Study on stability of produced water in ASP flooding based on critical micellar theory
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Study on stability of produced water in ASP flooding based on critical micellar theory Dawei Zhang1 · Zhongxi Chen2 · Lu Ren3 · Xiangchun Meng2 · Wenge Gu2 Received: 11 April 2020 / Revised: 12 November 2020 / Accepted: 17 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The basic properties of produced water and the effect of oil displacement agent for its stability were obtained, through measuring and analyzing water quality characteristics, relationship between critical micelle concentration-oil displacement agent, temperature, pH and content of inorganic salt, particle size distribution and morphology of Nan4-8 and Sanyuan-6 alkali-surfactant-polymer (ASP) produced water of Daqing Oilfield. The critical micelle concentration of ASP flooding was less than its own concentration, and the double bilayer was formed in system. Critical micelle concentration of ASP produced water was less affected by the system temperature and greatly affected by pH. Polymer increases viscosity of produced water and has the properties of surfactant, which partially hydrolyzes under the action of alkali to form polyelectrolyte and promotes the formation of double electric layer. Therefore, the coalescence of oil droplets in ASP produced water is difficult, and the stability is greatly enhanced. ASP produced water contains a large amount of inorganic salts, which can shield the electrostatic repulsion between the surfactant ion head groups, compresses the thickness of the double electric layer, and promotes the formation of surfactant micelles. When it settles after a certain period of time, part of ASP produced water has a particle size distribution less than 100 nm, the micelles are generated in the system, which enhances the stability of ASP produced water. Keywords ASP flooding · Alkali · Polymer · Surfactant · Critical micelle concentration
* Zhongxi Chen [email protected] 1
College of Chemistry and Pharmaceutical Engineering, Jilin Institute Chemical Technology, Jilin City 132022, China
2
Daqing Oilfield Design Institute, Daqing 163000, China
3
College of Aeronautical Engineering, Jilin Institute Chemical Technology, Jilin City 132022, China
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Polymer Bulletin
Introduction ASP flooding is a new oil flooding technology developed on the basis of alkaline water flooding, surfactant flooding and polymer flooding. The composite system formed by this technology has a higher viscosity and a larger spread factor, (the ratio of the volume of the oil layer affected by the oil displacing agent to the total oil volume) and oil‒water interfacial tension is significantly reduced, and the flooding effect is significant. Crude oil recovery can be increased by 10‒20% compared with water flooding and polymer flooding, therefore, it is considered to be the most effective chemical flooding technology at present [1–7]. However, with the continuous promotion of ASP flooding technology, the output of ASP produced water has also increased, which has also brought a lot of
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