Page 30: of Marine Technology Magazine (September 2015)

Subsea Blockages

Tackling Subsea Tackling Subsea

BlockagesBlockages

By Angus Macaulay ubsea blockages are a common industry challenge that of reasons and some simply come down to a lack of infra- can be so complex and costly to treat that some opera- structure maintenance. Whatever the cause, the effect can be

S tors are known to leave multiple ? ow lines blocked for a signi? cant loss of revenue with far-reaching consequences. over a decade. A buildup of wax, scale, asphaltene or hydrates will severely

This issue is set to become more challenging to solve, as affect production and hamper ? eld pro? tability. Remediation we deal with complex reservoir conditions and ? uids and methods are historically costly and include deploying a coiled- more challenging ? ow-assurance conditions. With oil and gas tubing system from a rig into the pipeline or undertaking subsea production venturing into deeper waters, increasing tie-back intervention via remotely operated vehicle (ROV) or saturation distance, higher temperatures and greater pressures, the reme- divers. The requirement for a rig or vessel to undertake the work diation of restrictions and blockages in subsea pipelines will can also signi? cantly delay the time to implement a solution, become more dif? cult to combat as time moves on. further contributing toward making these options uneconomical.

Within subsea infrastructure, blockages can affect risers, Replacing the pipeline can be a time consuming and costly ex- ? ow lines, pipelines, umbilical, pipeline end terminations ercise to undertake. The blocked line would still require decon- (PLETS) and manifolds. Blockages can occur for a variety tamination as per the Department of Energy and Climate Change

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