CommentComment on “Behavior of Re and Os during contact between an aqueous solution and oil: Consequences for the application of the Re-Os geochronometer to petroleum” [Geochim. Cosmochim. Acta 158 (2015) 1-21]

In a recent study, Mahdaoui et al. (2015) simulated the contact of oil with Re/Os-bearing aqueous fluids in petroleum reservoirs and concluded that both metals could be rapidly and substantially enriched in the oil fraction. These findings could have significant geological ramifications for the use of rhenium-osmium (Re-Os) geochronology in the age-dating of oil deposits. However, the lack of data reproducibility between parallel experiments and misused parameter of “recovery rate” has cast doubt on the main conclusions of the paper. Re-analyses of the raw data provided sufficient evidence to suggest that in petroleum basins with very low abundances of Re and Os, the extraction of these metals to oil is unlikely to be a geologically instantaneous process as the authors implied in their study. In addition, the possibility of reactor leakage in the contacting experiments cannot be completely ruled out.