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Audit of production line to Tyrihans

The Petroleum Safety Authority Norway (PSA) has conducted an audit of Statoil's management of "double-jointing" of the 16" and 18" production lines to Tyrihans. We did not find any nonconformities in the audit, but we have identified three areas where there is potential for improvement.


The audit activity was conducted at the premises of the subcontractor PTL (Pipeline Technique Limited) in Bremen on Tuesday, 26 September 2006 in the form of a meeting, verification at the production area and a summary meeting at the end of the day.

About Tyrihans

Tyrihans is located on Haltenbanken in the Norwegian Sea, about 40 km southeast of the Kristin field. The field consists of Tyrihans Sør, which is an oil field with a gas cap and Tyrihans Nord, which is a gas and condensate field with a thin oil zone.

Lokasjon Tyrihans (kilde: OD)

The plan is to develop Tyrihans by means of 12 subsea wells distributed among five templates. The production will be transferred via a 43-km long pipeline to the Kristin facility, before it is sent with Kristin gas through Åsgard transport to Kårstø.

The plan is to develop Tyrihans by means of 12 subsea wells distributed among five templates. The production will be transferred via a 43-km long pipeline to the Kristin facility, before it is sent with Kristin gas through Åsgard transport to Kårstø.

The liquid production (condensate and oil), together with the production from the Kristin field, will be stabilized and routed through an already existing pipeline to Åsgard C for further transport via tanker.

Background for the audit

A key priority in our HSE follow-up activities is to ensure that the players follow up the technical condition of the facilities. In this context, it is important to monitor material properties that change as the facilities age, while simultaneously mapping other potential degradation mechanisms for the materials.

In connection with our consideration of the Plan for Development and Operation (PDO) of the Tyrihans field, several areas were identified for follow-up in our ongoing work on this project.

With regard to the production line, the PSA identified factors including selection of materials, selection of system for cathodic protection and selection of system for direct electrical heating (DEH) for hydrate control.

Tyrihans is a demanding project in terms of technology. Statoil has chosen the "BuBi-pipe" type of pipeline for the production line.

This is the first time Statoil is implementing a pipeline project with a combination of S-laying and the longitudinally welded BuBi-pipe. There is limited operational experience with this type of pipeline.

Purpose of the audit

The purpose of the audit was to verify that the operator's management system safeguards the assumptions made as regards design, choice of materials and qualification of technology in the fabrication of the production line to Tyrihans ("BuBi-pipe").

A further objective was to verify the operator's system for following up suppliers, and ensuring that the management systems safeguard the transfer of experience in following up the choice of materials and fabrication.

Result of the audit

Statoil has established a management system for delivery of the BuBi-pipe pipeline to Tyrihans, and this management system has been implemented in the project.

No nonconformities were found during the audit, but we have identified three areas where there is potential for improvement. These areas are cleaning of pipe after welding seam preparation, continuous improvement and follow-up of the results of production testing.

Contact person i the Petroleum Safety Authority
Mike Theiss