In Situ Produced Nanoparticles at the Oil-Water Interface for Conformance Control and Enhanced Oil Recovery.

Area of Science:

• Petroleum Engineering
• Materials Science
• Chemical Engineering

Background:

• Nanoparticle-assisted enhanced oil recovery (Nano-EOR) shows promise but faces challenges with nanoparticle stability and delivery in reservoirs.
• Existing methods often rely on injecting pre-synthesized nanoparticles, which can be inefficient and costly.

Purpose of the Study:

• To develop and evaluate a novel method for in situ synthesis of nanoparticles at the oil-water interface for enhanced oil recovery (EOR).
• To investigate the mechanisms by which in situ generated nanoparticles improve oil recovery efficiency.

Main Methods:

• Pore-scale flooding experiments were conducted to compare EOR efficiencies with and without in situ nanoparticle synthesis.
• Bulk-scale experiments were used to analyze the effects of nanoparticle synthesis and assembly on interfacial tension and interface elasticity.

Main Results:

• In situ synthesis of SiO2 nanoparticles significantly improved tertiary oil recovery efficiencies, reaching up to 25.4% with a relatively quick reaction rate.
• The generated nanoparticles altered substrate wettability, assembled at the oil-water interface to resist deformation, and formed a gel-like barrier in brine flow paths.
• These effects led to a "shut-off" phenomenon, diverting fluids to unswept areas and increasing sweep efficiency.

Conclusions:

• In situ nanoparticle synthesis at the oil-water interface is a viable and effective strategy for enhancing oil recovery.
• The mechanism involves wettability alteration, interface stabilization, and fluid diversion, leading to improved sweep and overall oil recovery.
• This approach addresses key limitations of traditional Nano-EOR by enabling on-demand nanoparticle generation within the reservoir.