Abstract: The retrieving tool engages an equalizing sleeve on a jar down movement while the packer or bridge plug release sleeve is held fixed with a locking dog. The initial jarring down allows the tool to engage the equalizing sleeve and pull it up subsequent to the initial engagement by jarring down. Pulling or jarring up then opens the equalizing ports while still holding the release sleeve locked using a trapped collet. A subsequent jarring down allows engagement of a second sleeve so that a subsequent pulling or jarring up moves the second sleeve away from the collet that had otherwise held the set position of the packer or bridge plug. A pull or jar force up brings up the now released packer or bridge plug.

Abstract: This invention relates to a jar used to dislodge tools stuck in a well. The jar includes two housing portions movable with respect to each other. A release collet forms a portion of one of the housings. A release sleeve is carried by a mandrel and is located within the release collet. After a given amount of movement of the housing with respect to the mandrel, the release mechanism is activated and the two housing sections rapidly move with respect to each other. A hammer portion of the mandrel then strikes an anvil in the anvil housing, thus applying an upward force to the tool lodged in the well.

Abstract: A method and apparatus for delivering repetitive jarring impacts to a stuck object downhole. The jarring tool is deployed on coiled tubing or other tubular well conduit, and fluid pressure is used to cycle the jar without reciprocating the well conduit at the wellhead. The tool includes a hydraulic reset assembly. The hydraulic chamber is in fluid communication with the flow path through the tool. Thus, when the internal fluid pressure inside the tool exceeds the external pressure in the well, the fluid pressure drives the piston in the hydraulic chamber to urge the tool toward the contracted position. In this way, the reset assembly can overcome the tendency of fluid pressure to extend the tool. The reset assembly can be configured to balance or equalize the extension pressure, to prevent undesired cocking of the tool, or to overcome the extension pressure to contract the tool for recocking the jar mechanism.

Abstract: A transport assembly comprising: an attachment member attachable to a downhole tool; normally two rotatable members, connected to the attachment member, the rotatable members being arranged to rotate around their main longitudinal axis; a plurality of engaging members attached to each rotatable member and extending radially outwards therefrom with respect to the main longitudinal axis; the engaging members being helically arranged around the rotatable members. The transport assembly can thus be driven into a well in a ‘corkscrew’ type manner. Embodiments include a jarring mechanism which may be reset downhole and can jar attached tools in either direction.

Abstract: This invention relates to a jar used to dislodge tools stuck in a well. The jar includes two housing portions movable with respect to each other. A release collet forms a portion of one of the housings. A release sleeve is carried by a mandrel and is located within the release collet. After a given amount of movement of the housing with respect to the mandrel, the release mechanism is activated and the two housing sections rapidly move with respect to each other. A hammer portion of the mandrel then strikes an anvil in the anvil housing, thus applying an upward force to the tool lodged in the well.

Abstract: A bidirectional jarring tool that allows repetitive firing in one direction without firing the tool in the opposite direction. One of the tubular members provides up and down anvil surfaces, and the other member provides up and down hammer surfaces. Inner and outer tubular members define a hydraulic chamber with a restricted section that divides the chamber into an upper section and a lower section. Upper and lower pistons, each with a valved flow channel, reciprocate through the restricted section to produce up and down jarring impacts. When the restricted section is disposed between the upper and lower pistons, the tool is in a neutral position and can be jarred repetitively in either direction.

Abstract: A jarring tool having an extensible joint connecting first and second sub ends. A first inner latch piece connects to the upper sub end, and a second outer latch piece connects to the lower sub end. The joint, in a latched position, has the outer latch piece latched to the inner latch piece and the inner and outer latch pieces restrained from unlatching by a stationary restraining collar. Under tensile force the joint unlatches into an unlatched position by the outer latch piece pulling the inner latch piece through the restraining collar into a position where the inner and outer latch pieces are free to separate. An impact force is generated from the tensile force when the joint unlatches and reaches a maximum extension.

Abstract: A drill string includes a bit sub mounted to a lower end of a plurality of tubular sections, where at least one tubular section is a jar. The jar and the tubular sections have an inner diameter that is at least 4¼? and an outer diameter that is 7? or less. A method of drilling includes the steps of inserting the drill string into a downhole formation; causing the bit sub to drill a core sample that is received within a tubular section; and inserting a core retrieval tool through the drill string to retrieve the core sample.

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: A staging tool arrangement for gas well production assistance, comprising an elongated staging tool having an elongated upper portion and an elongated lower portion. The upper portion has a sliding relationship with the lower portion thereof. A displaceable annular seal is arranged about the lower portion. A displaceable enclosure is arranged on the elongated lower portion so as to slidably expose and to slidably enclose the annular seal.

Abstract: A tool having a first lower sub end, a second upper sub end, and an extensible joint connecting the first and second sub ends. The joint has a first inner latch piece connected to the lower sub end, and a second outer latch piece connected to the upper sub end, and a stationary restraining collar. The joint, in a latched position, has the outer latch piece latched to the inner latch piece and the inner and outer latch pieces restrained from unlatching by the restraining collar. The joint, under tensile force, unlatches into an unlatched position by the inner latch piece pulling the outer latch piece through the restraining collar into a position where the inner and outer latch pieces are free to separate. An impact force is generated from the tensile force when the joint unlatches and reaches a maximum extension.

Abstract: A shifting tool is run on slickline and has an on board power supply. Rotary motion of the motor is converted to linear motion of the shifting tool using a ball screw device. The grip is obtained with longitudinal motion of a grip linkage and an on board jar then can do the shifting. Alternatively a linear motor can be used to extend and retract the grip assembly and shift using the jar tool. Optionally the tool can be anchored and linear motion from the on board power source operating a motor can do the shifting.

Abstract: A stroker tool for providing an axial force in an axial direction of a downhole tool. The stroker tool has a pump, a driving unit for driving the pump, and an axial force generator. The generator has an elongated piston housing having a first and a second end, and a piston provided on a shaft, and the shaft penetrates the housing for transmitting the axial force to another tool. The piston is provided in the piston housing so that the shaft penetrates the piston and each end of the piston housing and divides the housing into a first and a second chamber, and the first and the second chamber are each fluidly connected to the pump via at least one duct so that the pump can pump fluid into one chamber by sucking fluid from the other chamber for moving the piston within the housing, and thereby moving the shaft back and forth.

Abstract: The invention relates to oil and gas industry and can be used in well drilling as a part of a Bottom Hole Assembly (BHA) to releasing stuck tools or equipment by applying axial and torque impacts. The claimed jar allows to increase the effectiveness of BHA operation in well drilling, especially when BHA comprises a telescopic system, since exception of unauthorized accidental operations of a jar substantially reduces the risk of failure in telescopic system electronic components, make the drilling process more predictable and enhance endurance of a jar itself. In case of emergency, the probability of retrieving stuck assembly will be incomparably higher, since the claimed jar provides the possibility to make simultaneously axial and torque impacts.

Abstract: A bidirectional drilling jar, capable of repeated unidirectional firing, including a sliding assembly that is disposed in a sliding relation to the interior of a barrel assembly. A portion of the inner diameter of the barrel assembly forms a restricted barrel segment. The restriction intermediate an upper chamber and a lower chamber. A metering system comprising an upper flange a meter valve, and a lower flange. The meter valve slideably disposed on the sliding assembly between the upper and lower flanges. The metering system travels between the upper chamber and the lower chamber providing limited, controlled flow of the fluid contained therein when passing through the restriction in order to pressurize the system and produce a jarring stroke. Alternatively, the metering system comprises an upper flange, a meter ring, a meter valve, and a lower flange. The meter valve and meter ring are slideably disposed on the sliding assembly intermediate the upper and lower flanges.

Abstract: The retrieving tool engages an equalizing sleeve on a jar down movement while the packer or bridge plug release sleeve is held fixed with a locking dog. The initial jarring down allows the tool to engage the equalizing sleeve and pull it up subsequent to the initial engagement by jarring down. Pulling or jarring up then opens the equalizing ports while still holding the release sleeve locked using a trapped collet. A subsequent jarring down allows engagement of a second sleeve so that a subsequent pulling or jarring up moves the second sleeve away from the collet that had otherwise held the set position of the packer or bridge plug. A pull or jar force up brings up the now released packer or bridge plug.

Abstract: A progressing cavity pump/motor includes an upper stator tube (14), a lower stator tube (16), a rotor (20) sitting between the upper and lower stator tubes, and a coupling assembly (30) interconnecting the stator tubes comprising an outer sleeve (32), an inner sleeve (36) and a nut (60) for threaded engagement with at least one of the sleeves to bring a stop surface on the inner sleeve into mating engagement with the stop surface on the outer sleeve. The pump/motor is usually assembled in the field while maintaining precise axial and rotational positioning of the stator tubes.

Abstract: A jar is disclosed comprising: an outer housing; an inner mandrel at least partially disposed telescopically within the outer housing to define a fluid chamber between the inner mandrel and the outer housing, the fluid chamber containing fluid and being sealed; a valve disposed within the fluid chamber, the valve having a restriction surface facing, during setting, a cooperating restriction surface on one of the inner mandrel and the outer housing and a pressure surface facing the other of the inner mandrel and the outer housing, the valve being movable between a seated position in which the valve seats against the other of the inner mandrel and the outer housing and an unseated position; the cooperating restriction surface cooperating with the restriction surface to set the jar for a jar in a first direction; the pressure surface being exposed to fluid within the fluid chamber when the jar is set and pressuring up for a jar in the first direction; the pressure surface being indented to cause uneven radial mo

Abstract: A fluid bypass tool that can be incorporated into a fishing arrangement between a fluid-operated latching tool and a fluid-operated jarring tool. The latching tool is actuated with fluid from the surface to be latched to and unlatched from a stuck tool in the wellbore. The bypass tool permits fluid flow to the latching tool to be interrupted so that the jarring tool may be operated without risk of inadvertently causing the latching tool to unlatch from the stuck 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: A double-acting jar is disclosed comprising: an outer housing; an inner mandrel at least partially disposed telescopically within the outer housing to define a fluid chamber between the inner mandrel and the outer housing, the fluid chamber containing fluid and being sealed; a valve disposed within the fluid chamber on one of the inner mandrel and the outer housing; the valve having a downhole portion that is movable between a downhole seated position in which the valve seats against the one of the inner mandrel and the outer housing and an unseated position, the downhole portion having a downhole restriction surface; the valve having an uphole portion that is movable between an uphole seated position in which the valve seats against the one of the inner mandrel and the outer housing and an unseated position, the uphole portion having an uphole restriction surface; the other of the outer housing and the inner mandrel having a cooperating restriction surface that cooperates with the downhole restriction surfac

Abstract: A backoff sub includes a housing and a backoff facilitator at least partially within the housing. The backoff sub is a part of the string that is stuck and is capable of adding energy to the string within which the sub is disposed to facilitate backing off of a portion of that sting close to a stuck point of that string. A method is included.

Abstract: A backoff sub includes a housing; and a backoff facilitator at least partially within the housing. Capable of adding energy to a system within which the sub is disposable. A method for managing a stuck string in a wellbore is also included.

Abstract: A method usable with a subterranean well that includes actuating a downhole tool (a valve assembly, for example). The method also includes applying at least one of an impulse stimulus and a vibration stimulus to the tool during the actuating to enhance operation of the tool.

Abstract: A tool having a first lower sub end, a second upper sub end, and an extensible joint connecting the first and second sub ends is disclosed. The joint has a first inner latch piece connected to the lower sub end, and a second outer latch piece connected to the upper sub end, and a stationary restraining collar. The joint, in a latched position, has the outer latch piece latched to the inner latch piece and the inner and outer latch pieces restrained from unlatching by the restraining collar. The joint, under tensile force, unlatches into an unlatched position by the inner latch piece pulling the outer latch piece through the restraining collar into a position where the inner and outer latch pieces are free to separate. An impact force is generated from the tensile force when the joint unlatches and reaches a maximum extension.

Abstract: A jarring tool having an extensible joint connecting first and second sub ends is disclosed. A first inner latch piece connects to the upper sub end, and a second outer latch piece connects to the lower sub end. The joint, in a latched position, has the outer latch piece latched to the inner latch piece and the inner and outer latch pieces restrained from unlatching by a stationary restraining collar. Under tensile force the joint unlatches into an unlatched position by the outer latch piece pulling the inner latch piece through the restraining collar into a position where the inner and outer latch pieces are free to separate. An impact force is generated from the tensile force when the joint unlatches and reaches a maximum extension.

Abstract: A downhole rotation tool comprises a housing rotatable and axially slideable in relation to a gear shaft. The gear shaft is located interior of the housing. A tube gear is located intermediate the gear shaft and the housing. Helical threading on the gear shaft exterior interacts with helical threading interior of the tube gear to impart rotation of the tube gear upon linear movement of the gear shaft. A gear face at a lower end of the tube gear interacts with a corresponding gear face on the housing. Face gear teeth of the tube gear and the housing include axially-aligned engaging surfaces to rotate the housing in a preferred direction on downward stroke of the gear shaft and include inclined slip surfaces to allow relative rotation of the housing gear face and the tube gear face upon upward stroke of the gear shaft.

Abstract: A double-acting compounder is disclosed having a first end and a second end, and comprising an outer housing, an upper mandrel, and a lower mandrel. The outer housing defines the first end. The upper mandrel is at least partially disposed telescopically within the outer housing to define an uphole fluid chamber between the upper mandrel and the outer housing, the upper mandrel defining the second end. The lower mandrel is at least partially disposed telescopically within the outer housing to define a downhole fluid chamber between the lower mandrel and the outer housing. The uphole fluid chamber and the downhole fluid chamber each contain fluid, have a variable stroke-dependent volume, and are sealed at an uphole end and a downhole end. The upper mandrel has a first shoulder engagable with and facing a second shoulder of the lower mandrel to move the lower mandrel during at least a portion of a stroke.

Abstract: A jarring tool is disclosed. The tool has a segment of sub housing containing an upper stop proximate a first end thereof. An outer latch piece is connected to an upper end of the lower shaft inside the sub housing, and an upper shaft passes through the stop and connects on a first end thereof to an inner latch piece. A cap is on a second end of the upper shaft retaining a washer stack against the upper stop. A retainer is inside the sub housing and has an first piece providing a restraining region and an open region and a second piece attached to the sub housing. The retainer retains the inner and outer latch pieces in a latched position in the restraining region until the latch pieces are displaced toward the second end of the sub housing through the retainer to the open region as a result of a tensile force on the outer latch piece.

Abstract: A drilling and vibratory jarring device is provided. The device has an inner mandrel shiftable upward or downward in an outer housing from an intermediate position in the outer housing. When the inner mandrel is in the intermediate position within the outer housing mating splines, one set of splines attached to inner mandrel, the other set of splines attached to the outer housing, engage and rotatably lock inner mandrel and outer housing together. When the inner mandrel is shifted to the upward position said splines disengage and the saw-tooth surfaces of an upper pair of jars engage creating longitudinal vibratory forces down-hole when inner mandrel is rotated with respect to outer housing. When the inner mandrel is shifted to the downward position said splines disengage and the saw-tooth surfaces of an lower pair of jars engage creating longitudinal vibratory forces down-hole when inner mandrel is rotated with respect to outer housing.

Abstract: The present invention generally relates to an apparatus and method of jarring with an overpull generator. In one aspect, a method of dislodging an object stuck in a wellbore is provided. The method includes the step of running an assembly into the wellbore on a conveyance member and attaching the assembly to the object, wherein the assembly comprises an overpull generator and a delay force release device. The method also includes the step of generating an overpull force in the wellbore by selectively activating the overpull generator. Additionally, the method includes the step of applying an impact force to the object by activating the delay force release device and releasing the generated overpull force, thereby dislodging the object stuck in the wellbore. In a further aspect, an assembly for dislodging an object stuck in a wellbore is provided. In yet a further aspect, an overpull generator for use in generating an overpull force in a wellbore is provided.

Abstract: A fluid bypass tool that can be incorporated into a fishing arrangement between a fluid-operated latching tool and a fluid-operated jarring tool. The latching tool is actuated with fluid from the surface to be latched to and unlatched from a stuck tool in the wellbore. The bypass tool permits fluid flow to the latching tool to be interrupted so that the jarring tool may be operated without risk of inadvertently causing the latching tool to unlatch from the stuck tool.

Abstract: A device is described for removal of a plug which is used in a well, a pipe, or the like for carrying out tests, and it is characterised by an element which, with an applied forced, is arranged to penetrate into the plug material so that this is crushed, said element is arranged to be supplied said force from an above lying element. The element (16) is preferably a ring (1) the lower end of which is arranged to be forced in a radial direction into the plug element at axial driving of a hydraulic pressure piston. Furthermore, the element is integrated into the plug.

Abstract: A double-acting jar is disclosed comprising: an outer housing; an inner mandrel at least partially disposed telescopically within the outer housing to define a fluid chamber between the inner mandrel and the outer housing, the fluid chamber containing fluid and being sealed; a valve disposed within the fluid chamber on one of the inner mandrel and the outer housing; the valve having a downhole portion that is movable between a downhole seated position in which the valve seats against the one of the inner mandrel and the outer housing and an unseated position, the downhole portion having a downhole restriction surface; the valve having an uphole portion that is movable between an uphole seated position in which the valve seats against the one of the inner mandrel and the outer housing and an unseated position, the uphole portion having an uphole restriction surface; the other of the outer housing and the inner mandrel having a cooperating restriction surface that cooperates with the downhole restriction surfac

Abstract: An example of an apparatus for jarring a wellbore tool from an obstruction includes four sub-assemblies in communication with three springs such that the springs may be compressed forcing the subassemblies to become adjacent to one another. When the springs are actuated, the sub-assembly units spring apart from one another force dislodging the lower most sub-assembly component from the obstruction.

Abstract: Devices, systems and methods for equalizing pressure in a gas well are provided. A jar device is coupled to a pump deployed in a gas well between areas of low pressure and high pressure. The jar device includes a mandrel and a no-go sleeve. A jarring tool is operated to transfer an axial force onto the jar device that is large enough to shear a shearable connection between the mandrel and no-go sleeve and thereby cause the mandrel to slide from a first position to a second position with respect to the no-go sleeve. A seal that seals between the no-go sleeve and mandrel when the mandrel is located in the first position is unsealed as a result of the movement of the mandrel and thereby fluid communication is allowed between the area of high pressure and low pressure. This allows for easier retrieval of the pump.

Abstract: An example of an apparatus for jarring a wellbore tool from an obstruction includes four sub-assemblies in communication with three springs such that the springs may be compressed forcing the subassemblies to become adjacent to one another. When the springs are actuated, the sub-assembly units spring apart from one another force dislodging the lower most sub-assembly component from the obstruction.

Abstract: A method and downhole tool are presented herein for driving completion equipment in a borehole. The method comprises the steps of positioning the completion equipment in the borehole; and moving the completion equipment along the borehole by operation of a downhole driving tool connected to the completion equipment. Operation of the driving tool comprises accumulating energy in the driving tool and releasing the energy to force a moveable member against an impact surface in the driving tool to provide a driving force which is applied to the completion equipment to move the completion equipment in the borehole, wherein the step of accumulating energy in the driving tool comprises providing energy to the driving tool by means of an energy source located at the surface selected from the group consisting of an electrical energy source provided by a wireline cable, a hydraulic energy source provided by a pipe, and combinations thereof.

Abstract: A double-acting jar comprises an inner mandrel and an outer housing. The inner mandrel is disposed telescopically within the outer housing to define a fluid chamber in between. There is an uphole restriction and a downhole restriction spaced from one another within the fluid chamber. An uphole valve is disposed within the fluid chamber, the uphole valve having a first seating surface engageable with an uphole facing sealing shoulder in the fluid chamber. There is a downhole valve disposed within the fluid chamber, the downhole valve having a second seating surface engageable with a downhole facing sealing shoulder in the fluid chamber.

Abstract: A stroker tool for providing an axial force in an axial direction of a downhole tool. The stroker tool has a pump, a driving unit for driving the pump, and an axial force generator. The generator has an elongated piston housing having a first and a second end, and a piston provided on a shaft, and the shaft penetrates the housing for transmitting the axial force to another tool. The piston is provided in the piston housing so that the shaft penetrates the piston and each end of the piston housing and divides the housing into a first and a second chamber, and the first and the second chamber are each fluidly connected to the pump via at least one duct so that the pump can pump fluid into one chamber by sucking fluid from the other chamber for moving the piston within the housing, and thereby moving the shaft back and forth.

Abstract: An unsticking assembly for releasing a tool that is stuck in a wellbore including a first anchor actuatable between an engaging position wherein the first anchor engages a wall of the wellbore and a retracted position wherein the first anchor does not engage the wall; a second anchor actuatable between an engaging position wherein the second anchor engages a wall of the wellbore and a retracted position wherein the second anchor does not engage the wall; and a control module in connection with the first and second anchor to selectively actuate each anchor between the engaged and retracted positions. The assembly is adapted for positioning in the wellbore and in connection with the tool when the tool is stuck in the wellbore. The assembly may be a stand-alone assembly that is connectable to the tool after the tool is stuck in the wellbore. The assembly may include the wellbore tool as an interconnected element.

Abstract: A double-acting jar compounder is disclosed having a first end and a second end, and comprising an outer housing, an upper mandrel, and a lower mandrel. The upper mandrel defines the first end. The upper mandrel is at least partially disposed telescopically within the outer housing to define an uphole fluid chamber between the upper mandrel and the outer housing, the upper mandrel defining the second end. The lower mandrel is at least partially disposed telescopically within the outer housing to define a downhole fluid chamber between the lower mandrel and the outer housing. The uphole fluid chamber and the downhole fluid chamber each contain fluid, have a variable stroke-dependent volume, and are sealed at an uphole end and a downhole end. The upper mandrel has a first shoulder engagable with and facing a second shoulder of the lower mandrel to move the lower mandrel during at least a portion of a downjar or upjar stroke.

Abstract: A double-acting jar comprises an inner mandrel and an outer housing. The inner mandrel is disposed telescopically within the outer housing to define a fluid chamber in between. There is an uphole restriction and a downhole restriction spaced from one another within the fluid chamber. A uphole valve is disposed within the fluid chamber, the uphole valve having a first seating surface engageable with an uphole facing sealing shoulder in the fluid chamber. The uphole valve has a first exterior surface that fits with close tolerance within the uphole restriction over at least a portion of the first exterior surface. There is a downhole valve disposed within the fluid chamber, the downhole valve having a second seating surface engageable with a downhole facing sealing shoulder in the fluid chamber. The downhole valve has a second exterior surface that fits with close tolerance within the downhole restriction over at least a portion of the first exterior surface.

Abstract: Embodiments of the present invention generally relate to signal operated tools for milling, drilling, and/or fishing operations. In one embodiment, a mud motor for use in a wellbore includes: a stator; a rotor, the stator and rotor operable to rotate the rotor in response to fluid pumped between the rotor and the stator; and a lock. The lock is operable to: rotationally couple the rotor to the stator in a locked position, receive an instruction signal from the surface, release the rotor in an unlocked position, and actuate from the locked position to the unlocked position in response to receiving the instruction signal.

Abstract: A backoff sub includes a housing; and a backoff facilitator at least partially within the housing and capable of adding energy to a system within which the sub is disposable and method.

Abstract: A fluid actuated downhole tool for inducing movement of a downhole apparatus is described. The tool comprises a body for coupling to downhole apparatus, the body being adapted to accommodate now of fluid therethrough and including a flow-modifying arrangement for modifying the flow of fluid through the body. The flow-modifying arrangement is configurable in an inactive configuration and in an active configuration. The fluid activated tool is selectively operated from the surface by varying an operating condition which causes the flow through the tool to either bypass or flow through the flow-modifying arrangement to induce movement of the downhole apparatus.

Abstract: The present invention generally relates to an apparatus and method of jarring with an overpull generator. In one aspect, a method of dislodging an object stuck in a wellbore is provided. The method includes the step of running an assembly into the wellbore on a conveyance member and attaching the assembly to the object, wherein the assembly comprises an overpull generator and a delay force release device. The method also includes the step of generating an overpull force in the wellbore by selectively activating the overpull generator. Additionally, the method includes the step of applying an impact force to the object by activating the delay force release device and releasing the generated overpull force, thereby dislodging the object stuck in the wellbore. In a further aspect, an assembly for dislodging an object stuck in a wellbore is provided. In yet a further aspect, an overpull generator for use in generating an overpull force in a wellbore is provided.

Abstract: The invention relates to a jar operated by fluid pressure, specially designed for use in drilling or maintenance operations carried out in oil or gas wells. The jar comprises a first (1) and a second (2) end piece, where the second end piece (2) comprises a jar shoulder (15), an inner, cylindrical string part (8) connected to a valve head (9) with a first valve surface (14), and to a weight (12), an outer, cylindrical string part (17), arranged axially movably to the inner cylindrical string part (8), and comprising a second valve surface (30), which is arranged to go into abutment against the first valve surface (14) on the valve head (9). The jarring function is achieved by the inner string part (8) and thereby the weight (12) being set in axial motion and striking the shoulder (15).

Abstract: An intelligent downhole impact jar device is described that is able to sense well bore angle or deviation and alter the effective jar impact load based upon the sensed information. The impact jar device includes a jarring portion for creating jarring impacts within a wellbore toolstring. The jarring portion is adjustable so that jarring forces of various levels can be produced. The jarring portion is adjusted in response to sensed wellbore conditions, such as the angle of deviation of the surrounding wellbore.

Abstract: An apparatus for freeing a cable that is lodged in a wellbore without dislodging the well tool carried by cable includes a housing connectable about the cable and means for engaging the cable upon impact with the well tool to reduce the impact of the outer housing on the well tool.