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.

A system can be used for drilling a wellbore. The system can include a steering collar, an actuation cylinder, and a radial seal. The steering collar can be positioned on a drilling tool for forming a wellbore. The actuation cylinder can be positioned on the drilling tool for abutting a steering pad for actuating the steering pad. The radial seal can be positioned on the drilling tool between the steering collar and the actuation cylinder.

A drill bit can include a bit body having an upper portion, a central bore, and an adjustable inner gauge. The central bore can define a bore surface, and the bit body can include a plurality of fixed cutters formed on the upper portion. The adjustable inner gauge may be movably positioned within the bit body central bore to increase or decrease an exposed area of the bore surface for adjusting stability or steerability of the drill bit while forming the wellbore.

A steering head for steering a drill string may include a pad pusher including a steering pad and a piston. The steering pad may have a pivot axis, and be rotatable about the pivot axis between retracted and extended positions. The pad pusher may further include a motion restrictor to restrict rotation about the pivot axis. The steering head may further include a housing having a motion restrictor disposed at a position corresponding to the pad pusher motion restrictor. The pad pusher motion restrictor may be engageable with the housing motion restrictor to restrict motion of the steering pad relative to the housing.

An executing mechanism for a rotary guide device includes a driving valve core, a driven valve core, a first cavity, a second cavity and a high-pressure slurry driving channel. The first cavity includes a first low-pressure port communicating with a low-pressure slurry; and a first high-pressure port communicating with a high-pressure slurry. The driving valve core adjusts a pressure in the first cavity; and the driven valve core moves in response to a pressure difference between the first cavity and the second cavity. The high-pressure slurry driving channel switches between an open state and a close state in response to movement of the driven valve core. A rotary guide device includes a rotary main shaft, a drill bit, a push mechanism, and the executing mechanism. The push mechanism includes a push block and a push plunger piston, the high-pressure slurry driving channel communicates with one end, distal from the push block, of the push plunger piston.

A push type rotary guide drilling system includes a drill bit and a rotating shaft, the rotating shaft including an upper rotating shaft and a lower rotating shaft; a steering portion, sleeving an outer side of the rotating shaft; a push assembly, including a plurality of push pieces spaced along a circumferential direction of the steering portion; a transmission device, including a transmission mechanism for driving the push pieces to extend out of the steering portion, the transmission mechanism including a driving electromagnetic gear arranged on the upper rotating shaft and a driven electromagnetic gear arranged on the steering portion and further including a motion conversion unit converting rotary motion of the driven electromagnetic gear into linear motion of the push pieces; and a control unit. The control unit is configured to modulate a magnetic field to make the driving electromagnetic gear and the driven electromagnetic gear realize linkage through magnetic coupling.

A steerable drilling system in accordance to an embodiment includes a bias unit integrated with the drill bit to form a steering head and an electronic control system located remote from the steering head and electrically connected to a digital valve of the bias unit.

A rotary drill bit includes movable gauge elements biased to protrude radially through a circumferential engagement surface of a gauge pad. The gauge elements are retractable to protrude a lesser distance against the bias of a biasing mechanism. Fluid chambers are defined adjacent the gauge elements, and fluid is permitted to be bled into and out of the fluid chambers to delay and slow the retraction and extension of the gauge elements. During straight drilling operations, the biasing mechanisms maintain the gauge elements in an extended position providing stability to the drill bit. When a steering force is applied to the drill bit, the gauge elements retract slowly as fluid is bled from the fluid chambers. As the gauge elements rotate with the drill bit, the retracted configuration may be maintained as gauge elements disengage the geologic formation on a side of the drill bit opposite the steering direction.

The disclosure relates to a system for drilling a vertical well in soil according to a substantially vertical theoretical drilling trajectory comprising a drilling device including a hollow core having a longitudinal axis, the hollow core being provided with a drilling tool; a rotating driving device exhibiting an active state in which the driving device is oriented with respect to the soil in an angular correction position, and a passive state in which the driving device does not modify the displacement trajectory of the drilling device; a device for measuring the deviation of the hollow core; a control device configured to make the driving device swivel when a deviation is measured, in order to bring it in its active state in an angular correction position determined such that, considered in the horizontal plane, the trajectory correcting direction associated with the angular correction position is opposite to the deviation direction.

A variable build motor downhole tool allows changing the build rate in a directional drilling operation without pulling the drill string from the hole and replacing a fixed build sub in the drill string. A pad can be extended upon command to increase the build rate and retracted upon command to decrease the build rate. The pad is mounted on an insert disposed within an outer housing and extends outwardly through the outer housing by action of one or more pistons. Electronics housed in the variable build motor tool are used to receive commands from uphole and cause the pistons to extend, forcing the pad outward to increase the build rate.