The ultra-low permeability reservoir is regarded as an important energy source for oil and gas resource development and is attracting more and more attention. In this work, the active silica nanofluids were prepared by modified active silica nanoparticles and surfactant BSSB-12. The dispersion stability tests showed that the hydraulic radius of nanofluids was 58.59 nm and the zeta potential was − 48.39 mV. The active nanofluids can simultaneously regulate liquid–liquid interface and solid–liquid interface. The nanofluids can reduce the oil/water interfacial tension (IFT) from 23.5 to 6.7 mN/m, and the oil/water/solid contact angle was altered from 42° to 145°. The spontaneous imbibition tests showed that the oil recovery of 0.1 wt% active nanofluids was 20.5% and 8.5% higher than that of 3 wt% NaCl solution and 0.1 wt% BSSB-12 solution. Finally, the effects of nanofluids on dynamic contact angle, dynamic interfacial tension and moduli were studied from the adsorption behavior of nanofluids at solid–liquid and liquid–liquid interface. The oil detaching and transporting are completed by synergistic effect of wettability alteration and interfacial tension reduction. The findings of this study can help in better understanding of active nanofluids for EOR in ultra-low permeability reservoirs.

超低渗透储层被认为是油气资源开发的重要能源，受到越来越多的关注。在这项工作中，通过改性的活性二氧化硅纳米粒子和表面活性剂BSSB-12制备了活性二氧化硅纳米流体。分散稳定性测试表明，纳米流体的水力半径为58.59 nm，ζ电位为-48.39 mV。活性纳米流体可以同时调节液-液界面和固-液界面。纳米流体可以将油/水界面张力（IFT）从23.5降低到6.7 mN / m，并且油/水/固体接触角从42°更改为145°。自发吸收测试表明，与3 wt％的NaCl溶液和0.1 wt％的BSSB-12溶液相比，0.1 wt％的活性纳米流体的采油率分别高出20.5％和8.5％。最后，从纳米流体在固-液和液-液界面的吸附行为研究了纳米流体对动态接触角，动态界面张力和模量的影响。通过润湿性改变和界面张力降低的协同作用完成了油的分离和运输。这项研究的发现可以帮助更好地了解超低渗透储层中活性纳米流体的EOR。