Chevron and ExxonMobil are expected to report lower first-quarter profits than last year despite higher oil prices. Falling natural gas prices and lower refining margins impacted the oil majors' results. Natural gas makes up about a third of Chevron's hydrocarbon production, and prices were down 20% year over year. Investors will watch for updates on Chevron's proposed Hess acquisition and ExxonMobil's dispute over the deal. Analysts expect oil prices to remain above $80 but profits to decline in coming quarters.