Magnesium aluminum silicate nanoparticles as a high-performance rheological modifier in water-based drilling fluids

Horizontal well operations are playing an important role in extraction of oil and gas in recent years. However, cuttings sediments occurred frequently in the long horizontal section, causing friction increases and drill pipe sticking. This study demonstrated a nano-sized layered material, i.e. magnesium aluminum silicate (MAS), as a high-performance rheological modifier in water-based drilling fluids (WBDs) to avoid the sedimentation of suspended cuttings. A series of rheological tests indicated that low-concentration MAS suspensions exhibited better shear-thinning performance, higher gel strength, and quicker recovery ability of gel structure, which are the key factors for effectively carrying cuttings, than the commonly used high-concentration sodium bentonite (Na-BT) suspensions. The particle size distribution analyses revealed that the MAS maintained smaller particle size (d50 = 50.70 nm) than that of Na-BT (d50 = 9.99 μm), when dispersed in water. Furthermore, the results of transmission electron microscopy analysis demonstrated that nano-sized MAS formed much denser network structures than larger micron-sized Na-BT. In addition, scanning electron microscopy analysis indicated that MAS suspensions maintained much smoother filtrate cakes than Na-BT suspensions and effectively filled the tiny pore of filter paper with 80 nm pore size to mimic fine-grained formations. Moreover, after hot rolling at 150 °C and 120 °C, the pure MAS suspensions and WBDs containing MAS maintained better rheological and filtration properties, inferring excellent thermal stability of MAS. These results suggest that the MAS is expected to become a high-performance rheological modifier in WBDs for horizontal well drilling, by maintaining excellent rheological properties, exhibiting good thermal stability, forming smoother filtrate cakes and reducing the friction and torque.