The discovery of oil in sediments of Ordovician age in the Williston basin has required detailed analysis and correlation of various recognizable units. The outcrops areas on the fringes of the basin show Champlainian and Cincinnatian sediments.

The central area of the Williston basin contains a much greater thickness of Ordovician sediments. Possible correlations of the central area and the outcrops are discussed. Change of facies within the carbonate formations are noted.

The textural characteristics of the producing section and other zones are presented by microphotographs.

End_of_Article - Last_Page 2615------------