A study by Baker Hughes demonstrates that the FlowCam® imaging particle analysis technology is a more informative method than spectrophotometry to evaluate the demulsification of produced water. Produced water generated during oil extraction is held in skim tanks where it is treated with water clarifiers or demulsifiers. Reverse emulsion breakers (REBs) coalesce the oil into larger molecules to be skimmed, or removed, from the produced water. The efficacy of REBs and other water clarifiers on produced water is important because oil extraction companies must meet water quality environmental regulations before releasing produced water back into the environment, or they require a low oil content if the water is to be reused in the extraction process.
The oil content in water is typically analyzed using a spectrophotometer, however this method only quantifies the oil; it does not measure oil droplet size, calculate size distribution, nor provide information on the behavior of oil droplets in the water during the reverse emulsion process.
The Study's Objective
In this study, Feng et al. evaluated the efficacy of three different REBs for oil-in-water clarification using FlowCam technology. Oil droplet size, oil/solids concentration, and particle size distribution were measured in the produced water before and after REB treatment at 1 hour and 4 hour intervals. The FlowCam calculated the oil and solids concentrations in each sample.
The morphologies of the particles, as imaged by the FlowCam, were used to classify the particles. Spherical particles were classified as oil droplets and non-spherical particles were classified as solids or solid/oil aggregates. Particle size and concentration as a function of time could be quantified using the FlowCam-generated particle size distribution, which enabled Feng et al. to closely study the deoiling process and mechanism.
Feng et al. found that REB-treated produced water had substantially fewer oil droplets of all sizes compared to untreated produced water. The most effective REB helped remove oil droplets of all sizes and removed larger oil droplets completely. Increased treatment time also improved the REB efficacy as more oil droplets were given time to coalesce, larger droplets moved to the water surface, and only small oil droplets were left behind. (Image credit Feng et al., 2018).
Feng et al. found that the FlowCam imaging particle analysis technology was a successful technology to analyze oil in produced water. It is "quick and provides information on the oil/solids content, oil droplets size and size distribution using a small amount of sample. The analysis helps to understand the behavior and the performance of REBs in water clarification."
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The FlowCam has proven to be successful in many stages of the oil extraction process, from drilling mud material characterization and frac proppant analysis to hydraulic fluid monitoring and catfines analysis. The FlowCam even has an Oil-in-Water Algorithm used to classify oil droplets from solids. Download the FlowCam for Oil and Gas Applications brochure to learn about the unique benefits of the FlowCam technology for oil and gas extraction.
Feng, X., Fakunle, D., Osness, K., Khan, G., Sartori, L. (2018). Oil in water characterization by dynamic optical fluid imaging technology. Fuel, 234, 700-706. doi: 10.1016/j.fuel.2018.07.064