Oil companies rushed into Iraq, offering to rebuild its huge and dilapidated fields for such low fees (around $2 a barrel) that it made executives wince. Almost every big oil company did it. Executives argued quietly that they hoped Baghdad would remember their generosity in getting the country back on its feet once Iraq was ready to give them a chance to explore for new patches of its oil. The other upside of offering such services for a pittance was that Iraqi politicians gearing up for presidential elections next month may find it more difficult – though by no means impossible – to argue Iraq got taken for a ride from big bad oil and to overturn the deals.

But there is a very big, potentially global, downside people that in the industry are now beginning to quietly admit.

It has been a few years since Venezuela scared a number of the world’s major oil companies out of the country with the nationalisation of the energy sector. In 2007, ExxonMobil and ConocoPhillips – the US’ first and third biggest oil companies – were among those companies who decided the new terms being offered were unfair and left.

Exxon walked away from projects worth up to $2.3bn in Venezuela’s Orinoco Belt, which is believed to contain the world’s largest deposits of extra-heavy crude oil. ConocoPhillips’ departure resulted in a $4.5bn writedown.

Chevron, the other US major, decided to stay the course, along with the UK’s BP, French group Total and Norway’s StatoilHydro, accepting the revised terms.

Chevron has just been rewarded for that decision.