Abstract: A shock absorbing tool for use in pipelines and oil wells, particularly in combination with perforation guns comprises a central mass supported on two springs between the end terminal members. The shock wave is absorbed in the free oscillation of the mass. The mass is constituted by a piston assembly. A steel rope permits the shock absorbing tool to be maneuvered within the bore hole without damage to the springs.

Abstract: A thrust absorber is interposed between a thruster and an anchor that cooperate to axially displace another member. The thrust absorber includes an enclosure fixed to the anchor and a retainer connected to the thruster. A biasing member is operably associated with the retainer. During an overthrust condition, the thruster imparts a thrust force to the member, but the member is not substantially axially displaced. In such a condition, the biasing member absorbs the thrust that the thruster would otherwise impart to the member. A dampener is also included to dampen the movement of the thruster and anchor when the anchor is no longer anchoring the thruster.

Abstract: An adjustable down-hole tool, for example a drill-string stabiliser (10), comprises a body (12) having a through bore (16). A mandrel (18) is rotationally fixed but axially movable in the body, the mandrel being movable by fluid pressure in the tool against the action of a first return spring (44) between a first, activated position and a second deactivated position. A sleeve (66) is between shoulders (68, 69) on the body and mandrel. Castellations (18a,b, 69a,b) are on the mandrel and facing edge or edges of the sleeve so that, when the castellations are in phase the mandrel is prevented from travelling from said first to second position and when they are out of phase they interdigitate and the mandrel is not prevented from travelling from said first to second position. A control piston (36) is slidable in the mandrel, being movable by fluid pressure in the tool against the action of a second return spring (50).

Abstract: An apparatus (60) for absorbing a shock comprises a first tubular member (62) and a second tubular member (80) that are slidable positioned relative to one another. A plurality of layers (94-104) of energy absorbing members (88) extend radially from the second tubular member (80) such that movement of the second tubular member (80) in a first direction relative to the first tubular member (62) sequentially deforms the layers (94-104) of energy absorbing members (88). As the layers (94-104) are sequentially deformed, a subsequent layer (96) of energy absorbing members (88) begins to deform before the previous layer (94) of energy absorbing members (88) is completely deformed. The deformation of the energy absorbing members (88) absorbs the shock.

Abstract: A telescopic drilling method includes the steps of drilling an outer bore through a surface, inserting a hollow outer conduit into the outer bore, and at least partially inserting a first hollow inner conduit through the outer conduit. Next, the method includes the steps of preventing the first inner conduit from moving longitudinal with respect to the outer conduit engaging a rotatable inner drill bit with a ring drill bit and further drilling the outer bore using a unitary drill bit head to a successive depth. The inner drill bit is disengaged from the ring drill bit and a second end of a successive hollow inner conduit is attached to a first end of a preceding one, and the preceding inner conduit is unclamped.

Abstract: This invention relates to a torque release coupling for use in drill strings comprising an outer string part (1) rotatably mounted outside a radially inner string part (2), and a rotation lock (3) positioned between them. The rotation lock (3) is coupled to a first of said spring parts (1, 2) with a coupling device (4, 9) adapted to allow axial shifts relative to the first string part, and comprising axial gripping organs (5) adapted for releasable engagement with cooperating gripping organs in the second string part, the rotation lock (3) comprising a spring (6) or similar adapted to apply an axial force on the rotation lock (3) directed against the cooperating gripping organs (5) from the first spring part.

Abstract: An apparatus (60) for absorbing a shock comprises a first tubular member (62) and a second tubular member (80) that are slidable positioned relative to one another. A plurality of layers (94-104) of energy absorbing members (88) extend radially from the second tubular member (80) such that movement of the second tubular member (80) in a first direction relative to the first tubular member (62) sequentially deforms the layers (94-104) of energy absorbing members (88). As the layers (94-104) are sequentially deformed, a subsequent layer (96) of energy absorbing members (88) begins to deform before the previous layer (94) of energy absorbing members (88) is completely deformed. The deformation of the energy absorbing members (88) absorbs the shock.

Abstract: The invention relates to a device for drilling, especially percussion drilling or rotary percussion drilling, holes (2), comprising a drill bit (3) with a drilling or breaking surface (14), a drill rod (4) for introducing a rotary or percussive force and for introducing a rinsing or cooling fluid into the drill bit (3) and a sheath pipe (5) which defines a hollow space (6) between the drill rod (4) and the inside of the sheath pipe (5) and which is supported on the drill rod (4) or which can be connected to the drill bit (3).

Abstract: The invention concerns a down the hole drill hammer assembly providing a full piston area exposure to driving fluid pressure by the omission of the usual finger valve from the upper piston area and providing the piston with blind bores at each end and passages through the piston wall enabling predetermined communication between the blind bores for exhausting pressure fluid through the drill bit assembly. Fluid transfer passages are also provided in the inner wall of an outer wear sleeve of the drill hammer assembly.

Abstract: A coupler system for downhole wellbore service tools comprises an elongated main body having a longitudinal bore, a plurality of release blocks disposed in slots in the main body wall, and an exterior spline about its circumference below the release blocks. The release blocks are movable radially inward and outward, and are biased inward by springs. A piston having a longitudinal bore is movably disposed within the main body bore. The piston has spaced apart larger diameter sections and a central smaller diameter section. A cylindrical washpipe body fits over the main body and has an internal spline for engagement with the main body spline, and shoulders (on the main body and on the interior of the washpipe body) limit downward movement of the washpipe body.

Abstract: Various embodiments of a downhole tool with a telescoping conductor member are provided. In one aspect, a downhole tool is provided that includes and a mandrel telescopically positioned in the housing. The mandrel and the housing define a pressure compensated substantially sealed chamber containing a volume of a non-conducting fluid. A conductor member is positioned in the housing for providing an electrically conducting pathway. The conductor member has a first segment and a second segment. The first segment is moveable with the mandrel and relative to the second segment. A portion of the conductor member is electrically insulated from an ambient fluid by the non-conducting fluid. A first biasing member is provided for maintaining a conducting pathway between the first segment and the second segment. The tool provides for electrical transmission in a telescoping tool.

Abstract: An apparatus and method for absorbing shock downhole in a wellbore. The kinetic energy from a moving tool is absorbed to dissipate such energy, to decelerate the moving tool, or to prevent impact damage s from contact between the tool and other downhole components. An actuator has an interference fit with a body such as the interior wall of a tubing section. When the moving tool actuates the actuator to move the actuator relative to the body, kinetic energy is dissipated into the body as the body elastically deforms due to the moving actuator. The amount of energy dissipated can be determined from the strength of the body, the contact dimensions between the actuator and body, and the length of moving contact between the actuator and body.

Abstract: Method of, and apparatus for, sinking bore holes, in particular exploratory and extraction bore holes, in the sea bed (40). The material from the sea bed is loosened with the aid of a rotating drill head (10) which is arranged at the bottom end of a drill string (5) which is suitable for transmitting a torque. The top end of the drill string is mounted on a floating platform (1), it being the case that the drill string (5) comprises at least two telescopically interengaging drill-string parts (6, 7) which, during a vertical movement of the platform, induced for example by the sea swell, execute a movement relative to one another, with the result that the drill head (10) rests with an essentially constant force on the surface which is to be cleared away.

Abstract: A down hole hammer comprising a cylindrical casing defining a piston chamber between a top sub at one end and a drill bit support at the other end, a piston within the piston chamber for reciprocation between the one and other end, the piston having a central portion which is sealingly engaged with the internal wall of the casing, one end portion of the piston being intended to impact on the drill bit with movement to an impact position at which position the one end portion sealingly defines a first space at the one end of the piston chamber, the internal wall of the casing adjacent the top sub having two sets of axially spaced fluid ports, the piston adapted to cooperate with a first set of the fluid ports to admit fluid into the first space when the piston is in the impact position and cause movement of the piston to a raised position where the piston is in spaced relation from the drill bit support, the piston adapted to cooperate with a second set of said set of fluid ports to admit fluid into a second sp

Abstract: A running tool which is intended to be lowered down a tubular member via a wireline extending from the surface to a connection to the upper end of the tool by which the tool is suspended, said tool being capable of advancing itself along the wall of the tubular member when required (e.g. when the tubular member is inclined to the vertical as a “lateral”), by repeated application and release of tension force in the wireline.

Abstract: A tractor for moving within a borehole comprises an elongated tractor body and two propulsion assemblies that are longitudinally movably engaged with the body. The tractor body has annular pistons configured to receive hydraulic thrust to propel the body longitudinally. Each propulsion assembly includes a gripper and one or more propulsion cylinders. The gripper has an actuated position in which the gripper limits relative movement between the gripper and the inner surface of the borehole, and a retracted position in which the gripper permits substantially free relative movement between the gripper and the inner surface of the borehole. Each propulsion cylinder contains one of the pistons. The tractor includes a control assembly having a plurality of valves and hydraulic circuitry which control the sequencing of fluid distribution to the propulsion cylinders, and of the actuation and retraction of the grippers. A throttle valve controls the fluid flowrate to the pistons.

Abstract: A cushion sub for absorbing both axial and torsional vibration in a drill string and including an outer casing connectable at one end to a section of a drill string, and an inner piston reciprocally mounted in a cylinder within the casing, the piston having a shaft projecting from the other end of the casing connectable to another section of the drill string. The cylinder includes a first cushion device at opposite ends thereof for engagement by the piston to absorb axial vibrations. A spline type connection prevents relative rotation between the piston and the cylinder. The cylinder is mounted for arcuate turning in a chamber within the casing, but the cylinder has vanes which are interposed between vanes fixed to the casing, and elastomeric material between the vanes of the cylinder and the vanes of the casing absorbs torsional vibrations being transmitted between the cylinder and the casing.

Abstract: A pneumatic impact damping device for a drill column comprises a first connection member for connection with the rear part of a drill column and a second connection member for connection with the front part of the drill column. Both connection members define a pneumatic cylinder chamber through which a bushing extends. The bushing has a passage moving Into and closed by a seal when an axial thrust force is exerted on the drill column. Thus, pressurized air is trapped and compressed in the cylinder chamber. In this manner, impacts applied to the front connection member by a deep-hole hammer drill are damped and prevented from acting on the rear part of the drill rod.

Abstract: In the field of drilling lateral channels from the cased bore of an oil well, a system is presented whereby a number of lateral channels can be drilled through the casing and out a distance into the formation with no requirement to move or raise the lateral drilling apparatus to the surface for each lateral channel drilled. The direction of the drilled lateral channel can be selected by the system operator at the well head. The system will allow the drilling of lateral channels with the well under pressure. A configuration is shown which will allow the installation of a flexible perforated liner in the channel, which flexible perforated liner will prevent the material around the channel from collapsing.

Abstract: A tool for expanding a hole size while drilling tool is disclosed. The tool utilizes a mechanically actuated mandrel and extendable cutting lugs designed in a configuration with fewer moving parts than previous designs. The cutting lugs have multiple cutting elements attached. The cutting lugs are driven between two cylindrical diameter surfaces to achieve a large differential between the retracted and extended positions of the tool, and to provide sufficient stability to allow the tool to be used in the extended position while drilling forward. The lugs are internally assembled and tapered to closely match the slots in the body of the tool for additional stability and to prevent complete passage through the tool for prevention of catastrophic failure. The tool has a locking mechanism to allow the tool to remain in the extended position when the weight is removed from the tool.

Abstract: An apparatus and method for absorbing shock downhole in a wellbore. The kinetic energy from a moving tool is absorbed to dissipate such energy, to decelerate the moving tool, or to prevent impact damage from contact between the tool and other downhole components. An actuator has an interference fit with a body such as the interior wall of a tubing section. When the moving tool actuates the actuator to move the actuator relative to the body, kinetic energy is dissipated into the body as the body elastically deforms due to the moving actuator. The amount of energy dissipated can be determined from the strength of the body, the contact dimensions between the actuator and body, and the length of moving contact between the actuator and body.

Abstract: A wellbore motion control apparatus for controlling the motion of a tubular wellbore string (in one aspect with an additional item and/or apparatus connected thereto) in a wellbore extending from a surface down into the earth has been invented which has, in one aspect, a central mandrel connected to the tubular wellbore string, a housing with a hollow interior and fluid therein, at least one fluid passage apparatus disposable in the hollow interior and having a fluid flow channel extending therethrough, and the at least one fluid passage apparatus secured to the central mandrel, the housing surrounding the central mandrel, the at least one fluid passage apparatus disposed for movement in a chamber defined by an inner surface of the housing and an outer surface of the central mandrel, the at least one fluid passage apparatus positioned within the chamber so that fluid therein is flowable therethrough permitting movement of the fluid passage apparatus within the chamber and thereby controlling movement of the m

Abstract: The present invention provides a disconnect which has the internal integrity to make it as strong as the rest of the drill string. The present invention can disconnect when desired, despite the fact that the apparatus is at that time subjected to significant tensile or compressive loads. The invention allows for disconnection by alternative methods. Accordingly, in one version of the tool, a ball can be dropped or pumped to a seat to facilitate disconnection. In another version of the tool, that may employ an internal wireline precluding the use of a ball, disconnection can be accomplished by compression of a stack of Bellville washers, in response to a tensile force, to release a collet-locking mechanism. Either design features a rotational locking component.

Abstract: A wellbore motion control apparatus for controlling the motion of a tubular wellbore string in a wellbore extending from a surface down into the earth and methods for using it. Such an apparatus, in one aspect, has a housing with a top end, a bottom end, and a hollow interior having an interior volume with fluid therein. There is at least one fluid passage apparatus having a top end and a bottom end and disposable in the hollow interior of the housing, the at least one fluid passage apparatus having a fluid flow channel extending therethrough from the top end to the bottom end.

Abstract: The present invention relates to a drilling tool for percussive drilling by means of a top hammer unit, which unit gives compressive pulses. The tool comprises at least one drill tube (12) and a drill bit (11), which cooperates via a connection. The drill bit comprises a bit head (13) provided with crushing means (15) and a shank (17). A shoulder (20) is provided in connection with the bit head, said bit portion having a first abutment surface (21) facing towards a free end of the tube. The free end of the tube facing towards the drill bit is povided with a second abutment surface (23), said top hammer unit being provided to tannsfer compressive pulses to the tube. Each compressive pulse is transferred to the drill bit via the impact surfaces (21, 23). The tube and the drill bit comprise cooperating device (19, 24, 25) for driving and retaining. The tool is defined by that it has a relation between the length of the shank and the length of the bit head that is 5 or more.

Abstract: Well completion apparatus and associated methods of completing wells provides repositioning of sand control screens and perforating guns without requiring movement of a packer in the wellbore. In a preferred embodiment, a well completion apparatus has a packer, a release apparatus, a telescoping expansion joint, a ball catcher, a sand control screen, and a perforating gun. In another preferred embodiment, a well completion method includes the steps of lowering a packer, release apparatus, telescoping expansion joint, ball catcher, sand control screen, and perforating gun into a well, perforating the wellbore casing, dispensing a sealing ball into the release apparatus, applying pressure to release the release apparatus, and applying pressure to expand the telescoping joint.

Abstract: A mechanical swivel apparatus which has a first upper body portion threadably attached to the lower end of a side entry sub apparatus, and a second lower portion which is threadably attached to a section of drill pipe, the apparatus positionable above the rotary table on the rig floor, and having a continuous bore therethrough for running wireline or the like. The upper body portion includes a counterbore for receiving the upper end of a mandrel, so that the mandrel is able to move within the counterbore of the upper body portion. The lower portion comprises an open-ended cap member which threadable engages the upper body portion, and has a shoulder portion which engages a flange around the body of the mandrel so that the mandrel is allowed to move within the upper body portion but cannot be slidably removed therefrom.

Abstract: The present invention provides a disconnect which has the internal integrity to make it as strong as the rest of the drill string. The present invention can disconnect when desired, despite the fact that the apparatus is at that time subjected to significant tensile or compressive loads. The invention allows for disconnection by alternative methods. Accordingly, in one version of the tool, a ball can be dropped or pumped to a seat to facilitate disconnection. In another version of the tool, that may employ an internal wireline precluding the use of a ball, disconnection can be accomplished by compression of a stack of Bellville washers, in response to a tensile force, to release a collet-locking mechanism. Either design features a rotational locking component.

Abstract: A shock tool includes a first tubular member, a second tubular member and a third tubular member. The first tubular member has an interior bore that extends between a first end and a second end. The second tubular member has an interior bore that extends between a first end and an attachment end. The second tubular member is rotatably supported by both radial and thrust bearings within the interior bore of the first tubular member with the attachment end protruding from the second end of the first tubular member. The third tubular member has an interior bore that extends between a connection end and a second end. The second end of the third tubular member being telescopically received within the interior bore at the first end of the second tubular member with the connection end protruding. The third tubular member is capable of limited reciprocal movement relative to the second tubular member. Shock absorbing medium is disposed between the third tubular member and the second tubular member.

Abstract: A dual acting hydraulic jarring enhancer which is particularly well suited for coiled tubing application. A common annular chamber is formed between reciprocating cylindrical assemblies, and a piston is positioned within the annular chamber. The inner cylindrical assembly has a member to contact the piston and move it relative to the outer cylindrical assembly in one direction while the outer cylindrical assembly has a member to prohibit longitudinal movement of the piston relative to the inner cylindrical assembly in a second direction. In this manner, the present invention provides a tool with overall minimal length by using a singular annular chamber capable of being divided into two other chambers and providing an accelerating effect to a hammer/anvil of an associated jarring tool in either an upjarring or downjarring mode.

Abstract: An accelerator having a tubular housing and a tubular mandrel substantially coaxial arranged for telescoping longitudinal movement within the tubular housing, the accelerator also including: a first piston positioned radially between the tubular housing and mandrel, the first piston being adapted for movement with the mandrel in response to movement of the mandrel in a first longitudinal direction relative to the housing and adapted to resist longitudinal movement in response to movement of the mandrel in a second longitudinal direction relative to the housing; and a second piston positioned radially between the tubular housing and mandrel, the first and second pistons forming a substantially sealed gas chamber therebetween, the second piston being adapted for movement with the mandrel in the second longitudinal direction relative to the housing and adapted to resist longitudinal movement in response to movement of the mandrel in the first longitudinal direction relative to the housing, and whereby the chambe

Abstract: A dual acting hydraulic jarring tool which includes dual acting metering devices and is particularly well suited for coiled tubing application. A common annular chamber is formed between reciprocating cylindrical assemblies and dual engaging and metering devices are used to engage and meter hydraulic fluid at a predetermined rate flowing from one chamber to another chamber defined within the annular space. An improved retarding and metering mechanism is also disclosed which serves to retard relative telescoping movement of one cylindrical assembly relative to the other cylindrical assembly and meter the hydraulic fluid at the predetermined rate. The present invention is particularly well suited for coiled tubing application due to its low load requirements, minimal overall length and enlarged interior bore for the passage of downhole tools; however, the present invention is well suited for use with conventional drilling strings as well.

Abstract: A deep-drilling system has a vertical tubular drill string having an upper section and a lower section, a rotatable bit at a lower end of the lower section so that when the string and bit are lowered into the ground longitudinally they form therein a bore. A drill mud is pumped at a working pressure longitudinally through the string to emerge at the lower end of the string and flow upward in the bore around the string. A hydrostatic compensator joint in the string between the sections is centered on an upright axis and has a tubular upper part, a threaded joint rigidly connecting the upper part to a lower end of the upper section, a tubular lower part, and a threaded joint rigidly connecting the lower part to an upper end of the lower part. Each part has surfaces directed radially and axially at generally complementary surfaces of the other part. The axially directed surfaces of the upper part are spaced axially from the respective surfaces of the lower part by at most 5 mm.

Abstract: The present invention is an improved apparatus for controlling the weight on the drill bit during operation. In this invention, an inner mandrel has a telescoping movement in response to added drill string length at the surface. As the inner mandrel telescopes closed, it approaches a restrictor which is fixedly disposed in the lower housing of the drill string assembly. When the inner mandrel mates with the restrictor, a stand-pipe pressure increase noticeable to the operator occurs. The operator then stops the drill string and allows the motor to drill ahead. As the motor drills ahead, the inner mandrel telescopes open and the operation is then repeated.

Abstract: A releasable connection between the lower end of a running string and a well tool that is subject to being stuck in a well includes inner and outer members movable telescopically between contracted and extended positions, a tension sleeve connecting the members in the contracted position and being disrupted by a predetermined pull to allow telescoping movement, a stop nut to limit such movement in the extended position of the members, and a mechanism responsive to a certain number of cycles of telescoping movement for disabling the stop nut to allow complete release and separation of the members.

Abstract: A device for controlling weight on bit of a drilling assembly for drilling a borehole in an earth formation, is provided. The device includes a fluid passage for the drilling fluid flowing through the drilling assembly, and control means for controlling the flow resistance of drilling fluid in the passage in a manner that the flow resistance increases when the fluid pressure in the passage decreases and that the flow resistance decreases when the fluid pressure in the passage increases.

Abstract: A jar enhancer including a housing in which is telescopically mounted a mandrel, with the mandrel rotationally locked within the housing, and the housing and mandrel being spaced apart by an amount R at one location between them to form a chamber of width R. The upper end of the chamber is closed by a face, at least part of which is a shoulder extending inward from the housing, and the lower end of the chamber is closed by a face, at least part of which is a shoulder extending from the mandrel. The housing is sealed to the mandrel above and below the chamber and a port is provided for filling the chamber with compressible fluid. At least one of the shoulders has width W less than R, such that only a part of one of the faces bounding the chamber moves upon relative movement of the mandrel in relation to the housing.

Abstract: A drilling tool, adapted to drill a wellbore in an earth formation, comprises a weight on bit equalizer shock sub. The weight on bit equalizer shock sub includes a precharged nitrogen chamber and additional chambers, the nitrogen in the nitrogen chamber adapted to telescopically open the equalizer shock sub during the drilling of the wellbore thereby maintaining a constant weight or force on the drill bit during the drilling operation. A force resultant from the pressurized nitrogen exists in the nitrogen chamber and additional forces resultant from a pressurized wellbore fluid exist in the additional chambers. The shock sub is specially designed in a particular manner to cause the sum of the force of the nitrogen in the nitrogen chamber and the additional forces of the wellbore fluid in the additional chambers to be equal solely to the force of the nitrogen in the nitrogen chamber.

Abstract: There is disclosed a single-acting hydraulic jar having upper and lower detent pressure chambers having upper and lower restrictions, respectively, formed on the inner diameter of its outer tubular member and through which upper and lower detent means carried about the outer diameter of the inner tubular member may be moved in order to impart an up jar.

Abstract: A new tool has been developed for, in one aspect, facilitating release of a tubular string coupled between a travelling block and elevators with insufficient clearance to release elevator slips in order to remove the tubular. In one aspect the releasing tool is effectively shortened permitting release of the elevators. Such shortening is effected by releasing an expansion sub and piston within the tool for relative movement with respect to other parts of the tool. Initially the expansion sub and piston are held in place by fluid in a first chamber. Movement of fluid from the first chamber and movement of fluid into a second chamber housing the piston results in piston movement (and movement of the expansion sub which is secured to the piston) to effectively shorten the tool. In one aspect the fluid moves in a closed loop between the chambers and no fluid is expelled to the environment. In another aspect only one fluid chamber is used.

Abstract: A casing joint is provided for use in landing a casing string in a well bore for an oil or gas well in a controlled manner so that movement of the casing string relative to the well bore does not cause the casing string to become damaged. The casing joint includes an inner tubular member disposed within an outer tubular member. The casing joint also includes a means for causing the inner tubular member to move axially relative to the outer tubular member in response to differential fluid pressures. The casing joint further includes a plurality of shear pins attaching the inner tubular member to the outer tubular member. The shear pins are selected to shear at a predetermined load so as to enable the inner tubular member to move axially relative to the outer tubular member. The casing joint also includes a pair of anti-rotation lugs which prevent the inner tubular member from rotating relative to the outer tubular member.

Abstract: There is a need for a device for driving plastic casing into a water well, or for removing such casing from the well without damaging the casing. This need is met by a casing drive apparatus which includes a shoe for attachment to the bottom end of a plastic well casing, an annular groove defining a pair of shoulders in the sleeve, a drive sub for insertion into the sleeve, a plurality of dogs pivotally mounted in the drive sub for engaging the shoulders, and helical springs for biasing the dogs outwardly into engagement with the shoulders, whereby, when the sub is slid into the sleeve and the dogs engage the shoulders, vertical force exerted on the sub results in movement of the dogs against the shoulders to effect vertical movement of the sleeve and consequently of the well casing.

Abstract: There is disclosed a double-acting hydraulic jar having upper and lower detent pressure chambers having upper and lower restrictions, respectively, formed on the inner diameter of its outer tubular member and through which upper and lower detent means carried about the outer diameter of the inner tubular member may be moved in order to impart either an up or down jar.

Abstract: There is disclosed a tool for enhancing the impact of a jar delivered to an object stuck in a well bore during both upward and downward jars to the stuck object. The tool includes a first tubular member having an lower end connectible to the tubular member of the jar on which the hammer is mounted and a second tubular member connectible to a well pipe string above it and arranged for reciprocation with respect to the first member to form an annular space between them. The space is divided into upper and lower chambers by means of seal rings disposed between the members and the spaces are filled with a compressible fluid which is compressed as the second tubular member is moved in either upward or downward directions.

Abstract: A cutting bit useful for cutting various earth strata and the cutting insert, which may be made from a polycrystalline diamond composite, for such a cutting bit. The cutting bit has at least one pocket at the axially forward end thereof which receives its corresponding cutting insert. The cutting insert has at least one exposed cutting edge which is of an arcuate shape.

Abstract: Directional drilling is achieved by a weight-on-bit control mechanism that is attached to a drill bit having asymmetrical cutters. A valve in the mechanism temporarily interrupts or bypasses mud flow toward the bit to correspondingly change the downward force acting thereon during a portion of each revolution. The bit will drill preferentially on that side of the bottom surface of the borehole where the downward force is increased, and thereby cause the borehole to curve in an azimuthal direction on such side.

Abstract: A rotary bearing downhole sub has an outer housing adapted to be connected to an upper drill string and to receive therein an inner mandril adapted to be connected to a lower drill string. Both the outer housing and the inner mandril are provided with radially directed splines which, when brought into meshed engagement, allow transmission of rotary motion between the upper and lower drill strings and through the sub.

Abstract: In a drill string jar apparatus having an elongated tool body positionable within a drill string, which would also include a latch mandrel movable within a bore of the tool body between a first neutral position and fired up or fired down positions; a substantially continuous channel formed in the interior wall of the tool body, a shoulder portion on the exterior wall of the latch mandrel body for latching into the channel of the tool body when the mandrel is in the neutral position and slots in the wall of the latch mandrel for allowing the mandrel body to flex inwardly sufficiently to disengage the shoulder portion from the channel in the tool body and allow the latch mandrel to move upward or downward within the bore of the tool body depending upon the direction of the force imparted on the mandrel and make contact with the upper or lower end of the tool in order to dislodge a tool below the jar apparatus.

Abstract: An orientation mandrel rotatable in an orientation body for providing rotational orientation and actuated by a hydraulic piston controlling the position of a helix. A thruster may be connected to the orientation mandrel and is adapted to hydraulically engage the well bore by plurality of elongate gripping bars. An annular thruster piston is hydraulically and longitudinally movable in the thruster body for extending the thruster mandrel outwardly from the thruster body. However, the orientating tool and thruster may be used separately.

Abstract: A movable joint bent sub for attachment to a well conduit for use in deviated drilling of a well. An elongated housing is provided having one end for attachment to a well conduit, a mandrel is telescopically movable in the bore of the housing, and a movable body is pivotally connected to the mandrel and is longitudinally movable in the housing. Coacting cam surfaces on the body in the housing pivot the body to a desired deviation when the mandrel is telescopically moved in the bore. A releasable lock may be provided between the mandrel and the housing.