Stable carbon isotope fractionation of individual light hydrocarbons in the C6-C8 range in crude oil as induced by natural evaporation: Experimental results and geological implications

► Carbon isotope fractionation of C6-C8 compounds during oil evaporation investigated. ► C6-C8 compounds in the residual liquid oils are progressively enriched in 13C. ► Significant isotopic variations by >1.0‰ occur when evaporative losses are >70%. ► Carbon isotope fractionation of C6-C8 compounds depend on hydrocarbon classes.