He Tāngata, he Tāngata, he Tāngata (It is the people, the people, the people)….Pohokura’s Offshore Project
After 10 years of producing 40 per cent of New Zealand’s natural gas, the Pohokura field required an extensive offshore refurbishment, centred around its small and remotely operated platform in the Tasman sea. Three offshore wells and the gas pipeline needed maintenance work, each piece of equipment on the platform would be assessed and if needed replaced, and the entire structure would be painted while at the same time continuing to produce energy.
Shell says 700 individuals from dozens of companies came together to safely carry out the $70 million project. A ‘one team’ approach was adopted and employees were encouraged to collaborate and apply innovation to overcome key challenges and achieve ‘Goal Zero’, no harm to people and protect the environment.
The final concept for the project, approved in March 2015, would take only 100 days over the 2015-16 summer. This accelerated timeframe would require precise planning and an extensive amount of team work. It was also tens of millions dollars less than the initial concept budget.
The ENSCO-107 drilling rig was finishing a job in New Zealand waters during the time that the project was proposed to be carried out. Although it was unconventional to use a drilling rig for platform maintenance, it was compatible with the project in many ways. This vessel was large enough to support the work programme, already had an existing safety case, and could carry out multiple jobs at the same time. Another important aspect of the rig was that it would be cost competitive.
A purpose-built six-storey 37-tonne stair tower was created to connect the rig to the platform. This was crucial for integrating the two structures as well as supporting the extensive 100 day work programme. To meet the schedule, the construction of it had to begin before the final design had been completed.
Another innovation involved the repair of the gas pipeline. A weld overlay, termed “buttering”, was used for this task which was completed while the pipeline still contained gas, but at a much lower pressure than normal. Though this was rare for New Zealand’s offshore energy industry, it was a complete success.
Well maintenance was also carried out, and with meticulous planning was able to take place at the same time as many of the other platform refurbishment tasks. Risk-based assessments underpinned this decision. A purpose-built hacksaw was used to help unscrew a locked well-head. This was the first time this method had been used in the Asia-Pacific region.
One technical challenge was the need to repaint every part of the offshore platform without spilling any debris into the sea. This required scaffolding the entire structure including its legs, and retaining the 397,000 litres of water blasted residue and specks of removed paint. An appropriate solution was discovered in Houston: Safway’s propriety QuikDeck scaffold. This had never been used in New Zealand, and proved effective because its component parts weren’t too heavy or large and didn’t require any special tools. It was fast to install and remove, and could be suspended on chains from the platform, so as to provide spacious load bearing work platforms to undertake the work. The team safely erected 483 square-metres of deck in 96 hours, around half the time of conventional scaffolding. QuikDeck was such a success it is likely to be used for other New Zealand projects.
Shell also took a proactive approach in communicating the project story and addressing concerns. The firm hosted on-rig tours for community, regulatory and media stakeholders. Community meetings were held and a project brochure produced. This open and transparent approach was highly effective in helping demystify the project. Although a complaints mechanism was put into place, none were received.
The Energy Project of the Year award category is sponsored by UGL