When negotiations started more than three years ago on the renewal of the 40-year concession held by Abu Dhabi Company for Onshore Petroleum Operations (Adco), ExxonMobil and Shell baulked at demands by Adnoc for hefty upfront payments.

The two former major Adco shareholders decided not to bid, fearing poor returns.

Adnoc, which has a 60% stake in Adco, did not panic. It took over full operatorship while seeking new stakeholders.