A key component that differentiates offshore drilling and production from onshore operations is the riser — the pipeline that connects the rig on the water surface to the wellbore at the seabed. Drilling and production risers must successfully isolate oil, gas and drilling fluids from the seawater, and be durable enough to withstand abrasion and corrosive chemicals.

    Drilling risers are typically rigid, top-tensioned systems, with a telescoping joint that allows the riser to compensate for the movement or pitch of the drilling vessel. Below this joint is the riser tensioning system (RTS, see Chapter 2). In contrast, production risers — while they may be top-tensioned — are usually designed to be flexible and assume a catenary profile as they make the transition from the horizontal seabed to the vertical side of the production platform.

    The concept of creating composite risers for significant platform weight savings has existed for more than 20 years, although actual field trials are only now beginning. Composite drill pipe, designed primarily for short-radius, horizontal drilling, has been available for more than a decade.