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

Marine riser insert sleeves

Patent ·
OSTI ID:6362679
Drilling operations are run in a riser pipe, eg., 20 inches in diameter, which extends from a ship to an anchored wellhead assembly on the ocean floor. Various strings of casing for lining the borehole wall are run down through the interior of the riser pipe. The first string of casing run is of relatively large diameter, eg., 9- 5/8 inches in diameter. Each successive string of casing which is run in this particular well is progressively smaller in diameter. Ideally, one would need a new and smaller riser in order to maintain about the same drilling fluid upward velocity. A high upward fluid velocity can be maintained by placing sleeve inserts in the annulus space between the drill string and the riser pipe interior wall. Additional strings of sleeves may be run inside the original sleeve to obtain a multiple effective sizing of the riser pipe.
Assignee:
Standard Oil Co (Indiana)
Patent Number(s):
US 4231436
OSTI ID:
6362679
Country of Publication:
United States
Language:
English