| In order to investigate the adaptability of nano-flooding enhanced oil recovery technology to low-permeability reservoirs,characteristics of nano-flooding are analyzed from the aspects of injectability,oil displacement mechanism,enhanced oil recovery ability,engineering applicability and economic applicability and compared to chemical flooding represented by ASP-flooding.Injectability of nano-flooding was analyzed by comparing pore size of low-permeability reservoir to nanoparticle size and core-injection experiment.The change of wettability of the two systems is compared by the change of oil droplet contact angle.The injectability of the chemical-flooding in low-permeability reservoirs was evaluated in terms of molecular weight and viscosity.Low-permeability(K<50×10-3?m2)and medium-permeability(K>100×10-3?m2)cores were used to carry out core-flooding experiments.The experimental results of two systems were compared for analyzing the adaptability of nano-flooding in low-permeability reservoirs.Nanoparticles have a stronger ability to change the wettability than chemical flooding.It also has an exclusive flooding mechanism as“wedge penetration”.It's confirmed by experimental results that nanofluid has a good injectability in low permeability reservoirs and chemical-flooding of any viscosity and molecular weight can conduct congestion to different extent in low permeability formations.Nano-flooding had a better EOR result than chemical-flooding in low-permeability cores but made a run-off in medium-permeability cores.By analyzing and summarizing the problems encountered by chemical flooding in engineering and combining economic considerations,it can be found that nano flooding has great potential for future development of low-permeability oil fields. |
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