Amoco Corporation

Other

J Ford Brett

Tommy M Warren

Warren J Winters

L Allen Sinor

Michael B Burton

Suzanne M Behr

A subterranean drill bit operable with a rotational drive source is provided for drilling in subterranean earthen materials to create a borehole having a borehole wall. The drill bit comprises a drill bit body having a base portion, a gauge portion and a face portion disposed about a bit axis. A plurality of diamond cutting elements are fixedly disposed on and project from the face portion and are spaced from one another. The cutting elements are disposed for causing a net radial imbalance force during the drilling along a net radial imbalance force vector substantially perpendicular to the bit axis. A substantially continuous cutter devoid region is disposed on the gauge portion about the force point, and a bearing support is disposed in the cutter devoid region about the force point for substantially continuously contacting the borehole wall during the drilling. The cutting elements are positioned to cause the net radial imbalance force to substantially maintain the bearing support in contact with the borehole wall during the drilling, to cause the net radial imbalance force vector to have an equilibrium direction, and to cause the net radial imbalance force vector to return substantially to the equilibrium direction in response to a disturbing displacement.

Low friction subterranean drill bit and related methods

An imbalance compensated drill bit is disclosed that takes advantage of undesired and destructive imbalance forces to prevent bit whirl. Methods of designing and making such imbalance compensated drill bits are disclosed whereby a drill bit body has at least one cutting zone with a plurality of cutting elements extending therefrom and at least one bearing zone. The bearing zone has a relatively smooth surface and is located at a position where the net imbalance force (from the cutting elements) is directed towards. When the drill bit is rotated, the imbalance force presses the bearing zone against the borehole wall, and the bearing zone slips along the wall, thereby preventing the center of rotation to shift and create the destructive whirling motion.

Imbalance compensated drill bit

Method of making imbalanced compensated drill bit

Apparatus for stabiliing a rotary drill string and drill bit used to drill a borehole in a material, such as a subterranean formation, includes an imbalanced drill collar and a drill bit connected to the drill collar. The imbalanced drill collar creates a drill string imbalance force directed radially outwardly from the center of rotation of the drill collar through a predetermined area on the circumference of the drill collar and urges the predetermined area into contact with the borehole wall as the drill string rotates. The drill bit includes a drilling surface for contacting the material and drilling the borehole in the material, the drilling surface including a cutting zone for cutting the borehole in the material and the bearing zone having a low coefficient of friction relative to the cutting zone. The bearing zone slidingly engages the wall of the borehole as the drill bit rotates and the drill bit is aligned with the drill collar so that the bearing zone and drill string imbalance force are in the same axially-extending radially plane. Preferably, the drill bit is imbalanced to create a drill bit imbalanced force directed radially outwardly from the center of rotation of the drill bit through the bearing zone in the same axially-extending radial plane as the drill string imbalance force.

Method for stabilizing a rotary drill string and drill bit

Apparatus and method for orienting a collar on a fluid conducting conduit, such as a drill string, includes an orifice through the wall of the conduit and a latch assembly for latching the collar to the conduit. The latch assembly allows fluid communication through the orifice and rotates the collar when the conduit is rotated in a first direction about the longitudinal axis of the conduit. The latch assembly unlatches the collar from the conduit, prevents fluid communication through the orifice, and allows the conduit to rotate relative to the collar when the conduit is rotated ion a second, opposite direction. Also included are apparatus and method for rotationally orienting a fluid conducting conduit including an insert connectable inside the conduit so that the insert is rotatable with the conduit; a flow passageway extending through the insert; a pilot passageway extending through the insert; a piston bore in the insert; a piston, reciprocably mounted in the piston bore, for reciprocating between the ends of the piston bore, the piston restricting flow through the flow passageway and creating a fluid pressure increase on the upstream side of the insert when the piston is in a restricted position in the piston bore; and a barrier mass for blocking the pilot passageway in a selected rotational position of the pilot passageway and conduit in order to increase the fluid pressure at the downstream end of the piston bore and move the piston to the restricted position in the piston bore.

Apparatus and method for rotationally orienting a fluid conducting

A whirl resistant drill bit is disclosed for use in rotary drilling. The drill bit includes a generally cylindrical bit body with a plurality of cutting elements extending out from a lower end surface. The cutter elements are grouped in sets such that a first set of cutters are disposed at substantially an equal radius from a center of the bit body to create a groove in the material being drilled. A second set of cutters is connected to the lower end surface with each cutter therein in overlapping radial relationship with each other and extending a maximum distance from the lower end surface less than that of the first set of cutters. At least one cutter of the second set is in overlapping radial relationship with at least one of the cutters within the first set of cutters. This cutter arrangement causes the drill bit to cut grooves within the formation material that tends to prevent destructive bit whirl. Further, adjustments can be made to vary the back rake angle and side rake angle to prevent bit whirl.

Whirl resistant bit

A method of apparatus for controlling in a wellbore the force applied to a rotating drill bit of the type having fluid circulating through an opening in the lower end thereof. One aspect of the method comprises sensing the torque in the drill bit and varying the flow of the circulating fluid through the drill bit responsive to the torque. Apparatus is provided for maintaining constant torque in the drill bit by varying the fluid flow through the bit, which varies in turn the weight applied to the bit and therefore bit torque.

Apparatus for controlling the force applied to a drill bit while drilling

A turbine for driving a drill bit includes means for locking the turbine rotor. A generally cylindrical locking assembly is connected to the rotor via a splined connection which permits relative axial movement of the locking assembly and rotor while restricting relative rotational movement thereof. A tab extends radially outwardly from the locking assembly and is receivable in an axial groove formed on the inner surface of the turbine case. When so received, rotational movement of the locking assembly and thus the rotor is prevented. An annular cavity is formed on the inner surface of the turbine case adjacent one end of the groove. When the tab is received therein, rotational movement of the locking assembly and rotor relative to the turbine case is permitted. A wellbore may be reamed and washed with the rotor in its locked condition by rotating the drill string as in conventional rotary drilling and circulating fluid.

Method and apparatus for reducing drill bit wear

A method and apparatus for controlling the rotational torque of a drill bit powered by a downhole motor. The downhole motor is suspended from a hydraulic ram at the lower end of a string of drill pipe. A torque sensor detects the reactive torque in the downhole motor during drilling. In response to the detected torque level, pressurized drilling fluid from the downhole motor is provided to the hydraulic ram thereby varying the weight applied to the drill bit in order to maintain a constant torque level.

Method and apparatus for controlling the rotational torque of a drill bit

An improved drill bit and a method for making the same. A body having an upper end is adapted for connection to a source of rotary motion. A curved surface formed on the lower end of the body includes a plurality of cutting elements embedded therein. A port provides drilling fluid between the curved surface and the bore during drilling. The cutting elements and fluid courses formed on the curved surface define a gap between the surface and the bore during drilling. The gap is formed to provide no more than a substantially linear reduction in drilling fluid pressure with increasing bit radius. In making the bit, a bottomhole pattern and a substantially constant flow area are selected. Dimensions of the lower drill bit surface are calculated to provide the selected flow area over the surface when the bit is in position above the bottomhole pattern. Thereafter, the lower bit surface, including fluid courses thereon, is constructed in accordance with the calculated dimensions and diamonds are embedded therein to support the drill bit surface over the bottomhole pattern by a distance which produces the selected flow area.

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Tulsa, OK, United States of America

J Ford Brett