By Nick Katiforis, Oceaneering

AN UNNAMED operator approached Oceaneering with an interesting challenge in the fourth quarter of 2013.

Not only did the operator require the repair of a shut-down pipeline, it needed Oceaneering to carry out the in-service inspection of another unpiggable pipeline that also contained some rather unique alignment joints.

On top of this was a tight deadline, driven by the availability window of a suitable vessel.

To meet the schedule, a team of experts in inspection, ROVs, installation and pipeline repair combined their experience to work towards a fully integrated solution.

Oceaneering’s tethered, self-propelled pipe intruders would normally be used to inspect an “unpiggable” pipeline, but in this case, the non-linear nature of the alignment joints precluded this approach.

So Oceaneering’s Asset Integrity group proposed Neptune, a proprietary, ROV-deployed ultrasonic inspection system instead.

Oceaneering Australia’s general manager for Asset Integrity, Roger Thorne, said Neptune boasted an external inspection system which clamped around a pipeline without interrupting production.

“Neptune easily delivered the high resolution wall thickness mapping the client required, including fine scan readings to 1mm x 1 mm,” he said.

The team needed to ascertain whether Neptune’s high resolution would be compromised by the non-linear nature of the seven alignment joints also requiring inspection.

“Although we were confident that Neptune could handle these, to make sure, a full SIT was performed on a sample alignment joint that we fabricated,” Mr Thorne said.

“This confirmed that not only was the Neptune able to navigate around the curved shape of the joints, but its resolution was not compromised by doing so, giving usand the client confidence that we had the right tool,” he said.

PIPELINE REPAIR CHALLENGE SOLVED

In keeping with the ‘non-standard’ theme of the campaign, the pipeline needing repair generated a large temperature gradient during normal operation and at shut-in.

Ordinarily, a customised pipeline repair solution would be designed and manufactured by Oceaneering’s Pipeline Connection & Repair Systems (PCRS) group, but this would not meet the project’s timeline.

PCRS General Manager John Charalambides said the available Smart Clamps Oceaneering were diver installed, and did not contain any thermal compensation system to deal with the temperature gradient – posing a challenge for the company.

“But we were confident we could modify one in time to meet the client’s needs.”

By converting an off-the-shelf diver installed Smart Clamp to an ROV installable one, and fitting a thermal compensation system, the fabrication cycle of manufacturing was reduced to seven weeks, and the clamp was delivered in time for vessel mobilisation.

For the installation phase, the standard water jet pipeline coating removal process lacked the precision the client desired.

The team turned to Oceaneering’s local Deepwater Technical Solutions (DTS) group for a solution.

The DTS team designed and built a new, self-contained coating removal tool that used two high-pressure jetting heads which travel 360 degrees axially along the full length of the pipe in a controlled coating removal process. They dubbed the tool the “Master Blaster”.

Finally, the project required the removal of significant volumes of soil matter to enable clear pipeline access. The soils contained cemented calcarenites, making them very stiff, requiring Oceaneering’s local 12 inch dredging system to efficiently remove the soils whilst specialised cleaning tools cleared away built up marine growth on the pipelines themselves.

INTEGRATED SOLUTIONS ESSENTIAL TO TEAM SUCCESS

To meet the strict window reserved for executing the campaign, all equipment and personnel were managed through centralised coordination.

Project manager Colin Convey said the company set up a common, internet based project platform which all people working on the project could access from anywhere in the world.

“This was important as our global business units were heavily involved in developing the right solutions – Aberdeen Asset Integrity for Neptune, Houston PCRS for the Smart Clamp and Perth DTS for the Master Blaster and dredging equipment,” he said

“Our project management and crews on board knew exactly what was required and how all the equipment worked and interfaced in the field. Even the ROVs were Oceaneering’s own Millennium Plus systems.”

More importantly, Mr Convey said, the client only needed to deal with one contractor.

“With no subcontractors involved, we were accountable for every aspect of the campaign. The plan was implemented successfully and executed on schedule.”