Magnesium Aluminum Silicate Nanoparticles and Polyanionic Cellulose as Additives in Low-Solid Water-Based Drilling Fluids

This work demonstrated a nanosized material, magnesium aluminum silicate (MAS), as a rheological modifier for low-solid water-based drilling fluids (WBDs) to prompt the development of the safe and high-performance low-solid WBDs. To maintain good filtration property, the polyanionic cellulose (PAC) was introduced into the MAS suspension. Meanwhile, a comprehensive comparison between MAS cooperating with PAC and BT mixing with PAC was conducted. The addition of 0.5 wt% PAC increased the yield stress and generated better shear-thinning performance for 1 wt% MAS and 4 wt% bentonite (BT). The 1 wt% MAS/0.5 wt% PAC exhibited higher yield stress and shear-thinning performance than 4 wt% BT/0.5 wt% PAC. In addition, low-concentration MAS and MAS/PAC suspensions showed higher gel strength and rapider recovery performance compared with high-concentration BT and BT/PAC suspensions. MAS and MAS/PAC maintained excellent thermal stability, compared with other common rheological modifiers, such as xanthan gum (XG), hydroxyethyl cellulose (HEC). After hot rolling at 120 °C for 16 h, WBDs prepared by MAS/PAC exhibited a slight decrease of rheological parameters, which indicated high ability to resist high temperature. The XRF, particle size distribution, and TEM analysis revealed the mechanism of low-concentration MAS and MAS/PAC maintaining better shear-thinning performance, higher gel strength and yield stress. As the excellent rheological properties and thermal stability, MAS has the great potential to be a rheological modifier for low-solid WBDs.