Potential of Using real-time OiW monitoring for control of produced water treatment in offshore oil & gas production

The produced water has been the largest produced fluid stream at most of the current offshore oil & gas production in North-sea. It is not uncommon that the water cut can reach 90% in many matured production fields. No matter the produced water will be eventually discharged to the ocean, or reused for injection purpose in the field, the hydrocarbon content in the produced water needs to be strictly limited either due to the hazardous environmental impact or EOR sweeping effectiveness. The real-time Oil-in-Water (OiW) monitoring is still an open issue in recent decade. The main challenges include: how to get reliable and accurate real-time measurement; how to interpret the measured data; how to use the measurement to feedback control the Produced Water Treatment (PWT) processes; as well as how to keep cost-effective on-site calibration and maintenance subject to offshore harsh conditions etc. The paper will report our latest achievements and observation in usage of florescence-based and microscopy-based OiW monitoring technologies for advanced PWT control design and evaluation, particularly by focusing on the de-oiling hydrocyclone installations.