Morgan Stanley analysts recently included this chart of crude production costs. Onshore Middle East oil sites are much cheaper to tap than North American shale, which costs about $65 per barrel to extract.
1. ponder-reflect deeply on a subject; I mulled over the events of the afternoon; philosophers have speculated on the question of God for thousands of years; The scientist must stop to observe and start to excogitate.
puzzle, perplex, bewilder, distract, nonplus, confound, dumbfound mean to baffle and disturb mentally. puzzle implies existence of a problem difficult to solve. the persistent fever puzzled the doctor; perplex adds a suggestion of worry and uncertainty especially about making a necessary decision.