--> Integration of Geochemical and PVT Data to Evaluate Regional and Well-Level Performance of Shale Liquid Plays: Examples From the Montney, Doig, Charlie Lake and Halfway Formations of the Western Canada Sedimentary Basin

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Integration of Geochemical and PVT Data to Evaluate Regional and Well-Level Performance of Shale Liquid Plays: Examples From the Montney, Doig, Charlie Lake and Halfway Formations of the Western Canada Sedimentary Basin

Abstract

Geochemical and PVT data were analyzed from source rocks and produced oils and gases in Triassic petroleum systems of the Western Canada Sedimentary Basin. The GeoMark-developed methodology under discussion has proven successful in the Eagle Ford Formation of south Texas, USA. WCSB formations are as amenable to the synergy of combining PVT and geochemical data as the Eagle Ford, as shown by parallel studies of Devonian, Jurassic and Cretaceous petroleum systems. GIS mapping facilitates interpolation of data values between control points, which for this study are production wells with complete PVT analyses. Carbon gas isotopes are generally better maturity indicators than vitrinite reflectance. Once calibrated, carbon isotope data were used to predict PVT properties by 1) correlation with measured GOR values, and 2) relating GOR to reservoir fluid density, viscosity, and API gravity. Reservoir temperature, formation volume factor, reservoir and saturation pressures were also mapped from PVT control points. Both legacy and newly acquired PVT data were useable after appropriate Quality Control procedures. Source rock quantity, quality and thermal maturity data were mapped and integrated with the reservoir engineering information to completely characterize both conventional and source-rock reservoirs in this study. Geochemical and PVT data can be interpreted via GIS mapping of key parameters to identify regions and wells near saturation. These wells are likely to suffer significantly reduced performance as two-phase separation occurs in the reservoir. To illustrate the stratigraphic and geographic variability, we note that the Degree of Undersaturation (Preservoir – Psaturation) in the Montney Formation increases slightly from near zero southeast of Grande Prairie, AB to the northwest near the Alberta-British Columbia border. However, the Halfway Formation shows a reversed trend increasing from north of Fort St. John, BC southeast to Grande Prairie, AB.