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Audit of site-specific mooring calculations - Transocean Leader

In connection with Norske Shell's planned use of the mobile drilling installation Transocean Leader on Haltenbanken PL 255, the Petroleum Safety Authority Norway (PSA), with assistance from the Norwegian Maritime Directorate, conducted an audit of the site-specific mooring analyses. The audit was conducted through meetings and a review of documentation.


Background for the audit

Norske Shell will be using the mobile drilling installation Transocean Leader on Haltenbanken PL 255. In this connection an audit of the site-specific mooring analyses was conducted.

Purpose of the audit

The goal of the audit was to supervise whether the site-specific mooring analyses are conducted in accordance with the regulatory requirements.
The most relevant regulatory requirement references for this audit were Section, 10, Section 13, Section 57 and Section 64 of the Facilities Regulations, and Section 3 of the Framework Regulations.

Result of the audit

The main impression following the audit is that the site-specific mooring evaluations were conducted in accordance with the regulatory requirements. Norske Shell had done extensive work on mapping the seabed, and had made sure the mooring lines were laid outside areas with corals. The PSA is of the opinion that the analyses seem to have been conducted by qualified personnel.

Some observations were nevertheless made concerning improvement potential. These observations are mainly linked to working routines for choice of anchor and control of the anchor holding power. Some observations involved quality assurance of data and software used by the engineering company that made the calculations.

Info on our follow-up after the audit

Contact in the Petroleum Safety Authority Norway

Ole-Johan Faret