The company said it spent $260 million to purchase new acreage in the Williston basin from an undisclosed private party.
Whiting said Tuesday it expected 85 percent of the 17.1 million barrels of oil equivalent in the new acreage to exist as oil.
Whiting, which has headquarters in Denver, said its overall production for the second quarter of 2013 was 93,380 barrels of oil equivalent per day, which it said represents a 4.8 increase from the previous quarter.
Whiting focuses on the Williston Basin, spread out over eastern Montana and the western Dakotas. Its production areas include the lucrative Three Forks and Bakken formations in North Dakota.
The North Dakota government said more than 800,000 barrels of oil per day was produced in the state in May, the last full month for which information is available.