Regional Mapping of Formation Waters from Brine Chemistry Integrated with Petrophysical Data
by John H. Doveton and Dana Adkins-Heljeson
A large digital database of brine sample chemistry and water resistivity measurements from a wide range of formations across Kansas is accessible at the Kansas Geological Survey website. Typically, these measurements include ion contents of sodium, calcium, magnesium, chloride, sulfate, and bicarbonate, as well as pH, specific gravity, and water resistivity. In cases where the formation water resistivity is not available, it can be estimated very closely by a simple algorithm from the brine composition. Although numerous, the geographic distribution of these data is markedly uneven, with a tendency to concentrate in areas of historically high production but with sparse control in peripheral regions. Consequently, systematic patterns from regional mapping of formation brine geochemistry are often localized with speculative extrapolations elsewhere. However, the increasing availability of digital well log files on the Kansas Geological Survey website gives the opportunity to augment brine analyses with computations of formation water resistivities and salinity estimations over larger areas. Kansas formations where this approach has particular value include the Arbuckle Limestone, Mississipian units, and the Simpson Sandstone. The mapping of formation-water characteristics of these and other units can be used to address questions of regional flow paths, compartmentalization, recharge and other aspects of interest in energy exploration and production.