Rotary Dysfunction of Motorized RSS
KRATOS drilling performance sensor set identifies adverse drilling dynamic events that will lead to damaged bit cutters, drilling motors, and/or drilling sensors.
- While drilling a vertical intermediate section of a well in the Permian Basin, a motorized RSS experienced intermittent severe rotary dysfunction. Additional weight on bit would initiate bit stall followed by reverse wrapping of 8” diameter drilling collars directly up-hole of the drilling motor.
- With the PDC bit buried in the formation, the motor torque would ramp up until enough load was applied to fail the rock at the cutting surface of the drill bit. The violent energy release of the wound-up drill collars accelerated the drill string rotation resulting in high impact forces experienced at the bit cutter. A series of these events led to significant bit cutter damage resulting in a unscheduled trip out of the well.
- Monitoring downhole drilling behavior while actively managing the rotary speed, bit speed, and applied weight allows the operator to resolve these issues. In this particular case, reducing weight on bit and increasing the rotary speed resulted in efficient drilling.
