Abstract: Embodiments disclosed herein relate to a downhole tool and a method to abate vibration with the downhole tool. The downhole tool may include a first stabilizing member, a second stabilizing member, a flexible member, and/or a dampening member, in which the downhole tool may be disposed downhole within a wellbore. The flexible member may enable the first stabilizing member and the second stabilizing member to articulate with respect to an axis of the downhole tool. The dampening member may enable vibration received by the downhole tool to be dampened. Further, the first stabilizing member and the second stabilizing member may be rotatable with respect to each other about the axis of the downhole tool.

Abstract: A subpart of a drill string is described having an outer circumferential surface which is contoured and adapted to engage the wall of the borehole with a small angle of attack while exerting during rotary drilling operations an compacting pressure on mud cake and/or cuttings present in the annulus between the drill string and the borehole.

Abstract: Drilling apparatuses and methods for limiting precession are provided. According to one embodiment, a drilling apparatus includes a non-rotating stabilizer. The non-rotating stabilizer includes a first blade and a second blade, the first blade being arranged opposite the second blade. The first blade is biased radially outwardly by a force of a first value. The second blade is not biased radially outwardly by a force corresponding to the first value. The second blade may be a blade which is slidable along the non-rotating stabilizer in an axial direction and allow free sliding axial contact with the formation.

Abstract: This invention relates to a downhole assembly and to a cutter assembly, and in particular to a downhole assembly including an apparatus for breaking up large-scale material which is present behind a drill bit, and to a cutter assembly for use in such a downhole assembly. The downhole assembly is suitably for use in a drillstring, the downhole assembly comprising a drill bit, a sensitive component, and at least one rotatable set of cutter blades located between the drill bit and the sensitive component.

Abstract: A turbine matrix sleeve in accordance with the invention includes an inner cylindrical structure made up of a first material. The inner cylindrical structure may include multiple blades and multiple channels running between the blades along an outside diameter thereof. The inner cylindrical structure further includes threads, such as right-hand or left-hand threads, on an outer surface thereof. An outer layer, made up of a second material different from the first material, is integrally bonded to the threads. This outer layer may be optionally embedded with hardened inserts or buttons, such as PDC inserts, diamond inserts, TSP inserts, or the like. The threaded surface on the inner cylindrical structure significantly improves the bond between the outer layer and the inner cylindrical structure and creates a mechanical lock therebetween.

Abstract: A dynamic damper for installation in a drill string (1), the purpose of which damper is to reduce the risk of jamming the drill bit (5), thereby avoiding damages in the event of unwanted extreme oscillations and rotational speed of the drill string caused by uncontrolled release of torsional energy in the drill string when the drill string suddenly breaks free of the jam. For this purpose, the damper is constructed from an outer and an inner string section (11) and (12), supported concentrically and interconnected through a helical threaded connection (10), so that relative rotation between the sections caused by torque (8) will give an axial movement that lifts and loosens the drill bit from the bottom of the hole in critical jamming situations. The spring (9) maintains the outer string section in an axial position against the shoulder (22). A hydraulic damping effect on the axial movements is achieved by oil volumes (16) and (17) being interconnected through narrow bores (18).

Abstract: The present invention generally relates to an apparatus and methods for improving the stability of a wellbore during drilling operations using a rotary drill string. More specifically, embodiments of the present invention provide systems and methods for enhancing the performance of the filter or mud cake layer on the wall of the wellbore as a protective and isolating layer.

Abstract: A directional drilling apparatus for mounting a drill bit on a rotatable drill support comprises a member for transmitting rotation from the drill support to a drill bit, and a body mounted to the member. The body is configurable to offset a portion of the member relative to an axis of the body such that directional drilling may be achieved.

Abstract: A roller sub system for reducing friction between a tool string and a wall in a well bore for use in the oil and gas industry. The apparatus has a roller body and wheel sub system, which is configured to have removably mounted wheels of variable diameters. A plurality of different diameter wheel sets are described for mounting on the roller sub axles and orientating the system in the well bore. The wheels are fixed to the roller sub axles through a quick-release mechanism. A single apparatus can thus be employed with different diameter wheels to operate in well bores of variable diameters.

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 when 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: A method and apparatus for allowing a downhole drill string to be stuck at one location and continue to rotate above the stuck section. The apparatus provides a method for collapsing the stuck subassembly by reducing its outside diameter. Simultaneous with the subassembly collapse, a jarring action is initiated from within the drill string to further loosen the stuck sections. At the same time drilling fluid inside the string is allowed to circulate outside the string through a circulation sub. The fluid is forced around the stuck subassembly further increasing the likelihood that the subassembly will be freed.

Abstract: According to one embodiment of the invention, a rotary steerable tool includes a drive shaft configured to be coupled to a drill string at an upper end thereof and configured to be coupled to a drilling tool at a lower end thereof. A middle portion of the drive shaft is disposed axially between the upper and lower ends and has a smaller diameter than each of the upper and lower ends. The drive shaft further includes a housing rotatably coupled externally to the drive shaft and at least one housing module coupled to a respective opening in the housing at an axial location corresponding to the middle portion of the drive shaft.

Abstract: A downhole tool comprises a joint, and a resilient member 65 which extends through the joint and provides a restoring force which tends to strengthen the joint. The joint may comprise a flex coupling 61 which allows limited articulation of the joint. First and second drill string sections 63, 64 may be interconnected by the joint, the resilient member 65 being fixed to interior surfaces of the first and second drill string sections 63, 64. A downhole tool may also comprise primary and secondary sleeves 46 that are supported relative to the mandrel 10 of the drill string. Rotational drive may be transferred from one of the sleeves to the other.

Abstract: An auger support assembly for use with an augering system for mining which bores a pair of side-by-side holes through a coal seam using dual side-by-side augers. Each auger includes a drilling section which is followed by a series of auger flights for conveying the bored coal back out of the respective hole. The augers are connected together in axially aligned pairs and are supported by the auger support assembly. The auger support assembly includes a pair of bearing housings that are disposed on drive shafts which extend outwardly from the first ends of a first pair of parallel augers and are received within the second ends of a second pair of parallel augers. The bearing housings are connected to each other by a tie bar. A single support leg extends downwardly from approximately the mid-section of the tie bar to engage the ground ledge that is formed between the counter rotating augers.

Abstract: A variable gauge drilling apparatus and a method for assembling a variable gauge drilling apparatus for insertion in a subject borehole. The variable gauge drilling apparatus includes: an apparatus housing having a housing size which is suitable for insertion in a subject borehole which has a subject borehole size within a design range of borehole sizes; a plurality of interchangeable borehole engaging devices having different device sizes for mounting on the apparatus housing to provide the drilling apparatus with a drilling apparatus size within a range of drilling apparatus sizes, wherein the range of drilling apparatus sizes is compatible for use of the drilling apparatus within the design range of borehole sizes; and a universal borehole engaging device mount located on the apparatus housing, wherein the mount is configured to accept for mounting any one of the plurality of interchangeable borehole engaging devices.

Abstract: The drill string element has at least one bearing zone for bearing against the wall of the borehole during drilling. The bearing zone comprises at least one bearing segment extending in the axial direction and having an outside surface that is cylindrical and of constant diameter greater than the diameter of any other portion of the surface of the element, and also having a guide zone that is circularly symmetrical about the axis of the drill string element. The bearing zone preferably also has a drilling fluid activation zone extending axially in a disposition adjacent to the bearing segment. The guide zone presents a radius of curvature not less than one-third the outside diameter of the bearing segment.

Abstract: A centralizer for use in oil well wireline toolstrings comprising a central mounting rod and floating spring mechanisms between which a number of jointed centralizer arms are connected. The jointed centralizer arms have a section with a concave profile disposed near to their pivot points so that a closing force acting on the arms acts at a greater distance from the pivot, thereby increasing the closing moment and making the centralizer easier to draw into a borehole with a narrow cross-section. The floating spring mechanisms also have a linkage to the presser plate of the spring such that an axial force pulling the centralizer apparatus into a borehole is transferred directly into a force on the spring, thereby reducing the opening moment the springs exert on the centralizer arms.

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 when 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: A blockless reamer drilling tool comprising an elongated tool body and a reamer unit. The reamer unit includes, a shaft having a first end and a second end and a cutter mounted on the shaft between the first and second ends. A pocket on the exterior surface of the tool body is sized to accept the reamer unit with a portion of the reamer unit recessed in the pocket. A plurality of pins engage the tool body and secure the reamer unit within the pocket. The plurality of pins includes a first pin engaging the tool body and passing through the shaft at the first end and a second pin engaging the tool body and passing through the shaft at the second end.

Abstract: A method and apparatus for advancing a rotating motorized downhole tool for operations in oil/gas wells. The apparatus is adapted for drilling and milling away of casing sections in the wells, as preparation for plugging the same. The apparatus includes a rotating tool and a driving motor indirectly suspended on coiled tubing. The apparatus also includes a carriage connected to the motor adapted to absorb torques that occur during use. The carriage is connected to the coiled tubing via a swivel coupling such that a tensile force on the coiled tubing provides an advancing force for the tool and motor.

Abstract: The stabilizer (1) has a tubular central body (3) having means for connection (3a, 3b) to a first and a second component of the string of drill rods and at least one external contact element (4) with a wall (2a) of the borehole (2). The external element (4) for contact of the stabilizer (1) with the wall (2a) of the borehole (2) has at least one means for activation (6) of a means (7) co-operating with the wall (2a) of the borehole (2) to limit the friction between the contact element (4) and the wall (2a) of the borehole (2). The activation means can consist of inter-blade spaces (6) for acceleration of the circulation (7) of the drilling liquid or by a means for coupling in rotation of the external element (4) and the central body (3) of the stabilizer (1).

Abstract: A drill pipe protector having a tubular sleeve that is attached to a section of drill pipe and resides over the outer diameter of the drill pipe while moving within an associated well casing or well hole. The sleeve has low-friction end pads positioned on the ends of the sleeve to reduce friction between the ends of the sleeve and the end of an adjacent thrust bearing collar used to hold the sleeve in place on the drill pipe.

Abstract: A method for drilling in unconsolidated formation is taught. In particular, a method for borehole stabilization in an unconsolidated formation includes providing a drill string; rotating the drill string to drive a drill bit to drill a borehole having a borehole wall; driving the drill string against the borehole wall while rotating the drill string to plaster the surface of the borehole wall.

Abstract: The stabiliser (1) has a tubular central body (3) having means for connection (3a, 3b) to a first and a second component of the string of drill rods and at least one external contact element (4) with a wall (2a) of the borehole (2). The external element (4) for contact of the stabiliser (1) with the wall (2a) of the borehole (2) has at least one means for activation (6) of a means (7) co-operating with the wall (2a) of the borehole (2) to limit the friction between the contact element (4) and the wall (2a) of the borehole (2). The activation means can consist of inter-blade spaces (6) for acceleration of the circulation (7) of the drilling liquid or by a means for coupling in rotation of the external element (4) and the central body (3) of the stabiliser (1).

Abstract: A friction reducing tool (1) having a generally tubular body (2) and three or more groups of rotatable castors (3) provided about the periphery of the body, wherein the castors of each group are substantially aligned in a longitudinal direction, and wherein each group of castors has at least one castor offset relative to at least one other castor of the same group.

Abstract: An auger flight support for use with an augering systems for mining which bores a pair of side-by-side holes through the coal seam using respective augers. Each auger includes a drilling section which is followed by a series of auger flights for conveying the bored coal back out of the respective hole. The auger flight support includes a pair of thrust bearing and housing assemblies which are tied together and each supported by a respective leg which lowers the friction between the auger flight and the bottom of the bore. This significantly reduces the power required to rotate the augers.

Abstract: A method and apparatus for milling a window in a downhole structure, such as a casing or a liner, includes a mandrel that supports milling elements arranged in a predetermined pattern. In one example, the milling elements are arranged in one or more continuous channels each having a generally helical pattern. The milling elements are able to cut the window in the downhole structure substantially continuously to the desired size.

Abstract: A casing centralizer is provided. Such a casing centralizer includes a tubular body substantially comprised of a plastics material and having an innermost surface, an outermost surface, and opposed ends. The tubular body is adapted to surround a well casing and to centralize the well casing within it wellbore. The innermost surface of the tubular body defines at least one recess that extends longitudinally and radially tapers along at least a portion of the innermost surface. An associated wellbore casing apparatus, downhole tool, and method of cementing a well casing into a well bore are also provided.

Abstract: The friction reducing drill pipe component in the form of a sub (10) is adapted to form part of a drill string. The sub (10) comprises a tubular mandrel (12) having first and second ends for connection to adjacent components of the drill string. A sleeve (18) is mounted on the mandrel (12), and first and second stops on the mandrel (16, 20) restrain the sleeve 18 against axial movement relative to the mandrel (12). One of the stops (20) is removable or retractable to permit the sleeve (18) to be removed over the first end of the mandrel.

Abstract: A drill pipe protector having a tubular sleeve that is attached to a section of drill pipe and resides over the outer diameter of the drill pipe while moving within an associated well casing or well hole. The sleeve has low-friction end pads positioned on the ends of the sleeve to reduce friction between the ends of the sleeve and the end of an adjacent thrust bearing collar used to hold the sleeve in place on the drill pipe.

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 when 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: A stabilizer especially adapted for use with an drill string having an eccentric drilling element, such as a bi-center bit. The stabilizer has a pair of circumferentially displaced blades that lie in a common circumferential plane and extend from a rotatable sleeve supported on the stabilizer body, as well as a stationary blade. The rotating blades are aligned with the stationary blade when in a first circumferential orientation and are disposed so that the mid-point between the rotating blades is located opposite the stationary blade, thereby providing full-gauge stabilization, when the rotating blades are in a second circumferential orientation. A magnetic systems senses the circumferential orientation of the rotating blades and transmits the information to the surface via mud pulse telemetry. A piston actuated by the drilling mud locks the rotating blades into the active and inactive positions.

Abstract: A centraliser (1) has a substantially annular body (6), a substantially cylindrical bore extending longitudinally through the body (6), and at least one roller ball (29). The roller ball (29) is preferably secured to the centraliser (1) in a manner which enables the roller ball (29) to rotate in all directions with respect to the centraliser (1), and one roller ball (29) is secured within at least one aperture (9; 109) provided in the sidewall of the body (6). Preferably, an assembly (27, 28, 39; 127, 128, 139) is provided to house the rollerball (29) within the at least one aperture (9; 109), and the roller ball (29) may be arranged to project either outwardly or inwardly from the sidewall.

Abstract: A drilling assembly for drilling deviated wellbores includes a drill bit and a drilling motor that provides rotary power to the drill bit. A steering device integrated into drilling motor assembly contains a plurality of force application members. In one embodiment, each force application member is adapted to exert an adjustable amount of force on the wellbore interior. A separate or common power unit at or uphole of the drilling motor provides power to the force application members. A control device and control circuit can cooperate to independently operate each of the force application members. An inductive transmission device can be used to transmit electrical signals and/or power between rotating and non-rotating section of the drilling motor. During drilling of a wellbore, the force application members are operated to adjust the force on the wellbore to drill the wellbore in the desired direction.

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: A centralizer having a first group of rollers (5) for reducing friction between the centralizer and an oil field tubular (7) and a second group of rollers (4) for reducing friction between the centralizer and the wall of a well. The axles of the first group of rollers (5) are generally aligned with the axis of the bore (2) to reduce rotational friction. The axles of the rollers of the second group of rollers (4) are generally transversed to the bore (2). The arrangement reduces rotational and axial drag between an oil field tubular (7) and the walls of a well, particularly when initiating rotation of an oil field tubular.

Abstract: A drill pipe (1; 12) has a journal (2; 15) formed thereon. Integrally formed stop collars (10, 11; 16, 17) are provided at each end of the journal (2; 15). The arrangement enables rotatable tools (18) to be fitted directly to a journal (2; 15) to reduce friction between the rotatable tool (18) and the journal (2; 15). The journal (2; 15) may be of a substantially greater length than the length of the rotatable tool (18) to facilitate lubrication and cooling. Alternatively removable stop collars (30; 31) are secured adjacent the ends of a journal (28) formed on the drill pipe (25). Methods of forming the journal surface (2; 15) during manufacture of a drill pipe are disclosed. There are also disclosed methods for reconditioning an existing drill pipe (20) to form a journal (21) thereon.

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 friction reducing fitting for downhole applications. The fitting has a body portion (3) for securement about a tubular member, the body portion having a pair of apertures (5, 6). A roller (1) is provided, and an axle (4, 11) passing through said roller and said apertures in the body at either end of said roller. The axle is deformed at at least one end to prevent movement of the end of the axle through the aperture in the body.

Abstract: In a drilling apparatus of the type comprising a rotatable drilling shaft and a housing for rotatably supporting a length of the drilling shaft for rotation therein, a rotation restraining device associated with the housing for restraining rotation of the housing. In one embodiment, the rotation restraining device is comprised of at least one roller on the housing, the roller having an axis of rotation substantially perpendicular to a longitudinal axis of the housing and being oriented such that it is capable of rolling about its axis of rotation in response to a force exerted on the roller substantially in the direction of the longitudinal axis of the housing. In a further embodiment, the rotation restraining device is comprised of at least one piston on the housing.

Abstract: A friction and/or torque reducing drillstring component has a one-piece mandrel body 5 with a mandrel body recess 13c considerably smaller than mandrel upper neck 13a and mandrel body lower neck 13b, dressed with an outer sleeve 18 which is interlocked with a two-piece inner bearing 20 through several integral dove-tailed splines 22b and grooves 22a. The combination of the outer sleeve 18 and inner bearing 20 is restricted in vertical movement over the said mandrel body 5 by an integral, optionally spirally, bladed first stop 15 and a removable second stop 16. The removable second stop 16 is locked onto the mandrel body upper neck 13a by means of threaded retaining bolts 24. Once the second stop 16 is removed, the one-piece outer sleeve 18 is retractable over the mandrel body upper neck 13a to allow the removal of the two-piece inner bearing 20. A second inner bearing 155 may also be provided.

Abstract: In general, the present invention provides a modular drilling assembly having a module for contactless power and data transfer over a nonconductive gap between rotating and non-rotating members of a steering module. The gap usually contains a non-conductive fluid, such as drilling fluid, or oil for operating hydraulic devices in the downhole tool. The downhole tool in one embodiment is a modular drilling assembly wherein a drive shaft is rotated by a downhill motor to rotate a drill bit attached to the bottom end of the drive shaft. A substantially non-rotating sleeve around the drive shaft includes at least one electrically-operated device. The drilling assembly is modular in that it includes at least one steering module at the bottom end of the drilling assembly that has at least one steering device module that provides power to the force application member.

Abstract: A damper for downhole tools consisting of a plurality of damping inserts arrayed about the tool body so that their radial protrusion describes a circumference greater than desired gauge of the borehole. The damper inserts are configured with rounded working surfaces that radially protrude from the tool body and are coated with an abrasion resistant, superhard material. The damper inserts are progressively arrayed so that they are constantly forced against the walls of the borehole. In this manner, they may plastically fail the formation by an indenting, brinelling, or crushing action that produces a constant torsional load on the downhole tools, and controls the torsional unloading of the downhole tools and absorbs the vibrations of the drilling tool as the formation is being drilled.

Abstract: A friction reducing tool for drilling applications having a plurality of rollers for about the periphery of the tool (3). The rollers (4) have extensions (7) which locate within cavities (8) to prevent the rollers from passing from cavity (10) to the exterior of the tool. The tool is formed in multiple parts (3a and 3b) having interengaging tongues (5 and 6) which are joined together by passing a rod (15) through bore (13). A groove (14) is provided in outer component (2) to enable rod (15) to be inserted in bore (13).

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 friction-reducing drill pipe component in the form of a sub (10) is adapted to form part of a drill string. The sub (10) comprises a tubular mandrel (12) having first and second ends for connection to adjacent components of the drill string. A sleeve (18) is mounted on the mandrel (12), and first and second stops on the mandrel (16, 20) restrain the sleeve (18) against axial movement relative to the mandrel (12). One of the stops (20) is removable or retractable to permit the sleeve (18) to be removed over the first end of the mandrel.

Abstract: A component which is adapted for use in a down hole environment such as in a well bore (WB), the component being provided with friction reduction means (20) comprising a rotatable member (28) mounted in a ball bearing race (27), the ball contacting the wall of the well bore (WB) such that the rotatable member (28) rotates upon the ball bearings to allow the component to be repositioned as necessary in any direction.

Abstract: Directional drilling apparatus (26) for location on a drill string (20) comprises a stabiliser (32) having a mandrel (38) for connection to the drill string (20) and an eccentric non-rotating element (46) mounted on the mandrel (38) for offsetting the string (20) in the bore (22) and a non-rotating offset mass (34) for maintaining the element (46) at a selected orientation relative to the bore (22) as the drill string (20) rotates.

Abstract: Directional drilling apparatus (26) for location on a drill string (20) comprises a stabilizer (32) having a mandrel (38) for connection to the drill string (20) and an eccentric non-rotating element (46) mounted on the mandrel (38) for offsetting the string (20) in the bore (22) and a non-rotating offset mass (34) for maintaining the element (46) at a selected orientation relative to the bore (22) as the drill string (20) rotates.

Abstract: In general, the present invention provides a modular drilling assembly having a module for contactless power and data transfer over a nonconductive gap between rotating and non-rotating members of a steering module. The gap usually contains a non-conductive fluid, such as drilling fluid, or oil for operating hydraulic devices in the downhole tool. The downhole tool in one embodiment is a modular drilling assembly wherein a drive shaft is rotated by a downhill motor to rotate a drill bit attached to the bottom end of the drive shaft. A substantially non-rotating sleeve around the drive shaft includes at least one electrically-operated device. The drilling assembly is modular in that it includes at least one steering module at the bottom end of the drilling assembly that has at least one steering device module that provides power to the force application member.