Application of Geochemical and Isotopic Tracers for Characterization of SAGD Waters in the Alberta Oil-Sand Region

Abstract

Summary Mineral precipitation (scale) can significantly hinder production in petroleum reservoirs. This includes steam-assisted-gravity-drainage (SAGD) operations used for bitumen recovery in the Athabasca oil-sand region (AOSR) of northeastern Alberta, Canada. We explored whether select geochemical and isotope tracers (δ2H, δ18O, δ11B, δ34S, δ13C, 87Sr/86Sr) in SAGD-water sources can help to improve the understanding of the dynamics of reservoir fluids and their mixing in SAGD operations that might contribute toward scale precipitation. Pore water, bottom-formation water, steam condensate, and returned emulsions (produced bitumen and water) were sampled from an SAGD reservoir in northeastern Alberta and analyzed for geochemical and isotopic parameters. The results obtained indicate distinct Na and Cl concentrations and δ18O and δ2H values for these fluid sources. Significant differences in δ13CDIC, δ11B, and δ34S values and 87Sr/86Sr ratios were observed between bottom-formation water, steam condensate, and returned-water samples and hence constitute excellent tracers for bottomwater (BW) influx.