Lime / Lime Drilling Mud Additive

Lime-based muds were used widely throughout the 1940's and 1950's. They were considered to be an inhibitive fluid with a tolerance to such common contaminants as salt, cement, and anhydrite. The rheologic properties of lime-based muds remain stable and low, even in a high-solids environment. They can be made with nearly any type of makeup water and easily maintained. As wells were drilled into deeper and hotter environments, however, severe gelation occurred; in the most severe cases, cementation of the mud occurred in the hole. Therefore, use of lime-based muds was restricted to environments with temperatures lower than 300°F and were discarded when a burned odor or severe gelation was observed during circulation after the mud was allowed to remain static in the hole. With more experience with lime-based muds, it was generally thought that a lower lime content could be used to increase the thermal stability of the mud at some expense toward inhibition. Thereafter, lime-based muds were classified as low-, medium-, or high-lime mud systems.