Isotopic constraints on the origin of BTEX, phenol and carboxylic acids in oilfield waters

摘要

We present stable C isotope data for BTEX, phenol and C_2-C_7 carboxylic acids dissolved in North Sea oilfield waters, and for phenol in coexisting oils. Calculated δ~(13)C values for the acids' alkyl chains are similar to values for saturated hydrocarbons in coexisting petroleum, suggesting an oxidative origin from hydrocarbons. δ~(13)C of aqueous and petroleum phenol are similar but up to 7 per thousand heavier than the BTEX, indicating that phenol and BTEX are not interrelated by chemical reaction. We infer from both concentration and isotopic data that the occurrence of phenol and BTEX in oilfield waters reflects partition with oil and that phenol in both kerogen and oil is derived from a fundamentally different biological precursor than the BTEX, perhaps the amino acid tyrosine.