Pressure-compensated dual marine riser
First Claim
1. Marine riser system for use in offshore well drilling operations, said system comprising two risers that are adapted to be vertically arranged with a substantially annular space therebetween, each riser consisting of a plurality of sections that are sealingly interconnected in end-to-end relationship, the outer riser comprising connecting means at the lower end thereof, said connecting means being adapted for connecting and sealing the lower end of the outer riser to a wellhead, said outer riser further comprising supporting means near the upper end thereof, said supporting means being adapted for being connected to a heave compensator system carried by a floating drilling means, sealing means being arranged for sealing off the annular space at, at least, the lower end thereof, and closeable fluid pressure equalizing means arranged in the wall of the outer riser, said means being adapted for equalizing the fluid pressures prevailing in the annular space and in the space outside the outer riser.
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Accused Products
Abstract
A dual marine riser for use in drilling deepwater oil and gas wells from a floating vessel, the marine riser incorporating concentric inner and outer risers, the outer riser being provided with one or more remotely-actuatable valves adapted to bring the annular space between the risers into communication with surrounding sea water in order to equalize pressures over the wall of the outer riser when the inner riser has been installed.
63 Citations
13 Claims
- 1. Marine riser system for use in offshore well drilling operations, said system comprising two risers that are adapted to be vertically arranged with a substantially annular space therebetween, each riser consisting of a plurality of sections that are sealingly interconnected in end-to-end relationship, the outer riser comprising connecting means at the lower end thereof, said connecting means being adapted for connecting and sealing the lower end of the outer riser to a wellhead, said outer riser further comprising supporting means near the upper end thereof, said supporting means being adapted for being connected to a heave compensator system carried by a floating drilling means, sealing means being arranged for sealing off the annular space at, at least, the lower end thereof, and closeable fluid pressure equalizing means arranged in the wall of the outer riser, said means being adapted for equalizing the fluid pressures prevailing in the annular space and in the space outside the outer riser.
Specification