Hard to handle, plenty of potential

There is a lot more oil in mature basins like the North Sea that can still be extracted, with the right techniques. The team on the Halfdan complex is somewhat successful in extracting more at relatively low cost and the lessons being learned can be applied elsewhere.

hard to handle

The Halfdan field

  • 210km west of Esbjerg
  • Discovered in 1999
  • Production start in 1999, 2004 and 2007
  • Water depth 43m
  • Reservoir depth 2,100m
  • 51 producing wells

The Halfdan field is mature. That does not mean it cannot deliver good returns for a canny operator.

The eight platform complex in the North Sea contributes about 40% of the total daily oil production in the Danish Underground Consortium (DUC), of which Maersk Oil is the operator.

Oil production from the tight chalk reservoir, with its small pores making extraction difficult, requires long horizontal wells to maximise production, which reached its peak in 2005. However, the Halfdan team has found a variety of opportunities to extend the field’s life in order to ensure that they can extract as much as possible, at the best value.

Getting water inspection right in a mature field is cheaper than developing a new field.

Brian Pagaard Nielsen

BRIAN PAGAARD NIELSEN, HALVDAN ASSET MANAGER

The Danish Underground Consortium

  • The Danish Underground Consortium (DUC) is a joint venture between Maersk Oil (31.2 %), Shell (36.8 %), Chevron (12 %) and Nordsøfonden (20 %) cooperating to recover oil from the Danish North Sea.
  • Today, The Danish Underground Consortium accounts for by far the majority of Danish oil and gas production and is the owner of the key points of the infrastructure of all activity in the Danish sector of the North Sea. Its sole concession covers 1,635.7 km² of the Danish shelf.

One new tool being used to maximise value in the Halfdan field is a technology which has the potential to unlock millions of barrels of oil. CannSeal is run into a well, where it injects liquid epoxy to create isolation plugs and facilitate the closing of fracture connections. The isolation of fracture connections improves waterflooding performance, the process of injecting water into the reservoir to increase pressure and hence oil production.

“Mature Fields still hold plenty of potential. There’s a lot more we can get out of Halfdan and other fields as well, especially if the new technology and work practices we are implementing turn out to be a success,” says Brian Pagaard Nielsen, Halfdan Asset Manager.

Millions of barrels

The result is more production at a cost-efficient level, building value for the operators and government, creating jobs and encouraging investment. The lessons can be applied in other mature fields and indicate the potential that still remains in areas like the North Sea.

“In the early stage of the field’s life, the focus was on drilling new wells. As the field has matured, that has shifted to maximising the value from the existing wells and facilities via collaboration and efficient workflows,” says Luke Vagg, Team Head for Reservoir Management.

Improving waterflooding could add millions of barrels of reserves to Halfdan, and there are significantly more in total still to be recovered across the DUC fields.

“If you compare the cost, getting the water injection right in a mature field is much, much cheaper than going out and developing a new field,” says Brian Pagaard Nielsen, Halfdan Asset Manager.

The Halfdan team are also using restimulation, when a vessel comes out to the field and injects fluid into a well to improve water injection. The estimated cost per barrel of additional production from the 2016 reservoir management projects – which include conformance and re-stimulation plans – is far lower than current market prices.

Predicting the maintenance

Mature assets also require more maintenance, which can be made more efficient by planning and carrying out the correct and required work in a timely manner.
Using data for example on previous performance, how parts were designed, recommended use from the manufacturer and other background information, enables the reliability and maintenance team to proactively manage the maintenance of the equipment, which reduces related costs and results in less breakdowns.

“There are many complexities in safely operating and maintaining a field such as Halfdan,” Nielsen adds.

“There is increasing water production – double as much since we’re treating oil – and very long wells. Imagine working 10km expand to optimise a well when you’re standing on a platform.”