NPD Reviews Stena Don's DP Operations

During the period September 1, 2003 to September 4, 2003, the Norwegian Petroleum Directorate (NPD) conducted a supervision activity concerning Stena Don AS (Stena) and the company's management of activities associated with dynamic positioning (DP) and crane operations on the drilling installation Stena Don.

The supervision activity was carried out through a meeting with Stena in Harstad and verifications and discussions with personnel on board the installation.

Background for the supervision
Stena Don has been in operation on the Norwegian shelf for just over one and a half years, having been delivered from the yard during the autumn of 2001.

Statoil was granted the initial consent to use the installation in December 2001 and Stena was granted the Acknowledgement of Compliance (AoC) in March 2002.

Stena Don is a DP class 3 drilling installation.There is limited experience in using DP in connection with drilling activities on the Norwegian shelf and loss of position is a major contributor to the risk level, cf. the NPD's report on risk level trend on the Norwegian shelf.

Some incidents have been registered in relation to DP operations, among them disappearance of DGPS reference signals.

Using hydro-acoustic reference systems also has its limitations, causing problems related to matters such as noise from propellers, depth, varying temperature and salinity in different layers of water.

These reference system limitations mean that greater demands are placed on other data/reference systems with regard to accessibility, reliability, etc.

Many incidents have been reported on Stena Don related to the use of lifting appliances; one of these was serious and led to crushing injuries, and several had the potential for major injury.

In addition to a review of DP operations on the installation, the supervision activity therefore included a review of incidents and the technical condition of lifting appliances, maintenance management for these, personnel competency and procedures for their use. Conditions that emerged during the processing of the AoC were used as a basis for carrying out the supervision.

The purpose of the supervision
1. Assessing the DP installation and associated emergency and operational procedures on Stena Don in relation to defined requirements.

2. Verifying the technical condition and the use of lifting appliances and lifting gear

3. Verifying that provisions and conditions in the AoC have been complied with.

Result of the supervision
In the NPD's assessment, the DP system on the installation functions satisfactorily. Analyses and assessments that have been submitted by Stena conclude that downtime and reported DP incidents are few and of a not too serious character. The installation appears effective in that it can be moved rapidly due to its DP system.

However, maintenance of important DP-related equipment will not be carried out according to plan because this move does not allow for sufficient shutdown of equipment and systems.

The company's management system is deficient in relation to requirements in the NPD's regulatory requirements. These deficiencies are mainly related to requirements for competence and training, deviation handling, investigation of incidents and requirements regarding crane and lifting operations.

Deficiencies were also uncovered concerning compliance with some procedures in the above-mentioned areas.

Several of the deficiencies identified had been confirmed as complied with by the company when the NPD issued the AoC.

The supervision activity, which only covers a limited area, shows that the company must further develop and update its entire management system in order to ensure that regulatory requirements are complied with.

On the basis of this supervision, the NPD has given Stena a notification of order.