An operator was seeking to replace a section of oil pipeline. Having commissioned a design house to undertake the detailed design phase of the work, we were asked to carry out the verification of this work to confirm the acceptability of the pipeline design.
The development was located in the North Sea at water depths of approximately 140m and consisted of two well clusters. The original 24” pipeline ran from the operator’s platform to an unmanned platform approximately 80km away. Following two previous intelligent pigging campaigns, significant levels of internal corrosion had been identified in the first 8-10km of the pipeline from the platform.
As a consequence, the maximum allowable operating pressure (MAOP) of the pipeline was reduced in order to continue operation. Following several attempts to mitigate the corrosion, the first 8-10km of the oil export pipeline required replacing to avoid reducing the MAOP further and to restore the MAOP of the pipeline to the original design value.
We undertook a detailed review of the pipeline design documents and assessed each document for completeness. Each review considered appropriateness of the methodology, compliance with industry design codes, adherence to best practice and consistency with other project documentation. Where required, we carried out our own independent calculations using MathCAD and Abaqus to validate the solution. Where non-conformances were identified, our client was notified immediately to enable remedial action to be taken quickly.
Adopting a collaborative approach, we were able to offer an alternative perspective and troubleshoot any design problems which arose, minimising the cost of any rework.
We demonstrated that the final design was fit for purpose and provided our client with the assurance they needed to progress the development.