•The types and quantities of solids present in drilling mud systems determine the fluid’s density, viscosity, gel strengths, filter-cake quality and filtration control, and other chemical and mechanical properties. •Solids and their volumes also influence mud and well costs, including factors such as –Rate of Penetration (ROP), –hydraulics, –dilution rates, –Torque and drag, –surge and swab pressures, –Differential sticking, –lost circulation, –Hole stability, –balling of the bit and the bottom-hole assembly. •Since it is not possible to remove all drill solids either mechanically or by other means they must be considered a continual contaminant of a mud system. •Solids removal is one of the most important aspects of mud system control, since it has a direct bearing on drilling efficiency. •Money spent for solids control and for solving problems related to drill solids represents a significant portion of overall drilling cost