Microscale investigation of DNAPL displacement by engineered graphene quantum dots in heterogeneous porous media

This x-ray microtomography study investigates the dynamic pore-scale displacement of a dense non-aqueous phase liquid (DNAPL) such as heavy crude oil in heterogeneous aquifer rock using carbonaceous nanoparticles. The nanoparticles were synthesized from Wyoming coal and consisted mixture graphene quantum dots (GQD) engineered (E-GQD) equal proportions. Synergistic interactions between GQD E-GQD at oil/water interface reduced DNAPL/brine interfacial tension (IFT) 13.4 mN/m to 5.4 mN/m. In addition, nanofluid altered wettability minerals found (quartz, carbonate, feldspar) oil-wet water-wet with average contact angles 66°, 51°, 60°, respectively. alteration was more pronounced carbonates due tendency adsorb on these surfaces. Analyses saturation profiles fluid occupancy maps revealed that not instantaneous required short soaking time for fluid-rock take place. IFT reduction alone enough displace DNAPL early stages flooding because high density viscosity oil. As result, did outperform brine after 1 pore volume (PV) injection. On other hand, able invade small pores accessible 3 PV injection both angle reduction, which lowered threshold capillary pressure pores. Subsequently, medium large invaded by continued, leading an 11% increase recovery 20 injection, compared waterflooding. incremental is significant considering experiments performed ambient temperature, representative conditions. Thus, GQD-based has potential achieve much larger recoveries deeper reservoirs provided allowed. insights this could be used validate network models or guide design selection effective nanomaterials remediation enhanced applications.