Updated

Leading oil officials from around the world meeting in Abu Dhabi remain tense over low crude prices, though they are trying to sound optimistic.

That's in contrast to last year's Abu Dhabi International Petroleum Exhibition & Conference, which had a more-upbeat tone.

Monday's event started with the officials acknowledging the pinch of low oil prices, now around $50 a barrel, down from over $100 in mid-2014.

OPEC Secretary-General Mohammad Sanusi Barkindo of Nigeria warned those prices were cutting into development of new fields.

ExxonMobil CEO and chairman Rex W. Tillerson says: "We don't need any more uncertainty."

But with U.S. shale oil posed to re-enter the market if prices rise much higher and OPEC members still with high production, the uncertainty and lower prices may continue.