As much as 90% of the land surface of the earth is covered with loose,unconsolidated material such as soil,clay,silt,sand ，gravel and boulders,which varies in depth form a few centimeter to hundreds of meters. Drilling through this so-called overburden is often problematic,due to the tendency of the earth to cave in behind the drill bit. This makes it difficult to retrieve the drill string after the hole has been drilled.In practice the bore hole is often lost befort a casing tube can be inserted to support it.
In places where clay,slit and sand overburden strata are mixed,or when their drill ability is unkown,the best solution for drilling with such situation to use casing system equipment is effective.
WORLDRILL product styucture of eccentric casing system :
1.The surface of the parts has been strengthened, which increases the working life, and the anti-wear ability is strong.
2.Simple structure,easy to operate.
3.Stable and reliable performance, high drilling speed .
