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.
Synonyms for careful: absorbed, alert, attentive, cautious, concentrating, concerned, considering, diligent, engrossed, enraptured, entranced, fascinated, hearkening, heedful, immersed, intent, interested, mindful, rapt