Hectorite Nanoparticle as a Shear-thixotropic Plugging Agent in Water-based Drilling Fluids

In this research, we demonstrated an artificial nano-clay particles, Hectorite, as a shear-thixotropic plugging agent for Lost Circulation Control in water-based drilling fluids. We compared the shear-thixotropic properties of hectorite and other nano particles, as well as the inorganic plugging properties of hectorite and calcium carbonate in water-based drilling fluids. In stress-shear rate test, the rheological models of several nano particles were consistent with H-B model, but Hectorite had the highest R² value of 97%. Hectorite had an intermediate n value with good shear thinning behavior, which was also confirmed by the viscosity-shear rate test, the largest k value with the best thickening properties, and a higher yield point of 6.44Pa with better suspension performance. In thixotropic test, the recovered G’ of 1% Hectorite in the three interval thixotropy test (3ITT) performs better than other nano-clay particles, and its thixotropic area has the biggest value at 3089Pa/s. In particle plugging tests (PPT), 0.8% Hectorite (6.8 mL) leaked less than 2% calcium carbonate (72.5 mL) in 40–60 mesh quartz sand at 90 °C and 4 MPa after 30 minutes. The flat surface of the Hectorite filter cake was seen in TEM pictures, which helped to explain its effective plugging properties.