Renewable Energy Global Innovations features: Enhanced Oil Recovery (EOR) Using Nanoparticle Dispersions: Underlying Mechanism and Imbibition Experiments

Significance Statement

Nanofluids have become attractive agents for EOR recently. Higher ultimate oil recovery has been reported previously by using nanofluids. The two major mechanisms reported in literature in achieving this feature include: The reduction of interfacial tension between the aqueous phase and oil phase, and the rock wettability alteration. Despite recently widely conducted research using a nanofluid for EOR, the underlying operating mechanism of recovery by a nanofluid is still not well understood.

A new approach which makes use of nanofluids for displacement of oil from solid substrate by nanoparticle structuring leads to structural disjoining pressure which separates oil from the solid substrate. Other factors such as combination of nanoparticle formulation, contact angle and capillary pressure are also known to influence the separation of oil from substrate.

Researchers from Illinois Institute of Technology at Chicago presented results of imbibition experiments using a silica nanofluid and an Illinois Institute of Technology (IIT) nanofluid that displaces crude oil from Berea sandstone and single-glass capillaries. The researchers developed a nanoparticle formulation in view of surviving at a high-salinity environment containing calcium and magnesium ions accompanied with study of structural disjoining pressure mechanism for crude oil displacement. The work was published in peer-reviewed journal, Energy & Fuels.

Through imbibition test, 55% of the crude oil was recovered using the silica nanofluid, compared to only 2% recovered with the pH 9.7 DI water after 15 days. At an increased temperature of 55 ^oC, the IIT nanofluid displaced crude oil approximately 50% from Berea sandstone compared with 17% by the brine solution.

For the mechanistic study, the researchers observed rapid shrinkage of contact region after introduction of brine and the position of contact region didn’t change with time after wedge region was formed, hence oil drop was not detached. However, for the nanofluid case, a new contact line (inner contact line) appears and spreads due to nanoparticles ordering in the oil/solid/aqueous three phase contact region after the wedge film formed. This confirms the structural disjoining pressure mechanism. It is the first time that this mechanism of crude oil displacement from a solid substrate is demonstrated experimentally.

The authors finally conducted model studies of crude oil displacement using single glass capillaries to directly visualize the crude oil displacement process from inside the pore. Around 60% crude oil was displaced by IIT nanofluid compared to 3% in the brine. Moreover, the authors were able to show from their results that the IIT nanofluid thrives in harsh saline environment where silica nanoparticles cannot.

 

About The Author

Hua Zhang is a Ph.D. Student in the Chemical and Biological Department at Illinois Institute since 2011. He received his B.S. and M.S. degrees in Chemical Engineering from Beijing University of Chemical Technology, China in 2008 and 2011 respectively.

His research area lies in wetting and spreading of nanofluids on solid substrate; dynamics of liquids in the capillary; surface cleaning and enhanced oil recovery using nanofluids.  

Journal Reference

Hua Zhang, Alex Nikolov, Darsh Wasan.  Enhanced Oil Recovery (EOR) Using Nanoparticle Dispersions: Underlying Mechanism and Imbibition Experiments, Energy Fuels 28 (2014) 3002-3009.

Department of Chemical and Biological Engineering, Illinois Institute of Technology, Chicago, Illinois 60616, United States.

 

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