Halliburton Co HAL.N added 2.1% to lead gains among oil and gas producers on Monday. By Devik Jain and Sabahatjahan Contractor March 8 (Reuters) - U.S. stocks were set for a mixed open on Tuesday after suffering hefty losses a day earlier, as investors assessed the economic impact of a spike in oil prices and Western sanctions on Russia over its invasion of Ukraine. Crude prices spiked to $128 per barrel and European equity markets sagged as investors remained on edge over the prospect of severe oil supply shortages fueling ever higher inflation.