Thermo-responsive polymer-based Janus biogenic-nanosilica composite, part B: Experimental study as a multi-functional synergistic shale stabilizer for water-based drilling fluids

Abstract

Wellbore instability caused by shale swelling and dispersion has always been a thorny issue for drilling complex formations. Nanotechnology has offered a revolutionary solution for shale stabilization in water-based drilling fluids (WBDFs). Recent technological advancement in nanomaterials for optimal performance using economically and environmentally sustainable pathway is an utmost desire in oil and gas industries. In this research, Janus nanocomposite (TRJN) with rice husk (RH)-extracted biogenic nanosilica core (RH-NSP) having the shell integrating synergistic benefits of thermo-responsive and amino-based materials, which was reported in our previous work was assessed as a novel shale stabilizer in drilling fluids. The product is anticipated to simultaneously improve the chemical inhibition and nanoplugging performances in shaly formations. TRJN was assessed as an additive in WBDF in comparison with symmetrical thermo-responsive polymer-based nanocomposite (TRN) counterpart and parent RH-NSP. Results from the rheological test revealed that, albeit both nanocomposites (i.e., TRN and TRJN) could provide a certain rheological control above the LCST compared to RH-NSP, but TRJN-blended fluid was less sensitive to increasing temperatures. The inhibitory effects were investigated based on cuttings hot rolling recovery rate, linear swelling rate, pressure penetration rate, tensile strength of shale reduction rate, and high temperatures and high pressures filtration loss. TRJN demonstrated higher chemical inhibition compared to RH-NSP and TRN, driving a better capacity to control pressure penetration. The higher mean free energy of TRJN/Na-Mt (sodium montmorillonite) system than TRN/Na-Mt system was an indication of its stronger interactions with Na-Mt particle, which triggered changes in microstructures, considering the results of zeta potential, FT-IR, surface wettability, X-ray diffraction, and SEM analyses. This, therefore contributing to firmly trap the TRJN into the multi-scale pore structure of the shale and beneficially promoted the construction of a tight hydrophobic plugging layer over the shale surface from the outward face. Lastly, the synergistic enhancement mechanisms of shale inhibition with TRJN was further proposed.