Riser system for sub-sea wells and method of operation
US6276456A · kind A · utility
Inventor
Key dates
| Filing date | Feb 3, 1999 |
| Grant date | Aug 21, 2001 |
| Priority date | — |
| Expiry date | Feb 3, 2019 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B17/085
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A riser system connecting a oil or gas well head and a surface vessel comprises a first riser section maintained substantially vertically under tension, attached for example by a tension cable to a constant load tensioner means mounted on the vessel, and a flexible second riser section arranged above the first riser, the second riser being able to flex to accommodate movements in the surface vessel. The second riser section includes a curvature limiter, achieved for example by making the riser from a material of variable stiffness along the riser's length. An emergency disconnect valve is provided between the lower riser section and the upper flexible section. An alternative curvature limiter comprises a plurality of discrete collars which are connected together and surround the outer diameter of the second riser.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.