Print this pageRed River "B" Zone - Southwest Williston Basin: Application of Horizontal Drilling in a Thin Oil Zone
McCLELLAN, THOMAS S., JAMES BURD, and RICHARD GABER
The Red River "B" zone dolomite averages 10 feet thick, has high porosity but typically low permeability, and covers a large area in the SW Williston Basin. This oil-saturated reservoir has frustrated explorationists for many years in trying to turn a profit. Meridian Oil first exploited the "B" zone in the mid-8Os, drilling vertical wells on the flank of Pennel and Cabin Creek Fields along the Cedar Creek Anticline, Montana. Development was uneconomic due to marginal production rates and dropping oil prices. The second try in 1989 involved drilling 5 horizontal wells in an attempt to make the play economic. Although higher production rates were achieved, they did not offset higher horizontal drilling costs and low oil prices. In 1993, the third program finally yielded economic returns, through improved drilling technology, lower costs, higher production rates, and secondary recovery. A pilot water flood using horizontal injectors and producers was initiated, which was followed by the unitization of a 39-section area for secondary recovery. In 1994, Meridian expanded the play southeast into Bowman County, North Dakota. A horizontal "B" zone wildcat was drilled in September 1994, yielding exceptional production rates. This was the first wildcat discovery in over a decade in Bowman County. Since discovery, more than 110 additional horizontal "B" wells have been drilled in the play through 1996 with as many as 8 rigs active. Teamwork and perseverance have transformed the formerly unattractive "B" zone into the most active play in the Williston Basin.