The scope

We were asked to assist our client with a pre-FEED study into a new tie-back development in the North Sea.

The new development was located in the Norwegian sector of the North Sea in 360 m of water. The objective of the development was to take oil and associated gas from two new wells and either tie-back to an existing platform or to a new standalone platform.

The new platform option also required new export oil and gas pipelines. The proposed pipeline system included a pipe-in-pipe production pipeline, water injection and gas lift pipelines.

The solution

We carried out the pre-FEED study, including general design activities such as:

  • Wall thickness
  • Stabiltiy
  • Routing
  • Expansion
  • Buckling
  • Fatigue

The work also included a full riser analysis involving flexible risers to the proposed platforms. The water depth meant that a mid-water arch was proposed, but space restrictions around the existing platforms made the design challenging.

The pipeline design included considerations for the pipe-in-pipe (PIP) system to control temperature drops and therefore the presence of hydrates. Standard calculations were modified to account for the effects of the PIP and insulation on expansion, buckling and stability. Strict U-values had to be adhered to during the design.

Our team carried out the pipeline and riser scope of the pre-FEED, whilst our client worked on other aspects such as subsea hardware and flow assurance. To ensure a smooth and efficient project execution, we seconded two engineers to the client’s offices for three months to work alongside their team.

The benefits

Our expertise in pipeline design enabled our client to investigate a vast number of design cases for each option in order to compare results and refine the selected options. Our client was then able to cost-up the options and present each of the solutions to their client.

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