Produced Water Quality and Microfluidic Methods for Studying Drop-Drop and Drop-Bubble Interactions in Produced Water
Abstract
Produced water originates from crude oil production, during which it is extracted to the surface together with hydrocarbons. It consists of various dissolved and dispersed components, such as dissolved organic and inorganic compounds, suspended solids, production chemicals, and oil dispersed in the form of droplets. The latter is typically targeted by several treatment processes before the water can be discharged to sea or re-injected to an underground formation. Typical treatment processes, such as gravity or enhanced-gravity separation, strongly rely on the rising velocity of the dispersed droplets, whereas gas flotation aims at enhancing the density difference between the continuous and the dispersed phases through attachment of gas bubbles. This means that the fundamental phenomena occurring on a microscale, like droplet growth through coalescence or bubble-droplet interactions, will play a key role during these processes. That is why the development of new, microfluidic research tools and their application for studying these interactions in various conditions was one of the main goals of this thesis.
First, the produced water quality and its connection to both crude oil and water compositions was investigated. The water was mixed with crude oil and later analysed with respect to the total oil concentration, droplet size, total organic carbon and pH change. Next, a microfluidic method was developed to study the coalescence of model oils in the presence and absence of dissolved atmospheric gases, also at elevated pressures. This was followed by a report on the application of microfluidics for probing coalescence between crude oil droplets in produced water. Various aspects, like the oil and water composition, the presence of dissolved components or pressure levels were studied. Finally, a novel microfluidic methodology for investigating the removal of dispersed hydrocarbons through spreading on gas bubbles was presented. It also involved changing relevant parameters and testing their effect on the spreading process.
Has parts
Paper 1: Dudek, Marcin; Kancir, Eugènie; Øye, Gisle. Influence of the Crude Oil and Water Compositions on the Quality of Synthetic Produced Water. Energy & Fuels 2017 ;Volum 31.(4) s. 3708-3716 https://doi.org/10.1021/acs.energyfuels.6b03297 Reproduced with permission from Energy Fuels Copyright © 2017 American Chemical SocietyPaper 2: Dudek, Marcin; Muijlwijk, Kelly; Schroën, Karin; Øye, Gisle. The effect of dissolved gas on coalescence of oil drops studied with microfluidics. Journal of Colloid and Interface Science 2018 ;Volum 528. s. 166-173 https://doi.org/10.1016/j.jcis.2018.05.083
Paper 3: Dudek, Marcin; Bertheussen, Are; Dumaire, Thomas; Øye, Gisle. Microfluidic tools for studying coalescence of crude oil droplets in produced water. - © 2018 This manuscript version is made available under the CC-BY-NC-ND 4.0 license. The final published version is available in Chemical Engineering Science 2018 ;Volum 191. s. 448-458 https://doi.org/10.1016/j.ces.2018.07.006
Paper 4: Removal of Crude Oil Droplets through Spreading on Gas Bubbles Studied with Microfluidics - Reproduced with permission from Energy Fuels, Article ASAP Copyright 2018 American Chemical Society. The final published version is available at https://doi.org/10.1021/acs.energyfuels.8b02236