Offshore research holds future challenges

Judy Maksoud
International Editor
Offshore

The offshore industry has made tremendous technical strides, but more challenges lie ahead. Dr. Subrata Chakrabarti, president of Offshore Structures Analysis Inc., told attendees at the 24th annual Offshore Mechanics and Arctic Engineering conference that more work is needed on a number of industry facets.

Chakrabarti pointed to present shortcomings in deepwater floaters as an example. Floaters comprise three elements, Chakrabarti said, a floating hull, a mooring system, and a riser system.

"We've already solved hull issues to our satisfaction," he said, "but work remains to be done on moorings and risers."

Fatigue is a primary concern for mooring systems, Chakrabarti said. There is limited information on hydrodynamic properties, for example. Specific areas requiring research include line-soil interaction and mooring system fatigue.

Riser design also needs improvement, according to Chakrabarti. In his estimation, present design procedures based on 3D numeric analysis, including fatigue analysis, needs improvement.

The industry also needs more research on riser interference, Chakrabarti said. Riser interference, or riser clashing, is becoming a critical concern as operators employ tiebacks more extensively in deepwater.

Coupled analysis between risers and hulls and between moorings and hulls are other areas that require improvement. "Much more work is needed," Chakrabarti said. "Limited capability in coupled analysis thus far has shown this area of research to be a very important factor."

The future of the offshore industry will reveal answers to many technology issues, Chakrabarti said, including:
• More reliable damping data for floaters
• More research on wave run-up and overtopping
• Reliable mooring and steel catenary riser analysis, including soil
• Less empirical riser and vortex induced vibration analysis
• Improved efficient numerical coupled analysis
• More research into deepwater system stability
• Improvement on hybrid model testing technology
• Reliable, high Reynolds number and computational fluid dynamics methods
&bul; Systematic validation of computational fluid dynamics results.

06/13/05