Enhancing Oil Field Emulsion Destabilization Through Selective Surface Patterning of Microfluidic Devices

Abstract

Enhanced oil recovery (EOR) is a technology used to recover most of our limited crude oil reserves. With the continuous increase in energy demand, enhanced oil recovery will not only achieve huge economic benefits, but also greatly help in the exploitation of crude oil reserves. Recently, nanoparticle flooding has been the focus of many researchers and is considered to be the main technology among all different EOR methods. Although nanofluids can improve the efficiency of oil recovery by stabilizing the oil-water emulsions produced in the extraction stage, they have an adverse effect on the subsequent oil-water separation process. Therefore, it is necessary to destabilize these emulsions before proceeding to any subsequent downstream processing.

Microfluidics provides an attractive alternative for destabilizing emulsions compared to conventional techniques, where microfluidic platforms offer precise control over fluid manipulation and enable efficient modulation of flow conditions for targeted destabilization of emulsions. While these platforms are adequate to investigate the formation of emulsions under homogenous wettability conditions, mixed-wettability conditions may affect the emulsions stability; this instability can be utilized to provide a new method for droplet-based separation in microfluidics platforms. To enable the design of microfluidic coalescer unit of nanofluids-oil emulsions that are produced during EOR, separation in microfluidic platforms was explored by changing the surface energy of microchannels to improve the fusion/coalescence process. By focusing on this aspect, we aimed to enhance the efficiency and effectiveness of the coalescer unit, thus paving the way for its practical implementation on a larger scale.

This dissertation presents the development of selective surface energy patterning techniques in microfluidic channels to improve the fusion process/demulsification of the water-oil emulsions formed by nanoparticles flooding fluids during EOR. Graphene oxide (GO) and zeolites are used for patterning the wettability of the microchannels. The patterned surfaces were characterized to assess their wettability, morphology, and adhesion characteristics. The effect of different configurations of the hydrophilic and hydrophobic regions of the microchannels on the emulsion stability was investigated, in addition to the influence of key parameters such as surface wettability, total flowrate, and nanoparticle concentration. Moreover, the deposition of nanoparticles on the patterned surfaces during the coalescence was examined. The formation of nanofluid in oil emulsions was achieved through a hybrid droplet generation microfluidic device made of cyclic olefin copolymer and polydimethylsiloxane materials. In addition, a newly developed bonding process based on organosilane coupling agent was utilized to achieve an irreversible bonding between the two polymers. The findings reveal that GO and SAPO-34 deposition significantly enhance the surface energy of cyclic olefin copolymer. Additionally, destabilization tests on the patterned and functionalized microdroplet device demonstrate the effectiveness of both GO and zeolite patterns in destabilizing silica nanofluid emulsions. The critical adhesion velocity of GO patterned microchannels varies with nanofluid concentration, while the critical adhesion velocity of zeolite patterned microchannels remains constant. Moreover, microstructures (micropillars) within microchannels promote droplet coalescence even without GO deposition using only plasma treatment. Notably, GO-coated micropillars are found to effectively trap silica nanoparticles.

The outcomes of this research contribute to the advancement of microfluidic-scale separators for EOR emulsion separation, offering potential scalability and reduced energy requirements.

Date of Award	26 Dec 2023
Original language	American English
Supervisor	Nahla Al Amoodi (Supervisor)