"Ultra-deep" wells, drilled in water at least 1.5 km deep into several more kilometers of rock...

|By:, SA News Editor

"Ultra-deep" wells, drilled in water at least 1.5 km deep into several more kilometers of rock to the reservoir below, now account for more than half the world's new discoveries so far this year. The risks are great, as evidenced by BP's 2010 Gulf spill, but the potential rewards are huge: the average ultra-deep find adds 140M boe in reserves, vs. 55M for deepwater and just 12M for a conventional onshore well.