Riser
AssigneeCameron Iron Works, Inc.
InventorsEdmund A. Fisher, Emanuel Schnitzer
Life of this patent
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Abstract
A riser structure for connecting from a floating structure to a subsea wellhead for drilling or production which has an upper flexible steel section and a lower flexible section connecting from the wellhead to the upper steel section, the lower section, cantilevered from the wellhead, having an increasing flexibility in the upward direction and having a greater flexibility near its upper connection than the upper section. The lower section is preferably of a more flexible material, such as titanium, with a thinner wall at its upper end than at the lower end.
Claims6
A riser adapted to extend from a subsea wellhead to a structure at the water surface comprising
- a lower section having means for connecting to the subsea wellhead, and
- an upper tubular section having means for connecting to the lower section and to the surface structure,
- said lower section having a smaller cross sectional area at its upper end whereby it has an increased flexibility at its upper end as compared with its lower end,
- the upper end of said lower section being of a less rigid material than the upper section whereby it has a greater flexibility than said upper section whereby a substantially longer life expectancy of the riser is achieved.
A riser adapted to extend from a subsea wellhead to a structure at the water surface comprising
- a lower tubular section having means for connecting to the subsea wellhead, and
- an upper tubular section having means for connecting to the lower section and to the surface structure,
- said lower section being of a material having a substantially lower modulus of elasticity than the material of said upper section whereby a longer life expectancy of the riser is provided.
Dependencies are inferred from the claim text.