Abstract: A retrievable whipstock assembly for a wellbore includes a whipstock including a longitudinal body and an anchor connection, a deflection surface provided on the longitudinal body with a first engagement element, and a drilling assembly including a drill housing and a second engagement element. The second engagement element is selectively extendible between a recessed position and an extended position. In the extended position the second engagement element is engageable with the first engagement element.

Abstract: The present invention relates to a downhole tool for guiding a device into a side track of a borehole, the tool having a tool axis and comprising a tool housing connected to an energy source. The invention further relates to a method for moving the downhole tool into a side track.

Abstract: A device useful for conducting lateral or transverse excavating operations within a wellbore comprising a rotating drill bit with jet nozzles on a flexible arm. The arm can retract within the housing of the device during deployment within the wellbore, and can be extended from within the housing in order to conduct excavation operations. A fluid pressure source for providing ultra high pressure to the jet nozzles can be included with the device within the wellbore. The device includes a launch mechanism that supports the arm during the extended position and a positioning gear to aid during the extension and retraction phases of operation of the device.

Abstract: A rotary vector gear for controlling longitudinal axis offset about a central longitudinal axis is disclosed. The device uses single rotary motion through a rotary vector gear to produce hypotrochoidic offset similar to a flower petal and is capable or ready return to zero offset. The device may be used in downhole rotary steerable oil and gas drilling tools and in computer controlled milling machines for providing controlled offset.

Abstract: An assembly for sidetracked drilling in a wall of a borehole previously drilled or cored in a formation includes a guide element and an expansible device fixed to the front end of the guide element operable to be selectively expanded by an actuation means. A sidetracking channel is formed in the guide element in alignment with an internal space, upstream of the expansible device in the direction of advance. A longitudinal cavity is formed in the guide element parallel to the longitudinal axis and arranged to allow passage from the internal space to the actuation means of the expansible device. Within the internal space of the guide element, an external tube of the core barrel includes a core bit fixed to the front end of the external tube and arranged to slide, after having been released, in the internal space and in the sidetracking channel and then progress to the formation.

Abstract: A drilling device for producing undercut holes. The drilling device includes a drilling tool having an axis of rotation and a cutting portion arranged such that the cutting portion drills a hole with a longitudinal axis that is radially offset with respect to said axis of rotation and a centering device operable to apply a lateral force to said drilling tool for moving said axis of rotation towards said longitudinal axis to cause said cutting portion to form an undercut in a said hole.

Abstract: An assembly for sidetracked drilling in a wall of a borehole previously drilled or cored in a formation includes a guide element and an expansible device fixed to the front end of the guide element operable to be selectively expanded by an actuation means. A sidetracking channel is formed in the guide element in alignment with an internal space, upstream of the expansible device in the direction of advance. A longitudinal cavity is formed in the guide element parallel to the longitudinal axis and arranged to allow passage from the internal space to the actuation means of the expansible device. Within the internal space of the guide element, an external tube of the core barrel includes a core bit fixed to the front end of the external tube and arranged to slide, after having been released, in the internal space and in the sidetracking channel and then progress to the formation.

Abstract: A splitter assembly 10 is positioned downhole within a conductor 50 for separating two or more tubular strings placed within the conductor. A splitter housing may include a first bore 26 and a second bore 28 for separating a first well from a second well, and a plug 24 positioned in one of the bores including a top face 25 sloping downwardly toward the other bore. One or more guide plates 18 secured to the splitter housing and positioned above the plug guide a bit or other tool toward one of the first bore and the second bore. The splitter housing 10 may be positioned along the conductor 50 after the conductor is jetted in place. According to the method, the plug in one of the bores is retrieved after a casing is run in one well, so that the second bit and the second casing will pass through the bore which previously included the plug.

Abstract: A whipstock assembly includes a whipstock body 8 having a whipstock center of gravity offset radially from the central axis of the whipstock body, a counterweight to releasably secured to the whipstock body, with a counterweight having an offset counterweight center of gravity, an orientation device 5, and a neutralizer 11. The neutralizer causes the combined whipstock/neutralizer center of gravity to be substantially closer to the central axis of the whipstock body compared to the whipstock center of gravity. An attaching mechanism 6, 12 allows the neutralizer to be returned to the surface after the whipstock body is set in the well.

Abstract: A lockable motor assembly for use in a well bore comprises a PDM motor having a rotor and a stator. A locking member has a splined projection which is received within a splined recess of the rotor and external splines which mate with splines provided on a sub connected to the stator. The components are held in this configuration by a shear ring until the fluid pressure within a chamber defined between the locking member and the sub is sufficient to cause the shear ring to shear. The locking member may then move out of the engagement with the rotor to free the motor for operation. The locking member is held in this position by a ratchet mechanism.

Abstract: Apparatus and methods are provided which enhance drilling and completion of wellbore intersections. In a described embodiment, a cutting tool diverter is used to drill a branch wellbore extending outwardly from a main wellbore. The diverter is provided with an outer easily millable portion which reduces the amount of time needed to retrieve the diverter. In another embodiment, a substance is injected into a formation surrounding the intersection of the main and branch wellbores, to thereby facilitate sealing of the intersection.

Abstract: A drilling shaft deflection assembly for a drilling direction control device of the type comprising a rotatable drilling shaft and a housing for supporting a length of the drilling shaft for rotation therein. The deflection assembly is contained within the housing and is axially located between a first support location and a second support location for bending the drilling shaft between the first support location and the second support location. The deflection assembly includes a deflection mechanism for imparting lateral movement to the drilling shaft to bend the drilling shaft, a deflection actuator for actuating the deflection mechanism in response to longitudinal movement of the deflection actuator, and a deflection linkage mechanism between the deflection mechanism and the deflection actuator for converting longitudinal movement of the deflection actuator to lateral movement of the drilling shaft.

Abstract: The side tracking system includes a window mill having a full diameter cutting surface and a reduced diameter tapered cutting surface and a whipstock having a ramp engaging the reduced diameter cutting surface. The materials of the whipstock have a first cutablity and the materials of the casing have a second cutability. The reduced diameter cutting surface contacts the whipstock ramp at a first contact area and the full diameter cutting surface contacts the wall of the casing at a second contact area. As weight is applied to the mill, there is a first contact stress at the first contact area and a second contact stress at the second contact area. A cutability ratio is the first cutability divided by the second cutability and a contact stress ratio is the first contact stress divided by the second contact stress. The mill cuts the casing rather than the whipstock by maintaining the product of the cutability ratio and the contact stress ratio less than one.

Abstract: Apparatus for boring a hole from an inside of a casing outwardly at an angle relative to a longitudinal axis of the casing comprises a drill shoe having a longitudinal axis and being positionable in the casing, the shoe having first and second passageways which converge into a third passageway exiting the shoe, a torsional load transmitting element and a cutting element connecting to one end of the torsional load transmitting element, the torsional load transmitting element and cutting element being positioned in the first passageway during non-use and in the third passageway during use, and a fluid conduit and a nozzle connected to one end of the fluid conduit, the fluid conduit and nozzle being positioned in the second passageway during non-use and in the third passageway during use.

Abstract: The well reference apparatus and method of the present invention includes an anchor member with a orientation member preferably permanently installed within the borehole at a preferred depth and orientation in one trip into the well. The orientation member provides a permanent reference for the orientation of well operations, particularly in a multi-lateral well. The assembly of the present invention includes disposing the anchor member and orientation member on the end of a pipe string. An orienting tool such as an MWD collar is disposed in the pipe string above the anchor member. This assembly is lowered into the borehole on the pipe string. Once the preferred depth is attained, the MWD is activated to determine the orientation of the orientation member. If the orientation member is not oriented in the preferred direction, the pipe string is rotated to align the orientation member in the preferred direction.

Abstract: Apparatus for boring a hole from an inside of a tube outwardly perpendicular to a longitudinal axis of the tube comprises a drill shoe having a longitudinal axis and being positionable in the tube, the shoe having an inlet, an outlet perpendicular to the shoe longitudinal axis and a passageway connecting the inlet and outlet, a torsional load transmitting element having no torsional flexibility in relation to its bending flexibility, having a longitudinal axis and being disposed in the passageway, the torsional load transmitting element being movable relative to itself with no resistance about first and second perpendicular axes both of which are perpendicular to the longitudinal axis of the torsional load transmitting element, a hole saw connected to one end of the torsional load transmitting element and a motor rotatably connected to the other end of the torsional load transmitting element.

Abstract: A method and apparatus for predictable downhole milling of a casing window having predetermined location, orientation, dimension and contour geometry. An elongate substantially rigid milling shaft has at least one casing window milling element in fixed relation therewith and has a pilot mill in articulated and rotary driven connection with the milling shaft. The milling shaft is in articulated and rotary driven connection with a rotary drive mechanism. The articulated connection of the pilot mill and milling shaft may incorporate an articulation control system to permit the pilot mill to be maintained substantially coaxial with the milling shaft so that its trajectory at a predetermined stage of window milling can be controlled by the milling shaft when positive guiding by a deflecting tool can no longer be ensured.

Abstract: The invention concerns a method which consists in: introducing into a pre-drilled portion of a well (16) a drilling system comprising a drilling bit (11) assembled with tubular lining elements (15), means for measuring the inclination and azimuth direction of said pre-drilled part of the well, means for rotary friction (26, 27) against the wall of said pre-drilled part and controlled means capable of modifying the friction coefficient of said friction means against the wall; measuring the azimuth direction of the pre-drilled part of the well (16); and varying the friction coefficient of said friction means (26, 27) sufficiently to influence the azimuth direction of the next well portion to be drilled.

Abstract: Apparatus for boring a hole from an inside of a tube outwardly perpendicular to a longitudinal axis of the tube comprises a drill shoe having a longitudinal axis and being positionable in the tube, the shoe having an inlet, an outlet perpendicular to the shoe longitudinal axis and a passageway connecting the inlet and outlet, a torsional load transmitting element having no torsional flexibility in relation to its bending flexibility, having a longitudinal axis and being disposed in the passageway, the torsional load transmitting element being movable relative to itself with no resistance about first and second perpendicular axes both of which are perpendicular to the longitudinal axis of the torsional load transmitting element, a hole saw connected to one end of the torsional load transmitting element and a motor rotatably connected to the other end of the torsional load transmitting element.

Abstract: Apparatus for boring a hole from an inside of a casing outwardly at an angle relative to a longitudinal axis of the casing comprises a drill shoe having a longitudinal axis and being positionable in the casing, the shoe having first and second passageways which converge into a third passageway exiting the shoe, a torsional load transmitting element and a cutting element connecting to one end of the torsional load transmitting element, the torsional load transmitting element and cutting element being positioned in the first passageway during non-use and in the third passageway during use, and a fluid conduit and a nozzle connected to one end of the fluid conduit, the fluid conduit and nozzle being positioned in the second passageway during non-use and in the third passageway during use.

Abstract: The side tracking system includes a window mill having a full diameter cutting surface and a reduced diameter tapered cutting surface and a whipstock having a ramp engaging the reduced diameter cutting surface. The materials of the whipstock have a first cutablity and the materials of the casing have a second cutability. The reduced diameter cutting surface contacts the whipstock ramp at a first contact area and the full diameter cutting surface contacts the wall of the casing at a second contact area. As weight is applied to the mill, there is a first contact stress at the first contact area and a second contact stress at the second contact area. A cutability ratio is the first cutability divided by the second cutability and a contact stress ratio is the first contact stress divided by the second contact stress. The mill cuts the casing rather than the whipstock by maintaining the product of the cutability ratio and the contact stress ratio less than one.

Abstract: Apparatus for boring a hole from an inside of a tube outwardly perpendicular to a longitudinal axis of the tube comprises a drill shoe having a longitudinal axis and being positionable in the tube, the shoe having an inlet, an outlet perpendicular to the shoe longitudinal axis and a passageway connecting the inlet and outlet, a torsional load transmitting element having no torsional flexibility in relation to its bending flexibility, having a longitudinal axis and being disposed in the passageway, the torsional load transmitting element being movable relative to itself with no resistance about first and second perpendicular axes both of which are perpendicular to the longitudinal axis of the torsional load transmitting element, a hole saw connected to one end of the torsional load transmitting element and a motor rotatably connected to the other end of the torsional load transmitting element.

Abstract: An assembly for formation and completion of deviated wellbores is disclosed which includes a toolguide and a casing section which can be used together or separately. The toolguide includes a lower orienting section and a whipstock having a sloping face, commonly known as the directional portion of a whipstock. The toolguide is coated with a material such as epoxy or polyurethane to provide a repairable surface and one which can be removed to facilitate removal of the toolguide from the well bore. The lower orienting section has a latch which extends radially outwardly from the section and can be locked in the outwardly biased position.

Abstract: A method and apparatus that comprises releasably securing a milling tool to a deflecting tool using a securing mechanism. The securing mechanism comprises a member that is adapted to be broken by milling action of the milling tool. In addition, in some arrangements, a protective mechanism protects abrasive inserts on a pilot mill of the milling tool.

Abstract: A one trip whipstock system includes both a one trip combination mill and associated whipstock. The one trip combination mill comprises an upper cutter and lower cutter below the upper cutter. The upper cutter and lower cutter are joined by a cone that widens towards the upper cutter. In operation, a whipstock is connected to the drilling sub by shear bolts. A guide lug on the whipstock faces the drilling sub between the lower cutter and upper cutter for riding on the cone when the drilling sub is advanced along the whipstock. Preferably the shear bolts connect to the lower cutter. Also, the lower cutter has smaller gauge than the upper cutter, to such an extent that the relative gauge sizes of the lower cutter and upper cutter permit the upper cutter to exit casing during drilling before the lower cutter exits casing. Further, there may be provided a watermelon mill and a string mill above the upper cutter and the watermelon mill, string mill and the upper cutter preferably have the same gauge.

Abstract: A method for replacing an old drive pipe in a slot on an offshore platform. The old drive pipe is first cut to provide an upper portion and a stub portion which remains firmly embedded in said marine bottom. Next, a guide cable is affixed to the stub portion of the old drive pipe and extends to the platform. The upper portion is then retrieved to the surface. A new drive pipe which carries a whipstock at its lower end is then made-up and lowered over the guide cable until the whipstock engages the stub portion where the new drive pipe is then diverted by the whipstock into a different path from that of the old drive pipe.

Abstract: A method and apparatus for predictable downhole milling of a casing window having predetermined location, orientation, dimension and contour geometry. An elongate substantially rigid milling shaft has at least one casing window milling element in fixed relation therewith and has a pilot mill in articulated and rotary driven connection with the milling shaft. The milling shaft is in articulated and rotary driven connection with a rotary drive mechanism. The articulated connection of the pilot mill and milling shaft may incorporate an articulation control system to permit the pilot mill to be maintained substantially coaxial with the milling shaft so that its trajectory at a predetermined stage of window milling can be controlled by the milling shaft when positive guiding by a deflecting tool can no longer be ensured.

Abstract: Down hole assembly and method for forming a longitudinal window and a key-way in communication with the longitudinal window used in drilling multi-lateral well bores and for entry and reentry thereafter comprising, a first milling drill bit for milling the longitudinal window, a first whip stock having a guide surface, and orientation and positioning members located on the first whip stock for orienting and positioning tools to be used in forming the key-way in communication with the longitudinal window. A guide surface member is provided on the first whip stock member for guiding the first milling drill bit for milling a longitudinal window. A housing member for slidable mating with the first whip stock having a second drill bit member mounted in the housing member is provided for forming a down hole orientation key-way in communication with the longitudinally milled window.

Abstract: A single trip whipstock assembly which can be run into a well, set, and operated from a window in the well casing in a single trip includes a milling tool (5) attached to the upper end of a whipstock (6) to the lower end of which is attached a packer (7) or anchor which can be set by appropriate means prior to detachment of the mill from the whipstock to initiate window formation. The packer may be hydraulic and may be set by means of a setting tool (4) located above the mill (5) and connected to the packer by a hose (21). The mill (5) incorporates circulation ports which are initially isolated from the central chamber thereof to permit flow of hydraulic fluid from the setting tool to the hose (21) via the interior of the mill. Once setting has been effected, the hose (21) is severed, permitting the piston of the setting tool to operate a flow diverter within the mill and open the circulation ports to the interior of the tool for subsequent drilling mud circulation during milling operation.

Abstract: A wellbore mill system having a first mill with a main body with a top end and a bottom end, milling structure on the main body, and a hook portion projecting from the bottom end of the main body for supporting at least one member below the first mill, the hook portion having a lip. One such system has a whipstock having a top lug, the top lug resting on the lip of the hook portion of the first mill, the top lug having a hole therethrough, the hook portion of the main body of the first mill having a hole therethrough, a shear stud with a portion extending through the hole in the top lug and a portion extending through the hole in the hook portion thereby releasably securing the first mill to the whipstock.

Abstract: Multiple drain drilling and production apparatus (16) comprising a generally cylindrical body (18) adapted to be located within a well, and an orienting assembly (24, 28) adapted to be received in the body (18) to deviate a drill string received within the body, at a predetermined depth, from a path coaxial with the body to a path at a predetermined angle to the axis of the body. The apparatus comprises at least one outlet (20) comprising a generally tubular element (42) received within the body and opening thereinto and displaceable from a first position generally coaxial with the body, into a second position at a predetermined angle thereto, by an actuator (200) received within the body, the orienting assembly being located adjacent the outlet (20).

Abstract: Wellbore operations (e.g. for milling and/or drilling) are disclosed which require a reduced number of tool trips into a wellbore to create a cut-out pocket or window in a tubular such as casing in the wellbore and, in some aspects, to continue into a formation adjacent a main wellbore forming a lateral wellbore in communication with the main wellbore. Preferably one trip is required. A milling apparatus has been invented with milling apparatus for milling a tubular member and a nose cone releasably connected to the milling apparatus and releasably connectible to a diverter that directs the milling apparatus toward the tubular member. A nose cone for a milling apparatus has been invented with a body member, the body member having a mid portion, a top portion and a lower nose portion, and the top portion releasably securable to the milling apparatus and the lower nose portion releasably securable to a concave of a whipstock.

Abstract: A whipstock for guiding a cutting tool within a cased borehole. The whipstock having a guide surface for guiding engagement with the cutting tool. The guide surface having a first taper with the axis of the whipstock and a greater taper with the axis of the whipstock at the point that the center of the cutting tool reaches the inside diameter of the wall of the casing thereby more quickly moving the center point of the cutting tool across the wall of the casing.

Abstract: An assembly for drilling multiple laterals (26) from a borehole and into a formation includes a whipstock assembly having a radially movable lug (82). An elongate tubular secured within the borehole has one or more non-ferrous portions (30) and a ferrous portion (52) adjacent and below a respective non-ferrous portion. A locator (54) is fixed within each ferrous portion at a desired axial spacing relative to the non-ferrous portion. According to the method of the invention, the whipstock assembly is lowered below the locator (54) and pulled upwardly to rotate the whipstock assembly to a selected azimuth within the tubular. The lug (82) on the whipstock assembly fits within the locator to axially position the whipstock face (97) within the non-ferrous portion of the tubular. A drill bit (96) engages the whipstock face and drills a window through the non-ferrous portion of the tubular and then into the formation.

Abstract: The retrieving tool includes a first mandrel having an upper end adapted for attachment to a running string, and a lower end. A second mandrel is positioned below the lower end of the first mandrel. The second mandrel and first mandrel are interconnected by a cam/grip link mechanism. An external actuator cylinder extends over the upper mandrel into attachment to the lower mandrel such that the cam grip mechanism is moved into engagement with the upper end of a whipstock by movement of the upper mandrel away from the lower mandrel and the cam grip mechanism is released by movement of the lower mandrel through its connection to the external actuator toward the upper mandrel.

Abstract: A starter mill adapted for use with a whipstock to mill a window through the casing of a well for deviating the direction of drilling. The starter mill includes a bearing nose which is utilized to indicate completion of the milling process. As the mill nears completion of the milling process, the bearing nose will become wedged between the whipstock face and the casing preventing further downhole movement. The bearing nose will engage whipstock and casing, allowing the work string to continue to rotate although the decreased torque resulting from the absence of milling provides a clear signal that the milling operation is complete. The cutters of the mill are spaced a predetermined distance from the bearing nose to ensure completion of the casing window.

Abstract: A retrievable whipstock which can be hydraulically set within a wellbore and following the drilling procedure mechanically released and retrieved for future use. The whipstock includes a whip which directs a milling tool from the main well and a hydraulically actuated packer or anchor for setting the whipstock in the wellbore. The retrieval tool includes a nose piece to ensure proper orientation relative to the whipstock and a die collar to threadably engage the whip. An adapter on the retrieval tool wedges the whip away from the casing wall to ensure mating engagement between the retrieval tool and the whip. The whipstock is released through the application of tension through the retrieval tool allowing removal from the wellbore.

Abstract: A retrievable whipstock/anchor assembly is used to allow drilling of additional wellbores from an original or primary wellbore (which may be a highly deviated or horizontal open wellbore). The retrievable whipstock assembly is comprised primarily of two sections, an anchor section and a whip stock section. The anchor section provides resistance to compression and rotation forces, and provides rigidity for the whipstock. The whipstock provides a support face for drilling the additional wellbores. The whipstock can be oriented radially to allow drilling at any radial angle, and can be set at any depth. Anchoring of the retrievable whipstock assembly is provided by means of an inflatable element which expands to grip the inside wall of the wellbore. Radial orientation can be provided by rotating the retrievable whipstock assembly from surface or other means until the whipstock is at the desired orientation.

Abstract: A retrievable whipstock which can be hydraulically set within a wellbore and following the drilling procedure mechanically released and retrieved for future use. The whipstock includes a whip which directs a milling tool from the main well and a hydraulically actuated packer or anchor for setting the whipstock in the wellbore. The whip includes ratchet teeth on its side edges for mating engagement with a retrieval tool. The retrieval tool includes a nose piece to ensure proper orientation relative to the whipstock and a clamping ring with ratchet teeth to engage the teeth of the whip. The whipstock is released through the application of tension through the retrieval tool allowing removal from the wellbore.

Abstract: A whipstock setting apparatus includes a whipstock with a mandrel secured thereto and depending therefrom. A cutter, or mill is connected to a work string and releasably connected to the whipstock. A packer assembly including a mechanical weight set packer and upper and lower cone and slip means are mounted on the mandrel above and below the packer. The mandrel is releasably connected to the packer assembly to prevent premature longitudinal movement therebetween and to accommodate relative longitudinal movement therebetween when desired.

Abstract: A one-trip whipstock assembly incorporating a hydraulically set anchor which includes an interlock for maintaining the anchor in its set position upon interruption of hydraulic pressure. The anchor is connected to the lower end of the assembly which also includes a whipstock for diverting cutting tools and a locator sub for positioning the assembly in the cased well bore. The whipstock assembly is designed to be run into the well using a running string or a mill attached to the upper end of the whipstock in order to locate and set the whipstock and mill the casing in only one trip.

Abstract: A directional drilling apparatus for drilling offset wellbores from a main borehole using a steering tool to orient a guidance tool body and wherein the tool body has a pair of angularly intersecting passageways including a first smaller passageway that communicates with a packer, and a second larger passageway that cradles a smaller drill string for drilling the offset boreholes and wherein the smaller drill string will not fit in the first smaller passageway.

Abstract: The present invention comprises a novel method and apparatus for sinking drill holes in underground rock formations while generating drill cores as rock samples. More particularly, the present invention discloses a method and apparatus which allows for an expanded analysis of ground formations over a larger area through the extraction of drill cores as rock samples. The method and apparatus herein disclosed allows one to drill a number of core shaft sections from the base of a main shaft section in various directions in order to obtain a number of sample cores.

Abstract: A directional guidance device, for deflecting a drill bit away from the longitudinal axis of a substantially horizontal section of a wellbore, takes advantage of gravitational force to move a deflector member therein between first and second positions. In the first position, the deflector member prevents the drill bit from advancing past the directional guidance device. In the second position, the deflector member allows the bit to pass out of the guidance device, and deflects the bit away from the longitudinal axis of the horizontal section of the wellbore.

Abstract: In order to salvage a slot path on an offshore platform wherein the original conductor pipe has become clogged or otherwise rendered unusable, the original conductor is cut off below mudline, thereby leaving a stub forming a base upon which a suitably oriented deflector trough is attached. A new or replacement conductor is installed along the same slot path until the deflector trough causes the new conductor to follow a deviated path so as to avoid the original conductor. The direction of the deflector trough is selected to avoid existing wells already driven from such structure.

Abstract: Directional drilling is carried out by orienting and positioning a whipstock having a curved guide surface at a predetermined rotational angle with respect to the desired azimuth so as to compensate for lateral deviation of the original bore or rathole. The curved guide surface of the whipstock is given a radius of curvature in a longitudinal direction corresponding to that of the drainhole section radius and is provided with a concave face in a transverse direction which defines lateral wings along the guide surface to control the advancement of the drilling tool along the desired course and avoid objectionable helixing. Proper orientation and guidance of the drill tool by means of the radius whipstock as described permits accurate determination of the drainhole orientation vertical drill distance between the zenith and nadir of the drainhole as well as the actual drilled depth between those points.

Abstract: Two methods and four mechanisms are disclosed for drilling at right angles to a vertical well at any location or depth in the well. The drilling mechanisms each comprises a flexible spring biased telescopic fluid conduit having a turbodrill on the lower end thereof for extending from an opening in the side of an elongated cylindrical housing for drilling at right angles to the well. The flexible spring biased telescopic fluid conduit comprises a plurality of axially aligned spools with cylinders interconnecting the adjacent ends of adjacent spools and with a compression spring in each cylinder between the two adjacent spool ends for permitting flexibility and telescopic action of the fluid conduit while resisting high compression and torque loads.