Effect of the progressive precipitation of petroleum asphaltenes on the Re–Os radioisotope system

Behavior of Re and Os during contact between an aqueous solution and oil: Consequences for the application of the Re–Os geochronometer to petroleum

“…Re and Os, like many other metals (Ali et al, 1983(Ali et al, , 1993Caumette et al, 2009), are principally located in the heavy fraction of oil (asphaltenes; Selby et al, 2007). Moreover, within the asphaltene fraction, Re and Os are both concentrated in the most polar constituents, suggesting a similar mode of incorporation (Mahdaoui et al, 2013). Our results are consistent with this preference of Re and Os for the heavy fraction.…”

“…b Os concentration of V-oil calculated from the Os concentration in asphaltene (Mahdaoui et al, 2013) and the asphaltene proportion, assuming asphaltene contains all of the Os (Selby et al, 2007). c Elemental analysis courtesy of TOTAL.…”

Further evaluation of the Re-Os systematics of crude oil: Implications for Re-Os geochronology of petroleum systems

“…To date, the studies of Re-Os elemental and isotopic systematics have been conducted on sequentially precipitated fractions from asphaltenes (Mahdaoui et al, 2013;DiMarzio et al, 2018). For the two samples studied by Mahdaoui et al (2013), sequential precipitation of asphaltenes was conducted with a mixture of dichloromethane (CH 2 Cl 2 , DCM) and n-heptane or n-pentane. The Re and Os concentrations of the progressively precipitated asphaltene fractions decrease throughout the process, however both the ratios of the Re/Os and 187 Os/ 188 Os of the fractions remain nearly constant.…”

A Matrix‐Matched Reference Material for Validating Petroleum Re‐Os Measurements

“…These studies have demonstrated that the Re-Os isotope systematics of petroleum (crude oil, bitumen) allow the direct dating of the processes related to petroleum generation and evolution, and also provide insights into the source of the petroleum. Laboratory studies have also been carried out on the Re-Os isotope systematics of crude oil fractions (Selby et al 2007, Mahdaoui et al 2013, Georgiev et al 2016). These studies have discussed the possible influences of geological processes on the Re-Os systematics of petroleum and its application to petroleum systems, for example the timing of oil generation, the precipitation of asphaltene and the effect of contact with basinal fluids.…”

“…They include not only conventional crude oil, but also the altered forms, for example bitumen of different origins. The Re-Os measurement methods were initially set up for rock samples, for example sulfides and organic-rich mudrocks (Cohen et al 1999, Reisberg and Meisel 2002, Marques 2013, Zimmerman et al 2014, and then adapted for the specific characteristics of petroleum samples , Mahdaoui et al 2013, Sen and Peucker-Ehrenbrink 2014, Georgiev et al 2016. In general, current petroleum Re-Os measurement procedures adopt similar chemical purification procedures among different laboratories with the main differences being the digestion (i.e., choice of vessels and acids) and mass spectrometry (N-TIMS and ICP-MS) methods.…”