Smart Bentonite Drilling Muds Modified with Iron Oxide Nanoparticles and Characterized Based on the Electrical Resistivity and Rheological Properties with Varying Magnetic Field Strengths and Temperatures

Abstract

Abstract In this study, the effects of magnetic field strength and temperatures on the electrical resistivity and rheological properties of a sensing smart bentonite drilling mud modified with iron oxide nanoparticles (nanoFe2O3) were investigated. The bentonite contents in the smart drilling muds were varied up to 6% by the weight of water, and the temperature was varied from 25°C to 85°C. The magnetic field strength was varied up to 0.6 T. The nanoFe2O3 contents (particle size of 30 nm and surface area of 38 m2/gm) in the drilling muds were varied up to 1% by the weight of drilling mud to enhance the sensing electrical resistivity and the rheological properties of the drilling mud. The initial resistivity of the 2% and 6% bentonite drilling mud were 9 Ωm and 5.5 Ωm, a 39% reduction in resistivity, a good sensing property. The electrical resistivity of the drilling mud modified with of nanoFe2O3 decreased by 15% to 50% based on the nanoFe2O3 content, temperature and magnetic field strength. The rheological properties of the drilling muds were characterized by high strain rate to determine the nonlinear behavior of the shear thinning drilling mud. Based on the new Vipulanandan rheological model, the yield stress (o2) of the modified drilling mud increased by 6% to 100% depending on the bentonite content, nanoFe2O3 content, temperature and magnetic field strength. Based on the Bingham plastic model the plastic viscosity of the modified drilling mud were increased by 50% to 90% based on the bentonite content, nanoFe2O3 content, temperature and magnetic field strength. The shear thinning behavior of the drilling mud with and without nanoFe2O3 has been quantified using the Vipulanandan rheological model and compared with the Herschel-Bulkley model. Based on the Vipulanandan rheological model the maximum shear stress produced (maximum shear stress tolerance) by the 2% bentonite drilling mud modified with zero and 1% of nanoFe2O3 at the temperature of 25°C with no magnetic field strength were 26 Pa and 64 Pa respectively. Increasing the magnetic field strength to 0.6 T increased the maximum shear stress produced by the 2% bentonite drilling mud modified with 1% of nanoFe2O3 at the temperature of 25°C to 80 Pa, a 25% increase. With the 6% bentonite drilling mud the trends were similar but the magnitude of the maximum shear stress produced was almost doubled. The rheological properties of the drilling mud modified with nanoFe2O3 under different magnetic field strength have been correlated to the electrical resistivity of the drilling mud using the three parameter Vipulanandan property correlation relationship.