Identifying the sources of contamination at a site often requires interpreting significant quantities and types of environmental data. When groundwater studies are performed near secondary recovery operations, and it is determined that the groundwater has elevated chlorides, our investigations may hastily evolve from the preconceived assumption that chlorides from the injection of produced water caused the elevated groundwater chlorides.

This paper uses a case study to illustrate how "multiple working hypotheses" were used at the Northeast (N.E.) Fitts, Oklahoma, waterflood operation to avoid a narrowly focused groundwater investigation. The study demonstrates that interpretation of data with respect to the natural distribution of potential contaminants can result in more accurate identification of contaminant sources in groundwater.

Using the multiple working hypothesis approach, data which previously suggested oilfield contamination now clearly illustrate that groundwater chlorides were naturally occurring. Supporting evidence included increasing salts with depth, differences in salt composition, and the observation that time dependency of groundwater salt concentrations resulted from monitor well construction and development.

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