Drilling Bentonite

Drilling mud serves to lubricate and cool the rotary cutting bits and also to bring the chips and powders up from the bore hole. The purpose of adding bentonite is threefold:(i) It should increase viscosity of the drilling mud.(ii) It should increase water suspension of mud.(iii) It should seal the wall of the hole to prevent fluid loss.(iv) It should condition the wall rocks to prevent caving.Approximately 15 tons of bentonite is required for drilling 1000 m. of well.Sodium bentonite satisfies all the requirements. Its swelling is high and, consequently, it forms a highly viscous mass with water. When in the form of fine particles, it remains in suspension almost indefinitely. Further, being highly impermeable, it is an effective sealing agent.