This paper presents a laboratory evaluation to study the effect of adding different nanoparticles on the rheological properties of water-based drilling fluids. Four different nanoparticles including aluminum oxide (Al₂O₃), magnesium oxide (MgO), titanium dioxide (TiO₂), and copper oxide (CuO) were added to a 7% bentonite water-based mud at two different concentrations; 0.5% and 1.5% by Vol. The rheological properties including plastic viscosity (PV), yield point (YP), and gel strength, were evaluated using a standard viscometer to quantify the effect of nanoparticle addition by comparing it to the reference drilling fluid containing 7% bentonite. In addition, a parametric study was conducted to better understand the effect of the different parameters including rheological properties, hole size, flow rate, on hole cleaning efficiency. The results show that nanoparticles, in general, have a high potential in improving rheological properties when compared to the reference point. A favorable reduction in the PV up to 50% along with an increase of 231% and 95% in the YP and gels strength, respectively, were observed. The addition of nanoparticles has improved hole cleaning efficiency, when compared to the base case, for up to a maximum of 30% using 0.5% by Vol. of MgO nanoparticles. Also, an improvement by 67% in the hole cleaning was observed with 0.5% MgO for the largest cutting sizes when compared to 7% bentonite. In general, MgO showed the highest improvement in hole cleaning, while TiO₂ resulted in the lowest improvement. The parametric study revealed that rheological properties along with the cutting size have the highest effect on hole cleaning, while the effect of varying the flow rate was minimal when the rheological properties were high. Moreover, the effect of nanoparticles addition on hole cleaning was more pronounced for larger hole sizes with larger cutting sizes when compared to the base case containing 7% bentonite only, which demonstrate the feasibility of using nanoparticles to enhance the hole cleaning.

The significant surge of ionic liquids (ILs) research over the past decade has led to the formation of various novel ionic liquid compounds and their diverse applications. Enhanced geothermal systems (EGS) for geothermal power generation are an emerging IL application as a heat extraction fluid. The once widely held belief in the environmentally friendly characteristics of ionic liquids, mainly due to their insignificant vapor pressure, is now being scrutinized. It has become apparent that while ILs do not readily evaporate into the atmosphere, they are not guaranteed to remain entirely isolated from the environment. Recent attention has been directed toward toxicological studies, including ecotoxicity impacts, with the long-accepted assumption of ILs having low toxicity being invalid. This paper aims to shed light on the toxicity of hexylepyradinium bromide (HPyBr) IL and a deep eutectic solvent (DES) comprising choline chloride with magnesium chloride hexahydrate (ChCl:MgCl₂·6H₂O) to five test species, an algal species (Raphidocelis subcapitata), the water flea (Ceriodaphnia dubia and Daphina magna), the fathead minnow (Pimephales promelas), and the earthworm (Eisenia fetida), to measure acute and chronic toxicity. Additionally, new approach methods (NAMs) are presented using the fathead minnow embryo and the rainbow trout (Oncorhynchus mykiss) gill cell line and the RTgill-W1 assay to compare sensitivity across species. Overall, ChCl:MgCl₂·6H₂O displayed lower toxicity, while HPyBr demonstrated higher toxicity, highlighting the need for caution in handling it to prevent harm to aquatic ecosystems. Comparative analysis underscored the potential threat of ChCl:MgCl₂·6H₂O to aquatic life, highlighting the cumulative effects of the environmental components.