Chevron Corp’s first-quarter profit fell 27 percent from a year earlier due to lower crude oil prices and weaker margins in its refining and chemicals businesses, but topped forecasts and signaled it is committed to buying smaller rival Anadarko Petroleum Corp. FThe No. 2 U.S. oil and natural gas producer this week found itself in a takeover duel for Anadarko, a smaller oil and gas producer, when Occidental Petroleum Corp made a $38 billion offer that topped Chevron’s $33 billion bid. [nL3N226349] Chevron’s oil and gas production rose during the quarter, and profits in its U.S. exploration business jumped 15 percent from a year earlier. But weakness in refining and international exploration knocked overall profit down 27 percent on a 6.8 percent decline […]