Influence of MoS₂ Nanosheet Size on Performance of Drilling Mud.

Water-based drilling mud (WBM) is a non-Newtonian fluid that has a variety of applications such as in transporting cuttings during drilling, protecting the borehole, and cooling the drill bit. With the development of nano-technology, various nanoparticles have been synthesized and have been added to WBM to improve its performance. Shear thinning is the most important factor in drilling mud and this attribute can be improved when two-dimensional particles are added. MoS₂ nanoparticles, which represent a typical two-dimensional material, are easy to synthesize in large quantities and have a high thermal conductivity and low coefficient of friction. Since the two-dimensional structure, thermal conductivity, and low coefficient of friction of MoS₂ would improve the performance of WBM, we experimented with MoS₂ nanosheets as an additive, under optimal conditions, using various samples each with uniform sizes and thicknesses of nanosheets. A large amount of MoS₂ nanosheets was synthesized, sorted by thickness and diameter, and added to drilling mud. The diameter of MoS₂ was divided into a small diameter group (about 100⁻400 nm) and a big diameter group (about 300⁻650 nm), and the thickness was divided into 1⁻2 nm and 5⁻10 nm groups. Experimental results showed that when MoS₂ is added to WBM, shear thinning occurs more strongly. In addition, the addition of MoS₂ with a thickness of 1⁻2 nm and a diameter of 300⁻650 nm resulted in the highest increase in viscosity and thermal conductivity of WBM. As a result, we experimentally confirmed that MoS₂ can be used as an additive to increase the thermal conductivity and viscosity of WBM and to make shear thinning phenomenon more.