Bentonite is most commonly known for its use as a major component of drilling mud, particularly for oil wells, but is also widely used as an additive for viscosity and filtration control.  When exposed to water, Bentonite, characteristic of all clays, swells considerably, making it ideal for protecting subterranean formations from invasion by the other drilling fluids making up the mud by providing a thixotrophic effect.  However, it is mainly used as circulation mud in rotary drilling systems.  Bentonite’s chief purpose as a drilling mud is to lubricate and to cool the cutting bits, to carry away cut rock fragments, and to act as a seal against the escape of gas from the bore hole.  Other related functions of such Bentonite based fluids is to prevent the hole from blowing out, as well as, to condition the wall of the drill hole to prevent caving-in.  
The bentonite which made by Weifang Huaxia Bentonite Co.Ltd, it has the following excellence:good suspension property and thixotropy,good wall building property,less filtering amount,easy to configure,easy to adjust the specific weight of drill fluid,etc,it is essential basic material for deep and offshore drilling enginerring