Enhanced Riser Drilling Operation capability in Strong Currents

Chikyu carried out riser drilling operations in the strong current area of Nankai Trough. Riser fairings were installed on riser joints located in the strong current zone to reduce vortex induced vibrations (VIV*); this is aimed at extending the risers' fatigue lifespan. Riser movement over the entire 2,000 m was recorded, and will be analyzed to improve operational procedures.

Objective:

Develop and install riser fairings to suppress VIV for riser drilling in strong currents.

Tank test for optimizing fairing shape

Installing riser motion measuring devices

Installing riser fairings (NanTroSEIZE, 2009)

* VIV: Vortex Induced Vibration (VIV) is a transverse oscillation of a pipe placed in high current, and is caused by vortices forming down-current of the pipe. Long-term VIV will cause an accumulation of fatigue damage.