Rotary drilling rig deep hole Doumen difficulties what happened?
It can not be completed by simple drilling technology (rotary drilling rig does not need gas, water circulation is not needed, and soil is imported by spiral sheet, which we call simple drilling process)
Cobble formations, which carry out drilling and collapse, are very difficult formations
It is better to take the way of impactor + water injection drilling, according to the formation conditions, match the appropriate proportion of water injection, while the impactor breaks the rock, while retaining the shaft lining with proper viscosity to prevent collapse
