Fabrication of ionic liquid-cellulose-silica hydrogels with appropriate thermal stability and good salt tolerance as potential drilling fluid

This paper investigates the rheological properties of methylcellulose-silica-ionic liquid nanocomposite (2-MCPS-MC) on the rheological properties (apparent viscosity (AV), plastic viscosity (PV), yield point (YP), 10-s gel strength, 10-min gel strength, and thixotropy according to API requirements) of water-based mud, and comparing these properties with the properties of the silica-free methylcellulose (MC) as drilling fluid additive. The physicochemical properties of the MC and 2-MCPS-MC compounds were studied using ¹H NMR, FTIR, Raman-spectroscopy, XRD, FE-SEM, AFM, and TGA. By FE-SEM and AFM, it is proven that the silica had an excellent dispersion in a spherical shape on the MC polymer. Three samples were prepared: the first is the commercial water-based mud, while the second and the third samples are MC and 2-MCPS-MC, respectively. The samples of MC were prepared in four concentrations (2%, 1.5%, 1.0% and 0.5% by weight). Throughout the test, density remained at 7.6 (lbs/gal) for mud fluid and 8.5 (lbs/gal) for MC and 2-MCPS-MC at pH 9.0. The results confirmed that the optimum concentration of MC and 2-MCPS-MC, which meet the required API code, was between 1 and 1.5%. The addition of 2-MCPS-MC to water-based mud enhances filtration properties. Response surface technique (RSM) with central composite design (CCD) was also used to optimize the drilling fluid properties to achieve the optimal response to AV, PV, YP, Gl, and Thixotropic using a Design expert software. The results obtained by RSM showed consistency between the experimental and theoretical data.