Effect of the surface charge of entrapped polypropylene at nanosilica-composite on cuttings transport capacity of water-based muds

Field experience has shown that inadequate cuttings transportation and hole cleaning results in wellbore drilling challenges, such as pipe sticking, high torque and drag, low rate of penetration, formation damage, etc. Designing a drilling mud with optimum rheological properties would be crucial to improve cuttings transportation efficiency. Several studies have shown that drilling muds that combine polymers with silica nanoparticles (SiO₂ NPs) to form polymer nanocomposite (PNC) can effectively modify the rheology and enhance the filtration properties of water-based muds (WBMs). Studies on the significant decrease of the yield point that may lead to a huge reduction in the transport capacity of drilled cuttings using polypropylene-silica nanocomposite (PSNC) have not been reported. In this study, the effect of surface charge of newly developed PSNC on rheological and filtration characteristics of WBMs were examined. The results from zeta potential measurements showed that the newly developed PSNC and bentonite particles are both negatively charged at different levels of pH, which would lead to decrease in the yield point of the PSNC bearing mud samples. This problem was resolved using (3-aminopropyl) triethoxysilane (APTES) to modify the surface of the newly developed PSNC. From the experimental results, the amino-modified PSNC showed better performance in controlling filtration and modifying rheology than the unmodified PSNC due to the electrostatic attraction between bentonite and modified PSNC. The concentration of 1.5 g of the modified PSNC has a significantly higher yield point of 16.0 lb/100 ft² than the unmodified PSNC with 6.4 lb/100 ft² at 78 °F; demonstrating its capacity to provide better cuttings transportation than the unmodified PSNC. The surface functionalization of the newly developed PSNC in WBMs showed promising results in the rheology and filtration properties which demonstrates the viability of using them in drilling operations.