Abstract: A method of dislodging a tubular string or well equipment connected to the tubular string can include connecting a dislodging tool in the tubular string, so that a flow passage of the dislodging tool extends through the tubular string, deploying a plug into the dislodging tool, applying a pressure differential across the plug, thereby displacing the plug through a seat of the dislodging tool, and dislodging the tubular string or the component in response to the displacing. A dislodging system can include a dislodging tool connected as part of a tubular string, the dislodging tool including a flow passage and a seat configured to sealingly engage a plug deployed into the tubular string, and at least one of a jarring force, load, impact, shock wave, elastic strain release and pressure pulse being generated in the tubular string in response to displacement of the plug through the seat.

Abstract: A bottomhole assembly includes: a drill bit operable to vibrate when engaged with a formation and rotated; and a suspension sub including: a stator barrel for connection to a pipe string; a traveler barrel for connection to the drill bit; a slip joint longitudinally coupling the traveler barrel to the stator barrel while allowing movement of the traveler barrel between an extended position and a retracted position; a torsional joint connecting the traveler barrel to the stator barrel at and between the positions; and one or more springs disposed between the stator barrel and the traveler barrel. The suspension is tuned relative to the drill bit to: dampen the vibration of the drill bit when the BHA is rotated at a first angular velocity; and resonate the vibration of the drill bit when the BHA is rotated at a second angular velocity, thereby imparting percussive energy to the drill bit.

Abstract: A perforating apparatus for a gun string is presented. The apparatus experiences an axial load and potentially a radial load during use. A central charge-carrier supports shaped-charges and substantially bears the axial load on the apparatus during use. The charge-carrier is positioned within an exterior sleeve and the plurality of shaped-charges, upon detonation, perforate the exterior sleeve. The exterior sleeve does not bear a substantial portion of the axial load on the apparatus and can therefore be thinner and cheaper than in prior art assemblies. An annular space can be defined between the charge-carrier and exterior sleeve. The exterior tubular can bear the radial load due to differential pressure in one embodiment. Alternately, the apparatus includes radial support members extending between the charge-carrier and sleeve for transmitting radial load to the charge-carrier. Alternately, the sleeve and charge-carrier abut one another along a substantial portion of the length of the charge-carrier.

Abstract: A downhole jarring apparatus for use in jarring an object in a bore includes a first jarring portion including a first impact surface and a second jarring portion including a second impact surface. The apparatus includes a rotatable jarring arrangement operable to translate a rotational drive movement to cause relative axial movement of the first and second impact surfaces to establish axial impact therebetween.

Abstract: A downhole apparatus includes a pressure pulse generator and a pulse reflector. The pulse reflector reflects at least a portion of an incident pressure pulse from the generator as a reflected pressure pulse. The apparatus is configured to provide the reflected pressure pulse with a phase shift with respect to the incident pressure pulse. A method of transmitting pressure pulses downhole includes generating a pressure pulse and reflecting at least a portion of an incident pressure pulse at a pulse reflector as a reflected pressure pulse. A phase shift of the reflected pressure pulse with respect to the incident pressure pulse is controlled.

Abstract: A drilling system for drilling a lateral borehole from a main borehole comprises a tubular conduit through which a fluid can be pumped, and a drilling assembly connected to the tubular conduit so as to receive fluid pumped therethrough. The drilling assembly comprises a power conversion unit, through which the fluid flows and which operates to provide a downhole power output; a drilling unit including a drilling apparatus powered by the output of the power conversion unit and operable to drill a lateral borehole into the formation surrounding the main borehole, and a liner unit for storing one or more liners for installation into the lateral borehole; and an anchor unit operable to anchor the drilling assembly in the main borehole when the drilling unit operates to drill the lateral borehole.

Abstract: A downhole jarring tool includes a mandrel having a small diameter portion and a large diameter portion, a detent cylinder sealingly disposed around the mandrel forming an enclosure, a divider disposed in the enclosure between the mandrel and the detent cylinder, wherein the divider partitions the enclosure into a storage chamber and a metering chamber, and a metering system disposed around the mandrel. A method of applying an impact force using a downhole jarring tool includes moving a mandrel with respect to a detent cylinder by applying an axial force, positioning the mandrel such that a metering system disposed on the mandrel enters a reduced diameter portion of the detent cylinder, transmitting energy to an energy storing component disposed inside the detent cylinder, metering a fluid through the metering system, and accelerating the mandrel with respect to the detent cylinder.

Abstract: A percussion drilling assembly for boring into the earth is disclosed. The percussion drilling assembly includes a top sub, a casing coupled to the top sub, and a feed tube assembly disposed within the top sub and the casing. The feed tube assembly includes a non-rigid coupling having a throughbore and a tubular body disposed therein. The tubular body is translatable in the radial position and/or rotatable relative to a longitudinal centerline extending through the non-rigid coupling.

Abstract: A steerable ground piercing tool includes an elongated outer housing having a lengthwise extending bore and an inner assembly at least in part disposed within the outer housing. The inner assembly includes a rotatable chisel having a longitudinally extending shaft at least in part disposed within the housing bore. The chisel has a first end defining an asymmetric tip and a second end defining a first impact surface for receiving a reciprocating action impact to drive the tool through the ground. The inner assembly further includes a conversion mechanism to selectively convert upon activation thereof at least a first portion of the reciprocating action imparted to the first impact surface into combined reciprocation and rotation of the tool.

Abstract: A steerable ground piercing tool includes an elongated outer housing having a lengthwise extending bore and an inner assembly at least in part disposed within the outer housing. The inner assembly includes a rotatable chisel having a longitudinally extending shaft at least in part disposed within the housing bore. The chisel has a first end defining an asymmetric tip and a second end defining a first impact surface for receiving a reciprocating action impact to drive the tool through the ground. The inner assembly further includes a conversion mechanism to selectively convert upon activation thereof at least a first portion of the reciprocating action imparted to the first impact surface into combined reciprocation and rotation of the tool.

Abstract: A double action locking jar is operable to provide a jarring force in an upward or downward direction. A pair of pressure pistons form a pressure chamber in which a Belleville spring stack is located. A metering orifice in one of the pistons serves to provide a delay mechanism for release of a mandrel within the housing. Two collets are located within the housing for mechanically releasing the mandrel when a tension or compression force is applied to the mandrel. The jar may be mechanically actuated only by allowing the pistons to freely move within the housing without hydraulic resistance.

Abstract: The device has a drill body, of generally cylindrical shape, connected by a flexible pipe to a high-pressure water pump placed on a low-height carrying vehicle. A striking piston is mounted movably, and is resiliently returned, in the drill body, and is subjected to a pulsed high water pressure so as to be moved with a percussive movement against a bit-carrying anvil, the pipe simultaneously transmitting to the drill body an alternating rotary movement about its principal axis. A solenoid valve, interposed between the pump and the point of departure of the pipe, receives successive electrical pulses causing opening and closing, which create shock waves in the water column contained in the pipe, which transmits these shock waves to the striking piston of the drill body. Applications: underground workings, mine workings, particularly for use in low-height galleries.

Abstract: An impact jar including a biasable member, an impactor and an impactee slidably coupled to the impactor. The impactor includes a first down-hole tool connector. The impactee includes a second down-hole tool connector distal from the first down-hole tool connector and a plurality of flexible coupling fingers. The biasable member is detachably engaged by the plurality of flexible coupling fingers in a pre-impact position and is configured to disengage the plurality of flexible coupling fingers in response to a tensile force applied across the first and second down-hole tool connectors reaching a predetermined quantity. The impactor and the impactee are configured to impact in response to the disengagement of the biasable member and the plurality of flexible coupling fingers. In one embodiment, the impact jar may be employed in either of e-line and slickline applications.

Abstract: An arrangement by a hydraulic jar device, especially for use in underground wells, where the jar device is installed in a pipe string led down into the well, and designed so that e.g. a stuck object in the well may be loosened or broken up by upward or downward percussions from the jar device. The jar device is actuated by increasing the flow of drill fluid. Alternatively, the device is actuated by compression. A valve (27, 37, 38) closes off the flow of drill fluid, whereby a percussion cycle is initiated. The valve is designed so as also to seal during strong lateral accelerations.

Abstract: An impact jar including a biasable member, an impactor and an impactee slidably coupled to the impactor. The impactor includes a first down-hole tool connector. The impactee includes a second down-hole tool connector distal from the first down-hole tool connector and a plurality of flexible coupling fingers. The biasable member is detachably engaged by the plurality of flexible coupling fingers in a pre-impact position and is configured to disengage the plurality of flexible coupling fingers in response to a tensile force applied across the first and second down-hole tool connectors reaching a predetermined quantity. The impactor and the impactee are configured to impact in response to the disengagement of the biasable member and the plurality of flexible coupling fingers. In one embodiment, the impact jar may be employed in either of e-line and slickline applications.

Abstract: The invention relates to a method for horizontal drilling with a percussion implement and a percussion head or percussion head element mounted in a movable manner relative to the percussion implement, the percussion impulse being transmitted in at least three steps.

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.

Abstract: A dust collection unit suitable for use with a hand held drilling and/or hammering tool, comprising a shroud (34) which is adapted to extend around a tool or bit (24) of such a hammering and/or drilling tool so as to collect dust in an airflow passing through the shroud which dust is generated by such a tool or bit. A tube like extension sleeve (28) extends forwardly from the shroud, with respect to such a tool or bit, which extension sleeve (28) is tapered at its forward end so as to have a forward rim which fits into a corner of a surface to be worked. A slideable sleeve (54) is slideably mounted on the extension sleeve so as to move between a retracted position in which the tapered forward rim of the extension sleeve (28) is engageable with a corner surface to be worked and an extended position in which a forward rim of the slideable sleeve (54) is engageable with a surface to be worked.

Abstract: A downhole jarring apparatus including a shaft and a first mandrel configured to releasably engage, a collar operatively attached to the shaft such that an axial position of the collar relative to the shaft is adjustable by access through an opening in an outer surface of a second mandrel, and an energy store configured to exert a force against the shaft, wherein the force is adjustable in response to the axial position of the collar relative to the shaft.

Abstract: The down hole motor is a self-contained radial drive unit that is driven by a linear input, which can be supplied from various sources. As linear motion is applied to the input of the tool, drive pins on a drive shaft follow a helical path, converting the linear motion into radial motion at the attached mandrel end. This may then be utilized in various activities such as drilling, boring and obstruction removal. This tool may also be used in conjunction with jarring mechanisms in order to create an impact drilling device, or a percussion motor.

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 apparatus for use in a wellbore comprises a housing having a longitudinal axis and a mechanism having one or more impact elements adapted to move along the longitudinal axis in an oscillating manner to impart a back and forth force on the housing to vibrate the housing. In another arrangement, an apparatus for use in a wellbore comprises a housing and at least one impact element rotatably mounted in the housing. The at least one impact element is rotatable to oscillate back and forth to impart a vibration force to the housing.

Abstract: An apparatus for jarring a portion of drill string lodged within a borehole, by jarring downhole using tension only, including a first member for attaching a first lower end of the apparatus to the upper end of the lodged tool or pipe through a threadable attachment; a second member for attaching a second end of the apparatus to a drill string on its upper end portion; a third anvil or hammer member which is triggered by spring having stored compressional force transferred by tension from the drill string to the apparatus when the drill string is pulled upward. There is also provided an actuator for rapidly releasing the tension force provided by the spring downward onto the stuck pipe in order to provide an impacting, downward force onto the pipe in an effort to dislodge the pipe. There is further provided a slow release mechanism for slowly releasing the tension force stored by the spring in the event the tool is not fired downhole.

Abstract: A double acting jar enhancer tool is capable of storing energy to enhance both upward and downward impacts delivered by a drilling jar. The enhancer stores energy in a single energy storage stack, typically of either bellville washer springs or a coil spring, and stores the energy in the storage stack irrespective of which direction it is moved, obviating separate energy storage stacks for upward and downward blows.

Abstract: An apparatus for dislodging stuck tools downhole, which includes a tool body; a mandrel moveable within the tool body; a spring member for allowing the mandrel to move with jarring force within the tool body when actuated; actuating fluid allowing the mandrel to travel a portion of the distance in a controlled manner, and at a predetermined point, accelerate its travel to provide a jarring force against the tool body; wherein the actuating fluid includes a first and second volumes of fluid through which a portion of the mandrel travels; the first volume providing controlled travel, and the second volume allowing accelerated travel of the mandrel.

Abstract: An impact boring tool according to the invention suitable for using with a directional boring machine has a tubular housing and a head mounted at a front end of the housing. The head preferably includes a chisel configured for breaking loose rocks and stones encountered in soil. A striker is disposed within the housing for delivering an impact force to the head, either directly or through one or more intervening parts. A trigger mechanism causes the striker to deliver an impact to the head and chisel only when an external force exerted on the impact tool in its lengthwise direction exceeds a predetermined level. This predetermined level generally coincides with a maximum effective amount of pushing or pulling force for moving the tool through the ground exerted by an external device such as a directional boring machine.

Abstract: An impact driven oil and gas well tool for use with an elongated tubular string having a central flow conveying bore is provided for channeling pressurized fluid to the tool body. The apparatus further includes an elongated longitudinally extending tool body having a connecting end portion at its upper end for connecting the tool body to the pipe string. A fluid chamber in the tool body is provided that is in fluid communication with the pipe string bore. A stem is reciprocally movable within the tool body in a telescoping fashion. The stem includes a lower end portion for carrying a working member such as a drill. A pressure responsive valve is provided for controlling relative movement of the stem and the tool body. An anti-chatter annular sleeve is positioned in the fluid chamber and about the valve member. A spring extends between the sleeve and the valve member for holding the valve member off the seat until a predetermined flow rate through the tool body is reached.

Abstract: An impact driven oil and gas well tool for use with an elongated tubular string having a central flow conveying bore is provided for channeling pressurized fluid to the tool body. The apparatus further includes an elongated longitudinally extending tool body having a connecting end portion at its upper end for connecting the tool body to the pipe string. A fluid chamber in the tool body is provided that is in fluid communication with the pipe string bore. A stem is reciprocally movable within the tool body in a telescoping fashion. The stem includes a lower end portion for carrying a working member such as a drill. A pressure responsive valve is provided for controlling relative movement of the stem and the tool body. An anti-chatter annular sleeve is positioned in the fluid chamber and about the valve member. A spring extends between the sleeve and the valve member for holding the valve member off the seat until a predetermined flow rate through the tool body is reached.

Abstract: A multi-impact jarring apparatus for retrieving objects stuck within a well bore comprises (1) an operating mandrel reciprocatively mounted within an upper housing attached to a fishing operating string, the mandrel acting as a hammer against the housing for creating a series of successive upwardly directed impact forces, (2) a releasable spring compressible between the mandrel and an upper portion of the housing and responsive to tension applied to the operating string, (3) releasable latching means for releasing the mandrel from the upper portion of the housing when the latching means is moved past a preset release position. The movement of the mandrel responsive to tensional force of the operating string allows for sudden release of the release spring and causes sudden upward movement of the mandrel resulting in impact of the mandrel against the upper portion of the housing and in immediate reposition of the latching means to reconnect the mandrel and a bottom portion of the upper housing body.

Abstract: A moling apparatus comprises a housing having a head for penetrating ground, an anvil in the housing connected to the head, and a hammer in the housing and spaced therefrom by a spring. A vibrator unit is spaced from the hammer and arranged to transfer vibration to the housing and the hammer. In a first mode of the apparatus, vibration transmitted to the housing causes fluidization of the surrounding ground to allow progressive penetration of the apparatus. In a second mode, the braking effect of the ground on the head causes the hammer to move against the spring and impact the anvil thereby driving the head through the ground, the apparatus being operable at or between each mode.

Abstract: An elastomeric joint that can be used, as part of an articulated coupling in a progressive cavity device, including using the articulated coupling for converting the complex motion of the rotor into simple rotation. The coupling includes two shafts coupled to one another by coupling assemblies connected to opposite ends of an intermediate shaft. The coupling assemblies include interlocked threaded and tapered portions and an elastomer filling the spaces between the threaded portions. Under loading the male and female portion move relative to one another so that the elastomer is subject to both compression and shear. Should the elastomer fail, the threaded portions simply lock together thereby allowing fail safe operation. Provisions are also made to protect the integrity of the coupling under reverse torque. The moving components within the coupling are perfectly isolated from the surrounding environment.

Abstract: A rotary jar is described that is part of a drill string and includes a mandrel and an anvil that move longitudinally in opposite directions to deliver a sharp upward or downward blow that is transmitted to a fish, which may be a separate tool or a portion of the drill string that is stuck in the well bore in an effort to free the fish or the stuck portion of the drill pipe. The mandrel carries rollers that move through longitudinally extending grooves when the jars are tripped. In the jars of this invention, the grooves follow a serpentine path to cause the mandrel to transmit a torsional force on the fish to try to rotate the fish as well as providing an upward or downward blow.

Abstract: A mechanical-hydraulic double-acting drilling jar includes an inner tubular mandrel telescopingly supported inside an outer tubular housing. The mandrel and the housing each consist of a plurality of tubular segments joined together, preferably by threaded inner connections. Upper and lower pressure pistons are slidably disposed within the housing, respectively closing upper and lower substantially sealed hydraulic chambers. Longitudinal movement of the mandrel engages the collet, which in turn, translates either the upper piston or the lower piston, depending on the direction of mandrel movement. As one of the pistons is moved, fluid pressure builds in the associated hydraulic chamber, retarding further movement of the mandrel, enabling potential energy to build in the drill string.

Abstract: A jar apparatus (jar) 10 includes a plurality of pistons 16 that are secured together to form a piston assembly 23. Piston assembly 23 is movable axially in response to an actuating pressure differential between the jar bore 17 and the portion of borehole 19 that surrounds jar 10. Biasing spring 28 biases piston assembly 23 to return to a closed position when the actuating pressure differential is reduced by a predetermined amount. Piston assembly 23 forces a hammer member 32 and a movable anvil portion 30A axially to cock the jar in response to the applied actuating pressure differential. When the pressure differential is reduced, biasing spring 28 moves movable anvil portion 30A against anvil support portion 30B. Detent assembly 47 temporarily limits the velocity of hammer member 32 towards movable anvil portion 30A after the pressure differential is reduced. Compressed nitrogen 64 in nitrogen chamber 31 biases hammer member towards movable anvil portion 30A to deliver a jar impact.

Abstract: There is disclosed a tool for enhancing the impact delivered to an object stuck in a well bore by means of a jar having a first tubular member connected to the object and a second tubular member having a hammer arranged to deliver an upward blow to an anvil on the first member in response to raising and a downward blow in response to lowering of the second tubular mandrel member with respect to the first member, the tool comprising a first tubular member having a lower end adapted to be connected to the second tubular member of the jar for raising and lowering therewith, a second tubular member vertically reciprocable with respect to the first member to form on annular space between them and having an upper end adapted to be connected to a well pipe string above it, and first and second sets of upper and lower longitudinally spaced seal rings within the annular space and sealably slidable with respect to equal diameter portions of each of the tubular members to form upper and lower fluid chambers between the

Abstract: An automatic set bi-directional apparatus for jarring an object in a well bore is disclosed. The apparatus comprises a tubular member having a portion defining an upper and lower striking shoulder, said tubular member having one end connected to a work string capable of creating a longitudinal force. A mandrel is connected to the object and the mandrel is concentrically disposed within said tubular member. The apparatus further includes a plurality of elongated members and an upper and lower ring members which serve as latch means. The mandrel further comprises a first and second grooved portion which are used for releasing the tubular member in order to deliver either an upward or downward jarring impact upon a stationary anvil.

Abstract: A reduce waiting time drilling jar 1 includes a mandrel 2, a housing 3 telescopingly positioned about the mandrel 2, and first and second pistons 89, 111 positioned axially between the mandrel 2 and the housing 3. The pistons 89, 111 are spaced longitudinally apart, forming a substantially sealed chamber 88 therebetween. The first piston 89 has a first and second substantially parallel flow passage 94, 200 formed therein and extending longitudinally therethrough to provide first and second flow characteristics. A valve 204 is hydraulically connected to the second flow passage 200. The valve 204 is translatable between first and second operating positions, wherein fluid flows relatively freely through the second flow passage 200 in the first operating position, but is restricted in the second operating position.

Abstract: An upstroke jar for use in downhole operations in an oil or gas well and for connection between a wireline and a tool comprises a casing defining an anvil and for connection to the tool, a hammer slidable axially within the casing for impacting with the anvil and for connection to the wireline, a hammer holder, a spring arrangement located between an abutment on the casing and an abutment on the hammer holder for compression on an operative movement of the hammer holder as a consequence of tension on the wireline and a connector releasable to free the hammer from the holder at the completion of the operative movement so that the freed hammer may impact with the anvil. The compression load on the spring present at the release is dependant on the extent of the operative movement from a rest position and the degree of compression of the spring means to obtain the operative movement. Adjustment of the release load present at the instant the hammer part is released by the connector is provided.

Abstract: A jarring and bumping tool is provided, having a mandrel telescopically received within a barrel for relative longitudinal movement. Upper and lower seals form an oil-containing annular space therebetween. The mandrel carries a free-floating annular primary piston which sealably engages a reduced-diameter piston fitting section of the barrel when passing therethrough. The mandrel also carries a secondary cylinder assembly with a transverse top wall and a downwardly extending annular secondary cylinder beneath the primary piston, forming a piston chamber between the mandrel and secondary cylinder assembly. The mandrel also carries a spring which biases a free-floating annular secondary piston upwards into the piston chamber. A port through the top wall of the cylindrical member provides fluid communication between the annular space and the piston chamber.

Abstract: A combined accelerator, for accumulating energy, and jar, for sudden release of accumulated energy, for delivering up or down jarring impacts to objects stuck downhole in a wellbore, includes upper and lower tubular members which are telescopically connected within an integral outer tubular housing. The upper tubular member is connected to a pipe or tubing string inserted into the wellbore and cooperates with the outer tubular housing through mechanical spring means so as to accumulate a selected amount of energy to be released as a jarring impact. The lower tubular member is connected to the stuck object and cooperates with the outer housing through spring biased, tapered latch bars, so as to provide a sudden energy releasing means. A threaded adjusting bushing is provided within the outer housing so as to allow selection of a desired amount of spring bias, imposed on the latch bars, thereby providing a convenient field means for controlling the amount of jarring impact imparted to the stuck object.

Abstract: A jar mechanism is described, which comprises a piston (5) movably mounted in a fluid chamber (9). A jar member (2) is releasably coupled to the piston (5) by a release device (3, 4; 3, 38, 39, 40, 54, 64) so that when the piston (5) is in a first position in the fluid chamber (9), the jar member (2) is coupled to the piston (5) by the release device (3, 4; 3, 38, 39, 40, 54, 64). A first force exerted on the jar member (2) moves the piston (5) to a second position within the fluid chamber (9) against the resistance of the fluid (11). When the piston (5) is in the second position, the action of the first force applied to the jar member (2) actuates the release device (3, 4; 3, 38, 39, 40, 54, 64) to enable the jar member (2) to be uncoupled from the piston (5).

Abstract: A multiple blow percussion drill assembly is specially configured to provide significantly increased maintainability and adjustability in the field, thereby greatly extending its service life and usefulness over a wide variety of drilling conditions. Both spring replacement and impact hammer delay time variations are rapidly accomplished by virtue of unique positioning and interactions of the internal components, without the need for dissassembly of the sealed high impact energy portion of the drill assembly. Advantageously, a first chamber housing the high impact energy transferring components is isolated from a second chamber housing the control components, such that the control components may be rapidly cleaned, adjusted, or replaced via a simple access port.

Abstract: A jar tool for inclusion into a well fishing operating string which provides resilient tensional stretch to operate the tool. The tool is adapted to compress an upper release spring to store energy corresponding to tensional force in the operating string force. A release latching lug array connects the spring to a central mandrel having an impact hammer. The tool housing forms an impact anvil. The spring is compressed to a designated compressional force by the distance that the latch lug array is moved in an adjustable latch release sleeve before suddenly releasing the spring from the mandrel. The tension in the operating string then pulls the mandrel hammer into jarring impact with the housing anvil. Provision is made for designating this pre-release movement of the latching lug array and also provides apparatus for adjusting the distance of the pre-release movement and thereby the compressional force imparted into the spring.

Abstract: A jar tool for inclusion into a well fishing operating string which provides resilient tensional stretch to operate the tool. The tool is adapted to compress an upper release spring to store energy corresponding to tensional force in the operating string forces. A release latching lug array connects the spring to a central mandrel having an impact hammer. The tool housing forms an impact anvil. The spring is compressed to a designated compressional force by the distance that the latch lug array is moved before suddenly releasing the spring from the mandrel. The tension in the operating string then pulls the mandrel hammer into jarring impact with the housing anvil. The provision is made for designating this pre-release movement of the latching lug array and also provides remotely actuated apparatus for adjusting the distance of the pre-release movement and thereby the compressional force imparted into the spring.

Abstract: A hydraulic well jar mechanism capable of developing jarring force in an upwardly or downwardly direction or in both upward and downward directions for imparting jarring forces to stuck well pipe. Inner and outer tubular members cooperate to define an annulus therebetween, which annulus contains a volume of metering liquid such as oil. One or more metering valves are disposed within the annulus and establish metering of the metering liquid during a portion of the stroke of the well jar to thus retard movement thereof. After a certain metering movement has occurred, the operative metering valve will be clear of the metering surface and the jar mechanism will then have relatively free movment from the retarded position to the jarring position. Closing movement of the jar mechanism may be induced by a compression spring closure.

Abstract: A downhole tool for use with a ball and seat travelling valve associated with a moveable plunger includes a means for causing relative movement between the upper and lower housings forming the downhole tool, whereby a bumping force may be imparted to the plunger to unseat the ball during the downstroke of the downhole tool.

Abstract: An energy accumulator for use with a well pipe string to enhance the jarring impact delivered to an object stuck in a well bore by an up and/or down jar mechanism includes inner and outer telescopically connected members relatively movable longitudinally to accumulate energy in a mechanical spring arrangement, gas or compressible liquid in the accumulator. Cooperating surfaces on the inner and outer members of the energy accumulator assure that the jarring impact of the jar mechanism members is delivered to the stuck independently of the tensile or compressive load applied to the object jar mechanism and independently of the load rate of accumulating energy in the energy accumulator.

Abstract: A jar accelerator including an elongated tubular tool body and an elongated mandrel axially slidingly mounted within the tool body and having an outwardly facing shoulder. A composite plurality of frusto-conical disc springs are disposed inside the tool body about the mandrel and between the shoulders to provide a preselected accelerating function.

Abstract: An accelerator for a fishing jar is disclosed. The accelerator includes front, compression, rear, and air chambers. These chambers insure that the pressure of the fluid in the compression chamber is substantially independent of the temperature of the fluid and the hydrostatic pressure of the well. These chambers also insure that the high pressure seals of the compression chamber are lubricated on each side of each seal. The accelerator also insures that a threshold upward force which is proportional to the hydrostatic pressure must be applied to the drill string before the fluid in the compression chamber begins to be compressed, thereby providing an accelerator that has a higher maximum load in deep wells.

Abstract: A percussion drill apparatus is provided which isolates the surfaces that pound on one another from borehole cuttings, while also sealing in grease, all in a compact assembly. The percussion sub which holds the drill bit and which has an anvil surface which can be repeatedly struck, includes a cylindrical outer surface extending down from the anvil surface. The outer barrel, which has a hammer surface that hammers the anvil surface, carries a cage which surrounds the cylindrical surface, and which holds a seal assembly which seals to the cylindrical surface. Thus, percussion occurs in a sealed area.