Session: 04-03-01 Rigid Risers

Submission Number: 180668

Challenges and Solutions in HPHT Riser: From Design to Installation 

The development of ultra high pressure deepwater fields have driven the need for 20k subsea system, presenting new challenges to riser design and installation. Currently, only steel riser can contain such high pressures. This paper discusses the key design considerations for the steel catenary risers of the recent Shenandoah 20K project in the Gulf of Mexico.

The immediate impact on riser design from 20K pressure containment requirement is increased wall thickness which subsequently brings challenges to pipe manufacture and riser fabrication such as welding and NDE. The increased riser weight certainly tests the limits of installation vessel. On riser extreme dynamic responses during hurricanes, while it could potentially benefit from larger tenson to improve responses at the TDP, the stresses at the top could be worsened. The major challenge for riser design is fatigue at its inner diameter. This is because the 20k pressure limits H2S detection, which impose more stringent fatigue requirement such as knock down factors.

This paper presents an integrated 20k SCR design to address those challenges, which optimize riser configuration to meet extreme strength and fatigue criteria. In addition,  a novel installation approach in which temporary buoyancy modules are deployed to enable the recovery of the heavy 20k SCR.

Presenting Author: Jingyun Cheng subsea 7

Presenting Author Biography: riser engineer

Authors:

Jingyun Cheng subsea 7
Bin Yue 2H offshore Inc
Basim Mekha Cuneiform Offshore Consulting, LLC
Joris Van Den Hark Beacon Offshore Energy
Amik Bocage Subsea 7
Jeff Ward Subsea 7