Drilling practice in complex formations for exploration of Yema Copper Polymetallic Deposit， Gansu Province

Abstract:

The working area of Gansu Yema Copper Polymetallic Ore Exploration Project is located in uninhabited gobi desert area with harsh construction conditions. Affected by mineral genesis and geological structures， the strata in this area is featured by steep occurrence， frequent faults， and is prone to fragmentation， collapse and leakage. In addition， some strata show mud-making when encountering water. During the construction of inclined boreholes， pipe sticking and hole abandonment often occur， which caused economic losses and seriously affected the project schedule. Combined with drilling difficulties of the project， technical measures are adopted including tracked drilling rigs， low-solid-phase drilling fluid， and optimized borehole structure， providing experience for drilling engineering in similar mining areas.