Source identification for oil-based drill cuttings on the seabed based on stable carbon isotopes

Abstract

This paper demonstrates how stable carbon isotopes can be utilized to identify the source of oil-based drill cuttings discharges and estimate the time of their deposition. The base-oil used in drilling mud systems may be biodegraded by seabed microflora. Effects of such processes make it difficult to identify sources of discharges based on the oil's molecular structure. However, the stable isotope fingerprint of the base oil may vary for each batch of base-oil. Because carbon isotopic ratios in compounds with more than ten carbons are resistant to fractionation during biodegradation, this may be used as a tool to identify the source of drill cuttings discharges.

Organic Matter in the Hydrosphere

“…However, PAHs and further petroleum hydrocarbons are constituents of marine sediments not only as the result of shipping activities but also derived from offshore oil production. For example, drill cuttings have been reported to contribute significantly to sedimentary hydrocarbon pollution (Scholz-Böttcher et al 2008;Skaare et al 2008).…”