T he drilling mud is a fluid used in the design, to help the drilling process. Composition and physical properties of the mud is very influential on a drilling operation, because one of the factors that determine success or failure of a drilling mud is dependent on the drill being used. Drilling speed, efficiency, safety, and cost of drilling depends on the drilling mud is used. Due to various factors existing drilling mud drilling is absolutely necessary in the process. Development and swelling clay and shale formations can be reduced if mud is used to drill calcium. Calcium sludge better than the fresh water mud if used to drill the formation of gypsum and anhydrite, which also contains a lot of CO2 formation. If mud is added to a suspension of calcium bentonite, calcium ions will suppress sodium cations on clay slab, and an interesting attraction between clay particles become very strong, so the hydration of clays being blocked. Expected development of clay will be reduced by 50% when the concentration of calcium in the water to reach 150 ppm. For the final project, this time aimed to be able to examine the composition of mud and search for the right kind of mud calcium, and then will be analyzed at the lab on the effect of calcium composition, temperature and pressure on the low solids sludge, whether it will affect the mud density, rheology properties, the rate of filtrate and the resulting thick pulp, and physical properties of the fluid content and other chemical properties of the mud.