Citi still sees value in Big Oil

Their value screens pointed to 25% absolute upside and potentially more in relative terms as investors hunted for yield.

In their opinion, most companies in the space were capable of achieving notional break-even - sufficient cash flows to cover capital expenditures and dividends - with an oil price of between $55 to $60 per barrel in 2017, thanks to readjusted spending and higher growth.

It was precisely the scope for the group to reverse a multi-year collapse in its returns via self-help measures and higher oil prices which drove it to upgrade the sector one year ago.

Beyond next year, and looking out to 2018 to 2022, the industry was at least capable of keeping output levels flat, the analysts said.

GALP and ENI offered the strongest outlooks, with the latter being their favoured stock in the space due to the discount at which it was trading and the company´s long-term growth potential.

The broker said it also liked Conoco Philips, Chevron, BP, Statoil.

Exxon Mobil and Royal Dutch Shell on the other hand "may all struggle", analysts Alastair R. Syme and Michael J. Alsford said in a research note sent to clients.