Warren Buffett is loading up on this oil and gas dividend stock. Here's why you should, too.Occidental Petroleum (OXY 0.54%) stock has gained immense popularity among energy investors within a couple of years or so, and much of the credit goes to Warren Buffett. The legendary investor has been a consistent buyer of the oil and gas stock and now owns a significant stake in it through his company, Berkshire Hathaway. As of June 30, Berkshire owned a 28.8% stake in Occidental Petroleum.With reinvested dividend ...