Microfluidic Investigation of Crude Oil Droplet Coalescence: Effect of Oil/Water Composition and Droplet Aging

Abstract

The coalescence between crude oil droplets is a major factor influencing the efficiency of most produced water treatment processes. As the droplets grow bigger in size, it is easier to remove them from the continuous water phase, which will improve the quality of produced water and help meet increasingly stricter environmental and process regulations. Here we investigate the coalescence process of crude oil drops in water with the use of previously reported microfluidic tools. It was shown that the composition of both oil and water phases heavily impacts the merging between droplets, both outcome (final droplet size distribution) and the kinetics of the phenomena (coalescence time). In the droplet ageing experiments, the coalescence was always most extensive for the droplets with the shortest ageing time, while the coalescence typically decreased with increasing droplet size distribution, however this

Microfluidic testing of flocculants for produced water treatment: Comparison with other methodologies

“…This was in line with our previous findings and is due to migration of interfacially active crude oil components (i.e. resins and asphaltenes) to the oil-water interface where they build up an interfacial layer that opposes coalescence ( Dudek et al., 2020a ). The small difference between the coalescence in the short and medium length channels can probably be explained by relatively large molecular weights for the migrating components, that take longer time to adsorb at the oil-water interface.…”

“…Two crude oils produced at the Norwegian Continental Shelf (NCS) were used in this study. They are designated as crude oil E and G, in accordance with previous studies in our group ( Dudek et al., 2020a ). Both are light crude oils and are considered representative for the type of oil produced at NCS.…”

“…The recordings were processed with ImageJ to extract the position and size of droplets in each image, which were later used to calculate the coalescence frequency for each experiment. More details can be found elsewhere ( Dudek et al., 2020a ). All reported values were an average of at least three parallels.…”

“…It offers precise control over experimental conditions, possibility to study phenomena during flow and use very small (microlitres) sample volumes. It has been applied to study coalescence between droplets or bubbles ( Wang et al., 2016 , 2020 ), recently also in crude oil systems ( Dudek et al., 2020a ; Leary et al., 2020 ). The objective of this paper is to introduce microfluidic methodology as a viable way of determining the efficiency of flocculants during separation of crude oil from produced water.…”

Coalescence of Binary Droplets in the Transformer Oil Based on Small Amounts of Polymer: Effects of Initial Droplet Diameter and Collision Parameter

“…Fortelný et al reviewed the applicability of droplet diameter distribution in the processing of immiscible polymer blends [ 21 ]. Dudek et al proposed that, in the specific oil phase, the droplet diameter distribution increases and the coalescence efficiency decreases [ 22 ].…”