Hydrocarbon leaks shuts down Taranaki offshore gas pipeline
Tuesday, 10 April 2018
An underwater pipeline which carries well stream fluids, including 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 and gas condensate production from the Pohokura offshore well has been halted after a defect was found in a 10.8km km pipe which carries gas, and gas condensate to an onshore production station operated by Shell New Zealand.
The 10.8km pipeline carried 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 was piped to storage tanks near New Plymouth and shipped to refineries.
Shell NZ general manager Rob Jager said routine inspection of the pipeline using remote operated vehicle (ROV) found bubbling from the pipeline running between the offshore Pohokura Platform B and the on shore Pohokura pipeline.
**READ MORE:
* Spectacular gas flare well site lights up night sky**
*** [Multi-million dollar maintenance project at North Taranaki's Pohokura gas field
](https://www.stuff.co.nz/business/industries/73034206/Multi-million-dollar-maintenance-project-at-North-Taranakis-Pohokura-gas-field)*** Shell NZ assets sold to Austrian oil and gas explorer
Both the pipeline and production from the offshore Pohokura platform was shut down immediately to stop any discharge and an investigation was begun to find the cause of these 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 on site 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 are unaffected and Shell have kept stakeholders updated, Jager said.
Shell Taranaki operated the Pohokura field on behalf of Pohokura Joint Venture parties (Shell New Zealand, Todd Energy, and OMV) who all take a share of the gas and condensate.
Shell Taranaki, as operator of Pohokura Platform B (PPB) on behalf of the Pohokura joint venture parties completely stopped gas and associated condensate production from the offshore part of the Pohokura field.
The total gas and associated condensate volumes available from the Pohokura field for joint venture parties to sell had been negatively impacted, she 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 and 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.