"The advantage in most negotiations usually goes to the side that has time on their side and is willing to be patient," and Iran is "willing to suffer," Quantum Capital Group CEO Wil VanLoh said at the Austin conference. "Their people have already suffered a lot for many decades."

Analysts say China is in part helping to exacerbate the global supply pinch, resuming bigger purchases from international suppliers after relying for months on its own stockpiles of crude for nearly half of its daily consumption, which had provided a reprieve for oil markets.