Bubbling pipeline shut down
‘‘As always safety and protecting the environment are our top priorities.’’ Rob Jager
A subsea pipeline which carries millions of cubic metres of gas condensate from an offshore well in Taranaki to an onshore production facility is temporarily out of action after ‘bubbles’ were detected coming from the structure.
Gas production from the Pohokura offshore well has been halted after a defect was found in a 10.8 kilometre pipe which carries gas condensate to an onshore production station operated by Shell New Zealand.
The 10.8km pipeline carries up to 13 million cubic metres a day of gas condensate from offshore to the Pohokura production station to be processed into natural gas for distribution to the North Island gas network.
The condensate is piped to storage tanks near New Plymouth and shipped to refineries. Shell NZ general manager Rob Jager said a routine inspection of the pipeline using remote operated vehicle (ROV) found bubbling from the pipeline running between the offshore Pohokura Platform B and the onshore Pohokura pipeline.
Both the pipeline and production from the offshore Pohokura platform was shut down immediately to stop any discharge and an investigation was launched to find the cause of the bubbles, he said. The company had notified stakeholders, including rural neighbours, iwi, joint venture parties, customers and relevant regulators.
The inspection of the remainder of the pipeline, which consists of a flexible 9.3km section and a 1.5km solid pipe, had been completed and there was no sign of any more discharge in or around the pipeline – apart from the bubbles first seen, he said.
‘‘A dedicated project team is onsite and working with global pipeline manufacturers, Technip, and specialist contractors to investigate further and find both short and long-term options for testing and restarting the pipeline once we are satisfied it is appropriate to do so,’’ Jager said.
‘‘Some good progress has been achieved and there are a number of parallel work streams in place focussed on understanding the problem and exploring potential solutions to allow us to start using the line again.
‘‘As always safety and protecting the environment are our top priorities. It is not possible to say at this point when production from offshore wells will resume.’’
Production from the onshore Pohokura wells were unaffected and Shell have kept stakeholders updated, Jager said.
In 2015 the Pohokura offshore platform was extensively refurbished and repainted without disruption to the gas production.
Up to 400,000 litres of paint was removed from the structure, and 3.3 million litres of effluent removed from the living quarters and a rig taken back onshore for disposal.
Taranaki Regional Council reported two minor leaks of low toxicity hydraulic fluid totalling 20 litres from plug vents on the platform between 2015-2016.
TRC resource management director Fred McLay said senior staff had been briefed by Shell Taranaki Ltd about a small marine pipeline gas leak and the engineering options to address the leak.
Staff were considering remediation options, and authorisations under the Resource Management Act were being assessed, he said.