Experimental study of the mechanism of nanofluid in enhancing the oil recovery in low permeability reservoirs using microfluidics  

作　　者：Kang Wang Qing You Qiu-Ming Long Biao Zhou Pan Wang 

机构地区：[1]School of Energy Resources,China University of Geosciences,Beijing,100083,China [2]School of Petroleum Engineering,China University of Petroleum,Qingdao,266580,Shandong,China [3]Chengdu Natural Gas Chemical General Factory,Chengdu,610213,Sichuan,China

出　　处：《Petroleum Science》2023年第1期382-395,共14页石油科学（英文版）

基　　金：The authors sincerely appreciate the financial support from the National Natural Science Foundation of China(No.52074249,51874261);Fundamental Research Funds for the Central Universities(2-9-2019-103).

摘　　要：Due to the low porosity and low permeability in unconventional reservoirs,a large amount of crude oil is trapped in micro-to nano-sized pores and throats,which leads to low oil recovery.Nanofluids have great potential to enhance oil recovery(EOR)in low permeability reservoirs.In this work,the regulating ability of a nanofluid at the oil/water/solid three-phase interface was explored.The results indicated that the nanofluid reduced the oil/water interfacial tension by two orders of magnitude,and the expansion modulus of oil/water interface was increased by 77% at equilibrium.In addition,the solid surface roughness was reduced by 50%,and the three-phase contact angle dropped from 135(oil-wet)to 48(water-wet).Combining the displacement experiments using a 2.5D reservoir micromodel and a microchannel model,the remaining oil mobilization and migration processes in micro-to nano-scale pores and throats were visualized.It was found that the nanofluid dispersed the remaining oil into small oil droplets and displaced them via multiple mechanisms in porous media.Moreover,the high strength interface film formed by the nanofluid inhibited the coalescence of oil droplets and improved the flowing ability.These results help to understand the EOR mechanisms of nanofluids in low permeability reservoirs from a visual perspective.

关 键 词：NANOFLUID EOR mechanism MICROMODEL Low permeability Three-phase interface 

分 类 号：TE357[石油与天然气工程—油气田开发工程]