In the oil and gas industry, drilling fluids play an important role in the success of drilling operations. Hence, it is vital to predict accurately and maintain drilling fluid properties. Drilling fluids have multitude of functions, including but not limited to balancing the formation pressure, transporting cuttings, lubricating the bit, minimizing formation damage and maintaining well stability. Efficient completion of any drilling operation is governed by the selection of the proper drilling fluid. Growing hydrocarbon demand is driving the industry to explore unconventional resources such as shale formations and deep water and ultra-deep water areas where high temperature high pressure (HTHP) conditions persist. Generally, oil-based muds have been widely used in HTHP operations, as they can withstand high temperatures while offering high lubricity, but they are expensive and have an environmental impact. Water-based muds offer a cost-effective and environment-friendly option, but they have limited HTHP application, as they tend to break down, resulting in increased fluid loss and viscosity reduction. Also, upon exposure to high temperatures, they also face the issue of gelation and degradation of weighing materials and additives. Due to these issues with both oil-based muds and water-based muds, new drilling fluids are formulated regularly and the existing systems are tailored to curtail drilling operation costs. Most recently, nanoparticles have been recognized as an effective additive to improve the performance of drilling fluids, having the potential to overcome the limitations of current drilling fluid systems in challenging conditions. In this study, experiments have been conducted to investigate the impact of different nanoparticles on various drilling fluid properties, including rheology, filtration, and lubricity, considering a wide range of influence factors, such as nanoparticle concentration, particle size, nanoparticle type, temperature, and aging. The effect of nanoparticle concentrations (0.01 wt% ~ 1wt%) on drilling fluid properties has been first investigated using SiO2 nanoparticles with and without coating. Then the effect of nanoparticle size (5 nm ~ 50 nm) on drilling fluid properties has been examined using TiO2 nanoparticles. Subsequently, the impact of nanoparticle type, including four different nanoparticles, on drilling fluid properties has been tested. Moreover, the effects of temperature and aging on the nanoparticle-based drilling fluid properties have been investigated.