Nanoparticles
(NPs) exhibit great potential to improve various
properties of viscoelastic surfactant (VES) fracturing fluids in the
development of low-permeability reservoirs. In the present study,
the amphiphilic Janus NPs (JANPs) were fabricated via the Pickering
emulsion method and employed to construct the novel JA12C (JANPs with
dodecyl hydrophobic carbon chains)-assisted VES fracturing fluid (JAVES).
The successful fabrication of JANPs was confirmed via Fourier transform
infrared spectroscopy (FTIR) measurements and water contact angle
tests. The rheology behavior of the VES fracturing fluid incorporating
various SiO2 NPs including hydrophilic SiO2 NPs
(HLNPs), JA8C (JANPs with octyl hydrophobic carbon chains), and JA12C
was systematically investigated. It was revealed that the additional
JA12C significantly improved the tolerance and proppant suspension
properties. To explore the subsequent oil recovery performance of
various gel breaking liquids, the formation wettability and the oil–water
interfacial tension (IFT) were studied after the evaluation of breaking
properties and formation damage properties of various fracturing fluids.
The results suggested that the JAVES gel breaking liquid showed remarkable
wettability alternation capability and moderate oil–water IFT
reduction ability, which can partially reduce the impact on reservoir
permeability. Moreover, the formation mechanism of the JAVES was proposed
by molecular dynamics simulations at the molecular level, which was
further visually verified via the cryo-TEM images. The improved viscoelasticity
of developed the JAVES with moderate interfacial activity is advantageous
to enhance subsequent oil recovery.