Abstract: Expandable reamers for enlarging boreholes in subterranean formations include a tubular body and at least one member positioned in openings in the tubular body. The at least one member is configured to move between retracted and extended positions. A push sleeve is disposed at least partially within the tubular body and coupled to the at least one member. The push sleeve moves axially upward to move the at least one member to the extended position in response to a pressure of drilling fluid passing through a drilling fluid flow path in the tubular body. The push sleeve moves axially downward to move the at least one member to the retracted position in response to a pressure of drilling fluid upon a restrictive element disposed within the fluid passageway. The restrictive element disposed within the fluid passageway may be discarded from the fluid passageway by increasing the flow rate through the drilling fluid flow path.

Abstract: A hole opener having a hybrid reaming section for downhole earth boring operations may include a reamer body having an axis of rotation, an outer periphery, and upper and lower ends, a plurality of rolling cutters coupled to the outer periphery, the rolling cutters defining a rolling cutter cutting profile having a cutting diameter, a plurality of fixed blade cutters coupled to the outer periphery and defining a fixed blade cutter cutting profile having a cutting diameter, each fixed blade cutter being coupled between adjacent rolling cutters. At least one fixed blade cutter may be asymmetrically coupled about the axis. The cutting diameter of the fixed blade cutter cutting profile and the cutting diameter of the rolling cutter cutting profile may collectively define a gage diameter. At least a portion of the fixed blade cutter cutting profile may be deeper than the rolling cutter cutting profile.

Abstract: Exemplary drill tools for placement in a drill string may include a body; a plurality of reamer cutters; and a plurality of ball and socket connectors configured to attach the plurality of reamer cutters to the body. Each of the plurality of reamer cutters may be replaceable by removing at least one of the plurality of ball and socket connectors from the reamer body. Each of the ball and socket connectors may be attached to the reamer body with bolts. Each of the ball and socket connectors may include titanium dioxide and/or titanium carbide coatings where the connectors interface with the reamer cutters.

Abstract: The present invention discloses a cutting tool integrated in a drillstring for enlarging a borehole, where the cutting tool at least comprises: one or more side mills (12, 13, 14) arranged along the axis of said drillstring in a reamer housing (11), where the side mills (12, 13,14) are adapted to be rotated relative to the tool housing (11) by individual driving means. The self driven rotational side mills may be dome shaped cones where expand radially out of the reamer housing (11), or may be a special non-circular dome shaped cones where rotates without expanding.

Abstract: A bore hole rotary reamer includes a body having cutters rotatably mounted by one or more respective spindles. A bearing region is formed on the spindle. At least one annular seal prevents ingress of contaminant to the bearing region. A circumferential void is formed adjacent the seal. At least one passageway extends in an axial direction of the spindle to the circumferential void and a piston movable in the passageway in response to supply of pressure to an outer side of the piston from the environment which surrounds the reamer. The piston transfers pressure to fluid in the cylindrical passage on an inner side of the piston to supply pressure to the circumferential void and thereby to the seal. The pressure is substantially determined by the pressure of the environment surrounding the reamer.

Abstract: In one aspect of the invention, a downhole tool string component has at least one end adapted to connect to an adjacent tool sting component and a bore adapted to accommodate a flow of drilling fluid. A turbine is disposed within the bore and an actuating assembly is arranged such that a clutch may mechanically connect and disconnect with the turbine.

Abstract: An improved back reamer for horizontal directional drilling is provided with multiple components which can be assembled and disassembled before and after the back reaming process. The reamer includes a main shaft connectable to the drill string, a reamer head removably mounted on the main shaft, and a pull tab removably attached to the main shaft. Faceted couplings between the reamer shaft and head, and between the reamer head and pull tab preclude rotation between the components.

Abstract: A hole opener having a hybrid reaming section for reaming subterranean wellbores may include a tubular reamer body having a longitudinal axis and upper and lower ends, a rolling cutter mount coupled to the body, a rolling cutter rotatably coupled to the mount, and a fixed blade coupled to the body adjacent the mount. A method of forming a hybrid reamer tool for downhole use may include providing a tubular stem having couplers on the upper and lower ends, coupling a reamer body having an outer periphery to the stem between the stem upper and lower ends, coupling a rolling cutter mount to the outer periphery of the reamer body, the mount having a rolling cutter rotatably coupled thereto, and coupling a fixed blade to the outer periphery of the reamer body adjacent the rolling cutter mount.

Abstract: A back reamer includes a drive stem configured to support a main reamer body, the main reamer body including a plurality of receptacles, and a plurality of cutting leg assemblies in positive locking engagement with the plurality of receptacles to restrict radial movement of the cutting leg assemblies.

Abstract: An expandable reamer apparatus and stabilizer sub having at least one rib thereon attached thereto for drilling a subterranean formation.

Abstract: Methods and systems may be provided simulating forming a wide variety of directional wellbores including wellbores with variable tilt rates and/or relatively constant tilt rates. The methods and systems may also be used to simulate forming a wellbore in subterranean formations having a combination of soft, medium and hard formation materials, multiple layers of formation materials and relatively hard stringers disposed throughout one or more layers of formation material. Values of bit walk rate from such simulations may be used to design and/or select drilling equipment for use in forming a directional wellbore.

Abstract: A reamer includes a mandrel defining a mandrel axis and arms extending radially from the mandrel. Each arm has a proximal end and a distal end. The reamer includes a cutting head disposed on the distal end of each arm and cutting teeth disposed on each cutting head. The cutting heads are arcuately spaced about the central mandrel to allow the movement of debris axially along the central mandrel and at least one of the arms defines a square cross-sectional shape.

Abstract: A backreamer includes a distal end configured for connection to product and a proximal end configured for attachment to a distal end of a drill string. The backreamer includes a backreaming cutter having a cutting side that faces toward the proximal end of the backreamer. The backreamer also includes a proximal assembly that extends between the proximal end of the backreamer and the backreaming cutter. The proximal assembly defines a vacuum passage for removing material cut by the backreaming cutter. The backreamer further includes a drive stem for transferring torque to the backreaming cutter for rotating the backreaming cutter. The drive stem is rotatably supported within the proximal assembly such that the drive stem and the backreaming cutter are rotatable relative to the proximal assembly. The backreamer additionally includes a distal assembly that extends between the backreaming cutter and the distal end of the backreamer.

Abstract: An expandable reamer apparatus and methods for reaming a borehole, wherein a laterally movable blade carried by a tubular body may be selectively positioned at an inward position and an expanded position. The laterally movable blade, held inwardly by blade-biasing elements, may be forced outwardly by drilling fluid selectively allowed to communicate therewith by way of an actuation sleeve disposed within the tubular body. Alternatively, a separation element may transmit force or pressure from the drilling fluid to the movable blade. Further, a chamber in communication with the movable blade may be pressurized by way of a downhole turbine or pump. A ridged seal wiper, compensator, movable bearing pad, fixed bearing pad preceding the movable blade, or adjustable spacer element to alter expanded blade position may be included within the expandable reamer. In addition, a drilling fluid pressure response indicating an operational characteristic of the expandable reamer may be generated.

Abstract: An earth drilling reamer has an elongated body having an outer surface and a plurality of blade mounting supports extending radially outwardly from the outer surface of the body. Each blade mounting support has a primary blade engagement positioned parallel to the outer surface and a leading blade angled from the outer surface to the primary blade engagement. A removable primary blade is detachably secured to the primary blade engagement.

Abstract: An expandable reamer apparatus and methods for reaming a borehole are disclosed, including at least one laterally movable blade carried by a tubular body selectively positioned at an inward position and an expanded position. The at least one laterally movable blade, held inwardly by at least one blade-biasing element, may be forced outwardly by drilling fluid selectively allowed to communicate therewith or by at least one intermediate piston element. For example, an actuation sleeve may allow communication of drilling fluid with the at least one laterally movable blade in response to an actuation device being deployed within the drilling fluid. Alternatively, a chamber in communication with an intermediate piston element in structural communication with the at least one laterally movable blade may be pressurized by way of a movable sleeve, a downhole turbine, or a pump.

Abstract: A modular back reamer to be used in subterranean drilling includes a drive stem connected to a drill string and configured to support a reamer body, the reamer body providing a plurality of receptacles, wherein the receptacles are configured to retain a cutting leg assembly at varying heights within a predetermined range, and a plurality of shims engaged within the receptacles to secure the cutting leg assemblies at a specified height within the predetermined range, wherein the cutting leg assembly is secured to the reamer body with at least one mechanical fastener.

Abstract: This invention relates to a ground drilling or cutting tool comprising a cutting element removably attached thereto by attachment means, the tool further including retention means adapted to maintain attachment of the cutting element to the tool in the event that the attachment means fails. The retention means comprises a first surface on a side of the cutting element, a mounting recess in the cutting tool in which at least a portion of said cutting element locates, a second surface in a side of the mounting recess against which said first surface locates, channels in each of said first and second surfaces that align so as to cooperatively define a dowel hole when said first and second surfaces locate together, at least one dowel that locates in the dowel hole, and means for retaining the or each dowel within the dowel hole.

Abstract: A force balanced asymmetric drilling reamer comprising a plurality of blades, each blade having at least one cutter section and a gage section. The cutter section is designed to have a plurality of cutting devices for cutting through swelling formations and cutting free sloughing formations. The gage section has a full bore diameter with gage elements flushly coupled to gage section's outer surface. The blades may be curve/concave shaped or boomerang/chevron shaped, which thereby agitate the cutting beds. At least a portion of the drilling reamer's diameter is incrementally force balanced, starting from the outermost diameter, so that the net radial force is less than 10% of weight on bit with respect to the center of rotation. This balancing allows a greater cutter longevity and provides for a better wellbore condition. Optionally, at least a portion of the drilling reamer's surface may be treated by nitriding for repelling the cuttings.

Abstract: A method of removing a restriction in a tubular located in a well includes providing a drilling assembly with a drill bit and a reamer, the reamer having a cutting structure for removing the restriction; drilling through a lower portion of the tubular; expanding the reamer at a location below the restriction; and urging the reamer back toward the restriction to remove the restriction.

Abstract: A cutting structure for use with a reamer in enlarging a borehole in a subterranean formation includes a plurality of cutter blocks, radially extendable from a reamer body away from a central axis of the reamer body, each of the plurality of cutter blocks comprising at least one cutter blade thereon, wherein an angular spacing about the central axis of the reamer body between the at least one cutter blade on each of the plurality of cutter blocks is unequal.

Abstract: An expandable reamer apparatus and methods for reaming a borehole are disclosed, including at least one laterally movable blade carried by a tubular body selectively positioned at an inward position and an expanded position. The at least one laterally movable blade, held inwardly by at least one blade-biasing element, may be forced outwardly by drilling fluid selectively allowed to communicate therewith or by at least one intermediate piston element. For example, an actuation sleeve may allow communication of drilling fluid with the at least one laterally movable blade in response to an actuation device being deployed within the drilling fluid. Alternatively, a chamber in communication with an intermediate piston element in structural communication with the at least one laterally movable blade may be pressurized by way of a movable sleeve, a downhole turbine, or a pump.

Abstract: Impregnated drilling tools include elongated structures that provide enhanced properties. The drilling tools contain a diamond-impregnated cutting section that contains elongated structures made from carbon, glass, ceramic, and the like. The elongated structures can comprise tubes, fibers, or rods. In one or more implementations the elongated structures are nano-sized. The elongated structures can control the tensile strength and/or the erosion rate of the drilling tools to optimize the cutting performance of the tools. Additionally, the elongated structures may also weaken the cutting section in one or more implementations; thereby, allowing higher strength binders to be used. Such higher modulus binders can cost less and allow for tailoring of the cutting section to retain the diamonds for the desired amount of time. As the cutting section erodes, the elongated structures may also increase the lubricity at the face of the cutting section.

Abstract: Reamer bits have cutters with different effective back rake angles. Drilling systems include a pilot bit and a reamer bit, wherein cutters in shoulder regions of the reamer bit have a greater average effective back rake angle than cutters in shoulder regions of the pilot bit. Methods of drilling wellbores include drilling a bore with a pilot bit, and reaming the bore with a reamer bit having cutters in shoulder regions of the reamer bit that have an average effective back rake angle greater than that of cutters in shoulder regions of the pilot bit. Methods of forming drilling systems include attaching pilot and reamer bits to a drill string, and positioning cutters in shoulder regions of the reamer bit to have an average effective back rake angle greater than that of cutters in shoulder regions of the pilot bit.

Abstract: An expandable reamer apparatus and methods for reaming a borehole, wherein a laterally movable blade carried by a tubular body may be selectively positioned at an inward position and an expanded position. The laterally movable blade, held inwardly by blade-biasing elements, may be forced outwardly by drilling fluid selectively allowed to communicate therewith by way of an actuation sleeve disposed within the tubular body. Alternatively, a separation element may transmit force or pressure from the drilling fluid to the movable blade. Further, a chamber in communication with the movable blade may be pressurized by way of a downhole turbine or pump. A ridged seal wiper, compensator, movable bearing pad, fixed bearing pad preceding the movable blade, or adjustable spacer element to alter expanded blade position may be included within the expandable reamer. In addition, a drilling fluid pressure response indicating an operational characteristic of the expandable reamer may be generated.

Abstract: The present invention provides drilling assembles and methods that are especially useful for a bottom hole drilling assembly for drilling/reaming/ or other operations related to drilling a borehole through an earth formation. In one embodiment, the drilling assembly utilizes standard drill collars which are modified to accept force transfer sections. In another embodiment, the drilling assembly comprises a tension inducing sub which creates a force that may be used to place the bottom hole assembly or portions thereof in tension. In another embodiment, a reaming assembly is held in tension to provide a stiffer reaming assembly.

Abstract: An expandable reamer apparatus and methods for reaming a borehole are disclosed, including at least one laterally movable blade carried by a tubular body selectively positioned at an inward position and an expanded position. The at least one laterally movable blade, held inwardly by at least one blade-biasing element, may be forced outwardly by drilling fluid selectively allowed to communicate therewith or by at least one intermediate piston element. For example, an actuation sleeve may allow communication of drilling fluid with the at least one laterally movable blade in response to an actuation device being deployed within the drilling fluid. Alternatively, a chamber in communication with an intermediate piston element in structural communication with the at least one laterally movable blade may be pressurized by way of a movable sleeve, a downhole turbine, or a pump.

Abstract: A drilling tool has a body with a main drilling region and a pilot drilling region, eccentric to the main drilling region. The main drilling region has main blades and the pilot drilling region has pilot blades. The main drilling region has a main pass-through diameter, centered upon a first axis, one of the main blades extending to the main pass-through diameter, the pilot region having a pilot gauge diameter, centered upon a second axis of rotation at least one of the pilot blades extending to the pilot gauge diameter, wherein part of a circle of diameter equal to the pilot gauge diameter and centered upon the second axis of rotation extends outside of a circle of diameter equal to the main pass-through diameter and centered upon the first axis.

Abstract: A particle impact drilling system and method are described. In several exemplary embodiments, the system and method may be a part of, and/or used with, an apparatus or system, methods, to excavate a subterranean formation. The system can including, for example, removing near-borehole damage, casing, window milling, fishing, drilling with casing, under reaming, coring, perforating, effective circulatory density management, assisted annular flow, and directional control. Embodiments of associated systems and methods are also included.

Abstract: The present invention is a system and method for measuring borehole conditions, in particular for verification of a final diameter of a borehole. The system includes a drill string with a drill bit and a drilling mud circulation device, an underreamer attached to the drill string above the drill bit, and a tool body attached to the drill string, having a sensor for detecting downhole conditions, such as borehole diameter. The tool body is mounted above the underreamer and has a diameter smaller than the underreamer and drill bit. The sensor can be an ultrasonic transducer with adjustable signal amplitude and can be fixed in positions along the tool body. The system may also include a calibrator for sensor data, and an auxiliary tool body with another sensor between the drill bit and the underreamer. The method of the present invention is use of the system for final borehole verification.

Abstract: An expandable reamer apparatus and methods for reaming a borehole, wherein a laterally movable blade carried by a tubular body may be selectively positioned at an inward position and an expanded position. The laterally movable blade, held inwardly by blade-biasing elements, may be forced outwardly by drilling fluid selectively allowed to communicate therewith by way of an actuation sleeve disposed within the tubular body. Alternatively, a separation element may transmit force or pressure from the drilling fluid to the movable blade. Further, a chamber in communication with the movable blade may be pressurized by way of a downhole turbine or pump. A ridged seal wiper, compensator, movable bearing pad, fixed bearing pad preceding the movable blade, or adjustable spacer element to alter expanded blade position may be included within the expandable reamer. In addition, a drilling fluid pressure response indicating an operational characteristic of the expandable reamer may be generated.

Abstract: Embodiments provide apparatuses and methods for drilling and underreaming, particularly to underreamer expansion bits. Underreamer drill assemblies and underreaming bits manufactured in accordance with various embodiments may help to resist over-excavating or undermining, which may result in a more stable bore hole.

Abstract: A tool for enlarging a borehole that includes an elongated tubular body; at least one movable arm affixed to the tubular body, the at least one movable arm comprising an outer surface formed of at least one of a matrix material and an abrasive material; and at least one actuating member for expanding at least one movable arm from the collapsed state to an expanded state is disclosed.

Abstract: An underreaming tool may include a tubular body, a drive tube, at least one blade element (“the blade element”), at least one wedge element (“the wedge element”), and a stop mechanism. The drive tube may include at least one longitudinal groove (“the longitudinal groove”) axially disposed along a length of the drive tube. The wedge element may include a first side having at least one lateral projection (“the lateral projection”) configured to axially slide into the longitudinal groove to couple the wedge element to the drive tube. The stop mechanism comprises a threaded sleeve configured to screw onto the drive tube to lock the wedge element in the longitudinal groove once the lateral projection is slid into the longitudinal groove.

Abstract: A reamer for underground boring is provided. The reamer includes at least: (a) a center mandrel, wherein the center mandrel defines a mandrel axis; (b) a plurality of radial members extending radially from the center mandrel; (c) a plurality of cutting heads, wherein each of the cutting heads: (i) is supported by at least one of the radial members; (ii) is arcuately spaced-apart around the center mandrel from the other cutting heads; (iii) has a rounded surface; and (d) a plurality of cutting teeth on the rounded surface of each of the cutting heads. A method of horizontal drilling with the reamer is also provided.

Abstract: A secondary cutting structure for sure in a drilling assembly, the secondary cutting structure including a tubular body and a block, extendable from the tubular body, the block including a first arrangement of cutting elements disposed on a first blade and a second arrangement of cutting elements disposed on a second blade, wherein the second arrangement is a modified redundant arrangement. Also, a secondary cutting structure for use in a drilling assembly, the secondary cutting structure including a leading blade disposed on a first block and a trailing blade disposed on the first block adjacent the leading blade. Additionally, the secondary cutting structure includes a unique blade disposed on a second block, wherein a gage portion of at least one of the blades has a length between 30% and 45% of a total blade length.

Abstract: A reamer bit for use in earth boring operations comprising a body, mounting elements on the bit body having rolling cutters, and nozzles configured to emit a cleaning spray that is angled with respect to the well bottom. The cleaning spray may be angled up to about 20° with respect to the well bottom. The reamer may further include a pilot bit on a drill pipe extending downward from the reamer body.

Abstract: A bore hole rotary reamer includes a body having cutters rotatably mounted by one or more respective spindles. A bearing region is formed on the spindle. At least one annular seal prevents ingress of contaminant to the bearing region. A circumferential void is formed adjacent the seal. At least one passageway extends in an axial direction of the spindle to the circumferential void and a piston movable in the passageway in response to supply of pressure to an outer side of the piston from the environment which surrounds the reamer. The piston transfers pressure to fluid in the cylindrical passage on an inner side of the piston to supply pressure to the circumferential void and thereby to the seal. The pressure is substantially determined by the pressure of the environment surrounding the reamer.

Abstract: A reaming tool in the form of reamer shoe is adapted for location in a wellbore and has a rotationally balanced nose.

Abstract: A bottom hole assembly to directionally drill a subterranean formation includes a drill bit, a stabilizer assembly located proximate to and behind the drill bit, a drilling assembly comprising a drive mechanism and a directional mechanism, and a flex member. Optionally, the flex member may be located between the drilling assembly and the stabilizer assembly or an integral to a housing of the drilling assembly. A method to drill a formation includes positioning a stabilizer assembly behind a drill bit and positioning a flex member between an output shaft of a drilling assembly and the stabilizer assembly. The method preferably includes rotating the drill bit, stabilizer assembly, and flex member with a drilling assembly and directing the trajectory of the drill bit and stabilizer assembly with a directional mechanism of the drilling assembly.

Abstract: An expandable reamer apparatus and methods for reaming a borehole are disclosed, including at least one laterally movable blade carried by a tubular body selectively positioned at an inward position and an expanded position. The at least one laterally movable blade, held inwardly by at least one blade-biasing element, may be forced outwardly by drilling fluid selectively allowed to communicate therewith or by at least one intermediate piston element. For example, an actuation sleeve may allow communication of drilling fluid with the at least one laterally movable blade in response to an actuation device being deployed within the drilling fluid. Alternatively, a chamber in communication with an intermediate piston element in structural communication with the at least one laterally movable blade may be pressurized by way of a movable sleeve, a downhole turbine, or a pump.

Abstract: An expandable reamer apparatus and methods for reaming a borehole, wherein a laterally movable blade carried by a tubular body may be selectively positioned at an inward position and an expanded position. The laterally movable blade, held inwardly by blade-biasing elements, may be forced outwardly by drilling fluid selectively allowed to communicate therewith by way of an actuation sleeve disposed within the tubular body. Alternatively, a separation element may transmit force or pressure from the drilling fluid to the movable blade. Further, a chamber in communication with the movable blade may be pressurized by way of a downhole turbine or pump. A ridged seal wiper, compensator, movable bearing pad, fixed bearing pad preceding the movable blade, or adjustable spacer element to alter expanded blade position may be included within the expandable reamer. In addition, a drilling fluid pressure response indicating an operational characteristic of the expandable reamer may be generated.

Abstract: A reamer includes a mandrel defining a mandrel axis and arms extending radially from the mandrel. Each arm has a proximal end and a distal end. The reamer includes a cutting head disposed on the distal end of each arm and cutting teeth disposed on each cutting head. The arms are arcuately spaced about the central mandrel to allow the movement of debris axially along the central mandrel and at least one of the arms defines a square cross-sectional shape.

Abstract: A modular back reamer to be used in subterranean drilling includes a drive stem connected to a drill string and configured to support a reamer body, the reamer body providing a plurality of receptacles, wherein the receptacles are configured to retain a cutting leg assembly at varying heights within a predetermined range, and a plurality of shims engaged within the receptacles to secure the cutting leg assemblies at a specified height within the predetermined range, wherein the cutting leg assembly is secured to the reamer body with at least one mechanical fastener.

Abstract: The present invention provides drilling assembles and methods that are especially useful for a bottom hole drilling assembly for drilling/reaming/or other operations related to drilling a borehole through an earth formation. In one embodiment, the drilling assembly utilizes standard drill collars which are modified to accept force transfer sections. In another embodiment, the drilling assembly comprises a tension inducing sub which creates a force that may be used to place the bottom hole assembly or portions thereof in tension. In another embodiment, a reaming assembly is held in tension to provide a stiffer reaming assembly.

Abstract: An expandable reamer apparatus for drilling a subterranean formation includes a tubular body, one or more blades, each blade positionally coupled to a sloped track of the tubular body having a hardfacing material on a portion thereof, a push sleeve and a drilling fluid flow path extending through an inner bore of the tubular body for conducting drilling fluid therethrough.

Abstract: An apparatus for a drilling tool includes a pilot drilling bit, a reamer, and a pilot body which is disposed to support the reamer and the pilot drilling bit at the end of a casing tube. The reamer includes a closed position in which the parts of the tool are concentric with one another and displaceable through the casing tube, and an open position in which at least a part of the reamer is located radially outside the casing tube. The pilot body includes a male portion which extends through the reamer, the male portion of the pilot body forming a cam surface for transferring rotation energy to the reamer and for switching the reamer between the closed and open positions, and the male portion of the pilot body being insertable in a recess in the pilot drilling bit.

Abstract: A reamer for underground boring is provided. The reamer includes at least: (a) a center mandrel, wherein the center mandrel defines a mandrel axis; (b) a plurality of radial members extending radially from the center mandrel; (c) a plurality of cutting heads, wherein each of the cutting heads: (i) is supported by at least one of the radial members; (ii) is arcuately spaced-apart around the center mandrel from the other cutting heads; (iii) has a rounded surface; and (d) a plurality of cutting teeth on the rounded surface of each of the cutting heads. A method of horizontal drilling with the reamer is also provided.

Abstract: The fixed cutter drill bit disclosed utilizes a unique piloting section and reaming section carefully designed to impart several specific operational advantages. In the piloting section, cutting structures have been arranged so as to create offsetting cutting forces that result in a net zero imbalance during operation. Furthermore, the piloting section utilizes carefully placed shock studs which aid in protecting the primary cutting structure. In addition, the location of the fluid supply nozzles on the body of the reamer section serves to indicate the occurrence of a catastrophic cutting structure failure below the pilot gage.

Abstract: An expandable reamer apparatus and methods for reaming a borehole, wherein a laterally movable blade carried by a tubular body may be selectively positioned at an inward position and an expanded position. The laterally movable blade, held inwardly by blade-biasing elements, may be forced outwardly by drilling fluid selectively allowed to communicate therewith by way of an actuation sleeve disposed within the tubular body. Alternatively, a separation element may transmit force or pressure from the drilling fluid to the movable blade. Further, a chamber in communication with the movable blade may be pressurized by way of a downhole turbine or pump. A ridged seal wiper, compensator, movable bearing pad, fixed bearing pad preceding the movable blade, or adjustable spacer element to alter expanded blade position may be included within the expandable reamer. In addition, a drilling fluid pressure response indicating an operational characteristic of the expandable reamer may be generated.