Molecular indicators of secondary oil migration distances

The ability to determine the distance migrated by an oil from source rock to reservoir could greatly assist in the identification of new, economically viable accumulations of petroleum. Non-alkylated benzocarbazoles, which are present in trace quantities in oils, exhibit changes in both absolute and relative concentrations that correlate with migration distance, independent of the maturity of the oils. Such molecules appear promising as empirical-but quantitative-indicators of the relative migration distances of oils, and represent a first step towards true source-reservoir distance indicators.