We only sampled wells perforated over a single interval within a single geological unit. Collected samples typically contained a mixture of oil and water. We let the mixture gravitationally separate before sampling the water. Mixtures were heated to 80 degrees Celsius to facilitate separation, if necessary. The separated water phase was filtered through glass wool to remove remaining suspended oil followed by filtration through a 0.45 micrometre flow-through cartridge filter.

Exova Laboratories, in Edmonton, Alberta, analyzed the filtered water samples for pH, density and specific conductance and dissolved constituents, including sodium, potassium, calcium, magnesium, barium, strontium, lithium, iron, manganese, chloride, bromide, sulphate, sulphide, silica and inorganic carbon.

All samples submitted to Exova Laboratories were chilled to 4 degrees Celsius and kept in the dark until analysis. Samples for cation analysis were preserved by adjusting pH to <2 using high-purity nitric acid. Samples for sulphide analysis were preserved by adding sodium hydroxide and zinc acetate. Concentrations of alkalinity were determined by field personnel using potentiometric titration to an end-point pH of less than 3.0 within 12 hours of sample collection. Charge balance calculations based on the concentrations of major constituents fell within +/- 5.4% for all analyses. The Environmental Isotope Laboratory, of the University of Waterloo in Ontario, analyzed the filtered water samples for oxygen and hydrogen isotopes. Isotopic values of oxygen and hydrogen are reported in o/oo relative to Vienna Standard Mean Ocean Water (VSMOW). Dr. Robert Creaser, University of Alberta, Edmonton, Alberta, analyzed the filtered water samples for 86-strontium and 87-strontium.

Cation and anion data were initially reported in mg/L. These data were converted to ppm (mg/kg) through division by density. All converted data were rounded to represent the number of significant figures available in the initial analysis.