Abstract: The present invention relates to a combined crushing super-variable-diameter drill bit for natural gas hydrate exploitation, including a joint, an outer cylinder connected to the joint by thread, a nozzle I mounted in the outer cylinder, a mechanical locking mechanism, a blade telescoping mechanism, an end cap connected to the outer cylinder by thread, a seal ring IV mounted to the end cap, and a nozzle II mounted in the end cap by threaded connection. The present invention achieves integrated operation of conventional drilling and draw-back expanding, which can effectively solve the problems that the existing hydrate drill bit cannot drill a large borehole, cannot mechanically lock an extending position of the blade to stabilize the size of the borehole, and a single crushing method is inefficient.

Abstract: This disclosure relates in general to a method and system for controlling a drilling system for drilling a borehole in an earth formation. More specifically, but not by way of limitation, embodiments of the present invention provide systems and methods for controlling dynamic interactions between the drilling system for drilling the borehole and an inner surface of the borehole being drilled to steer the drilling system to directionally drill the borehole. In another embodiment of the present invention, data regarding the functioning of the drilling system as it drills the borehole may be sensed and interactions between the drilling system for drilling the borehole and an inner surface of the borehole may be controlled in response to the sensed data to control the drilling system as the borehole is being drilled.

Abstract: A method of milling a window through a casing in a primary well bore and drilling a sidetracked well bore into a formation including running a drilling assembly including a body having an axis defined therethrough, a piston that is movable within a cavity formed in the body, a stationary cutting structure coupled to the body, and a movable cutting structure coupled to the body, milling a window through the casing in a first trip into the primary well bore, drilling the sidetracked well bore in the first trip into the primary well bore, applying a differential pressure across the piston, and moving the movable cutting structure from the collapsed position to the expanded position. The movable cutting structure is coupled to the piston and is movable between a collapsed position and an expanded position.

Abstract: Described herein is a reamer tool (100) having a body (105) with bays (115) in which cutter arms (110) are mounted for deployment between a stowed position and a deployed position. A deployment mechanism is provided for deploying the cutter arms from their stowed position to their deployed position that maintains each cutter arm in a position that is substantially parallel to a longitudinal axis of the body (105) whilst in its stowed position and in its deployed position as well as during its deployment from its stowed position to its deployed position. A control module (300) is also described for controlling the deployment of the cutter arms (110). The control module (300) comprises a motor (310), a gearing mechanism (315) and a moveable element (320) that closes a port (385) in a first position and opens the port (385) in a second position.

Abstract: The present specification describes a drill bit for drilling a cavity. The drill bit may include a chassis, a plurality of gauge pad sets, and at least one gauge pad structure. The chassis may be configured to rotate about an axis. The plurality of gauge pad sets may each include at least one gauge pad. The at least one gauge pad structure may moveably couple at least one of the gauge pads of at least one of the plurality of gauge pad sets with the chassis.

Abstract: This disclosure relates in general to a method and system for controlling a drilling system for drilling a borehole in an earth formation. More specifically, but not by way of limitation, embodiments of the present invention provide systems and methods for controlling dynamic interactions between the drilling system for drilling the borehole and an inner surface of the borehole being drilled to steer the drilling system to directionally drill the borehole. In another embodiment of the present invention, data regarding the functioning of the drilling system as it drills the borehole may be sensed and interactions between the drilling system for drilling the borehole and an inner surface of the borehole may be controlled in response to the sensed data to control the drilling system as the borehole is being drilled.

Abstract: Expandable apparatus for use in subterranean boreholes include a tubular body having at least one opening and at least one member positioned within the at least one opening. The member is configured to move between a retracted position and an extended position. A sleeve member including a constricted portion may be disposed in the tubular body and may selectively retain the at least one member in the retracted position. In some embodiments, the sleeve member may be biased in an initial position. Methods of moving a member of an expandable apparatus include repeating retracting and expanding of the member. Methods of triggering an expandable apparatus include forming a constriction in a fluid flow path extending through a sleeve member to move the sleeve member in a downhole direction responsive to fluid flow.

Abstract: A drill bit direction system and method is disclosed that modifies or biases the stochastic movement of the drill bit to change a drilling direction of a drilling system. The direction of the drill bit is monitored to determine if the direction happens to align in some way with a preferred direction. If the direction isn't close enough to a preferred or desired direction, stochastic motion of the drill bit in the borehole may be controlled and/or motion of the drill bit under a side force acting on the drill bit to direct the drilling may be focused or biased to modify the direction of drilling closer to the preferred direction. Any of a number of stochastic motion control mechanisms or biasing mechanisms can be used. Some embodiments can resort to conventional steering mechanisms to supplement the stochastic motion control or side force biasing mechanisms.

Abstract: Described herein is a reamer tool (100) having a body (105) with bays (115) in which cutter arms (110) are mounted for deployment between a stowed position and a deployed position. A deployment mechanism is provided for deploying the cutter arms from their stowed position to their deployed position that maintains each cutter arm in a position that is substantially parallel to a longitudinal axis of the body (105) whilst in its stowed position and in its deployed position as well as during its deployment from its stowed position to its deployed position. A control module (300) is also described for controlling the deployment of the cutter arms (110). The control module (300) comprises a motor (310), a gearing mechanism (315) and a moveable element (320) that closes a port (385) in a first position and opens the port (385) in a second position.

Abstract: A method or corresponding apparatus in an example embodiment of the present invention relates to penetrating a particulate substrate using a compact, lightweight, low-energy, reversible, and dynamic device for burrowing through particulate substrates. In one preferred embodiment, the apparatus includes at least one vessel and a displacement module coupled with the vessel. The actuation of the displacement module fluidizes the particulate substrate proximate to the vessel and thereby reduces resistance of the particulate substrate to movement of the vessel and causes further penetration of the apparatus through the particulate substrate. The example embodiment utilizes volume contraction and localized fluidizing to efficiently move through substrates.

Abstract: A method or corresponding apparatus in an example embodiment of the present invention relates to penetrating a particulate substrate using a compact, low-energy, reversible, and dynamic device for burrowing through particulate substrates. In one preferred embodiment, the apparatus includes at least one vessel and a displacement module coupled with the vessel. The actuation of the displacement module fluidizes the particulate substrate proximate to the vessel and thereby reduces resistance of the particulate substrate to movement of the vessel and causes further penetration of the apparatus through the particulate substrate. The example embodiment utilizes volume contraction and localized fluidizing to move through substrates.

Abstract: A drill bit assembly comprising a bit body connectable to a tubular drill string, and provided with a longitudinal passageway for an operating tool; an externally removable closure element for closing the passageway for the operating tool; and a passage tool attached to or connectable to the closure element in its closing position, wherein the passage tool comprises a lower part to which the closure element is attached or connectable, which lower part is arranged so that it can be moved out of the bit body together with the closure element, and an upper tubular part which is arranged so that it can be moved along the passageway in the bit body, the upper tubular part forming a passage with a downstream opening for the operating tool when the lower part of the passage tool has been moved out of the bit body.

Abstract: An apparatus and method for forming a borehole in an earthen formation includes a side cutting device comprised of a laterally extendable side cutting element that can be actuated from a retracted position to an extended position in which the side cutting element is selectively employed to create a larger borehole diameter in a down hole location than the remaining portion of the borehole that is closer to the borehole opening.

Abstract: An expandable apparatus for use in a borehole includes a tubular body having at least one opening extending between a longitudinal bore of the tubular body and an outer surface of the tubular body and at least one member positioned within the at least one opening of the tubular body. The at least one member is configured to move between a retracted position and an extended position. An actuation structure is positioned within the tubular body. The actuation structure is coupled to the at least one member and is configured to move the at least one member from the retracted position to the extended position responsive to a flow rate of drilling fluid passing through the longitudinal bore.

Abstract: A method of milling a window through a casing in a primary well bore and drilling an enlarged sidetracked well bore comprises running into the primary well bore a drilling assembly comprising at least one cutting apparatus adapted to drill an enlarged borehole, milling a window through the casing, and drilling the enlarged sidetracked well bore, wherein the milling and drilling steps are performed in one trip into the primary well bore. A drilling assembly comprises at least one cutting apparatus operable to drill an enlarged borehole, wherein the drilling assembly is operable to mill a window through a casing in a primary well bore and drill an enlarged sidetracked well bore through the window in one trip into the primary well bore.

Abstract: A drill bit direction system and method is disclosed that modifies or biases the stochastic movement of the drill bit and/or stochastic interactions between the drill bit and an inner-wall of a borehole being drilled by a drilling system to change the direction of drilling of the drilling system. The direction of the drill bit is monitored to determine if the direction happens to align in some way with a preferred direction. If the direction isn't close enough to a preferred direction, a biasing mechanism modifies the stochastic movement in an attempt to modify the direction closer to the preferred direction. Any of a number of biasing mechanisms can be used. Some embodiments can resort to conventional steering mechanisms to supplement the biasing mechanism.

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: 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.

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: 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: Window reaming and coring apparatus has a reamer connected in the middle of the tool by mechanical joints which permit the reamer to be displaced substantially parallel to the rest, of the tool body. The apparatus is lowered adjacent a pre-determined zone of interest and mills a parallel window along the edge of an existing wellbore into which the reamer is displaced. Once the reamer is fully displaced laterally into the window, the reamer and coring head can be rotated parallel to the wellbore, in the zone of interest for obtaining and retrieving a crescent-shaped core which has a significant cross section and length, enabling improved analysis of the wellbore lithography.

Abstract: A borehole reamer which may be deployed to a desired depth in an existing uncased borehole or below existing casing and used to substantially expand the diameter of the borehole. The diameter may be expanded by an amount that ranges from a fraction to a multiple of the original diameter of the borehole. In this fashion, geological formations containing oil, gas or groundwater which were previously uneconomical to produce may be worked into a condition of economical production. In a preferred embodiment, the borehole reamer is formed as an elongated assembly having an outside diameter which is sized to fit within a diameter of a conventional borehole. The assembly is preferably attached to drill pipe and lowered into a borehole to an appropriate depth corresponding to a pay zone of interest. A lower portion of the assembly, which is located at the deeper depth in the borehole, is constructed in the form of a bellows which functions as a pilot/anchor for the assembly.

Abstract: The present application relates to a tool having a cutting means for enlarging a portion of an underground pile shaft. The tool is provided with a collecting means which is disposed below the cutting means in order that spoil generated when performing a cutting action on ground material surrounding the pile shaft can be collected. The size of the collecting means is adjustable thereby allowing the volume of spoil which may be accommodated by the collecting means to be varied. A compacting device for compressing the spoil collected in the collecting means may also be provided for reducing the volume of the spoil.

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: An underreamer for forming a cavity within a well bore is provided. The underreamer may include a housing rotatably disposed within the well bore. The underreamer may also include an actuation rod slidably positioned in the housing. The underreamer may further include a plurality of cutter sets where each cutter set is pivotally coupled to the housing and the actuation rod. The cutter sets are also pivotally coupled together. An axial force applied to the actuation rod operates to slide the actuation rod relative to the housing and extend the cutter sets from a retracted position radially outward relative to the housing to form the cavity when the housing is rotated.

Abstract: An underreamer for forming a cavity within a well bore is provided. The underreamer may include a housing rotatably disposed within the well bore. The underreamer may also include a sleeve slidably positioned around the housing. The underreamer may further include at least one cutter set where each cutter set is pivotally coupled to the housing and the sleeve. An axial force applied to the sleeve operates to slide the sleeve relative to the housing and extend each cutter set from a retracted position radially outward relative to the housing to form the cavity when the housing is rotated.

Abstract: A 2-stage underreamer for use in a subterranean wellbore includes a unitary body having upper and lower blades mounted in slots formed perpendicular to each other in the body. Separate upper and lower piston assemblies are provided for driving the blades respectively from a storage configuration in which they are located substantially completely within the slots to a use position. The blades each include a steel arm having mounted thereon a base of tungsten nickel cobalt matrix in which diamond and/or tungsten carbide inserts are provided. A signal is given to the surface that the blades are in their extended position by changing the mud.

Abstract: A drilling tool, for example a core barrel inner tube assembly or a drilling bit, is attached to the inner end of a latch body which is removably seatable on a landing shoulder of a drill string. The inner end of the latch body mounts a drilling tool such as a core receiving tool or a drag bit. An overcenter toggle latch assembly is mounted to the latch body, the latch assembly including a pair of latches having inner ends pivotally mounted to the latch body, toggle links that at their one ends are pivotally connected to the outer ends of the latches and at their opposite ends have a retractor link extended through elongated slots. The retractor pin is extended through an axially elongated slot in the latch body to limit the axial movement of the pin between a position that the latches are locked in a latch seated position and a position retracting the latch body and the drilling tool attached thereto.

Abstract: A hydraulically operated underreamer or reamer for enlargement of boreholes is to be connected to a rotating drill string. An outer movable cylinder extends the entire length of the reamer for protection of inner parts thereof. Cutter support arms are movable rectilinearly between an operative state whereat they extend from the cylinder and a closed state whereat they are completely retracted within the cylinder. Cutters are mounted on the support arms and are rectilinearly movable with support arms through openings in the cylinder.

Abstract: An ice auger includes a pair of ice boring blades fixedly attached to the bottom of a straight inner auger drive bar. A brace and bit arrangement at the top of the drive bar is for rotating the drive bar and either forcing it down toward the ice to bore a cylindrical hole of predetermined diameter through the ice or to force it up away from the ice after the hole has been bored to ream out a portion of that hole to form an inverted funnel shape opening. A tubular outer sleeve surrounds the drive bar and is movable between an upper boring condition and a lower reaming condition with respect to the drive bar. Two slotted longitudinally extending ice reaming blades are pivotally mounted at their top portions to the ream control sleeve. A reaming blade camming support bar attached to a bottom portion of the drive bar carries camming pins slidable in the reaming blade slots.

Abstract: A divided bucket type rotary excavator comprises cutter units constructed by dividing a bottomed cylindrical bucket into plural portions, whose curved sidewalls and bottom plates are provided with bits on their leading edges. The cutter units are arranged about a center shaft radially movably toward and away from the center shaft.The center shaft consists of an outer hollow cylinder having a polygonal cross-section and an inner hollow cylinder slidably fitted in the outer hollow cylinder.

Abstract: A bore hole enlarging method and arrangement for connection with a rotary pipe string includes inner and outer body sections which form a body structure to provide a fluid flow path therethrough for communicating with piston and cylinder means formed between the body sections for receiving drilling fluid to effect telescopic movement between the body sections. Cutter arms are pivotally mounted on the inner body section and a cooperable support arrangement on the cutter arms and outer body section cooperate to expand or move the cutter arms outwardly of the body structure upon telescopic movement of the body sections in one relative direction and assist in attracting the cutter arms when desired.

Abstract: An under reaming pile bore excavating bucket by which an under reamed part of a pile bore is excavated and the excavated soil is moved into the bucket for easy removal of the soil. In use, the bucket is lowered to the bottom of an already excavated straight pile bore; side apertures of the bucket are opened; the slidable wing drill bits are rotated and moved downward and outward along guide rails to excavate an under reamed part. The excavated soil is taken into the bucket through the side apertures and openable bottom apertures. When the drill bits reach their lowermost position, the drill bits are rotated reversely to house the drill bits again into the bucket and lastly the side apertures are closed. The soil within the bucket is raised from the excavated pile bore. In particular, a drive shaft is spline engaged with an outer pipe fixed to the center of the bucket body for allowing the slidable bits to rotate and further move downward or outward.

Abstract: An improved rotary expansion tool for reaming frustoconical undercuts in the walls of cylindrical holes is disclosed. The tool is comprised of an elongated sheath with a ram disposed in sliding engagement therein. The ram is provided with an enlarged head which is biased away from the open end of the sheath into which the ram is placed. A load bearing collar is disposed around the sheath intermediate the ends for governing the depth of insertion of the tool into a hole being undercut, and the longitudinal placement of the collar along the sheath can be varied in order to select the depth to which the tool is inserted into the hole. A stop ring is circumferentially disposed around the open end of the sheath to provide a stop for limiting the longitudinal progression of the ram into the sheath, and the longitudinal placement of the stop ring can be varied in order to selectively vary the distance the ram can be pushed into the sheath against the bias of the spring.

Abstract: A hole groover comprising a pair of grooving bits radially protruding from the surface of a drill rod and connected to swivel upwardly and downwardly near the end of the drill rod where the drill bit is connected. A connecting rod is connected to the inside ends of the groove bits and causes arcuate movement of the grooving bits as it reciprocates. The hole groover further includes a gear box which is connectable to a rotary drilling unit which converts rotational movement of the rotary drill until to reciprocating movement of a lever. The lever is connected to the connecting rod which causes movement of the grooving bits. The device is readily adaptable to be connected to most rotary drill units and the depth and intervals of the grooves can be easily controlled by adjusting the length of the grooving bits and the gear ratios. The device enables grooves to be cut in a wall hole surface, concurrently with the drilling of the hole.

Abstract: An improved expansible rotary power tool for reaming frustoconical undercuts in cylindrical holes contained in dense concrete, such as flint and chert aggregates, comprises a tool having a hollow elongated sheath provided with a pair of opposing longitudinal slots adjacent to the cutting end of the tool. An upwardly biased tubular ram is reciprocally disposed within the sheath and is provided with a clevis at its cutting end which extends into the longitudinal slots, and a power engaging head at the end of the tool which projects out of hole being undercut. A load bearing collar mounted adjacent the power engaging end of the tool provides a stop against which the tool rests to determine the degree of advancement of the tool into the hole.

Abstract: An under-reaming pile bore excavator by which a straight pile bore is first excavated vertically to a given depth by rotating the main drill bits and the under-reamed bore is next excavated downward and outward into a given shape by rotating the slidable wing bits. The under-reaming pile bore excavator of the present invention comprises a plurality of guide rails, and a plurality of slidable wing bits mounted on the guide rails which excavate the under-reamed bore, in addition to the conventional main drill bits which excavate the straight pile bore. In using the under-reaming pile bore excavator of the present invention, it is possible to obtain a stable impermeable soil surface on the excavated bore to prevent water from penetrating into the soil wall and to prevent lumps of soil from being dislodged therefrom.

Abstract: A method and an apparatus for excavating pile holes of various shapes, including a pile hole with a widened bottom and a pile hole with a widened top and widened bottom, by means of an excavating bit and widening bits.

Abstract: A drilling tool for drilling a cylindrical borehole of relatively great depth in a soft material and then forming a conical enlargement adjacent the bottom of the borehole includes an axially elongated tool shank with a first drill at one end for cutting the cylindrical borehole and a second drill adjacent the first drill for cutting the conical enlargement. The second drill is formed of bit holders pivotally connected to a flattened part of the tool shank. An adjustable stop is provided on the tool shank for determining the depth of the borehole. A connecting link guide located within the tool shank interengages the bit holders and the tool shank. When the desired depth is reached, due to relative axial displacement between the tool shank and the connecting link guide, the bit holders are pivoted outwardly so that the second drill can cut the conical enlargement.

Abstract: A mining auger comprises a cutting head carried at one end of a tubular shaft and a plurality of wall segments which in a first position thereof are disposed side by side around said shaft and in a second position thereof are disposed oblique to said shaft. A vane projects outwardly from each wall segment. When the wall segments are in their first position, the vanes together form a substantially continuous helical wall. A cutter is mounted on the peripheral edge of each of the vanes. When the wall segments are in their second position, the cutters on the vanes are disposed radially outward from the perimeter of the cutting head.

Abstract: An under-reaming pile bore excavator by which a straight pile bore is first excavated vertically to a given depth by rotating the main drill bits and the under-reamed bore is next excavated downward and outward into a given shape by rotating the slidable wing bits. The under-reaming pile bore excavator of the present invention comprises a plurality of guide rails, and a plurality of slidable wing bits mounted on the guide rails which excavate the under-reamed bore, in addition to the conventional main drill bits which excavate the straight pile bore. In using the under-reaming pile bore excavator of the present invention, it is possible to obtain a stable impermeable soil surface on the excavated bore to prevent water from penetrating into the soil wall and to prevent lumps of soil from being dislodged therefrom.

Abstract: Cables attached to a rotating Kelly nut of a drill rig serve to maintain the vertical level of pivot points of bell-cutting blades while the blades are swung outwardly about these stationary pivot points to cut a bell for a drilled hole. The bell cuttings gravitate to the bottom of the drilled hole which is disposed a predetermined distance below the location of the bell.

Abstract: Process and apparatus is described for mining of subterranean carbonaceous deposits such as tar sands, in which the deposit is treated in situ with circulating high pressure jets of heated mining fluid comprising water in admixture with gaseous hydrocarbons, or carbon dioxide and the deposit is also subjected substantially simultaneously to mechanical grinding in the vicinity of application of the circulating jets, so as to free and grind the deposit and float the separated carbonaceous portion to the surface. The mining tool has an umbrella-like action, comprising a plurality of mining arms carrying jets and potatable mining teeth or cutters, the tool being rotatable down hole to mine the deposit, and the mining arms thereof being radially expandable below ground, so as to enlarge a pilot hole drilled initially, into a large production hole for large scale mining projects.

Abstract: A combination drilling and belling apparatus includes a frame having at one end a drilling area for drilling a borehole in the earth. A pair of belling arms are pivotally carried by the frame and are selectively movable between a drilling position and a non-drilling position. The belling arms have a drilling surface such that when the belling arms are moved to the drilling position and the apparatus is rotated, the belling arms same form an enlarged bell-shaped cavity. When the belling arms are in a non-drilling position, a valve means is provided for closing an opening through a side wall of a drilling mud flow conduit, thereby preventing flow of drilling mud through the opening. When the belling arms are in the drilling position, the valve means is moved to an open position whereby drilling mud can flow from the cavity through the opening and upwardly through the conduit, carrying the cuttings therewith.

Abstract: An underreaming tool with cutter arm position indication. An elongated body portion has a coupling for coupling one end thereof to a lower end of a lower drill string. A pair of arms are pivotally mounted on the body portion. Means is provided for relatively positioning the cutter arms apart in a cutting position and closer together in a non-cutting position and having an overridable condition wherein either of the cutter arms may be either in a cutting or a non-cutting position. A fluid passage is provided in the body portion comprising an input port at one end of the body portion and first and second output ports. One output port is adjacent to each of the cutter arms.

Abstract: An underreamer includes a housing and a plurality of underreamer doors, each including a toggle mechanism for selectively extending and retracting the doors. Upon activation of the toggle mechanism thereby extending the doors, the doors are pivoted outwardly from the housing and the tops of the doors are simultaneously moved downwardly. In this manner the overall vertical height of an underreamer adapted to form a given diameter excavation may be substantially reduced.