The dating of petroleum fluid residence time in subsurface reservoirs. Part 2: Tracking effects of radiolysis on crude oil by comprehensive molecular analysis

•Oils with higher saturated hydrocarbon content are more prone to alteration by radiolysis.•Evidence suggests radiolysis-induced polymerization.•New hydrocarbon species with no or low aromaticity form.•Oxygenated species are plausible candidates for radiolysis proxies.•Carbon-carbon double bonds are the most promising radiolysis proxy.