Abstract: A downhole apparatus comprises a body, extendable members mounted on the body and being movable between retracted and extended configurations, and a remotely operable retaining arrangement for maintaining the extendable members in the retracted configuration. The extendable members may be cutters, such that the apparatus may be a cutting apparatus, such as a reamer. An operator may control the apparatus to retain the cutting members in the retracted configuration, or prevent the extension of the cutting members.

Abstract: The present invention relates to downhole tools, and in particular an underreamer tool for use in a wellbore of an oil or gas well and a method of actuation. In an embodiment, the underreamer tool has body having a longitudinal axis and a fluid conduit, a tool element and an actuation device configured to urge the tool element relative to the body from a first configuration into a second configuration. In this embodiment, a portion of the tool has a curved actuation surface and the tool element is urged across the curved actuation surface the tool element is moved radially with respect to the body of the tool. Typically, the actuation device may include a piston driven by pressure of fluid circulated through the fluid flow conduit.

Abstract: An expandable drilling apparatus includes a main body comprising a central bore and at least one axial recess configured to receive an arm assembly operable between a retracted position and an extended position, a biasing member to urge the arm assembly into the retracted position, a drive position configured to thrust the arm assembly into the extended position when in communication with drilling fluids in the central bore, a selector piston translatable between an open position and a closed position, wherein the selector piston is thrust into the open position when a pressure of the drilling fluids exceeds an activation value, wherein the drilling fluids are in communication with the drive piston when the selector piston is in the open position, and a selector spring configured to thrust the selector piston into the closed position when the pressure of the drilling fluids falls below a reset value.

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: A down hole well bore apparatus to underream and remove rock or cement or other material, cut or mill casing, clean or scrape casing, or centralize a drill string, which has a rotor which actuates blades, a compact overall length and can be operated with normal or reverse circulation. Simultaneous operations or multiple sequential operations can be made without removing the drill string.

Abstract: The present invention discloses a collapsible drilling assembly having field-replaceable cutter or stabilizer blades (214) and method of using and installing new stabilizer blades while at a job location. The drilling assembly is deployed upon a distal end of a drillstring, expanded to a gauge size, and used as an underreamer or alternatively a stabilizer. The drilling assembly operates between retracted and extended positions through the increase in pressure of drilling fluid flowing therethrough.

Abstract: Provided is a drilling tool that includes a tubular body defining a longitudinal axial cavity extending therethrough. The tubular body also defines at least one radial guidance channel extending radially from the axial cavity through the tubular body. A cutter element is disposed in the at least one radial guidance channel and includes an internal surface inclined at an angle to a longitudinal axis of the tubular body. The drilling tool also includes a wedge element having an external surface configured to engage the internal surface of the cutter element and to direct the cutter element from a retracted position to an extended position as the wedge element moves from a first position to a second position.

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: In one aspect of the present invention, a downhole assembly has a downhole tool string component with a bore adapted to accommodate drilling mud having a central passage and at least one periphery passage. At least two movable segments are peripherally positioned around a bore wall adapted to constrict a diameter of the central passage and are adapted to divert drilling mud into the at least one periphery passage. At least one opening mechanism is adapted to move a portion of the at least two movable segments toward the bore wall.

Abstract: An activating device is mounted in a drill string to control the activation and deactivation of an enlargement tool used for enlarging a bore hole. In order to assemble the activating device, pistons are mounted in passages and spline bars, in which plates are screwed, are then slid along T-slots of the body, through apertures of the pistons. In order to deploy the pistons and cutters, pressurized drilling fluid is applied to the inner faces of the pistons. When a pre-determined pressure level is reached, screws break and the pistons move from the inward position to the outwardly deployed position.

Abstract: An expandable drilling apparatus is deployed upon a distal end of a drillstring and includes a cutting head and a substantially tubular main body adjacent the cutting head providing a plurality of axial recesses configured to receive arm assemblies configured to translate between a retracted and an extended position. A flow switch actuates the arm assemblies when a drilling fluid pressure exceeds an activation value and the drilling apparatus includes a biasing member to reset the arm assemblies when the drilling fluid pressure falls below a reset value.

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: In accordance with an embodiment of the present invention, a drilling tool includes a tubular body defining a longitudinal axial cavity extending therethrough and defining at least one cutter element recess. The drilling tool also includes a cutter element at least partially disposed within the at least one cutter element recess and includes at least first and second cutting arms at least substantially disposed within the cutter element recess in a retracted position. The first and second cutting arms are operable to move from the retracted position to an extended position in which the first and second cutting arms extend at least partially beyond a periphery of the tubular body. The first and second cutting arms and the tubular body enclose a space when the first and second cutting arms are in the extended position.

Abstract: An expandable reamer apparatus for drilling a subterranean formation may include a tubular body, one or more blades, each blade positionally coupled to a sloped track of the tubular body, a push sleeve and a drilling fluid flow path extending through an inner bore of the tubular body for conducting drilling fluid therethrough. Each of the one or more blades may be configured to ream a subterranean formation. The push sleeve may be disposed in the inner bore of the tubular body and coupled to each of the one or more blades so as effect axial movement thereof along the track to an extended position responsive to exposure to a force or pressure of drilling fluid in the flow path of the inner bore. Each blade may include one or more roller elements for reaming a wellbore.

Abstract: An expandable downhole tool comprises a tubular body, at least one moveable arm disposed within the tubular body and being radially translatable between a retracted position and a wellbore engaging position, and at least one piston operable to mechanically support the at least one moveable arm in the wellbore engaging position when an opposing force is exerted. A method of reaming a formation to form an enlarged borehole in a wellbore comprising disposing an expandable reamer in a retracted position in the wellbore, expanding at least one movable arm of the expandable reamer radially outwardly into engagement with the formation, reaming the formation with the at least one moveable arm to form the enlarged borehole; and mechanically supporting the at least one moveable arm in the radially outward direction during reaming.

Abstract: An expandable drilling apparatus is deployed upon a distal end of a drillstring and includes a cutting head and a substantially tubular main body adjacent the cutting head providing a plurality of axial recesses configured to receive arm assemblies configured to translate between a retracted and an extended position. A flow switch actuates the arm assemblies when a drilling fluid pressure exceeds an activation value and the drilling apparatus includes a biasing member to reset the arm assemblies when the drilling fluid pressure falls below a reset value.

Abstract: In accordance with an embodiment of the present invention, a drilling tool includes a tubular body defining a longitudinal axial cavity extending therethrough and defining at least one cutter element recess. The drilling tool also includes a cutter element at least partially disposed within the at least one cutter element recess and includes at least first and second cutting arms at least substantially disposed within the cutter element recess in a retracted position. The first and second cutting arms are operable to move from the retracted position to an extended position in which the first and second cutting arms extend at least partially beyond a periphery of the tubular body. The first and second cutting arms and the tubular body enclose a space when the first and second cutting arms are in the extended position.

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, a push sleeve and a drilling fluid flow path extending through an inner bore of the tubular body for conducting drilling fluid therethrough. Each of the one or more blades includes at least one cutting element configured to remove material from a subterranean formation during reaming. The push sleeve is disposed in the inner bore of the tubular body and coupled to each of the one or more blades so as effect axial movement thereof along the track to an extended position responsive to exposure to a force or pressure of drilling fluid in the flow path of the inner bore. Other embodiments of the expandable reamer apparatus are provided.

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 under reamer for expanding a borehole through an earthen formation is taught. The under reamer includes: a mandrel including an end for connection into a drill string and an opposite end and a housing including an inner bore, telescopically disposed over the mandrel and axially moveable relative to the mandrel but rotationally moveable with the mandrel. A plurality of under reamer arms are carried on the housing, the under reamer arms are formed as blocks including cutter-supporting portions in which poly-crystalline diamond compact cutters are mounted. The under reamer arms are moveable by driving the housing axially over the mandrel between a retracted position extending into the bore of the housing and an expanded position wherein the under reamers arms are pivoted out of the housing inner bore and supported therebehind by the mandrel such that the cutter-supporting portions are exposed for use to enlarge a borehole.

Abstract: The invention relates to well reamer for borehole reaming within a specified interval. The well reamer has a housing with inclined slots, radial holes and a central straight-through channel, in which a spring-loaded rod with holes in the upper and lower parts is located. The upper holes of the rod are covered when the operating elements are extended into an operating position. A plurality of legs, including cutters rotatably supported on the legs, are moved by pistons between an operating position and a transport position along the inclined slots. Free-ends of the pistons may be connected to the rod by sliders, which are movable radially into openings in the rod to connect the rod to the pistons to move the rod with the legs.

Abstract: An expandable downhole tool comprises a tubular body having an axial flowbore extending therethrough, at least one moveable arm, and a selectively actuatable sleeve that prevents or allows the at least one moveable arm to translate between a collapsed position and an expanded position. A method of expanding the downhole tool comprises disposing the downhole tool within the wellbore, biasing the at least one moveable arm to a collapsed position corresponding to an initial diameter of the downhole tool, flowing a fluid through an axial flowbore extending through the downhole tool while preventing the fluid from communicating with a different flowpath of the downhole tool, allowing the fluid to communicate with the different flowpath by introducing an actuator into the wellbore, and causing the at least one moveable arm to translate to an expanded position corresponding to an expanded diameter of the downhole tool.

Abstract: An expandable drill bit for use with earth drilling equipment. The bit includes arms held in a closed position, so that the bit may be inserted through casing or a small bore hole. The arms are expandable to create an expanded drill bit having a crown profile common to a solid crown bit. The arrangement of the arms provides a short gauge length so that the expanded bit is steerable downhole. Embodiments of the expandable drill bit are detailed to show mechanisms for actuating the arms between the open and closed positions.

Abstract: A downhole tool comprises a body having slots communicating the outside of the body with the body through-bore. A sleeve actuator and mandrel are selectively axially slidable. The actuator has flanges extending into the slots. The flanges have ribs on their sides that are inclined at an acute angle to the longitudinal axis of the tool. Hollow bars are slidable in the slots and they have channels inside corresponding with, and engaged in, the ribs of the flanges. The sleeve actuator slides in the body between a tool actuated position and a tool deactuated position. The mandrel is selectively axially slidable between a tool actuated position, an interlock position and a sleeve-lock position. A lock ball locks the sleeve actuator with respect to the body in the tool deactuated position and while the mandrel is between the interlock and sleeve-lock positions. The lock ball also locks the sleeve actuator with respect to the mandrel while the mandrel is between said interlock and tool actuated positions.

Abstract: An expandable drill bit comprises a body for mounting on a support string and two roller cutters mounted on the body. The cutters are movable between a smaller diameter first configuration and a larger diameter second configuration. In one embodiment the bit is adapted to drill with the cutters in both the first and second configurations.

Abstract: A system is provided (1) for increasing the diameter of at least a portion of a well bore, the system being intended to be attached to a drill pipe (3), the system having a support element (10) bearing cutting arms (13, 14) which is movably mounted with respect to a body (4) and wherein the arms and the chamber (6) of the body (4) are designed so as to cooperated. A method is also provided for increasing the diameter of at least a portion of a well bore by drilling.

Abstract: An apparatus for use in a wellbore. The apparatus includes a body and a blade assembly. The blade assembly is movable between a collapsed position whereby the expandable apparatus has a smaller outer diameter and an expanded position whereby the expandable apparatus has a larger outer diameter. The apparatus further includes a pressure activated member for selectively allowing the blade assembly to move from the closed position to the open position. A method for using the apparatus, wherein a drill string with an expandable bit at the end thereof is lowered into the wellbore. Thereafter, the pressure activated member is activated to allow the cutting members to move from the collapsed position to the expanded position. Subsequently, the expandable bit is rotated to form a portion of the wellbore. Next, the expandable bit is deactivated and the cutting members are moved from the expanded position to the collapsed position.

Abstract: A downhole tool that functions as an underreamer or as a stabilizer in an underreamed borehole. The tool includes one or more moveable arms disposed within a body having a flowbore therethrough in fluid communication with the wellbore annulus. The tool alternates between collapsed and expanded positions in response to differential fluid pressure between the flowbore and the wellbore annulus. In one embodiment, the tool moves automatically in response to differential pressure. In a second embodiment, the tool must be selectively actuated before it is moveable. The tool may include borehole engaging pads that comprise cutting structures or wear structures or both, depending upon the function of the tool.

Abstract: The device for breaking rocks includes a hollow cylindrical chamber having a closed lower end, a closed upper end and an access aperture in the closed upper end and an outer circumstantial surface. A cylindrical plunger is longitudinally-reciprocally disposed within the interior of the cylindrical chamber, has a converging portion and is biased to a retracted position. Four spools are equally disposed around the circumference of the cylindrical plunger, each spool including a converging upper end which is configured to be in slidable contact with the converging portion of the cylindrical plunger. Four hardened inserts are secured to an outer face of an associated spool. Each spool and secured hardened insert is biased to an inner retracted position.

Abstract: A bore hole underreamer is provided having a hollow body with a longitudinal axis, which has an external wall, at least two cylindrical bores provided through the external wall and whose axes are transverse to the longitudinal axis. Each of the bores have a cylindrical widening arm for widening the hole, which is arranged in the bore like a hydraulic piston, so as to be able to slide therein between an active position and an inactive position. The underreamer has a locking member which can occupy a locking position in which this member locks the arms in their inactive position, and which, when it is released, can leave the locking position under a thrust from at least one of the arms subjected to the pressure capable of pushing the arm into its active position.

Abstract: A section mill for casings used in oil wells to cut predetermined portions for repair purposes. An elongated cylindrical assembly is inserted through the casing and it includes at least two spaced apart apertures with one blade member pivotally mounted within each aperture. First and second coaxially disposed tubular shaft assemblies with teethed portions to coact with the blades to selectively move them between two extreme position upon the application of a pressurized fluid. The fluid needs to overcome the spring biased applied to the shaft assemblies. The first set of blades is stopped and slidably rotates in contact with the internal surface of the casing. The second set cuts through the casing with one end and sections the casing with the other end. After wearing off, the first set of blades continues the sectioning work.

Abstract: A drilling assembly and an eccentric, adjustable diameter reamer are disclosed. The reamer includes cutter elements mounted on at least a first fixed blade for reaming a previously-formed borehole or for forming a borehole of increased diameter beneath an existing cased borehole. The method and apparatus provide for stabilizing the drilling assembly so that the reamer may be used in back reaming the hole. Retainer means, such as shear pins or spring-biased reciprocating latch members, are provided to prevent premature extension of the reamer's moveable members, including blades and pistons. The shear pins are preferably accessible from the outer surface of the reamer housing so as to expedite field replacement of the shear pins without requiring disassembly of the reamer. The spring-biased latching members repeatedly latch and unlatch so that field replacement is not required, and so that the movable members may be extended and contracted multiple times while the reamer is downhole.

Abstract: The invention refers to a rotary steerable drilling tool having a tool collar and a bit shaft. The bit shaft is supported within the tool collar for pivotal movement about a fixed position along the bit shaft. Moreover, the rotary steerable drilling tool includes a variable bit shaft angulating mechanism, located within the interior of the tool collar. The variable bit shaft angulating mechanism includes a motor, an offset mandrel, and a variable offset coupling. The motor is attached to the upper end of the offset mandrel and adapted to rotate the offset mandrel. The upper end of the variable offset coupling is uncoupleably attached to an offset location of the lower end of the offset mandrel, and the upper end of the bit shaft is rotatably coupled to the variable offset coupling. The rotary steerable drilling tool also includes a torque transmitting coupling adapted to transmit torque from the tool collar to the bit shaft at the fixed position along the bit shaft.

Abstract: A bore hole opener for enlarging a bore hole includes a longitudinal body, a duct for drilling fluid, formed longitudinally in the body, having a fluid passage cross-section of inside radius i, and at least two hole-opening arms, borne by the body, which have an active part equipped with cutting mechanisms, which are arranged therein in such a way that they can slide between a position of rest in the body and an active position partially out of the body, and which are guided and supported for this purpose in the body over a distance g and which, in the active position, project from the body by a length o, in which the values of i, g and o are chosen to simultaneously satisfy the conditions i+g+o S;

Abstract: Provided is a bore hole underreamer in a terrestrial formation, intended in particular for oil drilling. The underreamer has a hollow body and at least two cylindrical bores. The bores are provided through an external wall of the body and have axes that are transverse to a longitudinal axis of the body. The bores are distributed over the circumference of the hollow body and each bore contains a cylindrical widening arm. Each arm has a bladed cutting end disposed on the outside of the body that slides between active and inactive positions. Another end of each arm is disposed inside the body and receives fluid pressure for pushing the arm into the active position. The underreamer includes a locking member for locking the arms in their inactive position when the locking member is immobilised in the body in a releasable fashion in a locking position.

Abstract: An underreamer (5) is formed from a tubular body (10) having a longitudinal bore therethrough, and providing an integral piston actuator (20) responsive to hydraulic pressure to move cutters (40) into engagement with the well bore and springs (60) to resist premature engagement of the cutter arms (40) and to return the cutters (40) to the body upon conclusion of the underreaming job. Skewed longitudinal grooves (45) are formed in the tubular body thereby permitting the flowpath through the underreamer to provide substantially the same inner diameter throughout the tool (5).

Abstract: Drilling apparatus, such as an underreamer (20) comprises a generally cylindrical tubular body (22) and two cutting blades (26, 27) pivotally mounted to the body and movable between a retracted position and an extended position. Each cutting blade has a retracted position minimum gauge cutting portion (36) and an extended position maximum gauge cutting portion (35), with the blades in the extended position the gauge cutting portions (35) extending axially and being located in a transverse plane on or forward of the blade pivot axis.

Abstract: A single-blade underreamer for forming a cavity within a well bore includes a housing rotatably disposed within the well bore, and a stabilizer coupled to the housing. The stabilizer is operable to stabilize the housing within the well bore during formation of the cavity. The underreamer also includes a single cutter pivotally coupled to the housing, and a piston slidably disposed within the housing and adapted to engage the cutter. A downwardly disposed force applied to the piston is operable slide the piston relative to the housing to correspondingly extend the cutter outwardly relative to the housing from a retracted position to form the cavity during rotation of the housing.

Abstract: A balancing structure to reduce vibration created in a rotating body by imbalance comprises an annular groove formed in the body, the groove partially filled with a quantity of solid balls. The solid balls, by only partially filling the groove, provide a stabilizing force that tends to compensate for the imbalance caused by different amounts of solids adhering to one side or the other of the body, such as for example a drilling assembly. The groove is preferably wider in a region further from the axis of rotation from the rotating body for more efficient balancing effect.

Abstract: A drilling apparatus for underreaming includes a top sub, a pressure sleeve mated to the top sub, and a blade body mated to the pressure sleeve. A pilot bit is mated to the lower end of the blade body. A plurality of movable cutting blades are pivotably attached to the blade body by pivot pins. Each of the pins is inserted through the blade body and the cutting blade. Slidable covers, held in place by the pressure sleeve, are used to retain the pins. A mandrel is centrally positioned with respect to the pressure sleeve and the blade body and is axially movable therein. Each of the cutting blades includes an end which is operatively associated with channels transversely formed on one end of the mandrel. Movement of the mandrel in a first axial direction effects retraction of the cutting blades. Movement of the mandrel in a second axial direction effects extension of the cutting blades. The mandrel is held in its blade-retracting position by the biasing force of a spring.

Abstract: An underreamer opens a borehole below a restriction that is larger than the restriction itself. The underreamer includes cutters which engage the formation by traversing outward and upward. The force pushing the cutters to the extended position is supplied by a piston built into each cutter support. Pressure acting on these pistons comes from the pressure differential between the annulus and drill string during circulation of drilling fluid. The cutters are supported on both sides of the cutting structure by arms that are supported by and in sliding contact with the body. A spring opposes the upward and outward motion of the cutter mechanism and returns the cutters to their collapsed position in the absence of differential pressure. The body of the tool incorporates by-pass ports for transmitting fluid through the tool to the remainder of the bottom hole assembly.

Abstract: The invention combines a mud motor, a drill bit, a transmission, an underreamer and a torque tube to simultaneously drill a well by rotating the drill bit in one direction and the underreamer in the opposite direction to balance the torque supplied to the bit and the underreamer.

Abstract: Borehole opener, particularly for enlarging this hole underneath a casing in the field of oil prospecting, comprising a body (2) of longitudinal axis (3), a duct (4) for drilling fluid, formed longitudinally in the body (2), and at least two hole-opening arms (5) which have an active part (7) equipped with cutting means (8), which are distributed symmetrically in the body (2) about the longitudinal axis (3), and which are arranged therein in such a way that they can be moved between a position of rest (9) in the body (2) and an active position (10) partially out of the body (2); in this hole opener in order to move it from the position of rest (9) to the active position (10), each arm (5) has a face (12), internal to the body (2), designed to be subjected directly, in the same way as an active face of a piston, to the pressure of the drilling fluid flowing through the body (2).

Abstract: An actively controlled rotary steerable drilling system for directional drilling of wells including a tubular rotary tool collar having rotatably mounted thereabout a substantially non-rotatable sliding sleeve incorporating a plurality of elastic coupling members to maintain the sliding sleeve in coupled relation with the borehole wall during drilling. An offsetting mandrel is supported within the tool collar by a knuckle joint for pivotal movement and is rotatably driven by the tool collar and has a lower end extending from the collar and adapted for support of a drill bit. To achieve controlled steering of the rotating drill bit, orientation of the drilling tool is sensed by navigation sensors and the offsetting mandrel is maintained geostationary and selectively axially inclined relative to the tool collar by orienting it about the knuckle joint responsive to navigation sensors.

Abstract: The present invention is an apparatus for use in drilling operations. It uses an under-reamer having a plurality of elongated arms with cutting elements at the ends of the arms for enlarging a previously drilled borehole drilled by a drill bit. One or more stabilizers in close proximity to the under-reamer provide stability to the under-reamer and the drill bit. The stabilizer could be rotating or non-rotating; and could be positioned between the under-reamer and the drill bit, or above the under reamer or above a directional device on the drillstring. The cutting arms are selectively operable to perform the enlargement. The stabilizer may be provided with members that closely fit the size of the borehole.

Abstract: An underreamer with pressurized water activated lateral cutters pivotally mounted thereon and being spring biased to urge them in longitudinal alignment with the underreamer. A removable constrictor socket is cooperatively mounted adjacent to the distal end of the piston rod so that a user can select one of several designs depending on the magnitude of drill fluid pressure to be applied on the bottom of the well. The lower end of the underreamer is provided with several contiguous cutting teeth arranged in a circle with a relatively small separation inbetween so that it may continue to work even if the well collapses. The cutting teeth enhance the turbulence of the drill fluid. The underreamer is lubricated with drilling fluid applied up to a predetermined pressure without opening the lateral cutters. After a given predetermined amount of pressure, the lateral cutters open perpendicularly.

Abstract: An underreamer with pressurized water activated lateral cutters pivotally mounted thereon and being spring biased to urge them in longitudinal alignment with the underreamer. A removable constrictor socket is cooperatively mounted adjacent to the distal end of the piston rod so that a user can select one of several designs depending on the magnitude of drill fluid pressure to be applied on the bottom of the well. The lower end of the underreamer is provided with several contiguous cutting teeth arranged in a circle with a relatively small separation inbetween so that it may continue to work even if the well collapses. The cutting teeth enhance the turbulence of the drill fluid. The underreamer is lubricated with drilling fluid applied up to a predetermined pressure without opening the lateral cutters. After a given predetermined amount of pressure, the lateral cutters open perpendicularly.

Abstract: Section mills have been invented that have one or more blades one or more of whose tops are pivotably extendable outwardly from a mill body as bottoms of the blade(s) rotate about a fixed point, and one or more blades whose bottoms are pivotably extendable outwardly from the mill body, the blades pivotably secured to the mill body so that, in one aspect, in response to a downwardly moving wash tube contacting the blades, the blades move out from the mill body. In one aspect certain of the blades have a milling surface which is of such an outward extent and which is parallel to a central longitudinal axis of the mill body when the blades are fully extended so that "full sweep" milling is achieved.

Abstract: A cutting tool has been invented for use in a wellbore to cut formation through which the wellbore extends or to cut items in the wellbore, the tool having, in one aspect, a body disposable at a desired location in the wellbore, at least one first blade pivotably mounted to the body at a first height on the body, at least one second blade pivotably mounted to the body at a second height on the body, the second height above the first height, the blades movable from a first position against the body to a second position extending out from the body for cutting, and the first blades shorter in length than the second blades.

Abstract: Borehole opener, particularly for enlarging this hole underneath a casing in the field of oil prospecting, comprising a body (2) of longitudinal axis (3), a duct (4) for drilling fluid, formed longitudinally in the body (2), and at least two hole-opening arms (5) which have an active part (7) equipped with cutting means (8), which are distributed symmetrically in the body (2) about the longitudinal axis (3), and which are arranged therein in such a way that they can be moved between a position of rest (9) in the body (2) and an active position (10) partially out of the body (2); in this hole opener in order to move it from the position of rest (9) to the active position (10), each arm (5) has a face (12), internal to the body (2), designed to be subjected directly, in the same way as an active face of a piston, to the pressure of the drilling fluid flowing through the body (2).