Abstract

Many interesting and colorful stories are told of oil field discoveries throughout the world. Parshall is one of those. The geologic idea was conceived by using Montana’s Elm Coulee Field as an analog. Two key wells were identified in the Parshall area that had petrophysical characteristics similar to Elm Coulee producers. Both were offset using new horizontal drilling technology and are the discovery wells for Ross and Parshall fields.

A unique feature of Parshall Field is that the up dip trapping element is the transition zone between mature and immature Bakken shale. As sometimes happens, the original reservoir objective of both prospects is absent over most of Ross and Parshall fields. Incredibly, Parshall and its extensions now cover over 2.7 million acres making it the largest oil field in size in the U.S. with present recoverable oil reserves in excess of three billion barrels.