Pad in bit articulated rotary steerable system
AssigneeSchlumberger Technology Corporation
InventorMartin Thomas Bayliss
Life of this patent
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Abstract
A rotary steerable system (RSS) including an upper stabilizer connected to a collar of a drill string, an articulated section connected by a flexible joint to the collar, a drill bit connected to the articulated section opposite from the flexible joint, a lower stabilizer located proximate to the flexible joint and an actuator located with the articulated section and selectively operable to tilt an axis of the drill bit and the articulated section relative to the collar. A method includes drilling with the RSS a bias phase of a drilling cycle on a demand tool face and drilling a neutral phase of the drilling cycle on a 180 degree offset tool face from the demand tool face.
Claims8
A method for drilling a subterranean wellbore, the method comprising:
- (a) generating a net drilling curvature over a single drilling cycle of one bias phase and one neutral phase for drilling the wellbore with a rotary steerable system;
- (b) computing an instantaneous curvature of the wellbore, during the single drilling cycle, from a bias curvature of the rotary steerable system deployed in the wellbore and a neutral curvature of the rotary steerable system deployed in the wellbore;
- (c) processing the bias curvature, a steering ratio, and a rate of penetration of drilling with the rotary steerable system and computing a deviation of the instantaneous curvature from the net drilling curvature over the single drilling cycle;
- (d) choosing a drilling cycle time for cycling between the bias and neutral phases of the rotary steerable system, and by determining the deviation of the instantaneous curvature from the net drilling curvature computed in (c) is less than a maximum deviation for the single drilling cycle;
- and
- (e) cycling back and forth between the bias phase and the neutral phase of the rotary steerable system at the drilling cycle time chosen in (d) while rotating the rotary steerable system in the wellbore to drill.
Dependencies are inferred from the claim text.