UNITED STATES DEPARTMENT OF THE INTERIOR
MINERALS MANAGEMENT SERVICE
GULF OF MEXICO OCS REGION

NOTICE TO LESSEES AND OPERATORS OF FEDERAL OIL AND GAS LEASES
IN THE OUTER CONTINENTAL SHELF, GULF OF MEXICO OCS REGION

Accidental Disconnect of Marine Drilling Risers

Recently, an incident occurred on a drillship that had the potential for causing a serious well control event. An employee was attempting to conduct a function test of the blind-shear rams. However, he inadvertently pushed the lower marine riser package (LMRP) button instead of the blind-shear ram button on the control panel. Since the LMRP button was not part of the primary or emergency disconnect sequence, the pod stabs did not retract and the blind-shear rams did not close. The disconnect allowed the release of drilling mud from the riser. Fortunately, the wellbore was cased, and a well control event caused by a loss of riser hydrostatics did not occur.

Regulation 30 CFR 250.107(a) requires you to protect health, safety, property, and the environment by performing all operations in a safe and workmanlike manner. Regulation 30 CFR 250.400 requires you to take all necessary precautions to keep your wells under control at all times. Panels and processes that control important systems that are not designed to reduce the possibility of human error do not comply with these requirements.

Accordingly, to ensure that such an event does not occur while you conduct operations from floating drilling rigs, accomplish all of the following by March 17, 2000:

1. Implement measures to lock out any LMRP disconnect (hydraulic or electro-hydraulic) that is not part of a sequential disconnect process (i.e., a process that ensures that a well is secured by blind or blind-shear rams before the riser disconnects) before the BOP/LMRP enters the water. These measures can include the use of electronic exclusion switches and bolted covers. A cover that is easily removed or lifted to gain access to the LMRP release control function is not sufficient. Any computer-based LMRP disconnect function should also be equipped with an effective lock-out. The locking out of a nonsequential disconnect should not affect your ability to conduct a successful primary or emergency disconnect of the riser.
2. Ensure that your sequential LMRP disconnect process (including isolating the wellbore) is designed so that the LMRP can be disconnected only as the result of a deliberate act.
3. Implement human engineering measures such as labeling the LMRP panel button to clearly distinguish it from other functions and using warning labels.
4. Ensure that all of your floating drilling rig contractors, including those with stacked rigs and drilling rigs that are moving into the Gulf of Mexico, are aware of these safety requirements.

Paperwork Reduction Act of 1995 Statement

This NTL does not refer to or impose any information collection subject to the Paperwork Reduction Act of 1995.

Contacts

Please address any questions you may have on the content of this NTL to the appropriate MMS Gulf of Mexico District Drilling Engineer as follows:

New Orleans District, David Trocquet at (504) 736-2506
Houma District, John McCarroll at (504) 853-5892
Lafayette District, Buddy Stewart at (337) 289-5108
Lake Charles District, Larry Williamson at (337) 480-4606
Lake Jackson District, Lee Fowler at (979) 266-1004

Chris Oynes
Regional Director

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