should review their well
maintenance policies and activities.
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Lessees and Operators should communicate clearly and in
writing what is expected of all of their field representatives.
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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).
