Asia's sour crude demand is set to rebound from late in the second quarter as refiners return from maintenance and Exxon Mobil completes a Singapore refinery upgrade that is poised to increase its heavy oil use, traders and analysts said. The rise in demand from some of the world's top oil importers led by China will support Middle East benchmarks Dubai and Oman despite the prospect of more supply from OPEC+ after the group agreed to increase production from April.