Abstract: A downhole vibration tool includes a body, a mandrel, a spring, and a balance piston. The body may be generally tubular and may have one or more helical slots formed on an inner surface thereof. The mandrel may be generally tubular, may have a bore, and may be positioned at least partially within the body. The mandrel may have one or more helical splines formed on an outer surface of the mandrel, the helical splines engaging the helical slots of the body such that the mandrel is translatable axially relative to the body. The spring may be positioned in an annular space formed between the mandrel and the body defined as a spring chamber. The balance piston may be in an annular space formed between the mandrel and the body, wherein the balance piston separates an oil-filled chamber from an internal pressure chamber.

Abstract: A downhole hydraulic fracking system comprising of a downhole reservoir stimulating tool, an injector tool, and a compression tool, configured to convert compressional strain energy gained from the compression of the drilling tubulars above the tool into multiple high-pressure fluid pressure waves, that then propagates down the drill string and into the subsurface formation causing artificial cracks and fractures; resulting in enhanced rock permeability and increased production of fluids from the sub-surface formation.

Abstract: A wireline standoff that may ameliorate the effects of wireline cable differential sticking, wireline cable key seating, and high cable drags by reducing or eliminating contact of the wireline cable with the borehole wall during the logging operation. An embodiment includes a wireline standoff. The wireline standoff may comprise a pair of opposing assemblies. The opposing assemblies may each comprise a half shell, a cable insert configured to be disposed in the half shell, and external fins coupled to the half shell. The wireline standoff may further comprise one or more fasteners configured to couple the opposing assemblies to one another.

Abstract: An apparatus for drilling directional wellbores is disclosed that in one non-limiting embodiment includes a drive for rotating a drill bit, a deflection device that enables a lower section of a drilling assembly to tilt about a member of the deflection device within a selected plane when the drilling assembly is substantially rotationally stationary to allow drilling of a curved section of the wellbore when the drill bit is rotated by the drive and wherein the tilt is reduced when the drilling assembly is rotated to allow drilling of a straighter section of the wellbore, and at least one seal that isolates at least a surface of the member from outside environment.

Abstract: A wellbore assembly including a cable disposed within a wellbore and a fishing jar assembly coupled to the cable. The fishing jar assembly includes a housing assembly, a mandrel assembly, a fishing assembly, and an actuator. The housing assembly has an inwardly projecting shoulder defining an anvil surface and a hydraulic fluid chamber housing hydraulic fluid. The mandrel is movable along a central axis of the housing assembly and has an outwardly projecting shoulder that defines a hammering surface to strike the anvil surface. The mandrel assembly defines a piston disposed within the hydraulic fluid chamber. The fishing assembly engages a component stuck within the wellbore. The actuator moves the piston of the mandrel assembly along the longitudinal axis to pressurize the hydraulic fluid until the hydraulic fluid bleeds past a fluid port allowing the mandrel assembly to trip to strike the anvil surface with the hammering surface.

Abstract: A mechanically locking hydraulic jar device includes an outer sleeve, an inner sleeve partially disposed in an inner bore of the outer sleeve, and a mechanical lock engaging the outer sleeve and the inner sleeve in a default position to axially secure the inner sleeve to the outer sleeve. Activation of the hydraulic jar disables the mechanical lock to allow axial movement of the inner sleeve relative to the outer sleeve, which generates an impact force when the inner sleeve reaches an activated position. The hydraulic jar device also includes an upward block and a downward block configured to limit the upward and downward axial movement, respectively, of the inner sleeve relative to the outer sleeve when the mechanical lock is disabled.

Abstract: A jarring device includes a housing, a mandrel received within the housing, and a pressure chamber defined between the housing and the mandrel and filled with a hydraulic fluid. A hydraulic lock piston is arranged about the mandrel and radially interposes the housing and the mandrel. The hydraulic lock piston includes a pressure piston having a first end exposed to the pressure chamber, a second end, and first and second fluid flowpaths defined in the pressure piston and extending axially between the first and second ends. When the mandrel moves in a first direction relative to the housing, the hydraulic fluid is metered through the first fluid flowpath and the second fluid flowpath is occluded. When the mandrel moves in a second direction relative to the housing and opposite the first direction, the hydraulic fluid is metered through the second fluid flowpath and the first fluid flowpath is occluded.

Abstract: The present invention discloses a drilling speed improvement device capable of producing both hydraulic pulse and impact vibration. The device has a pressure transfer rod that is arranged at an upper end of a lower joint. A spring chamber is formed among a drill body, the pressure transfer rod and the lower joint. A spring is arranged in the spring chamber. A communicating hole is formed in the drill body. A piston is arranged at an upper end of the pressure transfer rod. A pressure bearing head is arranged at an upper end of the piston. A pressure bearing base is arranged on the inner side of an upper joint. Drill bit impact loads and drilling fluid pulse jets are modulated by the longitudinal vibration energy of a drill stem, the rock breaking efficiency of a drill bit is improved by both dynamic and static loads, and harm caused by vibration of the drill stem is reduced.

Abstract: The disclosed apparatus may include (1) a Field-Replaceable Unit (FRU) that (A) is designed to mate with a backplane of a telecommunications system and (B) facilitates communication among computing devices within a network and (2) at least one helical ejector that (A) is coupled to the FRU, (B) fastens to a housing of the telecommunications system to enable the FRU to mate with the backplane of the telecommunications system, and (C) includes at least one spring that, when the helical ejector is fastened to the housing of the telecommunications system, applies a force on the FRU that pushes the FRU toward the backplane of the telecommunications system. Various other apparatuses, systems, and methods are also disclosed.

Abstract: A pressure responsive downhole tool comprises a power piston pressure relief valve that is selectively activated and deactivated to allow pressure-related operations to be conducted. The pressure relief valve will not open until the power piston is activated, which also requires the operating element (ball valve, for example) to be opened, thereby avoided situations in which the ball valve is inadvertently placed in the Lock Open position.

Abstract: An apparatus for coupling between opposing first and second portions of a downhole tool string. The apparatus includes a housing having a port therein, a shaft extending within at least a portion of the housing, and a flow restrictor reducing a flow area of the port. The housing and the shaft move axially relative to each other. The port fluidly connects a space external to the housing with an annulus defined between the housing and the shaft.

Abstract: An adjustable bent housing assembly for a deviated direction drill string having 1.5° adjustment increments between an index sub housing and mandrel has variances of less than 0.02° at 0.25 nominal degree increments between 0° and 3.00° of drill direction deviation.

Abstract: A downhole assembly, including a downhole tool, a downhole force-creating device, and a shock damper. The shock damper includes a hollow housing including an annular shoulder near each end and extending radially inward from the housing. The damper also includes a mandrel located at least partially inside the housing to form an annulus between the mandrel and the housing, the mandrel including an annular shoulder near each end and extending radially outward from the mandrel. A spring is located in an annular cavity formed by the annulus and between both the housing shoulders and the mandrel shoulders. The mandrel is movable relative to the housing to an expanded position in one direction and to a compressed position in the other direction.

Abstract: The invention relates to a ram boring device for creating horizontal boreholes, having an impact piston which moves in an oscillatory manner within a casing of the ram boring device and of which the impact frequency or impact intensity can be varied by displacing the center position of the impact piston inside the casing.

Abstract: A drill bit is disclosed, comprising: a drill bit head having a cutting face with one or more fixed cutting elements; a flow passage extending through the drill bit head to the cutting face; a flow interrupter within the drill bit head and positioned to interrupt flow of fluid through the flow passage; and a power section connected to drive the flow interrupter and cause, in operation, variable flow of fluid through the flow passage. A method of drilling is also disclosed comprising: flowing fluid through a flow passage extending through a drill bit head to a cutting face of the drill bit head, the cutting face having one or more fixed cutting elements; and driving a flow interrupter within the drill bit head with a power section to interrupt the flow of fluid through the flow passage and cause variable flow of fluid through the flow passage.

Abstract: A percussion adapter that is driven to generate a percussive axial motion on a wellbore structure. One percussion adapter includes a drive connection to mechanically convert rotational drive to axially directed percussive motion. Another percussion adapter employs a valve that creates back pressure causing axially directed percussive motion. A wellbore tubular connection is also disclosed that transitions torque to resist back off when left hand or right hand torque is applied.

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 downhole tool comprises a pulse generator that can generate longitudinal pulses in a drill string. A poppet is longitudinally moved in and out of an orifice in the pulse generator reducing the flow of drilling mud temporarily, generating a longitudinal pulse. The longitudinal pulse generator may be combined with a conventional transverse pulse generator to create a pulse generator capable of generating pulses in both transverse and longitudinal directions.

Abstract: A jar comprises an outer housing; an inner mandrel within the outer housing to define a fluid chamber; a valve disposed within the fluid chamber with a restriction surface facing, during setting, a cooperating restriction surface on the outer housing and a pressure surface facing the inner mandrel, the valve movable between a seated position 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 movement, in a plane perpendicular to a jar axis, of the restriction surface towards the cooperating restriction surface when the jar is set and pressuring up for a jar in the first direction; and jarring surfaces.

Abstract: A hydraulic jar for delivering impacts downhole. The jarring mechanism includes a cup-type piston that moves through a seal bore. The cup is deformable in response to fluid pressure so that it expands each time it moves through the seal bore to compensate for wear on the lip. Since only minimum interference is required between the piston and seal bore, less material may be used. This reduces the force required to reset the tool, which is particularly advantageous in horizontal wells. The seal bore may be slightly wider at the exit; the cup expands to this exit diameter, ensuring an interference fit as the cup travels back through the smaller diameter entry section. The entry end of the seal bore may include longitudinal grooves. This prevents the piston cup from rupturing by preventing a fluid seal around the lip until the most of cup is inside the seal bore.

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 retaining assembly for a cylindrical member and support sleeve in the bore of a component of a DTH. The cylindrical member and support sleeve may, for example, be a foot valve assembly for insertion into a counter bore in a bit. The cylindrical member has a cylindrical member rigidity and at least a portion of the support sleeve has a rigidity greater than the cylindrical member rigidity. A gap is provided between the sleeve and the component bore of the DTH. The cylindrical member deforms in the gap, resulting in the cylindrical member being fixedly sandwiched between the support sleeve and the component bore.

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 drill bit comprises: a drill bit head having a cutting face with one or more fixed cutting elements; a flow passage extending through the drill bit head to the cutting face; a flow interrupter within the drill bit head and positioned to interrupt flow of fluid through the flow passage; and a power section connected to drive the flow interrupter and cause, in operation, variable flow of fluid through the flow passage. A method of drilling comprises: flowing fluid through a flow passage extending through a drill bit head to a cutting face of the drill bit head, the cutting face having one or more fixed cutting elements; and driving a flow interrupter within the drill bit head with a power section to interrupt the flow of fluid through the flow passage and cause variable flow of fluid through the flow passage.

Abstract: A hydraulic jar having multiple high pressure chambers includes a jar body comprising an inner body telescopically engaged by an outer body. There is a first contact surface carried by the inner body, and a second contact surface carried by the outer body that engage when the jar body is moved to the jarring position. A plurality of axially spaced pressure chambers are spaced axially along the jar body, with each pressure chamber having a hydraulic delay section and a jarring section. A piston separates the pressure chamber. A hydraulic delay is in fluid communication with a high pressure section and a low pressure section of each pressure chamber and permits movement of the piston toward the second end at a first speed. A jarring valve permits movement of the piston toward the second end at a second speed that is greater than the first speed when in a japing section.

Abstract: A double-acting compounder comprises: an outer housing; an inner mandrel disposed telescopically within the outer housing to define a fluid chamber; an equalizer, such as an equalizer piston, between the fluid chamber and an exterior of the outer housing for equalizing pressure; a movable seal assembly within the fluid chamber with a first end defining an end of the fluid chamber; the inner mandrel having an outer shoulder for moving the movable seal assembly with the inner mandrel when the inner mandrel moves in a first direction relative to the outer housing to compresses fluid within the fluid chamber; and the outer housing having an inner shoulder for preventing the movable seal assembly from moving with the inner mandrel when the inner mandrel moves in a second direction relative to the outer housing to compresses fluid within the fluid chamber.

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. A hydraulic reset assembly is included. 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 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 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 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 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: A down-the-hole assembly includes a housing assembly having a head end and a bit end. The housing assembly further includes an inlet joint having an inlet channel defined therein, a sealing portion positioned toward the bit end relative to the inlet joint, and an outlet portion positioned toward the bit end relative to the sealing portion. A hammer assembly including a piston has a piston channel defined therein that includes an inlet in fluid communication with the inlet channel and an outlet in fluid communication with the housing assembly.

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 percussive assisted rotary drill includes a top sub for connection with a drill pipe. The drill pipe imparts torque to the drill and also supplies motive fluid to the drill. The drill includes a shank adapter to facilitate affixing a rotary drill bit to the drill. The motive fluid is divided between a bit flow which flows through the bit to clear debris at the bottom of the drill, and an actuator flow. An actuator, which may be in the form of a reciprocating piston, moves within the drill under the influence of the actuator flow to impart cyclical blows to the shank adapter. At least a portion of the actuator flow portion of the motive fluid is exhausted through the top end of the drill.

Abstract: The invention relates to an arrangement designed to be inserted in a cavity (19) in a front part (14) of a rock drilling machine with a shank adapter (16). The arrangement comprises a cartridge (1) with a flushing head (2) and a guide (3) coaxially arranged to create a longitudinal channel (5) designed as a passage for the shank adapter (16).

Abstract: A hydraulic jar for a drilling assembly is disclosed. In some embodiments, the hydraulic jar includes a tubular housing, a mandrel disposed in the housing, an annulus between the mandrel and the housing, and a pressure relief mechanism disposed in the annulus. The pressure relief mechanism generally divides the annulus into first and second portions. The pressure relief mechanism includes first and second annular members in engagement with one another when the pressure in the second annulus portion is less than a predetermined value and a fluid flow path between the first and second annulus portions. The fluid flow path has a first size when the pressure in the second annulus portion is less than the predetermined value, and a second size that is larger than the first size when the pressure in the second annulus portion becomes equal to or greater than the predetermined value.

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 percussion drilling assembly for drilling through earthen formations and forming a borehole. In an embodiment, the percussion drilling assembly comprises a fluid conduit including a tubular body having a first end, a second end, a through passage extending between the first end and the second end, and an inlet port in fluid communication with the through passage. In addition, the percussion drilling assembly comprises an adjustable choke at least partially disposed in the through passage and including a first bypass port. The adjustable choke is adapted to decrease the volumetric flow rate of a compressed fluid through the first bypass port.

Abstract: A water hammer using a drive rod is provided.

Abstract: The present invention discloses a collapsible drilling assembly having field-replaceable cutter or stabilizer blades (214) and method of using and installing new stabilizer blades while at a job location. The drilling assembly is deployed upon a distal end of a drillstring, expanded to a gauge size, and used as an underreamer or alternatively a stabilizer. The drilling assembly operates between retracted and extended positions through the increase in pressure of drilling fluid flowing therethrough.

Abstract: A bit assembly is for a percussive drill that includes a casing with an interior chamber and includes a bit connectable with the casing and having a longitudinal bore and an axis through the bore. The bore has a retainer portion with one or more generally. conical inner surfaces extending circumferentially about and facing generally toward the axis. A generally cylindrical valve has a longitudinal passage with an inlet fluidly connectable with the casing chamber and an outlet fluidly connectable with the bit central bore and an axis through the passage. An engagement portion with at least one generally conical outer surface extends circumferentially about and faces generally away from the valve axis. The valve engagement portion is disposable within the bit bore retainer portion such that the valve conical outer surface is disposed within and against the bit conical inner surface to retain the valve coupled with the bit.

Abstract: In one aspect of the present invention, a drilling assembly has a string of downhole tools connected to a drill bit with a bit body intermediate a shank and a working face. The drill bit is connected to the string of tools at the shank. A continuous fluid passageway is formed within the bit body and the string of tools. A valve mechanism disposed within the fluid passageway is adapted to substantially cyclically build-up and release pressure within the fluid passageway such that a pressure build-up results in radial expansion of at least a portion of the fluid passageway and wherein a pressure release results in a contraction of the portion of the fluid passageway. The expansion and contraction of the portion of the fluid passageway varies a weight loaded to the drill bit.

Abstract: A drilling apparatus includes a cutting structure defined by a percussive action cutter and at least one other cutter. The percussive action cutter is adapted to be urged in a drilling direction by hydraulic pressure force, while the other cutter is urged in a drilling direction by mechanical force.

Abstract: A hydraulic jar for a drilling assembly is disclosed. In some embodiments, the hydraulic jar includes a tubular housing, a mandrel disposed in the housing, an annulus between the mandrel and the housing, and a pressure relief mechanism disposed in the annulus. The pressure relief mechanism generally divides the annulus into first and second portions. The pressure relief mechanism includes first and second annular members in engagement with one another when the pressure in the second annulus portion is less than a predetermined value and a fluid flow path between the first and second annulus portions. The fluid flow path has a first size when the pressure in the second annulus portion is less than the predetermined value, and a second size that is larger than the first size when the pressure in the second annulus portion becomes equal to or greater than the predetermined value.

Abstract: An axial bearing includes a first piston and a second piston. Axial contact surfaces between the pistons are arranged in the same pressure space. The same pressure fluid fed to the axial bearing acts on the contact surfaces and on working pressure surfaces of the pistons. A rock drilling machine is also provided with such an axial bearing.

Abstract: In one aspect of the invention a drill bit comprises an axis of rotation a body and a working face. The body comprises a fluid passageway with a first seat and houses a jack element substantially coaxial with the axis. A stop element is disposed within the passageway and has a first near-sealing surface. The jack element has a shaft intermediate an indenting end and a valve portion. The valve portion has a second near-sealing surface disposed adjacent the first near-sealing surface and a second seat disposed adjacent the first seat. As a formation strongly resists the jack element, the distance between the sealing surfaces narrows. This causes an increase in fluid pressure within the passageway and forces the indenting end down into the formation. This movement of the jack element relieves the pressure build up such that the formation pushes the jack element back, thereby oscillating the jack element.

Abstract: A pressure fluid actuated downhole percussion tool includes a reciprocating piston hammer with differential transverse pressure surfaces cooperable with a cylinder housing, a guide sleeve and a bit carried exhaust tube to form opposed pressure fluid chambers to which pressure fluid may be conducted to deliver repeated impact blows to a bit having circumferentially spaced bosses and replaceable cutting inserts. The bit is drivenly connected to the tool by plural drive pins supported in circumferentially spaced grooves in the bit shank and in a removable sub supported by the tool housing. Improved earth penetration performance is realized utilizing a claw bit with a pressure fluid actuated percussion tool providing rotation as well as selective deliverance of impact blows through the bit.

Abstract: A jar for use in a downhole environment comprises an hydraulic timing device which allows pressure to be controllably increased to a desired level and, on firing, a near-instantaneous release of that pressure, and which allows for selective bi-directional firing of the jar.

Abstract: A downhole tool is provided that creates balancing forces that allow a tool such as ajar to continue to function when intrusion of gas into the fluid chamber of the jar occurs to cause gas pressure in the jar to exceed hydrostatic pressure. The excess pressure is balanced by forming an area acted on by the gas pressure equal to the cross-sectional area of the mandrel, such that the forces on the mandrel are equal and opposite.

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.