Effect of Ionic Liquids as Additives in Water-Based Drilling Mud for Steel-Steel Friction Pair

Lubrication properties of drilling mud determine the performance of drilling operations. In this research, five imidazolium cation-based and two phosphonium cation-based ionic liquids (ILs) were studied as additives to evaluate the lubrication performance of water-based drilling mud. Results show that ILs remarkably improve the lubricating properties of drilling mud, which is ascribed to the tribofilm formation on the rubbing surface. The friction coefficient of ILs highly depends on viscosity due to interfriction forces of the bentonite on the worn surface and adsorption of ILs in bentonites, consequently limiting the formation of a protective film. In addition, worn surfaces with several cracks and crushed particles were observed by scanning electron microscopy (SEM) micrographs, indicating that microcutting and three-body abrasive wear are dominant.