Role of Ultralow Interfacial Tension in the Imbibition of Silica Nanofluids

Abstract

Nanomaterials have been widely used in oilfields and have attracted more attention. At present, the introduction of nanofluids plays an important role in the imbibition of low-permeability reservoirs. However, the interfacial activity of nanofluids is usually low. There are few studies on the effect of ultralow interfacial tension (IFT) on nanofluid imbibition. In this work, nanofluids with ultralow oil–water IFT of 10–3 mN/m were screened. The core huff–puff imbibition and static imbibition experiments were carried out to study the role of ultralow IFT in imbibition recovery. 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. The hydrogen nuclear magnetic resonance (HNMR) result illustrates the oil migration process of a huff–puff imbibition. Compared with the injection and production stages, the imbibition in the shut-in stage has a higher contribution to oil recovery. It is found that nanofluids with ultralow IFT have stronger wetting reversal ability at the initial stage by comparing the oil/water/solid three-phase contact angles of different systems. Finally, under the condition that the wetting reversal ability is almost the same, the ultralow IFT reduces the capillary effect and is not conducive to the process of imbibition.

Further Study on the Effect of Interfacial Tension on Cocurrent Spontaneous Imbibition Based on Direct Simulation and NMR

“…Gu found that larger IFT is beneficial to improve the recovery factor by the lattice Boltzmann method in two-dimensional SI . Zhao found ultralow IFT can make SI reach equilibrium more quickly, but its performance in improving the SI recovery factor is limited . Zhong found through phase-field modeling that for SI in low-permeability cores, low interfacial tension reduces the oil displacement factor due to low capillarity .…”