Mechanism of expanding swept volume by nano-sized oil-displacement agent

Abstract

The effect of expanding swept volume by iNanoW1.0 nanoparticles in ultra-low permeability core was studied by low-field nuclear magnetic resonance (LF-NMR) technology, and the mechanism of expanding swept volume was explained by oxygen spectrum nuclear magnetic resonance (17O-NMR) experiments and capillarity analysis. The results of the LF-NMR experiment show that the nano-sized oil-displacement agent iNanoW1.0 could increase the swept volume by 10%–20% on the basis of conventional water flooding, making water molecules get into the low permeable region with small pores that conventional water flooding could not reach. 17O-NMR technique and capillary analysis proved that iNanoW1.0 nanoparticles could weaken the association of hydrogen bonds between water molecules, effectively change the structure of water molecular clusters, and thus increasing the swept volume in the low permeable region. The ability of weakening association of hydrogen bonds between water molecules of iNanoW1.0 nanoparticles increases with its mass fraction and tends to be stable after the mass fraction of 0.1%. Key words: nanoparticles, nano-sized oil-displacement agent, water flooding swept volume, water molecular hydrogen bonding, capillary action