US energy giant ExxonMobil said Thursday it would boost its holdings of Bakken shale assets in North Dakota and Montana by 50 percent in a deal with Texas-based Denbury Resources. ExxonMobil Corporation said it had agreed to pay $1.6 billion in cash and swap interests in oil fields in Wyoming and Texas to the Texas-based Denbury. Under the deal, Exxon will acquire 100 percent of Denbury\'s Bakken shale assets. Exxon said the assets were expected to produce more than 15,000 oil equivalent barrels per day in the second half of 2012. The deal increases ExxonMobil\'s holdings in the Bakken region by about 50 percent to nearly 600,000 acres. \"This agreement provides a strategic addition to ExxonMobil\'s North American unconventional resource base,\" Andrew Swiger, Exxon senior vice president, said in the statement. Shares in Dow member Exxon were up 0.4 percent and Denbury gained 2.9 percent in morning trade on the New York Stock Exchange.