Impact of Oil Field Chemicals on the Coalescence and Detection of Oil Droplets in Produced Water

One of the main aspects of produced water (PW) treatment focuses on the removal of small hydrocarbon droplets. Oil platform operations are heavily reliant on production chemicals to avoid issues such as corrosion and microbial growth. Production chemicals typically contain surface-active constituents that may have adverse effects on the downstream treatment before discharge or reinjection. Oil droplets may be stabilised by either overdosage or synergistic effects of different chemicals. As a result, the removal of oil-in-water (O/W) content may be negatively affected. To get better insights into the optimization of the treatment efficiency, we have applied a series of methods to characterise and quantify the effects of chemicals on the oil content in water.
Bulk separation kinetics of oil and water with added chemicals are studied by measuring the resulting residual oil in water over time by fluorescence spectroscopy. This is compared with microfluidic studies of O/W droplets, where the coalescence frequency is analysed on high-speed movies. The microfluidics method can be used to quantify the combined effects of PW compositions relative to e.g. simple systems. The fluorescence properties of the generated droplets are studied to provide a fast and reliable benchtop quantification approach for the oil content. In combination with the fluorescence measurements, coalescence dynamics are studied for the chemical/surfactant-oil-water emulsion systems.
This is part of our larger effort to decrease the environmental impact of oil production by reducing both oil discharge and over-use of chemicals negatively affecting oil removal while leaving large amounts of production chemicals in the water phase.