--> Abstract: Correlating Formation-Waters Using Stable Isotopes in Mississippian Aquifers, Williston Basin, Canada and U.S.A., by Gavin K. S. Jensen and Benjamin J. Rostron; #90039 (2005)

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Correlating Formation-Waters Using Stable Isotopes in Mississippian Aquifers, Williston Basin, Canada and U.S.A.

Gavin K. S. Jensen and Benjamin J. Rostron
University of Alberta, Edmonton, AB

Mississippian aged strata (in particular the Madison Group) in the Williston Basin contain abundant hydrocarbon deposits and have produced oil for the last fifty years. The Williston Basin contains an active flow system and previous research has shown that stable isotopes (especially those of oxygen, hydrogen, and strontium) and selected tracers (e.g., bromine) have been useful for tracing fluid flow across the basin. Isotopic fingerprinting has been used in oil exploration and production operations to identify the stratal position of produced waters from oil reservoirs. This method has proven to be more accurate at determining the hydrochemical signature of formation waters than standard techniques using solute chemistry alone.

Water and oil samples were collected from more than 100 wells producing from the Midale Beds of the Charles Formation across the Williston Basin. Results indicate a large variation in isotopic compositions across the basin, with values ranging from –11.3 to 10.7 (per mil SMOW). These represent some of the highest values found to date in the entire basin and provide good indicators to identify/correlate Mississippian waters. Investigating the isotopic composition of the overlying Ratcliffe Beds and the underlying Frobisher Beds will refine the correlation of produced waters from these formations. Ultimately they will be useful in correlating Mississippian formation-waters and understanding the paleohydrogeology of the Williston Basin.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005