A new concept is proposed regarding a lifting system for the installation of risers in deeper water, 1,500 m~3,000 m. This system can also be used for lifting equipment other than risers. Also reviewed are some recent, key methods for the instillation of deepwater risers and related installation analysis methods. In addition, the latest advances on riser installation are described for the development of deepwater oil/gas in the South China Sea.
With energy needs rapidly increasing for several years now, deepwater oil/gas exploration and exploitation are undoubtedly becoming a trend. In developing the South China Sea offshore oil and gas reserves, China faces the cost-reduction challenge that arises when development moves into deeper water. Riser system technology and its cost are particularly sensitive to any increase in water depth; this is also true of riser installation costs. Current deepwater riser installation technique predominantly consists of lining up the pipes aboard the ship or surface platform, welding, inspecting the pipe using NDT and coating, then installing the risers at the predetermined site. Vessels with special devices are required to install these welded risers, thus incurring high day rates and mobilization costs. This paper reviews the deepwater riser and installation methods currently in practice for steel catenary risers (SCR) around the world, and it presents some achievements of a sub-project of the Chinese National 863 High-Tech Program, Technology Research of Deepwater Riser Installation. This is followed by the presentation of a new concept regarding lifting equipment for the installation of risers in deeper water.
A riser system basically consists of conduits between floaters or platforms on the surface and the subsea facilities (e.g. wellheads, manifolds) at the seabed. There are two kinds of risers: flexible and rigid.