This dataset contains geochemical analyses results for 22 water samples from 20 oil wells producing from the following geological units: Beaverhill Lake Group, Wabamun Group, Swan Hills Formation, Nisku Formation, and Leduc Formation. The wells are located in the Whitecourt, Swan Hills, Fox Creek and Valleyview areas of west-central and northwestern Alberta.
In the summer and fall of 2016 we collected water samples directly from the wellhead. Each of the filtered brines was analyzed for pH, density, total dissolved solids, alkalinity, specific conductance and over 30 dissolved constituents, including sodium, potassium, calcium, magnesium, barium, strontium, lithium, iron, manganese, chloride, bromide, sulphate, sulphide, silica, and inorganic carbon, as well as stable oxygen, hydrogen, and strontium isotope composition.
Major, minor, and trace-element concentrations were determined by Exova of Edmonton. The stable isotope values were determined by Isobrine Solutions’ Edmonton stable-isotope lab. The data are as they were received from the laboratories.
Spatial locations are unique with two duplicates, representing two duplicate samples taken at the wellhead.
Datasets are complete for each well although many results are at or below detection limit.
Charge balance on all analyses was within +/- 4.8%.
Labelling errors are documented in the comment field.
Greater delineation of the geological unit within GeoUnit field may be possible.
Attribute values were checked and are valid within their domain.
There are no presently known inconsistencies within the dataset.
Potential sampling wells were selected using the following preferred criteria for well selection:
• wells producing from a single perforated interval within one known geological unit,
• wells with a water cut of over 95%,
• wells with regular and current production, and
• wells not near injection wells.
Access and ease of sampling also constrained the well selection.
Samples were collected into plastic 4 litre jugs, directly from the wellhead (not from below the separator) and were composed of an oil-water mix. The use of a fitted sampling valve allowed the water-oil mixture to flow directly into the jugs, protecting it from the atmosphere. Depending on the rate of water production, sampling took between 30 minutes and an hour. Samples were left to gravitationally separate before sampling the water. Samples that did not separate easily were placed in a warm water bath at 80°C to encourage separation. 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, total dissolved solids, alkalinity, specific conductance and over 30 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 +/- 4.8% for all analyses.
Isobrine Solutions in Edmonton, Alberta, analyzed the filtered water samples for oxygen, hydrogen, and strontium isotope compositions. Isotopic ratios of oxygen and hydrogen are reported in per mil (o/oo) relative to Vienna Standard Mean Ocean Water (VSMOW). Strontium isotopic values are reported as the ratio of 87-strontium to 86-strontium.
Cation and anion data were initially reported in mg/L. These data were converted to ppm. All converted data were rounded to represent the number of significant figures available in the initial analysis.
Please refer to lab certificates included with this data release for detection limits, methods, and method references.
The authors would like to thank the operators at each of the wellsites for their time and assistance collecting the water samples.