Drill vessels float in aerated water
Model tests, calculations, and case studies prove that a floating vessel will not sink due to gas reducing the water density in or adjacent to a subsea blowout. Several floating drill vessels have been lost as a result of subsea blowouts. Reports have circulated that the rig sank into something similar to a hole in the ocean caused by gas bubbles suspended in the water reducing its specific gravity. These erroneous reports, believed as truth by many people, have resulted in the modification of operations resulting in decreased safety. Several subsea well control operations have caused accidents and losses because the riser was not disconnected. This action was taken in fear of sinking in aerated water. The losses occurred because the vessel winched itself off the drill site to get away from the subsea well before disconnecting. Due to the high riser/BOP angle, the riser could not be disconnected and well control was later lost and the gas/oil flowed directly to the rig floor where massive fire/explosion damage occurred. If there had been a better understanding of water density, the rig personnel could have closed all hatches, shut-down all engines, disconnected the riser and released mooring lines at one end of the rig, and safely removed the rig out of the aerated water. This paper presents some of the technical data and references available which prove that a floating vessel will not sink due to loss of water density.
- OSTI ID:
- 5299136
- Report Number(s):
- CONF-850941-
- Resource Relation:
- Conference: European offshore conference, Aberdeen, UK, 10 Sep 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
03 NATURAL GAS
42 ENGINEERING
BLOWOUTS
EMERGENCY PLANS
OFFSHORE PLATFORMS
ACCIDENTS
BLOWOUT PREVENTERS
OCCUPATIONAL SAFETY
SEAWATER
AERATION
DENSITY
BUBBLES
DRILLING RIGS
ENGINES
EXPLOSIONS
FIRES
HAZARDS
INCIDENCE ANGLE
MARINE RISERS
MOORINGS
NATURAL GAS WELLS
OIL WELLS
RISK ASSESSMENT
SHIPS
UNDERWATER OPERATIONS
HYDROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PIPES
SAFETY
WATER
WELLS
020600* - Petroleum- Health & Safety
030500 - Natural Gas- Health & Safety
020300 - Petroleum- Drilling & Production
030300 - Natural Gas- Drilling
Production
& Processing
423000 - Engineering- Marine Engineering- (1980-)