Drill vessels float in aerated water

Conference · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5299136

Hammett, D S

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-
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300 -- Petroleum-- Drilling & Production
020600* -- Petroleum-- Health & Safety
03 NATURAL GAS
030300 -- Natural Gas-- Drilling
Production
& Processing
030500 -- Natural Gas-- Health & Safety
42 ENGINEERING
423000 -- Engineering-- Marine Engineering-- (1980-)
ACCIDENTS
AERATION
BLOWOUT PREVENTERS
BLOWOUTS
BUBBLES
DENSITY
DRILLING RIGS
EMERGENCY PLANS
ENGINES
EXPLOSIONS
FIRES
HAZARDS
HYDROGEN COMPOUNDS
INCIDENCE ANGLE
MARINE RISERS
MOORINGS
NATURAL GAS WELLS
OCCUPATIONAL SAFETY
OFFSHORE PLATFORMS
OIL WELLS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PIPES
RISK ASSESSMENT
SAFETY
SEAWATER
SHIPS
UNDERWATER OPERATIONS
WATER
WELLS