Total saves time and money with Fusion 6G LBL offshore West Africa

Two multi-billion dollar field developments currently under construction off the coast o West Africa, are a step closer to first oil thanks to the time saving features of Fusion 6G acoustic positioning technology. We report on how French oil major Total, together with its construction and survey partners, have successfully installed fieldwide networks of the world’s most widely deployed LBL system to support the development of the Egina and Kaombo oil fields.

Located 150 kilometres off the coast of Nigeria, in water depths of up to 1,750 metres, the Egina field covers an area of around 1,300 square kilometres. Infrastructure will include an FPSO, an oil offloading terminal and subsea production systems with 52 kilometres of oil and water injection flowlines, 12 flexible jumpers, 20 kilometres of gas export pipelines, 80 kilometres of umbilicals, and subsea manifolds. Production at the field is expected to reach 200,000 barrels per day at its peak.

Kaombo was the second major West African project where Total and its consortium partners elected to use Fusion 6G LBL. Pictured here, are some of the Compatt 6 transponder frames being readied for deployment on the back deck. Image courtesy of Total.

Planning makes perfect

Compatt 6 LBL Transponder in Deployment FrameThe acoustic technology specified for Egina included a field-wide array of Compatt 6 seabed transponders, the essential component in any Long BaseLine (LBL) system.

Fusion 6G is Sonardyne’s sixth generation LBL platform, widely considered the industry standard tool for subsea construction and survey. Using it, major tasks such as structure installation, spoolpiece metrology, ROV tracking and route surveys can be completed quickly, accurately and reliably in any water depth.

Planning for Fusion’s deployment at Egina had begun several months earlier and involved senior project managers and surveyors from Total and its sub-contractor, Fugro Survey BV, working closely with personnel from Sonardyne’s in-house Survey Support Group (SSG).

The work undertaken by the SSG included analysing the proposed location for each of the Compatt transponders in the seabed network. This work verified that there was clear line of sight between each transponder in order that they could reliably range to each other. The SSG team also simulated acoustic coverage and calculated the expected positioning performance of the Compatts at all points of interest. The process involves specialist software and helps identify the optimum quantity of transponders that are needed to meet a project’s positioning specification.

8 days ahead of schedule At Egina, the investment in time planning acoustic operations onshore was rewarded with a highly successful offshore LBL campaign. The wide-area transponder array was deployed, installed and calibrated by Fugro, eight days ahead of schedule.

Frederic Auger, Chief Surveyor at Total E&P said, “The array installation and subsequent SURF (Subsea Umbilicals, Risers and Flowlines) campaign performed at the Egina field, has proven to be an extremely successful demonstration of Fusion’s capabilities.” He added, “The system’s quick setup and deployment, meant that the savings in vessel time alone has more than justified our decision to trust in Sonardyne’s low-risk digital technology platform.”

Setting records at Kaombo

Totals Kaombo projectEncouraged by the success of Egina, Total was quick to decide that Fusion 6G would also play a significant role in their development of the larger and deeper, Kaombo oil field offshore Angola.

Covering an area of around 1,300 square kilometres, Kaombo lies in water depths up to 1,750 metres. Development of the field will involve the drilling of 59 subsea wells, connected by over 290 kilometres of subsea lines leading to two floating production, storage and offloading (FPSO) vessels.

The campaign to deploy, calibrate and ready the field-wide array of transponder frames was completed in just 31 days using the seabed component of a Fusion 6G system. This was half the time budgeted for, a figure that is thought to have set a new unofficial record for this scale of operation.

The exceptionally fast deployment of Fusion 6G at Kaombo has been attributed, in part, to the extensive project planning workshops hosted by project partner Technip in France. Attended by teams from Total, Technip and Fugro, together with personnel from Sonardyne’s Survey Support Group, the sessions were used to review the full scale of the operation and consider the most efficient and cost effective configuration of the LBL transponder frame network.

Deciding the quantity, specification and location of each transponder within a seabed array is crucial to the success of any LBL project. As technical leader of the Technip and Heerema SURF Consortium, Technip conducted the LBL array planning themselves, a process that involved confirming that there was clear line of sight between neighbouring transponders and modelling acoustic network coverage at specific locations. By using the same specialist software as the SSG, Technip’s survey team was able to then share their proposed array design with Sonardyne for verification, thereby further increasing confidence in the plan prior to mobilisation.

Speaking afterwards, Regis Mortier, Senior Survey Consultant at Technip, France said, “Besides Sonardyne’s expertise and field proven subsea technology, there were a number of innovative firsts that paved the way for quick and efficient equipment deployment at Kaombo. The use of stackable frames optimised deck space, saving time as we only had to use one vessel and make one trip out to the field. In addition, our innovative spreader bar meant we could deploy five frames in one sequence, thereby speeding up overall frame and Compatt deployment.”

Echoing that positive sentiment, Steven Tonneman, Project Co-ordinator at Fugro Survey B.V. said, “The use of Technip’s two work-class ROVs operating concurrently in the field meant that we could simultaneously deploy, calibrate and move Compatts on the fly. Starfix.Acoustics, a Fugro specific variant of Fusion 6G batched simultaneous baseline collection feature, allowed data to be gathered during deployment operations and win back vessel time. Post deployment, the sound velocity data gathered by the Compatts meant that our calibration results met Total’s very stringent specifications.”

Total’s Frederic Auger added, “We can’t fault the preparation and professionalism displayed by all personnel involved with this massive project. With future time savings gained from not having to deploy many individual transponder arrays, the cost of installing a field-wide LBL permanent frame network that can be scaled from high accuracy metrology to LBL aided inertial and also LUSBL positioning for DP and drilling, means this investment will more than pay for itself within the first few years of the field development.” 

The SSG is frequently asked to assist with many different aspects of offshore survey campaigns. On this occasion we were involved in the planning stages and in the post project wash-up workshop. It’s been very rewarding to see such a well organised and executed project successfully achieve its aims and exceed expectations,” concluded Tom Bailey, Acoustics Surveyor with the SSG.  

“Besides Sonardyne’s expertise and field proven subsea technology, there were a number of innovative firsts that paved the way for quick and efficient equipment deployment at Kaombo. “

“Starfix.Acoustics, a Fugro specific variant of Fusion 6G batched simultaneous baseline collection feature, allowed data to be gathered during deployment operations and win back vessel time.”

“We can’t fault the preparation and professionalism displayed by all personnel involved with this massive project… this investment will more than pay for itself within the first few years of the field development. “

Feature image courtesy of Total.