Abstract: A rotary steerable system including a steering section having at least one piston, at least one distribution flow passage extending from a valve to one of the pistons, and two main flow passages bypassing the pistons. At least a portion of each main flow passage is closer to a central point of the steering section than an outer boundary of the distribution flow passage. At least a portion of each main flow passage may also be closer to the central point of the steering section than an inner boundary of the pistons in a retracted position. The distribution flow passages are contained within a central area, with a ratio of a central area diameter to steering section diameter being 0.5 or less, preferably 0.4 or less. The steering section may include two piston sets and two distribution flow passages each extending from the valve to a piston.

Abstract: A rotary steerable system including a steering section and a control section. A combined length of the steering section and the control section is less than 150 inches, preferably less than 80 inches, more preferably less than 75 inches, and most preferably less than 70 inches. A length to steering section diameter ration is less than 13, less than 12, less than 10, or less than 9. The steering section diameter is a minimum diameter of the steering section.

Abstract: A rotary steerable system including a steering section having not more than one piston or not more than two pistons in a transverse cross-sectional plane of the steering section. The steering section includes two distribution flow passages each extending from a valve to a piston. A ratio of a distribution flow passage diameter to steering section diameter is at least 0.07. The distribution flow passages are contained within a central area of the steering section, with a ratio of a central area diameter to steering section diameter being 0.5 or less, preferably 0.4 or less. The steering section may include two pistons having center points that are separated by an angle greater than 120 degrees, preferably about 180 degrees. A duration for which only one of the sets of pistons is activated is greater than 110 degrees of rotation of a valve rotor, preferably greater than 150 degrees.

Abstract: A rotary steerable system including a steering section having at least one piston configured to extend a stroke length radially outward from a default position when activated. A ratio of the stroke length to a steering section diameter is greater than about 0.06. The steering section includes two piston sets. A ratio of a length of the piston to a diameter of the piston is between 1 and 1.4.