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U.S. Department of Energy
Office of Scientific and Technical Information

Drilling fluid bypass for marine riser

Patent ·
OSTI ID:5865964
Method and apparatus are described to reduce the tension required on a riser pipe used in offshore drilling between a floating vessel and a subsea wellhead. Heavy drilling fluid is circulated down a drill pipe and up the annulus between the drill pipe and the borehole wall to a point just above a subsea wellhead. From this point, a separate drilling fluid return conduit extends to the floating vessel. Means are provided to maintain a constant level of an interface between the heavy returning drilling fluid and the lightweight fluid which can be confined within the riser pipe.
Assignee:
Standard Oil Co (Indiana)
Patent Number(s):
US 4291772
OSTI ID:
5865964
Country of Publication:
United States
Language:
English