Combustion operated drilling apparatus
Converter group and pressure converter for use therein
Downhole mud pressure intensifier
Downhole power generator and method
Drilling apparatus
Drilling apparatus
High pressure converter for deep well drilling
Hydraulic drive apparatus for downhole tools providing rotationa
Hydraulic in-the-hole percussion rock drill
Hydraulic in-the-hole percussion rock drill
Hydraulically operated downhole motor
Intermittent high-drag oil well drilling methods and apparatus
Mandrel and bearing assembly for downhole drilling motor
Pressure converter
Pressure converter
Pressure converter
Pressure converter (B)
Rotary fluid converter
Sinkerdrill
Turbine drill for drilling at great depths