Abstract: A wellbore drilling system has an umbilical that carries a drill bit in a wellbore. Drilling fluid pumped into the umbilical discharges at the drill bit bottom and returns through an annulus between the umbilical and the wellbore carrying entrained drill cuttings. An active differential pressure device (APD device), such as a jet pump, turbine or centrifugal pump, in fluid communication with the returning fluid creates a differential pressure across the device, which alters the pressure below or downhole of the device. The APD device can be driven by a positive displacement motor, a turbine, an electric motor, or a hydraulic motor. A controller controls the operation of the APD device in response to programmed instructions and/or one or more parameters of interest detected by one or more sensors. A preferred system is a closed loop system that maintains the wellbore at under-balance condition, at-balance condition or over-balance condition.

Abstract: A turbine is disclosed which includes a turbine blade housing having an inner facing portion of a first material having a first coefficient of expansion, and a turbine blade body having an outer facing portion of a second coefficient of expansion greater than said first coefficient. In a preferred embodiment, the blade housing comprises a number of steel shroud rings and the turbine blade body comprises a number of stators and rotors of a thermoplastic material. An interference fit between stator blades and the shroud rings is enhanced in use due to the difference in thermal and/or hydrophilic coefficients of expansion of the first and second materials.

Abstract: A tube (1) in a borehole (2) in the ground (3) is displaced. The tube is simultaneously displaced along and about its axis, such that it is axially introduced into or retracted from the borehole. According to the invention, displacing the composed tube about its axis comprises an oscillating movement. The invention further relates to a device for displacing a tube in a borehole.

Abstract: The steel drill string attached to a drilling bit during typical rotary drilling operations used to drill oil and gas wells is used for a second purpose as the casing that is cemented in place during typical oil and gas well completions. Methods of operation are described that provide for the efficient installation of a cemented steel cased well wherein the drill string and the drill bit are cemented into place during one single drilling pass down into the earth. Apparatus is described having a portion of a drilling assembly that is selectively removable from the wellbore without removing the casing. A one-way cement valve is installed near the drill bit of the drill string that allows the cement to set up efficiently under ambient hydrostatic conditions while the drill string and drill bit are cemented into place during one single drilling pass into the earth.

Abstract: A percussive tool adapted to receive rotational energy from the inner member of a dual-member drill string. In a preferred embodiment the percussive tool has a hydraulic pump, driven by a drive member, to operate the hammer assembly. In another preferred embodiment the percussive tool has a rotary-driven cam assembly adapted to mechanically operate the hammer assembly. This invention provides increased control and efficiency for the use of percussive force in horizontal directional drilling operations.

Abstract: A torque absorber is disposed on a drill string near the motor. The torque absorber automatically adjusts the weight on a drill bit and reduces the likelihood of motor stall caused by resistance to drill bit rotation. The torque absorber includes an upper unit assembly and a lower unit assembly. The upper unit assembly includes a top sub and a ball body. The lower unit assembly includes a bottom sub, a lead screw, and a ball retainer. The components of the lower unit assembly are free to rotate as a result of motor back torque, which is in a direction opposite of the direction of rotation of the drill bit during normal drilling. The upper unit assembly will remain stationary while the components of the lower unit assembly rotate in this opposite direction. A spring applies a force on the lead screw, causing the lower unit assembly to rotate back downward once the motor back torque reduces.

Abstract: A borehole may be drilled utilizing the bottom hole assembly 10, 50 with a downhole motor 14, which may offset at a selected bend angle. The motor housing is preferably run slick, and a gauge section 36 secured to the pilot bit 18 has a uniform diameter bearing surface along an axial length of at least 60% of the pilot bit diameter. The bit or reamer 16 has a bit face defining the cutting diameter of the drilled hole. The axial spacing between the bend and the bit face is controlled to less than fifteen times the bit diameter. The downhole motor, pilot bit and-bit may be retrieved from the well while leaving the casing string in the well.

Abstract: Apparatus for an improved method for drilling earthen boreholes with a fluid powered rotary motor mounted on the downhole end of a non-rotating, fluid conducting drill string has a fluid powered, axially reciprocating hammer coupled to the motor by means of a rotary coupling having freedom for axial movement, so that the hammer will be rotated by the motor and the motor will be axially isolated from the reciprocating hammer as both are powered by fluid conducted from the surface through the drill string.

Abstract: A steerable bottom hole assembly may be used for drilling both a curved section and straight section of the borehole, with the bottom hole assembly including a reamer beneath the downhole motor 12. The bottom hole assembly includes a bit 30 having a bit face defining a bit diameter, and a gauge section 32 having a substantially uniform diameter cylindrical surface approximating the bit diameter and having an axially length of at least 75% of the bit diameter. The motor is preferably run slick without stabilizers for engaging the wall of the borehole.

Abstract: A lockable motor assembly for use in a well bore comprises a stator, a rotor rotatably mounted within the stator, and a selectively removable flow restriction means. The lockable motor assembly may further comprise holding means for rotationally fixing the rotor to the stator. The flow restriction means limits the flow rate of fluid downstream of the rotor, thereby substantially balancing hydraulic pressure above and below the stator.

Abstract: A downhole drilling apparatus suspended by tubing includes a drill bit driven by an electric motor powered by a cable means. The motor is mounted upon a hollow shaft which allows fluid to pass through, so that a fluid circuit along the tube and back along the annulus between the borehole and the tubing via the drill bit is.established. The state of the motor, particularly its speed and torque, can be monitored, and the motor may then be regulated as a result of the this data. Various sensors may be included in the drilling apparatus, and the data gathered similarly used to regulate the motor. Thrust means are included to urge the drill along the borehole. Supplementary pumps may be provided to assist the fluid flow. Both the thrust means and the pumps may be controlled by the control means.

Abstract: The present invention provides a drilling assembly for drilling deviated wellbores. The drilling assembly includes a drill bit at the lower end of the drilling assembly. A drilling motor provides the rotary power to the drill bit. A bearing assembly of the drilling motor provides lateral and axial support to the drill shaft connected to the drill bit. A steering device is integrated into drilling motor assembly. The steering device contains a plurality of force application members disposed at an outer surface of the drilling motor assembly Each force application member is adapted to move between a normal position and a radially extended position to exert force on the wellbore interior wherein in extended position. A power unit in the housing provides pressurized fluid to the force application members. A control device for independently operating each of the force application members is disposed in the drilling motor assembly.

Abstract: The invention relates to a drive system, in particular a downhole drilling assembly (10). In the preferred embodiment, a bearing mechanism (14, 24) of the assembly (10) is isolated from a gear mechanism (20) of the assembly (10), to prevent failure of the bearing mechanism (14, 24) due to vibration and heat generated by the gear mechanism (20) in use. A lower bearing unit (24) of the bearing mechanism (24) is coupled to the gear mechanism (20) by a shock eliminating coupling assembly (22), which prevents the transmission of shock loads to the gear mechanism (20). Also, the gear mechanism (20) is coupled through a shock eliminating coupling assembly (18) to a turbine (16) and thus to an upper bearing unit (14). Sealing assemblies (60, 116) are provided for the gear mechanism (20) and the upper bearing unit (14) to prevent drilling fluid ingress and consequent damage. The assembly (10) may also carry a torsionally flexible drive shaft (46).

Abstract: A generator assembly for generating power in the downhole end of a drill string used to form a borehole in horizontal directional drilling. The drill string provides a fluid passageway in which the downhole generator is receivingly disposed, at least in part, to subject a rotatable turbine to a pressurized fluid flowing in the fluid passageway, thereby imparting a mechanical rotation to the turbine. The turbine is coupled to a generator so that the mechanical rotation of the turbine is transferred to a power output of the generator.

Abstract: This specification involves combining automatic fluid driven bit hammering apparatus with generic rotary drilling motor assemblies used on non-rotating drill strings to produce more effective well and earth borings.

Abstract: An actuator assembly is a valveless, high pressure, positive displacement, axial drive system including a hydraulic fluid reservoir and a hydraulic enclosure in an actuator housing with a bi-directional pump assembly driven by an electric motor and a piston assembly disposed within the hydraulic enclosure. The bi-directional pump accurately displacing the piston a given distance to exert a large drive or actuation force and to maximize that actuation force given a limited electrical current transmitted to the motor. Because the pump is bi-directional, the piston can be repositioned after actuation by reversing the direction of flow through the pump without using valves to direct the hydraulic fluid flow. The actuator assembly may also include a piston repositioning assembly connected to the hydraulic enclosure.

Abstract: A lockable motor assembly (1) for use in a well bore comprises a PDM motor (2) having a rotor (4) and a stator (3). A locking member (12) has a splined projection (13) which is received within a splined recess (14) of the rotor and external splines (15) which mate with splines provided on a sub (5) connected to the stator. The components are held in this configuration by a shear ring (23) until the fluid pressure within a chamber (28) defined between the locking member (12) and the sub (5) is sufficient to cause the shear ring to shear. The locking member (12) 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 (35).

Abstract: An apparatus and method for directional drilling utilizing a fluid hammer. The fluid hammer is coupled to a bent steering member which, in turn, is coupled to a drill string. The bent steering member includes means for rotating the fluid hammer independently of the bent steering member. The means for rotating may be a mud motor or a dual drive, pipe-in-pipe mechanism. The fluid hammer may be directed by rotating the drill string and bent steering member to point the fluid hammer in a desired direction. The bent steering member may include a sonde for monitoring its orientation. Fluid pressure capable of activating the fluid hammer is conveyed to the fluid hammer by means of the drill string.

Abstract: A system for downhole drilling and coring includes a roller vane motor for driving a drill bit. The motor has a single jacket with a lower end and an upper end and being embodied such that all drilling fluid passes inside the jacket to the drill bit. The system further has a bent sub connected to the upper end of the motor. The jacket has outwardly projecting curved members forming recesses therebetween for the passage of return drilling fluid, the curved members creating a circular surface having a diameter approximately equal to that of the drill bit. The curved members as well as the recesses therebetween each extend in longitudinal direction over the full length of the jacket of the motor.

Abstract: There is disclosed an improved downhole steerable motor assembly (5) and related method. A problem in known assemblies is that the distance from a bent housing bend axis to the face of a drill bit needs to be kept relatively short resulting in the length of the bearing package and its thrust capacity being restricted. Accordingly, the invention provides a downhole motor assembly (5) comprising a motor (115), at least one thrust bearing (116) and a bent portion (117), the assembly (5) having a first end (135) and a second end (140), the first end (135) being closer to surface than the second end (140), in use, wherein the bent portion (117) is closer to the second end (140) than is the at least one thrust bearing (116).

Abstract: A down hole motor assembly includes a hydraulic drive portion, a drill bit operatively connected to the drive portion and a disengage mechanism (11) arranged to disengage drive to the drill bit. The disengage mechanism (11) is arranged to be actuated by supplying drilling fluid to the drive portion at a flow rate which is greater than the flow rate at which fluid is supplied to run the drive portion during normal drilling. The disengage mechanism is arranged to be re-set so that drive is reconnected to the drill bit when the fluid supply to the drive portion is shut off.

Abstract: The present invention provides a drilling assembly that includes a mud motor that rotates a drill bit and a set of independently expandable ribs. A stabilizer uphole of the ribs provides stability. A second set of ribs may be disposed on the drilling assembly. Vertical and curved holes are drilled by rotating the drill bit by the mud motor and by independently adjusting the rib forces. The drill string is not rotated. Inclined straight sections and curved sections may be drilled by independent adjustment of the rib forces and by rotating the drill bit with the motor, without rotating the drill string. Inclined sections or curved sections in the vertical plane are drilled by superimposing the drillstring rotation on the mud motor rotation and by setting the rib forces to the same predetermined values. Rib forces are adjusted if the drilling direction differs from the defined inclination. The system is self-adjusting and operates in a closed loop manner.

Abstract: An improved down hole drilling motor suitable for drilling applications. The down hole drilling motor comprising a stator disposed in the tubular housing. The stator includes an internal cavity having one or more lobes. A rotor operatively positioned in the cavity of the stator is adapted to cooperate with the one or more lobes of the stator. The stator comprising a compound having improved manufacturing and performance characteristics.

Abstract: Method and apparatus for underground drilling and enlarging of holes, in particular in hard rock, by using a water-driven motor as drive unit.

Abstract: A downhole drilling apparatus for interconnection in a casing or liner string having a drill bit disposed thereon for enabling the drilling of intersecting wellbores without removal of the drill bit is disclosed. In a disclosed embodiment, the apparatus comprises a housing having a window. A whipstock is disposed within the housing. Between the window and the whipstock is a filler. The whipstock and the filler define a central bore providing a fluid path through the apparatus. A back pressure valve may be disposed within the central bore to prevent back flow of fluids through the apparatus. Once the total depth of an initial wellbore is reached, the casing or liner string, including the apparatus, may be cemented in place. Thereafter, an intersecting wellbore may be drilled by laterally deflecting a second drill bit with the whipstock through the window of the housing.

Abstract: A downhole mud motor (100) is disclosed which has an improved bearing mandrel (107) and a bearing stop (105) to transfer a larger percentage of the weight of a drill string to the bit. Also improved sealing systems (113) (114) (220) (515(706) for the transmission section and bearing section (116) (310) (117) (118) (119) prevent drilling mud from entering critical components. A piston stop is provided to prevent the piston from damaging other parts as the piston moves under pressure. Compensating pressure assembly (204) preferably including a disk (1408) is placed in the lower housing (108) to prevent pressure from building up in the bearing section (308). A combination of grooved ball seats (130) and circumferentially spaced balls (127) are provided in the transmission section (200) (207) to allow for greater flow of lubricant around the ball bearings.

Abstract: An improved coiled tubing directional drilling method comprises: providing a bent housing which is rotatably coupled to the coiled tubing, rotating the drill bit, and rotating the bent housing. Apparatus for achieving the method comprises: a rotary connection between the coiled tubing and the bent housing and means for rotating the bent housing relative to the coiled tubing and to the drill bit. A fluid pressure-operated clutch enables alternate rotation and locking of the bent housing. Preferably, a first downhole motor rotates the drill bit and a second downhole motor rotates the bent housing through the clutch or alternately a speed reducer permits the bent housing to contra-rotate slowly under reactive torque developed by the rotating drilling bit.

Abstract: Between a drilling motor and the upwardly continuing drill string a housing contains a speed sensor rotationally connected to the motor rotor. Motor speed is sensed and if rotating at a rate less than a selected speed, a cooperating by-pass valve opens to shunt drilling fluid to the well annulus to prevent damage to the stalled motor.

Abstract: A lubricant ejector used downhole has a reservoir holding replenishment lubricant, and it includes a driver to eject at least a portion of the lubricant. A flow coupler connected to the ejector channels lubricant to a connected apparatus. One specific ejector includes a hollow rotor of a downhole motor, and a specific flow coupler includes a cross-channel diverter that directs lubricant from the hollow interior of the rotor to a bearing pack and that directs drilling fluid, used to drive the motor and create pressure that moves a piston in the rotor, from outside the rotor to inside a passageway through the bearing pack. A method includes injecting lubricant from a reservoir in the downhole motor into the bearing pack as the downhole motor operates.

Abstract: An improved method and apparatus for sawing or drilling concrete or like material comprises use of a water-powered pump for introducing a metered amount of a speed-enhancing compound into a stream of water as the water is applied to a masonry saw or core drill during a sawing or drilling operation.

Abstract: A downhole mud motor is disclosed which has an improved bearing mandrel and a bearing stop to transfer a larger percentage of the weight of the drill string to the bit. Also improve sealing systems for the transmission section and bearing section prevent drilling mud from entering critical components. A piston stop is provided to prevent the piston from damaging any parts as the piston moves under pressure. A compensating pressure disk is placed in the lower housing to prevent pressure from building up in the bearing section. A grooved ball seat is provided in the transmission to allow for greater flow of lubricant around the ball bearings.

Abstract: An adjustable bent housing adapter for downhole mud motor directional drilling operations including a cylindrical housing having a first and a second end defining a central bore there through, the housing being divided into first and second body members, the body members being axially offsetable to one another, said first body member having a mandrel portion insertable along a portion of its length into the bore of the second body member with angularity between the first and second body members achieved by rotational displacement of a first outer indexing sleeve, having non-parallel ends, disposed annularly about the mandrel and a second inner eccentric sleeve also disposed annularly about the mandrel, the inner sleeve having a locking member for connecting to the outer sleeve and being axially movable relative to the mandrel in response to rotation of the outer sleeve, and a locking means provided for securing the outer sleeve to prevent rotation between the outer indexing sleeve and the first body member.

Abstract: A turbodrill comprises a housing coupled with its one end to a drill pipe for feeding drilling fluid, the housing accommodating a hydraulic downhole motor comprising a multistage turbine. Each stage of the multistage turbine comprises a directing stator disk defining through passages and a working rotor disk defining through passages, the rotor disk being installed on a shaft. The shaft is rotatably mounted in the housing on supports and carries a rock breaking tool on the end thereof facing the bottomhole. The total area of the inlet openings of the stator disk through passages is from about ⅕ to about ⅗ of the total area of the inlet openings of the rotor disk through passages.

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: The invention relates to a downhole rotary coring device placeable in a drill string and comprising a head section, a motor, and a core barrel having an outer motor comprising a rotor connected to the outer barrel and a stator to the head section, whereby the rotor and the stator are movable with respect to each other in the longitudinal direction of the drill string.

Abstract: There is provided an adjustable housing for use with a drill string for controlled directional drilling of a well hole. The housing includes an upper sub and a lower sub each having a first portion extending along a primary axis and a second portion extending along a secondary axis offset from the primary axis by a predetermined angle. The second portions are rotatably mounted together such that the secondary axes of the respective upper and lower subs are coincident. The upper sub is thus rotatable in relation to the lower sub between a bent position wherein the primary axes of the upper and lower subs are misaligned and a parallel position wherein the primary axes of the upper and lower subs are parallel to each other. A locking member is slidably mounted on splines extending radially from the second portion of the upper sub such that the locking member is slidable between an engaged position and disengaged position.

Abstract: A rotor (4) for an eccentric screw pump or a subsurface drilling motor consists of a straight, essentially cylindrical core element (21), onto which a shell (22) is forged by a cold-forging process. The forging gives the shell (22) the helical external form required for eccentric screw pumps (1). The rotor (4) described can be produced by non-cutting shaping, which is of considerable advantage in particular in the case of large rotor dimensions, since no waste material is produced.

Abstract: A by-pass valve is part of an apparatus arranged to function as a serial element of a drill string. An arbor is attached to the top end of a tubular motor rotor and extends some distance along the generally central opening of the housing which is attached to the top end of the motor housing. A head on the arbor comprises a normally closed valve which is capable of conducting fluid from inside the housing to the well annulus outside the drill string by way of the bore of the tubular rotor. The valve is opened by downward movement, in excess of a selected amount, of the rotor of the motor. The excessive downward movement of the rotor indicates problems in the motor bearing structure, or disruptive failure elsewhere in the bottom hole assembly. The opening of the by-pass valve reduces standpipe pressure which is a signal detectable at the surface. The signal indicates disruptive failure in the down hole assembly.

Abstract: An inverted motor with a drilling utensil attached to or integrated as part of an outer motor housing that rotates around a fixed non-rotating shaft or tube. The non-rotating shaft or tube is attached to a fixed base and can extend to the end or past the end of the drilling utensil. A rotary motor is positioned between the outer rotating housing and center fixed shaft and imparts force and motion to the housing and drilling utensil. A channel traverses through the length of the shaft or tube to allow fluids or wires to fully or partially bypass the motor.

Abstract: A drilling fluid powered rotary drilling motor is mounted on the downhole end of a non-rotating fluid conducting drill string has a drill bit on its distal end and a plurality of fluid engaging, rotating elements coupled to at least one speed reducing planetary gear stage that converts the kinetic and pressure energies of the drilling fluid to mechanical power for rotating the drill bit. The drilling motor includes a lubricator, a drilling fluid filter, a pressure relief valve, a bypass valve and a check valve and is mounted with an output isolation coupling and a bearing package sized to withstand drilling load conditions.

Abstract: The present invention provides a drilling assembly that includes a mud motor that rotates a drill bit and a set of independently expandable ribs. A stabilizer uphole of the ribs provides stability. A second set of ribs may be disposed on the drilling assembly. Vertical and curved holes are drilled by rotating the drill bit by the mud motor and by independently adjusting the rib forces. The drill string is not rotated. Inclined straight sections and curved sections may be drilled by independent adjustment of the rib forces and by rotating the drill bit with the motor, without rotating the drill string. Inclined sections or curved sections in the vertical plane are drilled by superimposing the drillstring rotation on the mud motor rotation and by setting the rib forces to the same predetermined values. Rib forces are adjusted if the drilling direction differs from the defined inclination. The system is self-adjusting and operates in a closed loop manner.

Abstract: A flow retarder is provided for use in the bearing assembly of a downhole drilling motor. The bearing assembly comprises an inner tubular mandrel and an outer tubular housing. The flow retarder comprises: an inner carbide sleeve connected to the rotating mandrel by a resilient elastomer layer bonded to a driver ring which is locked on the rotating mandrel; an outer carbide sleeve affixed to the stationary tubular housing; the sleeves forming a narrow annular clearance or metering gap between them; a secondary port extending through the mandrel side wall directly above the carbide sleeves; and a housing port extending through the housing side wall below the flow retarder sleeves. Drilling fluid leaks down from the adapter/adjustable housing clearance and passes through the metering gap to lubricate the carbide sleeves. Part of this fluid returns through the secondary port to the main bore of the mandrel.

Abstract: Downhole flow pulsing apparatus comprises a housing (14) for location in a drillstring, the housing (14) defining a throughbore to permit passage of fluid through the housing. A valve (27, 30) is located in the bore and defines a flow passage (29, 31). The valve includes a valve member (27) which is movable to vary the area of the passage (29, 31) to provide a varying fluid flow therethrough. A fluid actuated positive displacement motor (15, 16) is associated with the valve member (27). In a preferred embodiment, the apparatus is provided in combination with a drill bit (5) and a pressure responsive device, such as a shock-sub (3), which expands or retracts in response to the varying drilling fluid pressure created by the varying flow passage area. The expansion or retraction of the shock-sub (3) provides a percussive effect at the drill bit.

Abstract: A fulcrum bearing assembly for rotatably supporting a shaft within a housing, including at least one row of spherical thrust bearings positioned at a first axial position within the housing, at least one row of spherical thrust bearings positioned at a second axial position within the housing and at least one row of spherical radial bearings positioned at a third axial position within the housing. The third axial position is located between the first and second axial positions. Further, a bearing preload assembly for maintaining a bearing assembly in a preloaded condition, including a thrust bearing shoulder associated with a housing and a thrust bearing collar. The bearing assembly is axially maintained within the housing between the thrust bearing shoulder and the thrust bearing collar, wherein the thrust bearing collar is axially adjustable relative to the thrust bearing shoulder in order to preload the bearing assembly therebetween.

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

Abstract: Apparatus is provided for introducing a consistent series of small and localized rotary impacts to a PDC bit during drilling, to improve PDC drill bit performance. Rotary impact supplements the nominal torque supplied by the rotary drive thereby avoiding lockup and potentially damaging energy storage in the drill string following windup, should the bit slow or hang up when drilling in difficult formations. The apparatus comprises a rotary hammer which is rotated about a bit shaft's anvil, preferably by a drilling fluid driven turbine. As the hammer rotates, potential energy is built up. When the hammer and anvil connect, the energy is released into the bit shaft and thus into the bit, increases its instantaneous torque and allows it to more effectively cut through difficult formations.

Abstract: An improved coiled tubing directional drilling method comprises: providing a bent housing which is rotatably coupled to the coiled tubing, rotating the drill bit, and rotating the bent housing. Apparatus for achieving the method comprises: a rotary connection between the coiled tubing and the bent housing and means for rotating the bent housing relative to the coiled tubing and to the drill bit. A fluid pressure-operated clutch enables alternate rotation and locking of the bent housing. Preferably, a first downhole motor rotates the drill bit and a second downhole motor rotates the bent housing through the clutch or alternately a speed reducer permits the bent housing to contra-rotate slowly under reactive torque developed by the rotating drilling bit.

Abstract: Three air hammers are housed and arranged in a hammer case, and have bits at their respective ends. Each of the air hammers can be activated independently. In a normal excavation, the earth is excavated by activating all the air hammers. When correcting an excavating direction, only an air hammer positioned in the correct direction is activated first so that the earth in the correct direction is excavated in a predetermined amount. Next, all the air hammers are activated to excavate the earth. Thereby, a leading hammer can direct the excavation toward the correct direction, and thus the excavating direction is corrected.

Abstract: Between a drilling motor and the upwardly continuing drill string a housing contains a speed sensor rotationally connected to the motor rotor. Motor speed is sensed and if rotating at a rate less than a selected speed, a cooperating by-pass valve opens to shunt drilling fluid to the well annulus to prevent damage to the stalled motor.

Abstract: A system for downhole drilling and coring, said system includes a roller vane motor for driving a drill bit. The motor has a single jacket with a lower end and an upper end and being embodied such that all drilling fluid passes inside the jacket to the drill bit. The system further has a bent sub connected to the upper end of the motor. The jacket is provided with outwardly projecting curved members forming recesses therebetween for the passage of return drilling fluid, the curved members creating a circular surface having a diameter approximately equal to that of the drill bit. The curved members as well as the recesses therebetween each extend in longitudinal direction over the full length of the jacket of the motor.