Rotary Steerable System
Casing has a much higher rotational stiffness when compared to a drill string what results in strongly reduced string twist and stick/slip effects. For most wells, the relation between bit RPM and topdrive RPM becomes direct enough to allow bringing the control system to surface instead of using electronics downhole. The stability of casing drilling enables a unique drilling concept: a by the topdrive continuous controlled system that enables fully automated directional drilling. Standard MWD equipment is used close the control loop and no pressure pulses for down linking is required.
The combination of casing drilling and a point-the-bit Rotary Steerable System results in a low risk drilling system to can drill and install casing in the softest and most unconsolidated formations without problems. The Dog Leg Severity capability is 5 degree/30m. All equipment sits inside casing so small stick-out (<1m) and well protected