Role of Ultralow Interfacial Tension in the Imbibition of Silica Nanofluids

Nanomaterials have been widely usedin oilfields and have attractedmore attention. At present, the introduction of nanofluids plays animportant role in the imbibition of low-permeability reservoirs. However,the interfacial activity of nanofluids is usually low. There are fewstudies on the effect of ultralow interfacial tension (IFT) on nanofluidimbibition. In this work, nanofluids with ultralow oil-waterIFT of 10(-3) mN/m were screened. The core huff-puffimbibition and static imbibition experiments were carried out to studythe role of ultralow IFT in imbibition recovery. The experimentalresults show that ultralow IFT can make the static imbibition of nanofluidsreach equilibrium more quickly, but its performance in improving imbibitionrecovery is limited. The hydrogen nuclear magnetic resonance (HNMR)result illustrates the oil migration process of a huff-puffimbibition. Compared with the injection and production stages, theimbibition in the shut-in stage has a higher contribution to oil recovery.It is found that nanofluids with ultralow IFT have stronger wettingreversal ability at the initial stage by comparing the oil/water/solidthree-phase contact angles of different systems. Finally, under thecondition that the wetting reversal ability is almost the same, theultralow IFT reduces the capillary effect and is not conducive tothe process of imbibition.

Automated summary

Nanomaterials have been widely used in oilfields and have attracted more attention. However, there are few studies on the effect of ultralow interfacial tension (IFT) on nanofluid imbibition. In this work, nanofluids with ultralow oil-water IFT were screened and their role in imbibition recovery was studied. The experimental results show that ultralow IFT can make the static imbibition of nanofluids reach equilibrium more quickly, but its performance in improving imbibition recovery is limited.