A Detailed Study of the Red River Formation (C & D Members) in the U.S.A. Portion of the Williston Basin

Abstract

The Ordovician Red River Formation is a rather unique formation in that all the ingredients for a petroleum system, i.e., source, reservoir, trap, and seals are contained within this single formation. As such, a casual or surficial examination of it cannot reveal its true complexity and uniqueness with regards to hydrocarbon generation, migration and entrapment. On the surface, it appears that the Red River Formation is an ideal petroleum system containing many “conventional” hydrocarbon reservoirs. Upon closer examination, however, the Red River is found to contain “conventional” reservoirs in what is an inefficient petroleum system. This creates a play that is not unconventional, but is nevertheless non-traditional. Recognition of these characteristics and the uniqueness of the formation provide additional production opportunities that have heretofore been overlooked.

The source of Red River oil is the kerogenite beds within the Red River D Member. The individual source beds are thin, but can attain an aggregate thickness of nearly 20 feet. They are extremely organic-rich, reaching a maximum total organic carbon content of 46% by volume.

Hydrocarbon traps traditionally have been explored for based on seismically identified 4-way closed structures or structural noses. Discontinuous porosity within the Red River C and D members (particularly burrowed units) has been recognized to play an important role in trapping hydrocarbons, especially on the flanks of structures. Some stratigraphic traps have been recognized and documented in the literature, but the widespread occurrence of stratigraphic traps has not been previously documented. Loss of porosity and permeability laterally as well as vertically forms a seal to hydrocarbon migration. These permeability seals appear to be much more common than previously thought.

The C and D members contain the best, most widespread reservoirs within the Red River Formation, with the D being the best overall based on porosity and permeability cross-plots. Both members have long histories of oil and gas production in the Williston Basin, yet they still hold a vast resource of untapped, hydrocarbon potential. Over a billion barrels of oil is believed to yet be recovered from these two members. Proper understanding of the nature of these reservoirs holds the key to unlocking that potential.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018