ABSTRACT: Groundwater Chemistry of the Devonian Oil Fields of Southwestern Ontario

T. R. Weaver, S. K. Frape, J. A. Cherry

Groundwater was collected from Devonian oil fields in southwestern Ontario for detailed geochemical analysis. These analyses have enabled us to determine the degree to which both production practices and the hydrogeologic regime of the region have influenced the water chemistry observed in these oil fields.

Both recent and glacial stable isotope signatures have been observed in the water from different fields, indicating the amount of planned or inadvertent flooding of these fields that has occurred. Large variations in the major ion composition of groundwater within fields indicate local heterogeneity of the flow system. These variations imply that groundwater with a distinctly different chemical signature may have been emplaced into the Devonian formations in discrete areas. Potential sources for these inputs include the deeper, Silurian brines found in the region.

This geochemical survey of Devonian oil field waters in southwestern Ontario has allowed the evaluation of the impact of early production practices on these oil fields and has greatly improved our understanding of the flow regime in the Devonian oil-bearing formations of the region.

AAPG Search and Discovery Article #90998 AAPG Eastern Section Meeting, London, Ontario, Canada, September 10-12, 1990