Hess will acquire American Oil & Gas in an all-stock deal worth $450m to increase its holdings in the oilfields of North Dakota, US.
The purchase will boost Hess' strategic acreage position in the Bakken oil play by about 85,000 net acres.
Under the terms of the agreement, Hess will issue 0.1373 shares of its common stock in exchange for each outstanding share of American's common stock.
Hess will provide American with a $30m working capital credit facility to help finance its planned exploration and production activities.
Greg Hill, Hess president of worldwide exploration and production, said that the acquisition builds on the company's strong land position in Bakken, leverages nearby infrastructure and offers operational synergies.