Marine Safety on Mobile Offshore Drilling Units

Abstract Several years ago, Exxon instituted a survey of contracted mobile offshore drilling units to evaluate structural integrity and readiness to properly respond to marine emergencies that might arise offshore. Results showed structural integrity and marine readiness varied from rig to rig and prompted Exxon to implement an ongoing and more rigorous Marine Safety program throughout its offshore operations. This paper will briefly describe results of Exxon rig inspections and Exxon's on-going Marine Safety program. Work in progress by the American Petroleum program. Work in progress by the American Petroleum Institute (API) and the International Association of Drilling Contractors (IADC) to promote industrywide upgrading of the mobile drilling fleet will also be highlighted. Introduction During the past six years, the offshore drilling industry has experienced three major marine losses -the ALEXANDER KIELLAND, OCEAN RANGER, and GLOMAR JAVA SEA. ALEXANDER KIELLAND. The semisubmersible ALEX-ANDER KIELLAND was lost because of a structural failure. Results of the Official Norwegian Ministry of Local Government and Labour Inquiry indicated the initial structural failure occurred because of improper welding detail at a hydrophone - high stresses at this location propagated fatigue cracks which caused the member propagated fatigue cracks which caused the member to eventually fail during a storm. This first failure then led to the failure of other members and loss of the rig. One hundred and twenty-three men of the 212 on board were lost. OCEAN RANGER. The semisubmersible OCEAN RANGER was lost during a severe winter storm because of a stability problem. Results of Official Inquiries by the United States Coast Guard and the Canadian Royal Commission indicate the loss was due to a ballast control system failure. All 84 men on board were lost when personnel were unable to safely abandon the rig in heavy seas and cold weather following the ballast system breakdown. GLOMAR JAVA SEA. A recent United States National Transportation Safety Board report suggests the drillship GLOMAR JAVA SEA sank because of fractures in the hull caused by Typhoon LEX. The fractures allowed flooding of two tanks on the starboard side; the rig then lost stability and capsized. One lifeboat was launched, but it was never located. All 81 men on board were lost. Although the specific cause of each loss was different, these disasters had several factors in common: Rigs sank at night in severe weather All experienced high loss of life Emergency procedures and on board lifesaving systems were not effective. Exxon considers the first line of defense against a major marine disaster to be the structural integrity of the rig. However, in the event personnel must abandon the rig and helicopter support is not available, equipment and personnel training must be adequate to successfully abandon the rig. Surveys of rigs contracted to Exxon worldwide in areas such as Australia, Southeast Asia, Gulf of Mexico, Eastern Canada, and the North Sea indicated structural integrity and marine readiness varied from rig to rig. After careful evaluation of survey results, Exxon found it necessary to implement an ongoing marine safety program to assure both structural integrity and adequate emergency equipment and personnel training to successfully respond to emergencies. P. 379