The Bakken Formation, an organic-rich, oil-prone unit, is the source of the crude oils found in the middle Bakken and overlying Madison Group. Thickness, organic carbon, and vitrinite reflectance data for the Bakken were gathered from 101 wells within the Williston basin and evaluated in terms of source potential.

An index exists that combines sediment thickness, organic carbon content, and thermal maturity data into a single mappable parameter that indicates areas of potential hydrocarbon generation. Multiplying the average percent organic carbon by the effective source rock thickness of a formation yields a richness factor that is then multiplied by maturity scaling factors to give source potential ratings for oil and/or gas generation. By using burial-history curves and thermal-maturation modeling, the rating index can be used to look at source potential through geologic time. The Bakken Formation has been evaluated with the aid of the rating index.

The source-potential rating index provides objective semiquantitative measures by which the source potential of a single formation can be compared within an area or the source potential of two or more formations can be compared within the same or different basins. The Bakken did not begin to reach high source potential until toward the end of the Late Cretaceous. This contrasts with previous authorities who believed the Bakken was at peak generation and expelling hydrocarbons throughout the Cretaceous.

End_of_Article - Last_Page 860------------