The successful start-up of the R Cluster gas field in India is the latest in a line of projects using subsea tiebacks to deliver more competitive production – a key plank in our strategy to become an integrated energy company.
But what exactly is a subsea tieback?
A subsea tieback is an engineering process that connects an oil or gas discovery to an existing production platform. The system usually includes a subsea wellhead, Christmas tree and a flowline that carries the hydrocarbons back to the facility. It might also involve other commonly used pieces of equipment, such as manifolds and additional pipelines, and may require a bit of modification on the platform. Think of it as the plumbing between the seabed and the production facility.
Subsea infrastructure ready for load-out to the KG D6 offshore location in India
The oil and gas industry has been using subsea tiebacks for decades to help realize additional production value or unlock commercially complex reservoirs.
“Tiebacks help us to reach out into pockets and areas of oil or gas that might otherwise remain undeveloped,” says Aasha Marenghi, a project performance lead for the North Sea and Angola. “And because we can connect them to existing facilities, we can reduce our capital expenditure, extend an asset’s life, help to retain jobs and keep our environmental footprint to a minimum.”
These benefits are important in a region like the North Sea. The Oil and Gas Technology Centre (OGTC) estimates that of the 3.4 billion barrels of hydrocarbons sitting in more than 360 marginal developments, some 2.5 billion barrels could be developed via subsea tiebacks.
The control riser platform to which the KG D6 project is tied back
Umbilical load-out for KG D6
KG D6 pipeline in the seabed
But while the engineering isn’t novel, what has been new for bp is the fast-paced nature of their development, particularly in the North Sea, where bp’s teams and their partners have adopted a more agile approach to project development. This means “rather than taking four or five years of planning and development,” says Aasha, “we’re essentially developing them in one to two years.”
Working agilely means doing more things in parallel, more quickly, explains Marianne Wheeler, discipline manager for subsea project management. “Instead of having several major management approval stages, you have one final investment decision approval and then carry out appropriate self-verification checks along the way. Where you can put in some additional equipment and connect new wells to an asset that is already operating at good rates, your costs are that much lower, so your rate of return is that much higher. They are a very efficient, profitable way to develop new oil and gas resources.”
Marianne Wheeler, discipline manager for subsea project management