Measurement of oilfield chemical residues in produced water discharges andmarine sediments

During oil production, significant quantities of mater are produced with th e crude oil which, following treatment on the platform, are discharged to t he marine environment, This produced water contains residues of oilfield ch emicals added by the platform operators to the topside processing equipment to aid oil-water separation and mitigate operational problems. The levels of oilfield chemicals entering the marine environment via this route were i nvestigated using electrospray ionisation tandem mass spectrometry (ESI-MS/ MS) and wet chemical analysis techniques. The generic nature of different c hemical types was shown by ESI-MS/MS. Studies of the partitioning behaviour of corrosion inhibitors and demulsifiers between the oil and water phases of the produced fluids suggested corrosion inhibitors partitioned primarily into the aqueous phase and demulsifiers into the oh phase. This was reflec ted in levels observed ire produced water although, in the case of a corros ion inhibitor, lower than expected concentrations were measured, Scale inhi bitors were discharged with the produced water at their dosing concentratio ns, Marine sediments in the proximity of two North Sea oil platforms contai ned low levels of benzalkoninm quaternary ammonium salts (0.74-10.84 ng/g), typical corrosion inhibitor chemicals. Copyright (C) 2000 John Wiley &; So ns, Ltd.