Abstract: A damper device that suppresses arc discharge between electrodes generated by bubbles in an electro-rheological fluid, includes an inner tube housed in an outer tube forming an outer shell of a damper device. An electrode tube is arranged between the outer tube and the inner tube. An electro-rheological fluid is sealed in the outer tube. The inner tube and the electrode tube constitute a cathode and an anode, respectively, and apply a voltage to the electro-rheological fluid located between the inner tube and the electrode tube. An insulating layer is provided on a surface of the electrode tube on a side facing the inner tube or on a surface of the inner tube on a side facing the electrode tube. When a maximum voltage applied to the electro-rheological fluid is Vmax (V), a thickness t (m) of the insulating layer is set to satisfy Formula (1).

Abstract: A method for increasing an amplitude of reciprocal axial extensions and contractions of a shock tool configured to induce axial oscillations in a drillstring during drilling operations includes (a) selecting the shock tool. The shock tool has a central axis and an axial length. The shock tool includes an outer housing, a mandrel telescopically disposed within the outer housing, and a first annular piston fixably coupled to the mandrel. The shock tool has a first amplitude of reciprocal axial extension and contraction at a pressure differential between a first fluid pressure in the outer housing and a second fluid pressure outside the outer housing. In addition, the method includes (b) fixably coupling a second annular piston to the mandrel of the shock tool and increasing the axial length of the shock tool after (a). The second annular piston is axially spaced from the first annular piston.

Abstract: A bumper spring assembly having a one piece mandrel including an integral head piece is further configured with a cage assembly retained on the mandrel with a cage nut locked to the mandrel to obviate the need for pins, set screws, and the like, to provide a more robust assembly. In two embodiments the cage nut is locked to the mandrel in a swaging operation. Improved flow of fluids through and around the bumper spring assembly are also provided.

Abstract: A squeeze mode giant electrorheological fluid damper is disclosed. The squeeze mode giant electrorheological fluid damper comprises a support, a container and a connecting structure, wherein the support comprises a bottom plate, guide shafts and a top plate, the guide shaft is vertically fixed on the bottom plate, and the top plate is slidably arranged on the guide shaft; the container comprises a container body and two spiral spring pieces coaxially arranged in the container body, the container body is fixed on the bottom plate, the bottoms of the two spiral spring pieces are fixed to the bottom of the container, the two spiral spring pieces are not in contact with each other and are spaced by 180°; the top of the connecting structure is fixedly connected with the top plate, and the bottom of the connecting structure is fixedly connected with the tops of the two spiral spring pieces.

Abstract: A method is disclosed for surveying drill holes with a drilling arrangement and borehole survey assembly. The method can include providing a drill tool having at least one drill rod and a drill bit assembly, and providing a borehole survey tool having a sensor) for measuring a borehole. In the method a drill tool having a central flushing channel for conducting flushing fluid to the drill bit assembly is used, and the borehole survey tool is arranged in the central flushing channel so that flushing fluid can flow in the central flushing channel past the borehole survey tool.

Abstract: The invention provides a method of improving the preservation stability of glutathione in a solid composition containing glutathione and arginine. In particular, glutathione and arginine are made to be coexistent with an organic acid such as citric acid, tartaric acid, ascorbic acid, malic acid, malonic acid, succinic acid, fumaric acid, maleic acid and the like. The amount of the organic acid to coexistent with glutathione and arginine is generally 0.1-2 parts by weight relative to 1 part by weight of arginine.

Abstract: A shock tool for a drill string includes an outer tubular housing having female multi-spiral helical spline grooves disposed on an interior surface of the housing, and an inner tubular mandrel having a portion of an exterior circumferential surface with mating male multi-spiral helical splines. The inner tubular mandrel is telescopically and rotationally received in the outer tubular housing with the male splines received in the female spline grooves of the housing.

Abstract: A fluid flow control apparatus includes a biasing member applying a biasing force to a closure member, and a sealing member receiving the closure member. A dampener operatively connected to the closure member resists a force applied to the closure member. A fluid seal is formed when the biasing member presses the closure member against the sealing member. The closure member and sealing member may cooperate to control fluid flow along a fluid conduit formed in a wellbore tubular. The apparatus may include an actuator that controls the force applied to the closure member. The actuator may adjust the biasing force, and/or the dampening force. Also, a controller control the actuator may be responsive to a signal generated at a surface location, a downhole location, and/or a signal generated by a sensor.

Abstract: A vibration damping mechanism allows increase of an absorption amount of vibration energy, with less possibilities of increase in the manufacture cost of a vibration damping weight and of reduction in the strength of a shaft section. Within a cylindrical hollow portion formed inside the shaft section, there are accommodated a plurality of weight members divided from each other along the circumferential direction about the axis of the hollow portion. An urging member is provided for urging the weight members toward the axis such that dividing faces of adjacent weight members are brought into surface contact with each other.

Abstract: A technique provides a component actuation system in a space efficient form. A movable actuator member may be positioned within a corresponding housing in a manner which forms an annulus between the movable actuator member and the surrounding wall of the housing. A spring is located in the annulus and is designed such that the spring extends part way along a circumference of the actuator member to create an open annular region between circumferential ends of the spring. The open annular region provides space for a system related component without requiring additional longitudinal or radial space.

Abstract: A Tuned Mass Damper (TMD) for damping oscillations of a hanging vertical pump structure includes a removable mass symmetrically configured within the pump structure diameter and supported by a mechanism which provides damped mobility relative to the pump structure so as to absorb and dampen pump vibrations and oscillations. The TMD mass is easily removable before tipping of the pump between horizontal and vertical orientations during maintenance. In some embodiments, the TMD mass comprises fluid pumped by the pump to fully or partially fill a housing, the fluid being gravitationally drained therefrom when the pump is not operating. In other embodiments the TMD mass is supplied by removable solid weights. Damped mobility is provided by springs damped by mechanical or fluid friction, or by obstructed movement of fluid within a partially filled housing. In embodiments, the TMD mass is at least 5% of the total mass of the pump structure.

Abstract: A system for damping vibration in a drill string can include a valve assembly having a supply of a fluid, a first member, and a second member capable of moving in relation to first member in response to vibration of the drill bit. The first and second members define a first and a second chamber for holding the fluid. Fluid can flow between the first and second chambers in response to the movement of the second member in relation to the first member. The valve assembly can also include a coil or a valve for varying a resistance of the fluid to flow between the first and second chambers.

Abstract: A system for damping vibration in a drill string can include a valve assembly having a supply of a fluid, a first member, and a second member capable of moving in relation to first member in response to vibration of the drill bit. The first and second members define a first and a second chamber for holding the fluid. Fluid can flow between the first and second chambers in response to the movement of the second member in relation to the first member. The valve assembly can also include a coil or a valve for varying a resistance of the fluid to flow between the first and second chambers.

Abstract: A system for damping vibration in a drill string can include a valve assembly having a supply of a fluid, a first member, and a second member capable of moving in relation to first member in response to vibration of the drill bit. The first and second members define a first and a second chamber for holding the fluid. Fluid can flow between the first and second chambers in response to the movement of the second member in relation to the first member. The valve assembly can also include a coil or a valve for varying a resistance of the fluid to flow between the first and second chambers.

Abstract: A system for damping vibration in a drill string can include a valve assembly having a supply of a fluid, a first member, and a second member capable of moving in relation to first member in response to vibration of the drill bit. The first and second members define a first and a second chamber for holding the fluid. Fluid can flow between the first and second chambers in response to the movement of the second member in relation to the first member. The valve assembly can also include a coil or a valve for varying a resistance of the fluid to flow between the first and second chambers.

Abstract: A depth compensated passive eave compensator comprises a first cylinder connected at its upper end to a vessel. A piston rod extends from a piston located within the first cylinder through the lower end thereof and is connected to subsea equipment. A second cylinder contains a compressed gas which maintains pressure beneath the piston of the first cylinder. The upper end of the first cylinder is connected to the upper end of a third cylinder having a piston mounted therein. A piston rod extending from the piston of third cylinder extends through the lower end thereof thereby applying the pressure of the sea to the piston of the third cylinder.

Abstract: Device for a tool string (2) for insertion in a well, the tool string (2) being provided with a brake nose (1).

Abstract: A system for damping vibration in a drill string can include a valve assembly having a supply of a fluid, a first member, and a second member capable of moving in relation to first member in response to vibration of the drill bit. The first and second members define a first and a second chamber for holding the fluid. Fluid can flow between the first and second chambers in response to the movement of the second member in relation to the first member. The valve assembly can also include a coil or a valve for varying a resistance of the fluid to flow between the first and second chambers.

Abstract: A depth compensated passive eave compensator comprises a first cylinder connected at its upper end to a vessel. A piston rod extends from a piston located within the first cylinder through the lower end thereof and is connected to subsea equipment. A second cylinder contains a compressed gas which maintains pressure beneath the piston of the first cylinder. The upper end of the first cylinder is connected to the upper end of a third cylinder having a piston mounted therein. A piston rod extending from the piston of third cylinder extends through the lower end thereof thereby applying the pressure of the sea to the piston of the third cylinder.

Abstract: A system for damping vibration in a drill string can include a valve assembly having a supply of a fluid, a first member, and a second member capable of moving in relation to first member in response to vibration of the drill bit. The first and second members define a first and a second chamber for holding the fluid. Fluid can flow between the first and second chambers in response to the movement of the second member in relation to the first member. The valve assembly can also include a coil or a valve for varying a resistance of the fluid to flow between the first and second chambers.

Abstract: A shock absorbing apparatus and method includes a shaft travelling north and south within a tube. The tube is positioned south of a sucker rod. The shaft has a piston head coupled at a south end thereof, which piston head is received in an area of reduced diameter with the shaft. North pores and south pores permit the movement of fluid into and out of the interior of the tube, in response to the northward/southward movement of the piston head. Fluid entering through the pores provides a shock absorbing effect on both the upstroke and the downstroke. The shock absorbing effect on the upstroke can be rapidly eliminated and an upward shock force generated, through the shearing of a shear pin that maintains a bushing in position on the shaft, restricting northward travel of the piston head.

Abstract: The present invention provides a gun brake system adapted to slow the descent of a tool string in a well. In one embodiment, the brake system comprises a brake installed within the well and having a snug fitting restriction and one or more fluid channels extending along a portion thereof. The brake system further provides means for maintaining the fluid volume substantially constant within the production tubing to which the gun brake is installed.

Abstract: A load compensator is disclosed for use in connection with a pipe running tool. The load compensator includes an outer housing connected to the portion of the pipe running tool that holds the pipe segment. A piston is disposed within the housing, and is connected to a top drive system of the pipe running tool. The housing is formed with a first port through which pressurized air is delivered inside the housing to drive the piston within the housing. A second port is disposed at a selected location on the housing, such that when the piston is advanced past the second port, pressurized air passes through the port, and causes the control circuit to stop delivering air through the first port. Once pressurized air no longer flows through the second port, the control circuit causes air to be delivered to the first port.

Abstract: This invention is a shock absorber for a oil well pumping unit. When a oil well is being produced by means of a oil well pumping unit-the pumping unit sits on the ground surface and pumps in an upward and downward motion which works the sucker rod string that runs down the well bore with a oil pump attached to the bottom of the sucker rod string. The sucker rods are attached to the pumping unit by means of a polish rod. The polish rod is the top rod of the sucker rod string. This shock absorber fits over the polish rod and slides down to a desired position. It is attached to the pumping unit by either wire line clamps on the bridle arms or a carrier bar. It will fit any and all oil well pumping units. Other oil well shock absorbers will only fit oil well pumping units with special attachments. This shock absorber is to eliminate pounding and vibration from the pumping unit and sucker rod string.

Abstract: A rotary and longitudinal shock absorbing apparatus with an mandrel therein is connected to a drill string assembly to absorb abnormal longitudinal shocks and abnormal torsional shocks by cooperating hydraulic and mechanical means, while allowing communication of drilling fluid through the body of the apparatus. The construction of the apparatus is such that torque shock absorbing action is independent of the longitudinal shock absorbing action and the apparatus provides balanced internal and external pressure to permit its operation at all levels of hydraulic pressure.

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

Abstract: A down-hole decelerator for decelerating a device dropped down a borehole in a drilling mud column has an elongate casing immersible in the mud flow with its longitudinal axis along the axis of the borehole. A plunger is slidable axially within the casing to vary the volume of two chambers within the casing and terminates outside the casing in a nose for impacting on a landing plate within the borehole when the decelerator reaches the end of its travel on being dropped down the borehole.

Abstract: A shock absorber apparatus for inclusion in a tool string which consists of outer and inner casings telescopically assembled with one casing having an uphole threaded joint member and the other casing having a downhole threaded joint member. The concentric casings then define spaced, sealed voids communicating through a metering sleeve clearance that are filled with a compressible oil. Shock wave induced relative movement of the casings from either direction causes a shock absorbing instantaneous displacement of oil from one void to the other via the metering clearance. Alternatively, coil springs may be disposed in the voids to aid in shock absorption.

Abstract: In a preferred embodiment, an eletronic temperature gauge is carried into a well bore within a pressure-sealed housing which can free fall through a drill string to impact upon a drill bit connected at the bottom of the drill string. A shock absorber is connected at the bottom of the housing to absorb the shock upon impact of the apparatus on the drill bit. The shock absorber has a relatively linearized shock absorbing response in the preferred embodiment. Additional structural features provide further cushioning of the gauge during transit and upon impact.

Abstract: A drill string apparatus for the controlled absorption of both axial and torsional forces exhibited on the well string during drilling operations. The device is adapted to be connected in the drill string above the drilling tool in order to control the forces acting on the bit and to arrange the mean weight on bit for the selected drilling operation. Generally, the apparatus includes an outer casing coupled at its upper end to the drill string and an inner assembly telescopically received within the outer casing and connected at its lower end to the lower part of the bottom hole assembly or the drilling tool. Rotational torque is transferred from the drill string and outer casing to the inner assembly and drill bit by a series of helical splines. The mean weight on bit is controlled through an interchangeable pressure control nozzle mounted at the top of the inner assembly.

Abstract: A resilient unit able to accomodate a large movement comprises a stack of elastomeric bearing units arranged to be loaded in series and to deform primarily in shear. Preferably a plurality of the stacks are provided in a nested configuration and interconnected in series to enable even greater movements to be accommodated.The resilient unit is particularly suitable for use on an offshore platform to accommodate movement between the platform and a riser pipe while also maintaining a tension loading in the riser pipe.

Abstract: A downhole drilling motor is disclosed in which an output shaft is allowed to translate in axial direction relative to the motor housing over a predetermined stroke. Fluid pressure of a drilling fluid pumped to a rotary drill bit driven by the motor may be used during operation of the motor to exert a predetermined axial force to the output shaft so as to control the axial force exerted to the bit during drilling.

Abstract: A sub assembly for connecting a power swivel to a drill string. The assembly includes a telescopic sub having a preloaded spring. The telescopic sub has three discrete positions enabling it to travel in either direction from a normal position. This capability prevents thread damage for both when connecting and disconnecting a drill pipe to the drill string.

Abstract: A vibration isolator and shock absorber system which provides excellent protection to sensors against the deleterious effects of shock and vibration even under severe drilling conditions is presented. The vibration isolator and shock absorber system is enclosed within an outer cage and an inner yoke. The cage is attached to the drill collar which takes the full impact of the shock and vibration due to drilling. The yoke supports the sensor. Conical disc springs (e.g. Belleville springs) or the like are stacked between the yoke and the cage; and are supported by pairs of upper and lower support rings. These rings fit together to compress the springs and to allow for axial displacement as well as providing damping. The pairs of support rings are supported, in turn, between upper and lower elastomeric isolator rings. The upper elastomeric isolator ring is keyed to the yoke and the cage. Fluid is allowed to move through the system via orifices in both the elastomeric isolators and the pairs of support rings.

Abstract: A shock absorber for a wireline instrument, the shock absorber having solid, cylindrical upper body, a cylindrical sleeve, and a mandrel. The mandrel has a hexagonal upper portion, a circular center portion, and a lower nose portion. A bolt connects the mandrel to the upper body, so that the mandrel can move telescopically within the sleeve, but cannot fall out of the sleeve. Three carbide cutting elements are mounted on the sleeve adjacent to alternate sides of the upper portion of the mandrel for cutting chips of material off of the sides of the mandrel as the mandrel is moved into the sleeve.

Abstract: A vibration isolator and shock absorber device is presented wherein elastomeric vibration isolation elements interact with reaction elements to form differential springs, i.e., springs in which the deflection and load characteristics change with load. In the present invention, the load characteristics change from shear at low loading to compression at high loading, with a smooth transition between shear and compression.

Abstract: A well tool carried in a drill string for maintaining bottom hole contact while absorbing angular and axial shock forces of a rotating drill bit. The tool has an elongated body with pipe joint ends and includes a tubular mandrel slideably mounted within a tubular barrel. A groove and roller connection guides the mandrel within the barrel during drilling. Resilient shock absorbing members between metal guide rings are carried between stop elements on the mandrel and barrel. Shock forces are absorbed by the telescoping movements of the mandrel within the barrel and by in the members acted on by the stop elements. The mandrel is formed of two pieces that threadedly connect to one another between the resilient shock absorbing members and the groove and roller connection. A lifting lug positioned above the rollers and below the shock absorbing members within an elongate mandrel groove, engages the joint to transfer the weight of the mandrel to the barrel upon withdrawal of the tool.

Abstract: An oil well sucker well shock absorber having a cylindrical outer casing, a spring disposed therewithin, a plurality of apertures extending through the casing and allowing fluid communication with upwardly extending slidably disposed piston plunger rod attaching device. Thus, unwanted play and travel and its associated wear can be minimized by force dissipation through the associated spring within the casing.

Abstract: A telescopic shock absorber for use in a drill string includes a resilient arrangement to cushion telescopic contraction and extension of the shock absorber in response to shock loads and vibrations imparted during drilling. The shock absorber operates independently of the drilling fluid pressure conducted through the structure during drilling operations. A dampening system assists in cushioning the shock loads and vibrations and the dampening system and resilient arrangement are deactivated when jarring impacts are delivered to the well string by a drilling jar carried therein. The resilient arrangement provides a combination mechanical and hydraulic system for cushioning the impact loads and vibrations encountered.

Abstract: A holding or checking means for holding the control rod of a reciprocating drill feed control apparatus in position after each advancing movement of an automatic drilling machine during a "peck drilling" operation. The holding means includes a cylindrical body adapted to be fastened over the end of a drill feed control apparatus and with the control rod of the feed control apparatus extended through said body. A pair of pivotally mounted yoke arms are mounted on a cylindrical body and have semi-circular recesses adapted for friction holding engagement with the feed control rod to hold it in an advanced position when the reciprocating drill apparatus is retracted. The holding means includes a biasing means for biasing the yoke arms into friction engagement against the control rod.

Abstract: The invention pertains to tensioners for maintaining a load between two relatively movable structures, such as an offshore drill ship or the like and a riser pipe. First and second tensioner bodies are mounted for relative reciprocation, and are further functionally interconnected with the first and second offshore structures respectively. Relative movement of the offshore structures tends to cause corresponding relative reciprocation of the tensioner bodies. A force is applied between the tensioner bodies tending to reciprocate them in a first directional mode and thereby supporting the offshore riser pipe with respect to the offshore support structure. A balancing chamber cooperative between the tensioner bodies communicates with a source of pressurized fluid for resisting reciprocation of the tensioner bodies in the first directional mode, but includes an outlet for egress of the pressurized fluid to permit such reciprocation under controlled conditions.

Abstract: Adjustable torsional type latching means (5) for triggering a mechanical well jar tool comprises torsionally actuated gear racks (20,22) including acme threads or teeth which extend axially on opposite adjacent side portions of telescopic parts (1,2). The gear rack teeth which mesh in the latched position have incline tooth faces that can be disengaged by applying a strong axial force which torsionally stresses and rotates a torsion sleeve (16) portion of one telescoping part (1) and gear rack (20) thereon away from the other part (2) and gear rack (22). Upon release of the latching device (5) the telescopic parts (1,2) of the well jar and the kinetic energy stored therein are freed for a limited longitudinal jarring movement. The torsion sleeve portion (16) has an end portion connected to the other telescopic parts by a second slot-spline-gear (15) of relative short axial length, which serves as a torque support in the latched position and becomes deengaged during a jarring stroke.

Abstract: A well tool carried in a drill string for maintaining bottom hole contact while absorbing angular and axial shock forces of a rotating drill bit. The tool has an elongated body with pipe joint ends and includes a tubular mandrel rotationally and slideably mounted within a tubular barrel. A groove (preferably helical) and roller connection guides the mandrel from the barrel during drilling. Resilient shock absorbing members between metal guide rings are carried between stop elements on the mandrel and barrel. Shock forces are absorbed initially by the rotating/telescoping movements of the mandrel within the barrel. Excess shock forces are absorbed in the members acted on by the stop elements on further inward/outward movements of the mandrel rotating in the barrel. Unique cross-over rings (graphite-filled Teflon.RTM.) cushion the resilient members from impacts of the metal guide rings.

Abstract: A shock absorber assembly adapted to be used with a drill string dampening intermittent shocks and vibrational forces encountered with a drill string, the shock absorber assembly including a mandrel, a tubular body reciprocally mounted with respect to the mandrel, and a dampening device including an annular chamber adapted to be filled with a compressible fluid and a flexible wall with the mandrel adjacent the annular chamber for permitting flexure of the mandrel as needed for dampening.

Abstract: A well servicing system in which sonic energy is transmitted down a pipe string to a down hole work area a substantial distance below the surface. The sonic energy is generated by an orbiting mass oscillator and coupled therefrom to a central stem to which the piston of a cylinder-piston assembly is connected. The cylinder is suspended from a suitable suspension means such as a derrick, with the pipe string being suspended from the cylinder in an in-line relationship therewith. The fluid in the cylinder affords compliant loading for the piston while the fluid provides sufficiently high pressure to handle the load of the pipe string and any pulling force thereon. The sonic energy is coupled to the pipe string in a longitudinal vibration mode which tends to maintain this energy along the string.

Abstract: A shock absorbing apparatus for use in a drill string for earth boring operations has a pressurized lubrication system. The shock absorber has a tubular body and a mandrel reciprocally mounted in the body for rotation with it. The mandrel and body telescope with respect to each other, with an annular pressurized chamber being located between them for absorbing load and shock. Lubricant cavities contain lubricant for lubricating the seals of the pressurized chamber. The lubricant in the lubricant cavities is maintained at a pressure greater than ambient but less than that in the pressurized chamber. This is accomplished by utilizing a differential piston that operates in response to the pressure differential between the chamber and the lubricant in the lubricant cavity.

Abstract: A novel shock sub is disclosed for use in a drill string for absorbing longitudinal and impact loads. A tubular housing is provided for connection to one part of a drill string and a tubular mandrel extends into the housing for longitudinal sliding movement with an outer end portion for connection to the other part of the drill string. The mandrel and housing define an annular cavity when assembled. The mandrel has two slots, positioned 90.degree. apart circumferentially extending for length of the annular cavity. Annular spring washers positioned in the annular cavity are of a size having a sliding fit on the outside of the mandrel and inside the housing. The spring washers are each corrugated in a wave configuration and with a tab of a size fitting one of the mandrel slots and are placed on the mandrel with alternate ones having tabs fitting in one of the slots and the others having their tabs fitting another mandrel slot.

Abstract: For use in a string of drill pipe terminating in drill collars and a drill bit, a shock sub is disclosed which, in the illustrated and preferred embodiment, incorporates telescoping upper and lower mandrels. The upper mandrel incorporates a pin connection and supports concentrically deployed, inner and outer tubular sleeves defining an internal cavity. The lower mandrel incorporates an upstanding sleeve which telescopes into the cavity between the sleeves of the upper mandrel. A two-chamber fluid damping system constrains movement of the lower mandrel sliding in the cavity of the upper mandrel. The two chambers are defined by meshed splines which permit telescoping movement, but which prevent relative rotational movement.

Abstract: A shock absorber assembly for absorbing shocks encountered by a drill string wherein the shock absorber assembly is for use with a drill string having a working fluid therein and includes a body member affixed to the drill string, a mandrel mounted for reciprocal longitudinal movement with respect to the body member and a fluid dampening member floated within the central bore of the body member in engagement with the body member and the mandrel for absorbing shocks transmitted between the body member and the mandrel.

Abstract: A shock absorber assembly for absorbing shocks encountered by a drill string having a working fluid flowing therethrough wherein the shock absorber assembly includes a housing affixed to the drill string, a mandrel mounted for reciprocal longitudinal movement with respect to the housing, and a fluid dampening member replaceably sandwiched between the mandrel and housing for absorbing shocks transmitted between the mandrel and the housing during drilling operations.