The problem

Our client was undertaking a project to increase the production from one of its existing platforms in the North Sea by installing an additional platform and expanding the existing re-injection facilities.

We were asked to complete the front end engineering design (FEED) for eight 6-inch rigid risers and for two j-tubes to allow the installation of control umbilicals. Jee was to work with our client’s jacket design team to develop a solution that provided an optimised riser design that minimised the requirements on the jacket structure.

The solution

We reviewed the initial concept, identified potential cost savings in the design and undertook the engineering work required to ensure that accurate cost estimates could be produced to enable project sanction.

In-house MathCAD calculation sheets were used to undertake design calculations to ensure the risers and J-tube designs met the requirements of their respective design codes (PD-8010-2 for the risers and ISO 19902 for the J-tube and supports). Global stress analysis was undertaken to confirm that the designs met the requirements of the above two standards. We also undertook local component 3D FE analysis to confirm the design of the dead weight supports.

We worked closely with the projects jacket design team and the spool design team to ensure that interface loads were fully understood and worked to minimise the structural members needed to support the pipework without compromising the strength of the risers.

The benefits

Our work provided sufficient detail to enable our client to complete the structural design and develop detailed cost estimates for use in project sanction. We managed interfaces effectively during the FEED to deliver a robust design which took into account all of the projects requirements.

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