Abstract: A method of drilling vertical and horizontal pathways to mine for solid natural resources involves a drill bit, at least one reamer, a first plugging material, and a second plugging material; drilling a testing wellbore to a specific vertical depth with the drill bit and identifying at least one desired mining section wherein the desired mining section is associated with a corresponding vertical depth; creating a new bottom end for the testing wellbore by filling the testing wellbore up to an offset distance with the first plugging material; drilling a horizontal access hole from the new bottom end into the desired mining section with the drill bit and enlarging it with a reamer; excavating cuttings from the desired mining section through the horizontal access hole; filling the horizontal access hole with the second plugging material; and repeating the drilling, enlarging, and filling process to create a plurality of lateral holes.

Abstract: A directional drilling apparatus include a first cutter that substantially cuts a wellbore bottom along a first axis and a second cutter that cuts the wellbore bottom along a second axis different from the first axis. The second cutter may extend an adjustable amount out of the first cutter. The pilot string may connect the second cutter to the first cutter.

Abstract: A deflector assembly includes two deflectors that can cooperate for directing a bullnose assembly toward an intended bore in a multi-bore well based on a configuration of the bullnose assembly without requiring use of gravitational forces or requiring the assembly to be oriented in a certain manner. The deflectors can cooperate by being spaced by a certain amount that, depending on if the amount is less than or greater than a longitudinal length and diameter of a bullnose of the bullnose assembly, can allow the bullnose assembly to be diverted toward the intended bore.

Abstract: A whipstock features a spiral ramp so that, in a horizontal run, access to a milled window with other tools is not impeded because such tools can traverse onto the ramp and still be directed to the window. Angular rotation of the ramp can be at 180° or more and the pitch is selected to avoid getting the equipment being advanced into a bind. Optionally, a guide track can be configured into the whipstock ramp to help the mill follow the spiral path until the proper orientation is obtained and the track ends to allow separation of the mill from the track. A slot can be provided near the ramp upper end to aid in retrieval operations.

Abstract: Diameter based tracking for a window milling system. A window cutting system includes a cutting assembly with multiple cutting faces for cutting the window; and a diverter for guiding displacement of the cutting assembly relative to the window, the diverter including multiple separate guide paths for the respective multiple cutting faces. A method of cutting a window includes the steps of: positioning a diverter in a tubular string, the diverter including multiple separate guide paths for respective multiple cutting faces of a cutting assembly; and then contacting the guide paths with the cutting faces to thereby form the window. Another method of cutting a window includes the step of: positioning a diverter in the tubular string, the diverter including multiple separate guide paths for respective multiple cutting faces of a cutting assembly, with each of the guide paths providing a separate wear surface for the respective cutting face.

Abstract: A whipstock assembly for milling an aperture in a casing of an oil, gas or water well, the whipstock assembly having a whipstock with a deflection face (6) for deflecting a milling head of a milling device to cut through the casing. The whipstock has a plateau portion (7) raised above the plane of the deflection face to support the milling head as it engages the casing. The plateau can induce the milling device to pivot around one of the milling heads during some of the milling operations, which optimizes the stress applied to the heads of the milling device.

Abstract: Whipstocks and deflectors comprising a degradable composition, and methods of using same are described. A degradable composition may consist essentially of one or more reactive metals in major proportion, and one or more alloying elements in minor proportion, with the provisos that the composition is high-strength, controllably reactive, and degradable under defined conditions. Methods of using degradable whipstocks in oilfield operations are also described. This abstract allows a searcher or other reader to quickly ascertain the subject matter of the disclosure. It will not be used to interpret or limit the scope or meaning of the claims. 37 C.F.R. 1.72(b).

Abstract: A drilling system is presented for use in drilling lateral boreholes from a main borehole. The drilling system generally comprises a drilling machine, a drill string connected to the drilling machine so as to be driveable in an axial direction, and a guide connected to the drilling machine such that when the drill string is driven axially by the drilling machine, it interacts with the guide so as to be directed in a predetermined radial direction. A method of drilling a lateral borehole from a main borehole is also presented, comprising the steps of: positioning the drilling system in the main borehole; anchoring the guide in the borehole; operating the drilling machine to drive the drill string in an axial direction; and deflecting the drill string, by means of the guide, in a radial direction into the wall of the main borehole to drill the lateral borehole.

Abstract: A dual string drilling system for drilling a well bore in an earth formation, having a rotatable, tubular outer drill string and an upper rotatable, tubular inner drill string. An elongate tubular drill bit is mounted to a distal end of the outer drill string. The tubular drill bit having an interior passageway having a longitudinal axis which is inclined with respect to the longitudinal axis of the outer drill string. The drill bit is further provided with a cutaway portion extending through a wall of the tubular outer drill string. A lower rotatable inner drill string is coupled to the upper rotatable tubular inner drill string and is disposed within the interior passageway of the drill bit. A second drill bit is mounted to the distal of the lower inner drill string and is sized to extend beyond the drill bit mounted to the outer drill string.

Abstract: A sidetracking system has a pair of serially connected mills (8,9), each having a plurality of circumferentially arranged blades having a tapered cutting portion (82,93) thereon for cutting a window in a casing and then sidetracking in a formation. A whipstock has at least three axially spaced ramps, each ramp being interspaced by a substantially axially extending portion. Each of the ramps has the same angle of inclination to a longitudinal axis and the distance between the ramps is the same as the distance between the tapered portions on the mills (8,9) so that when, in operation, load is shared between both mills. The mills have a button (83,93) of hardened material located on the tapered cutting portions so that the button abrades the whipstock ramps (31,32,33).

Abstract: In accordance with one embodiment of the present invention, a method for drilling wellbores includes drilling a main wellbore, disposing a casing string having a deflecting member at a lower end thereof in the main wellbore, disposing a drill string having a drill bit at a lower end thereof in the casing string, and drilling, with the drill bit, a first lateral wellbore at a first depth in the main wellbore. The method further includes transferring the casing string to a second depth in the main wellbore that is less than the first depth, disposing a first temporary plug in the main wellbore at the second depth to prevent gas from flowing up the main wellbore past the second depth, transferring the casing string to a third depth in the main wellbore that is less than the second depth, and drilling, with the drill bit, a second lateral wellbore at the third depth.

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 method and apparatus for horizontally drilling in wells utilizing a shoe assembly at the down hole end of upset tubing. The shoe assembly includes a fixed section and a rotatable section suspended below the fixed section. An electric motor and associated batteries and a gyroscope carried on the rotatable section enable an operator on the surface to selectively rotate and position the rotatable section to any desired angular location for drilling a hole in the well casing. After one or more holes have been cut in the casing, a drill assembly can be removed from the upset tubing and be replaced by a high pressure blaster nozzle to bore into the formation zones. The gyroscope enables the operator to accurately position the rotatable section to the same locations at which the holes have been cut. The drill assembly includes an electric motor with an associated battery, flexible drive shaft, and a hole saw.

Abstract: In connection with a method and a tool for preparing a well for the production of hydrocarbons, it is aimed at perforating a casing portion (26) and working surrounding sediment (80) in a channel-forming manner. For this purpose the tool comprises a drilling means for drilling transverse holes through the casing wall when the tool (10), which is arranged to be raised/lowered and rotated about its longitudinal axis, shared by the casing (26), is placed in a fixed position within the well, through which transverse hole (40) and into surrounding sediment a jetting hose means (42,42a) is arranged to jet/dig its way in a channel-forming manner. The drilling and jetting hose means also have inactive stand-by positions protectively retracted within the tool housing (10a), from and into which they may successively be pushed forward into active working positions and again be withdrawn, as a channel (44) is completed in the sediment (80).

Abstract: A through tubing retrievable whipstock and installation method is disclosed. In the preferred embodiment, a plurality of anchor links pivot at one end and have wickers on an opposed rounded end. The links are configured to deliver an optimum contact angle with respect to the longitudinal axis of the whipstock in a variety of casing sizes and weights. A lock ring system holds the set position and the upper end is hinged and biased to stay out of the way of the mill or mills and yet be easy to engage by a retrieving tool.

Abstract: A method and apparatus for horizontally drilling in wells utilizing a shoe assembly at the down hole end of upset tubing. The shoe assembly includes a fixed section and a rotatable section suspended below the fixed section. An electric motor and associated batteries and a gyroscope carried on the rotatable section enable an operator on the surface to selectively rotate and position the rotatable section to any desired angular location for drilling a hole in the well casing. After one or more holes have been cut in the casing, a drill assembly can be removed from the upset tubing and be replaced by a high pressure blaster nozzle to bore into the formation zones. The gyroscope enables the operator to accurately position the rotatable section to the same locations at which the holes have been cut. The drill assembly includes an electric motor with an associated battery, flexible drive shaft, and a hole saw.

Abstract: A guide tube bundle includes two or more guide tubes. Each guide tube includes a first aperture at a first end and a second aperture at a second end. The longitudinal axis of the first aperture of each guide tube is offset from the longitudinal axis of the second aperture of the guide tube Furthermore, the guide tubes are configured longitudinally adjacent to each other and are twisted around one another.

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 one-trip through tubing window milling system is disclosed. The whipstock is delivered with the mill and downhole motor in a downhole assembly which further includes MWD equipment for proper whipstock orientation. The entire assembly is run through tubing and the MWD equipment orients the whipstock. A motor lock prevents the downhole motor from turning as fluid pressure is applied to properly anchor the whipstock below the production tubing. The motor lock is defeated and the milling commenced using the downhole motor. At the conclusion of the window milling, the bottom hole assembly, including the mill, is removed and a retrieving tool releases the whipstock for retrieval through the production tubing.

Abstract: The present invention generally provides an apparatus and method for forming a pilot hole in a formation. In one aspect of the present invention, the apparatus may comprise a starter mill connected to a bearing mill by a body joint. The apparatus may further comprise a lead bearing connected to a starter mill by a lead joint. Preferably, an outer diameter of the bearing mill is about the same as an inner diameter of a wellbore. As the lead bearing travels along the concave, the apparatus will bend between the bearing mill and the lead bearing. The bend urges the starter mill into contact with the wellbore wall. In another aspect of the present invention, a method for forming a pilot hole in a wellbore includes running a tool into the wellbore, the tool comprising a starter mill disposed between a first bearing and a second bearing. While running the tool along a concave of a whipstock, the tool bends between the first and second bearing and urges the starter mill to form the pilot hole.

Abstract: An improved method for drilling a lateral well from an existing wellbore is disclosed whereby a section of said existing wellbore is preferably enlarged such as by under-reaming. The enlarged section is filled with a material such as, for example, epoxy which hardens to form an impermeable body. The hardened material is drilled out laterally and also longitudinally, such that a sealed junction is formed within the impermeable body between the lateral well and existing well. The longitudinal drilling follows an arcuate path. In one embodiment of the present invention, a packer positioned within the enlarged section may be filled with the pumped material to thereby avoid any contamination of the material with other downhole elements such as mud and oil whereby the composition of the pumped material is consistent and known. In one embodiment, an arcuate drillable guide may be positioned in the enlarged section prior to filling the enlarged section with material.

Abstract: A section mill is positioned below a whipstock or other exit guide in a drill string assembly used to mill a section of steel casing below the whipstock and which as the section mill moves down and mills along the section of casing, causes the whipstock to be lowered down adjacent the milled-out casing and allows the drill bit and drill string to be run along the surface of the whipstock and into the earth formation. In an alternative embodiment, the combination of having the section mill below the whipstock is used in open hole operations having no casing. In yet another alternative embodiment, the section mill is positioned above the whipstock or other exit guide in a drill string assembly after the section mill has milled out in an appropriate length of the steel casing, the tubing string pulls both the section mill and the whipstock or other exit guide up to a position where the exit guide is adjacent the area of formation which has been exposed by milling along the steel casing.

Abstract: A self-advancing drilling system comprising a drilling apparatus, the drilling apparatus having at least one leading fluid cutting nozzle, means on the drilling apparatus to provide forward movement to the drilling apparatus, the drilling system further comprising a drill string formed from a recoverable flexible hose.

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: 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 whipstock assembly and method of operation is disclosed that automatically orients itself within a wellbore to a known first rotational position. The whipstock assembly is mounted on bearings that permit free rotation of the whipstock assembly within the wellbore. Due to gravitational forces, the eccentric weight load of the whipstock will automatically orient itself on the low side of the wellbore. Most wellbores are angled and the angle, azimuth, depth and other information about the wellbore is known so that the operator will know what position the whipstock assembly will automatically assume. A lower orientation section of the whipstock assembly is clamped into that first rotational position such as by a lower packer and/or slips. The whipstock is then rotated to the desired orientation by reciprocating the wellbore string. The whipstock is then clamped into the desired rotational position by activating an upper packer and/or slips. The running tool is removed and drilling or milling can be initiated.

Abstract: A wellbore casing, including a casing section, for deployment in a subterranean wellbore. The casing section includes a pre-milled windowed opening. A liner is disposed within the casing section covering the window opening from the inside. In addition, a rigid material is disposed outside of the casing section covering the window opening. A filer is located intermediate the casing section and the liner. The liner, filler and rigid material prevent cement from affecting the window opening when the casing section is being cemented in the wellbore.

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: 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: Methods and apparatus are described for forming a window of optimum dimensions in casing wall. A window of maximum width is cut when the center line of the mill tool is located inside of the inner diameter of the casing where a maximum amount of casing is drilled away by the mill tool. A whipstock is described which deviates the mill tool outwardly so that the center line of the mill tool is in approximately this position. The whipstock then maintains the mill tool at this approximate location until a window of desired length is cut having a substantially maximum width.

Abstract: An apparatus and several methods for forming one or more channels from an existing cased wellbore are disclosed. In one embodiment, the apparatus includes a notching device for forming an opening in the casing and having an integral guide shoe portion for guiding a nozzle to a position adjacent the opening to form the channel. The related method may involve lowering this apparatus into the well and then performing the notching or jetting operation, or separately lowering a notching device and a guide shoe, each carried on the end of a tubing, into the well. A guide shoe capable of positioning the nozzle close to the opening in the casing, such as one formed during the notching process, is also disclosed.

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: 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: An assembly for drilling at least one lateral well from a well bore having a longitudinally premilled window formed therein and having a first orientation key-way member formed in the premilled window and in communication with the premilled window and located on the down hole portion of the premilled window and having a second orientation key-way member formed in the premilled window and in communication with the premilled window and located on the up hole portion of the premilled window. The window is provided with a cover for closing the premilled window and first and second orientation key way members from fluid communication. A whip stock is provided for drilling at least one multilateral well. A key is provided which is spring loaded for being received into the premilled window and guided into locking engagement in the first orientation key way as the key is lowered down hole.

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: In a broad aspect, the invention may include a nipple, a deflector, and a conveying tool. The nipple may include an upper sealing surface and a lower sealing surface. The nipple may also include a discriminator/muleshoe having an alignment profile and an alignment slot. A protuberance/bump may be disposed in the alignment slot. The deflector may include an upper seal and a lower seal adapted for engagement with the upper and lower sealing surfaces, respectively, on the nipple. When the upper and lower seals are engaged with the upper and lower sealing surfaces, fluid circulation is substantially restricted thereby resulting in a increase in pressure that is detectable at the earth's surface. This pressure increase provides a signal that the deflector is properly positioned in the nipple. The conveying tool may include a flexible arm having a latching finger that is releasably engageable with a latching profile in the deflector. The latching profile may be on an inclined, concave surface of a whipstock.

Abstract: A directional or horizontal hole may be drilled into a formation by first positioning or orienting a window turning shoe in an original well bore. Once the window turning shoe has been positioned, a window is milled through the casing with a window mill. The window mill is then removed and a guide tool is then latched to the window turning shoe. Once in position, the guide tool enables a mechanical motor driven curve drilling assembly to create a curved hole. Following the completion of the curved hole, the directional or horizontal hole is extended with a conventional drilling assembly.

Abstract: A directional drilling control system allows dynamic orientation of downhole drilling equipment in unstable or corrupt natural magnetic fields without the use of gyroscopic measurement devices. The system is especially suited for sidetracking wells. The system includes a permanent or retrievable whipstock having referencing magnets embedded along the centerline of its face, and a measurement while drilling (MWD) instrument assembly. The instrument assembly contains at least one sensor which can accurately determine orientation of the mud motor relative to the reference magnets. The relative positioning of the mud motor is transmitted to the surface by way of a steering tool or MWD telemetry system. The direction of the mud motor or tool face is adjusted by turning the drill pipe at the surface. As drilling progresses, shifts in the orientation of the mud motor due to reactive torque at the drill bit will be indicated in real time so that adjustments may be made at the surface as required.

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: The milling and whipstock assembly includes a whipstock having a ramp portion for directing the milling assembly to cut a secondary borehole in an existing cased borehole. The milling assembly includes a shaft having rigid and flexible portions and an under gauge cutting tool disposed on the lower end of the flexible portion and a full gauge cutting tool disposed on the rigid portion. A third under gauge cutting tool is disposed on the flexible portion in between the full gauge and under gauge cutting tools. In operation, the milling and whipstock assembly is lowered into the borehole and then the milling assembly is detached from the whipstock assembly. As weight is placed on the milling assembly, the ramp portion places a side load on the lower under gauge cutting tool causing the flexible portion of the shaft to flex and pivot allowing the under gauge cutting tool to come into engagement with the wall of the casing allowing the under gauge cutting tools to cut a window in the cased borehole.

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: 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 an upper section 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 window assembly is provided for use at a downhole location in a first wellbore to control access to or allow isolation of a second wellbore extending from the first wellbore. The window assembly is included as an integral part of a production tubing string disposed within the first wellbore. A slot is formed in the window assembly. The window assembly is preferably installed at a downhole location aligned to an opening from the first wellbore into the second wellbore whereby well tools may move between the longitudinal bore of the window assembly and the second wellbore. Multiple guide surfaces are provided in the slot to direct movement of tools between the longitudinal bore and the window assembly and the second wellbore or vice versa. One of the guide surfaces on the slot preferably is formed with approximately the same angle at which the second wellbore intersects the first wellbore.

Abstract: The whipstock assembly comprises an assembly casing (9) with preformed windows connected to production casing (7); a landing tube (21) is located within assembly casing (9) for receiving whipstock shaft; a key is located within tube (21) for cooperation with J-slot on whipstock shaft. The whipstock consists of upper (49) and lower (55) portion which are fixed against relative rotation by splines. The assembly casing (9) with landing tube (21) is positioned in the borehole using a gyro survey tool for correct orientation of the windows. After a first side hole has been drilled, upper portion (49) is raised and rotated to place wedge surface (51) for drilling a second side hole. Tube (21) is initially closed by a cap containing a marking fluid; after the cap has been drilled out the marking fluid indicates the removal of the cap. In a second embodiment two vertically spaced side holes are drilled.

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 method for milling an opening in a tubular in a wellbore, the method comprising installing a mill guide in the tubular at a desired milling location, inserting milling apparatus through the tubular and through the mill guide so that the milling apparatus contacts the tubular at the desired milling location and contacts and is directed toward the tubular by the mill guide, and milling an opening in the tubular. In one aspect the method includes installing a whipstock in the tubular and disposing the mill guide adjacent the whipstock to protect a concave portion of the whipstock. In one aspect the method includes retrieving the mill guide from the wellbore and in another aspect includes retrieving the whipstock form the wellbore.

Abstract: A two trip sidetrack casing milling apparatus for elongating and enlarging a previously formed window in a cased borehole in preparation for a subsequent sidetracking drilling operation is disclosed. The apparatus consists of three mills on a shaft, a first window mill is secured to an end of a shaft. The first window mill forms a diameter larger than a diameter of a subsequent sidetracking drill bit that is passed through the window. A second pilot mill is secured to the shaft and strategically positioned above the first window mill. The second pilot mill forms a diameter that is less than the diameter of the first window mill. A third watermelon mill is secured to the shaft and strategically positioned above the second pilot mill. The third watermelon mill forms a diameter that is at least the same diameter as the first window mill.

Abstract: A wellbore sidetracking method has been invented which includes, in certain embodiments, milling out a casing section from a cased, cemented wellbore; placing a deflection device, e.g. a whipstock, so that, upon pivoting of the upper concave portion of the whipstock at least a top portion thereof extends up into and abuts casing above the milled out section and, in certain aspects, a portion of the whipstock also extends down into and abuts casing below the milled out section; introducing a mill into the wellbore to mill out a part of the casing above the milled out section which would interfere with the introduction of a drill bit; removing the mill; introducing a drilling system into the wellbore to be deflected into the milled out area; and drilling a new sidetracked bore with the drilling system from the milled out area. In one aspect a mill is provided which mills out the part of the casing above the milled out area without contacting the formation or with only minimal contact thereof.