Chevron's 240 million barrel Rosebank field, West of Shetlands and Statoil's 545 MMbbl Johan Castberg field in the Barents Sea, are facing continued delays for their final investment decisions for the projects.

GlobalData's upstream analyst covering Europe, Matthew Ingham, said the sanction of these projects was crucial to permitting the construction of much-needed infrastructure that will provide an export route for the remote regions' hydrocarbons, of which there are thought to be vast reserves.

"The implications of plummeting oil prices will be felt most heavily by the UK and Norway's governments, highlighting the ripple effect of petroleum production on state tax revenues," Ingham said.

"Although Rosebank is currently the only UK field to qualify for the large deepwater oil field allowance, further fiscal allowances may be required for the project to go ahead.

"As such, it would not be surprising to see further delays in the FID for Rosebank and Johan Castberg to 2016."

Despite this, the analyst noted that oil price volatility was expected to stabilise in the medium to long term and anticipated the development of the two projects to start, providing there are cost reductions and near field discoveries made for both projects.

The latest estimates put total development capital expenditure for Rosebank at $US9.68 billion, and Ingham said cost reductions of around 30% are required for the project to become economically viable.

"Assuming these reductions can be achieved and the project sanctioned, production seems likely to come on-stream in 2021, three years later than previously anticipated," Ingham said.

"For the Barents Sea project to progress, oil prices must return to levels of around $110 per barrel, if no tax allowances are forthcoming from the Norwegian government, to achieve a full-cycle net present value of $318 million and an internal rate of return of 11.1%.

"Assuming that Johan Castberg is sanctioned in 2015, Statoil will aim to commence production in 2020, two years behind schedule."