Developing a Method to Track Oil and Gas Produced Water Discharges in Estuarine Systems Using Salinity as a Conservative Tracer

Abstract

Produced water is a high salinity by-product resulting from oil and gas production. Disposal methods include surface water discharge from a point source. The current field method used for fate and effect determinations in open water estuarine systems involves extending a compass oriented transect (COT) from the point source discharge – a method designed for a uniform offshore environment that might be inappropriate for the hydrologic and geomorphologic complexities found in estuarine systems. Research was conducted in a canal and a small, semi-enclosed bay to observe effluent behaviour and to determine if salinity could be used to track the effluent. A salinity/conductivity/temperature (SCT) probe measured water properties within 1 cm of the sediment surface and identified a thin, bottom salinity plume that would have gone undetected by conventional instruments. The plume flowed across the sediment surface and towards greater depths. Plume-affected sampling stations exhibited higher levels of sediment contaminant indicators (SCIs) and indicated that station location could affect impact conclusions.