Williams Cos. Inc. (WMB)

[OilStockReport]

First it was Hess (NYSE: HES) backing up the truck with its proposed purchase of American Oil & Gas (AMEX: AEZ). Next came Enerplus Resources Fund (NYSE: ERF) padding its position in the play. Now Williams (NYSE: WMB) is joining the Bakken buyers' brigade.

On Monday, the integrated natural gas company announced that it's picking up more than 85,000 acres of core Bakken acreage for $925 million. The purchase is twice as large as the one Enerplus closed last month, and is located in the same Fort Berthold area in North Dakota. This lies to the south and west of the EOG Resources (NYSE: EOG)-dominated Parshall field, whose discovery broke the play wide open several years ago.

At more than $10,000 per acre, this acquisition provides another clear data point for valuing North Dakota Bakken operators. Williams picked up its acreage from private sellers, but there are plenty of publicly traded E&Ps with leasehold in the million-acre Fort Berthold Indian Reservation, which spans counties including Dunn, McKenzie, and Mountrail.