Water Droplets Tailored as Wax Crystal Carriers to Mitigate Wax Deposition of Emulsion

Qianli Ma; Chuanshuo Wang; Yingda Lu; Yang Liu; Xiaofang Lv; Shidong Zhou; Jing Gong

doi:10.1021/acsomega.2c06809

Water Droplets Tailored as Wax Crystal Carriers to Mitigate Wax Deposition of Emulsion

ACS Omega. 2023 Feb 15;8(8):7546-7554. doi: 10.1021/acsomega.2c06809. eCollection 2023 Feb 28.

Authors

Qianli Ma¹, Chuanshuo Wang¹, Yingda Lu², Yang Liu¹, Xiaofang Lv^{1

3}, Shidong Zhou¹, Jing Gong⁴

Affiliations

¹ Jiangsu Key Laboratory of Oil and Gas Storage and Transportation Technology, Changzhou University, Changzhou, Jiangsu 213164, China.
² Hildebrand Department of Petroleum & Geosystems Engineering, The University of Texas at Austin, Austin, Texas 78712, United States.
³ Institute of Petroleum Engineering Technology, Sinopec Northwest Oil Field Company, Urumqi, Xinjiang 830011, China.
⁴ National Engineering Laboratory for Pipeline Safety, MOE Key Laboratory of Petroleum Engineering, and Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum-Beijing, Beijing 102249, China.

Abstract

This study explores how the micro-distribution change of wax crystals from the continuous oil phase to the oil-water interface mitigates the macro wax deposition of an emulsion. Two types of interfacial actions between wax crystals and water droplets, interfacial adsorption and interfacial crystallization, which were induced by two different emulsifiers, sorbitan monooleate (Span 80) and sorbitan monostearate (Span 60), respectively, were detected by differential scanning calorimetry and microscopy observation. The wax interfacial crystallization promoted by Span 60 resulted in the wax being nucleated directly at the oil-water interface prior to the continuous oil phase, conferring the nascent wax crystals and water droplets to be combined as coupled particles. The utilization of the wax interfacial crystallization behavior to hinder wax deposition of an emulsion was further explored. When the coupled wax crystal-water droplet particles were formed during the wax deposition process, water droplets acted as wax crystal carriers, entraining these nascent wax crystals to disperse in the emulsion, which significantly reduced the amount of wax crystals available to form the network of the deposit. In addition, this change also led to the basic structural units in the wax deposit evolving from wax crystal clusters/networks to water droplet flocs. The study elucidates that through adjusting the dispersion of wax crystals from the oil phase to the oil-water interface, water droplets could act as a functional component to tailor the properties of the emulsion or resolve related flow and deposition problems in pipeline transportation.