Abstract: A drilling method comprises controlling operation of a drill string to maintain at least a portion of the drill string in forward whirl.

Abstract: A drilling method comprises controlling operation of a drill string to maintain at least a portion of the drill string in forward whirl.

Abstract: A method of running a bore-lining tubing string into a bore includes running a tubing string, typically a liner string, into a bore while agitating the string. The agitation of the string reduces the friction between the string and the bore wall and thus facilitates the translation of the string into the bore. The agitation may also take place while the tubing is being cemented in the bore. Pressure pulses may be applied to fluid in the bore, which fluid may be cement slurry.

Abstract: A drilling apparatus includes a cutting structure defined by a percussive action cutter and at least one other cutter. The percussive action cutter is adapted to be urged in a drilling direction by hydraulic pressure force, while the other cutter is urged in a drilling direction by mechanical force.

Abstract: A downhole tool comprises a body, radially extendable members mounted to the body and movable between retracted and extended positions, a cam member operatively associated with the extendable members and movable relative to the body to extend the extendable members, and a support member configurable to permit retraction of the extendable members from an extended position. The tool may be an under-reamer, and the extendable members may be cutting blades.

Abstract: Drilling apparatus comprises a cutting structure defined by a percussive action cutte (42) and at least one other cutter. The percussive action cutter is adapted to be urged in a drilling direct ion by hydraulic pressure force, while the other cutter (43) is urged in a drilling direction by mechanical force.

Abstract: A downhole adjustable orienting sub is included in a directional drilling tool string that is run into the borehole on coiled tubing. The bent housing of the tool string defines a bend angle and a bend point, and the bend point is oriented about the center of the bore by operating the orienting sub. The level of the reactive torque applied to the bent housing as the bit drills on bottom is controlled by selecting the amount of the weight of the coiled tubing that is applied to the bit. The orienting sub can be indexed downhole to provide different orientations of the bend point by temporarily reducing and then increasing the mud flow rate.

Abstract: In accordance with illustrative embodiments of this invention, a downhole adjustable stabilizer includes a sleeve having outwardly extending blades and mounted for limited rotation on a mandrel, vertically aligned sets of radially movable buttons mounted in bores in the blades, and longitudinal flats on the outer periphery of the mandrel that when radially aligned with the respective sets of buttons allows them to shift inward to positions where the stabilizer becomes undergage and can be tilted in the borehole. Some spring loaded buttons drag against the borehole wall to provide frictional restraint against rotation of the housing. The blades can each have an inclined side surface that causes the sleeve to be rotated to its position relative to the mandrel where the sets of buttons are retracted as the stabilizer slides downward in the borehole.

Abstract: Methods are provided for controlling the direction of a borehole drilled by a downhole motor, including the steps of positioning downhole adjustable bent housing and near-bit stabilizer in the drill string, adjusting the bent housing from its normally straight condition to its bent condition to effect borehole curvature, and using the stabilizer in its undergage condition to enhance the inclination. The Measurements are made from which the inclination with respect to the vertical and the azimuth can be determined and telemetered uphole for processing, display, and recording. Preferably the directional measurements are made at two locations, one below the bent point and one above it. These two sets of measurements can be compared to confirm the bend angle and to obtain a definition of the orientation of the plane of the bend angle so that the drilling path can be accurately controlled.