Energy groups have shelved nearly $400bn of spending on new oil and gas projects since the crude price collapse, pushing back millions of barrels a day in future output from areas including the Gulf of Mexico, Africa and Kazakhstan. In an authoritative study published on Thursday, the energy consultancy Wood Mackenzie says development of some 68 major projects, or 27bn barrels of oil equivalent in reserves, has been put back as companies scramble to curtail costs and protect dividend payouts. The latest figures show that the amount of deferred capital spending on projects awaiting approval has almost doubled since June, from $200bn to $380bn, with 2.9m barrels a day of liquids production — equivalent to Kuwait’s crude output — now not due to come on stream until early in the next decade. The savage new year sell-off in Brent crude, which has tumbled more than 70 per cent from its summer 2014 peak of $115 to about $30 a barrel — close to 12-year lows — has lent renewed urgency to cost-cutting.