DOHA (Reuters) -U.S. shale oil production will flatten out if prices remain where they are now and will start to decline with oil prices in the $50s per barrel, ConocoPhillips ( COP ) CEO Ryan Lance said on Tuesday.

"The breakeven probably hasn't moved a lot. I think long-term, if you're going to say oil prices in a comfortable range - maybe in the 70s, or 65-75, we'll still see continued modest growth out of the U.S," Lance added, speaking at the Qatar Economic Forum in Doha.

"But we see plateauing production, probably the end of this decade, coming out of the U.S., unless there's going to be another technological breakthrough in our business. And don't bet against our industry."

If oil fell below $60 a barrel, there would be a decline in investment and global power requirements would not be met, Qatar's Minister of Energy Saad al-Kaabi said, speaking alongside Lance at the same event.

He added that Qatar, one of the largest LNG global exporters, was "not worried at all" about a supply glut of liquefied natural gas (LNG).