Lime is the common name for calcium hydroxide, Ca(OH)2. It is used as a source of calcium and alkalinity in both water- and oil-based drilling fluids.
Caustic soda is sodium hydroxide, NaOH with a molecular weight of 40.0 g/mol. Caustic soda is extremely hygroscopic and quickly dissolves in water to form a solution. It is an effective pH modifier for aqueous systems.
Caustic soda is a highly alkaline compound used to control the pH of water base muds. Caustic soda will minimise the solubility of calcium and magnesium contaminants and corrosion rates are reduced in an alkaline water base system. Caustic soda will also solubilise lignosulphonates and lignite’s.