A three-and-a-half year project to support Australia’s Origin Energy in identifying and installing a jack-up rig offshore southern Australia has required DNV GL’s Noble Denton marine assurance and advisory service area to create a new rig-weight monitoring tool to meet the project’s specific technical needs.
The project began in 2011, with DNV GL’s team of jack-up and geotechnical specialists working alongside the operator in identifying the optimal jack-up rig to install alongside the already-operational Yolla A platform in the Bass Straight.
To perform this analysis, DNV GL’s experts had to consider a number of site-specific challenges. These included evaluating the area’s complex soil conditions, which were at risk of significant degradation during pre- and environmental loading. The implications of the site’s location in the Bass Strait - an area of frequent and often severe storms – were also considered.
To resolve these issues, DNV GL’s team of specialists in Australia and the UK developed a rig-weight monitoring tool to determine the weight and weight position necessary for the rig’s safe and secure installation. The new tool not only helped in the understanding of the project’s operational limits, but was also instrumental in obtaining wider stakeholder buy-in to the project. It also enabled Origin to make an informed decision on which rig to select. It chose the West Telesto rig for the job.
The site’s environmental conditions were such that the risk of platform contact and damage during installation was high. DNV GL experts from Perth, Brisbane, Singapore and London were asked to further support Origin and its partners in providing extensive and detailed analysis on allowable loading conditions in order to optimise the drilling programme while staying within the safety requirements of the project.
“The weather conditions in the Bass Straight can be severe, leading to restrictions and down-time during drilling operations. This has potential for project costs to rack up quickly,” says Mark Hayward, DNV GL’s jack-up and geotechnical manager in London.
“We provided analyses that determined allowable loading conditions across different seasons and potential storm events. This helped Origin to optimise the intended drilling programme and minimise potential for downtime due to weather to help keep the project running on schedule and within budget. Our findings also helped reassure all parties of the parameters for installation, and our review of operational capability and allowable loading conditions contributed to the safety case that Origin submitted to the Australian safety authority, NOPSEMA”, he adds.
Facing the onset of a deteriorating season, and after a short spell waiting on weather, the West Telesto was successfully installed alongside the Yolla A Platform under the watchful eye of DNV GL’s Australian office. The company’s Singapore office provided marine warranty approval for the project, and a geotechnical specialist from our London office was on board to assist with decision-making and verify our analysis by monitoring the real-time installation response.
Commenting on the installation, Origin’s drilling project manager, Ian Moyle, says: “It has been a long journey and has taken a remarkable display of teamwork and professionalism to achieve this milestone. The results speak for themselves.”
The complexity of the project has also deepened DNV GL’s breadth of knowledge, and led to a number of new projects offshore Australia