Norwegian classification society Det Norske Veritas is preparing to submit a risk analysis for subsea wellheads which could change the shape and content of sub-sea and drilling contracts in Norway.

DNV will submit wellhead risk analysis tools for industry hearing in autumn 2008 ahead of tacking a new wellhead fatigue dimension to the NORSOK 0001 standard for offshore contracts.

In his presentation on how weaknesses and eventual trouble in wellhead riser sections might nullify increased oil recovery gains, DNV well integrity section head, Lars Tore Haug, said drilling contractors might one day have to log load data for future risk analysis tools, part of an offering for oil companies worrying about long-life fields.

“Right now, no tool exists,” Haug told UTC 2008 conference-goers.

He said “front end” detailed data from contractors could include welding and cement data to develop risk cases for risk screening.

Analysis tools similar to Haug’s are being worked out for BP and StatoilHydro by individual engineering firms, DNV appears to have the edge on the total fatigue wellhead fatigue-risk picture.

He said the goal is an industry-wide database on wellhead stressors with data compiled for the broad range of riser types, sea states, water depths and drill-rig systems.

Standardization could, he said, improve the future specs for sub-sea wells, with, for example, greater care put into load-sharing between casing and conductors.

Tags: Det Norske Veritas