Abstract: A system for supporting tubing with an installable load shoulder. The system includes a wellhead formed with an enlarged first circumferential groove in the wall of the vertical bore of the wellhead, and a second circumferential groove extending upwardly or downwardly from the first circumferential groove. At least one opening is formed in communication with the second circumferential groove. An annular load shoulder is received within the first circumferential groove, and has an inner surface adapted to support a tubing hanger. The load shoulder is formed from at least three arc-shaped shoulder segments adapted to be received within the first circumferential groove. At least one of the shoulder segments has an engagement member configured to pass through the opening to be received within the second circumferential groove. Rotating the load shoulder such that the engagement member is out of alignment with the opening secures the load shoulder within the wellhead.

Abstract: The invention provides a wellhead and a method for installing a wellhead assembly. The wellhead or casing head assembly comprises a first tubular having at least one aperture extending through a side wall thereof. The wellhead or casing head also comprises a second tubular having a recessed portion in the exterior thereof. The second tubular is arranged to be at least partially inserted within the first tubular. The wellhead or casing head assembly also comprises at least one fastening member. The fastening member is removably accommodated within the aperture-(s) and recessed portion. The wellhead also comprises securing means for maintaining the fastening member-(s) within the aperture-(s) and recessed portion. The wellhead further comprises seal means arranged to provide a fluid tight seal.

Abstract: A bail support and a top drive system for an oilfield drill rig. The top drive system includes a drive apparatus, and the bails have bodies with upper head portions and two spaced-apart legs. Each leg includes an upper leg portion and a lower leg portion. The upper leg portions are non-parallel to each other and extend from the head portion at an angle to a centerline of the bail. Each lower leg portion extends down from its corresponding upper leg portion in a reverse bend.

Abstract: A wellhead completion assembly has a head connected to surface casing. A rotatable flange or the like can be used to connect various components to a threaded end of the head. A casing hanger installs in the head, and the hanger's upper end extends beyond the head's top edge. This exposed end has an external threaded connection to connect to various wellhead components using a rotatable flange or the like. For example, a locking ring can threadably connect to the head's threaded end to support the hanger in the head. Then, a rotatable flange can threadably connect to the hanger's exposed end so that another component, such as a completion spool or gate valve, can nippled up directly to the hanger. When the hanger is fluted, a pack-off assembly can allow testing off inner and outer sealing integrity via a test port accessible through an opening in the locking ring.

Abstract: A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

Abstract: A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

Abstract: A hybrid wellhead system is assembled using a plurality of threaded unions, such as spanner nuts or hammer unions, for securing respective tubular heads and a flanged connection for securing a flow control stack to a top of a tubing head spool. The tubing head spool is secured by a threaded union to an intermediate head spool. The intermediate head spool is secured by another threaded union to a wellhead. Each tubular head secures and suspends a tubular string in the well bore. The hybrid wellhead system is capable of withstanding higher fluid pressures than a conventional independent screwed wellhead, while providing a more economical alternative to a flanged, or ranged, wellhead system because it is less expensive to construct and faster to assemble.

Abstract: A wellhead assembly including a wellhead housing. The wellhead housing comprises a throughbore having a recessed sealing area and a tubing hanger positioned in the throughbore. A seal is positioned between the wellhead housing and the tubing hanger, the seal being positioned so as to form a gap between the seal and the wellhead housing. The wellhead assembly can further include a seal energizer capable of moving relative to the seal in a manner that forces the seal against the wellhead housing to bridge the gap. A method of installing a tubing hanger into a throughbore of a wellhead housing is also disclosed.

Abstract: Embodiments of the present invention generally relate to an apparatus for supporting a tubular that more evenly distributes stress along the contact length of a tubular. In one embodiment, an apparatus for supporting a tubular is provided. The apparatus includes a bowl having a longitudinal opening extending therethrough and an inner surface for receiving a gripping member. The gripping member is movable along the surface of the bowl for engaging the tubular. The apparatus is configured so that an upper portion of the gripping member will engage the tubular before the rest of the gripping member engages the tubular.

Abstract: An apparatus for retaining two strings of tubulars characterized in that said apparatus comprises body parts of a device for retaining a single string of tubulars and a converting member. A device for retaining a string of tubulars, said device comprising at least one body part having a curved tapered surface upon which inserts are located for engagement with said string of tubulars characterized in that said curved tapered surface comprises a recess for the passage of cables.

Abstract: A polish rod clamping device, for use as part of a wellhead production pumping tree to secure a polish rod. The device includes a pressure-containing body forming a central vertical and opposed first and second side bores. A pair of clamping rams are positioned in the side bores for sliding movement therealong, each clamping ram having a front and a rear end, the front ends of the clamping rams being configured to accommodate at least a portion of the polish rod between their front ends when the clamping rams are advanced across the central bore. The front end of at least one of the clamping rams is configured with a vertical V-groove for gripping the polish rod. The invention extends to the V-groove rams themselves and to composite wellhead assemblies containing the V-groove clamping device.

Abstract: A method and apparatus for facilitating the connection of tubulars using a top drive which, in one aspect, the apparatus includes a body connectable to said top drive. The body includes at least one gripping element radially displaceable by hydraulic or pneumatic fluid to drivingly engage a tubular to permit a screw connection between said tubular and a further tubular to be tightened to the required torque.

Abstract: A polish rod clamp apparatus has a body defining a lower rod aperture and a tapered body recess. A cap defines an upper rod aperture and a tapered cap recess. Tapered gripper dies have upper and lower outer surfaces sloping inward from a central portion and inner surfaces configured to bear against the polish rod. The dies are installed in the body recess such that inner surfaces bear against a polish rod and the lower outer surfaces bear against walls of the body recess. The dies are movable with respect to the body and are prevented from rotating. The cap is threaded onto the body such that the upper outer surfaces of the gripper dies bear against the walls of the tapered cap recess. Threading the cap onto the body forces the gripper dies against the outer surface of the polish rod passing through the body.

Abstract: A method for converting a kelly rig for handling casing includes the formation of a torque reaction guide with elongate members available at a drill site including for example, any of drill collar stands, casing strings, drill pipe stands and cables held in tension. A method for converting a kelly rig for handling casing may include the step of installing a torque reaction guide in a simple way, such as by securing the track to the monkey board. In one embodiment a torque reaction frame is used for securing between a torque generating device and a torque reaction guide that operates in a float mode to allow for misalignment of the torque reaction guide relative to the well hole center.

Abstract: An apparatus operatively coupled to a well having a production casing positioned therein, the apparatus including a first device having and internal bore, a second device having an internal bore, and a fracture isolation sleeve disposed at least partially within the internal bores of the first and second devices, wherein the fracture isolation sleeve has an internal diameter that is greater than or equal to an internal diameter of the production casing.

Abstract: A swivelling device is provided for picking up or backing off a drive string after it has been stuck in a down hole. The device allows the drive string to move longitudinally and rotate. The device has a shaft rotatably mounted in a housing so that the shaft can freely rotate but can not move radially or axially relative to the housing. A frame support is moveably connected to the housing and has an aperture that is attachable to a support system capable of lifting up the drive string. A pair of biasing mechanisms bias the housing towards the frame support. When a downward force is applied to the shaft by the drive string, the housing can be displaced downwards away from the support frame. Once the downward force ceases, the biasing mechanism moves the housing back towards the support frame.

Abstract: A tubing hanger suspension assembly for an oil and gas well completion system and a method of installing same. The tubing hanger suspension assembly includes a tubing hanger housing which is positioned in the wellhead housing. The tubing hanger assembly includes a sealing and lockdown mechanism capable of providing sealing and load support of the production tubing in the production casing string. A stab sub assembly connected to the upper end of the tubing hanger suspension assembly and lower end of the Christmas tree assembly provides downhole hydraulic and electric functionality and annulus access to the production tubing.

Abstract: A tubular handling apparatus comprising a slotted member having a plurality of elongated slots each extending in a direction, a recessed member slidably coupled to the slotted member and having a plurality of recesses each tapered in the direction from a shallow end to a deep end, and a plurality of rolling members each retained between one of the recesses and one of the slots, wherein each rolling member partially extends through the adjacent slot when located in the shallow end of the recess, and wherein each rolling member retracts within an outer perimeter of the slotted member when located in a deep end of the recess. The apparatus may further comprise a plurality of biasing elements each biasing a corresponding one of the rolling members towards the shallow end of the corresponding recess.

Abstract: Wellhead assembly and method for providing a power connection to a downhole electrical device, such as a heater. Pressure-containing wellhead body members enclose a vertical wellbore and support therein an isolated tubing hanger and a grounding tubing hanger. The isolated tubing hanger suspends a conducting tubing string, while the grounding tubing hanger suspends a grounding tubing string concentrically spaced from the conducting tubing string. The isolated tubing hanger has an outer housing, an inner electrically conducting portion supported by the outer housing operative to provide electrical connection with, and suspend, the conducting tubing string, and insulation between the housing and conducting portion to electrically isolate the housing portion. Hot electrical connection is made for electrical connection to the conducting portion of the isolated tubing hanger or the conducting tubing string.

Abstract: A self-tightening safety tubular clamp for suspending a casing string or other tubular member within a well. In one embodiment, a base has an opening for receiving the casing string. A first gripping member and an opposing second gripping member are each adapted to frictionally engage the casing string. First and second pivot arms include parallel linkages for supporting the gripping members. Each parallel linkage is pivotally secured to the base at one pivot pair, and pivotally secured to one of the gripping members at an upper pivot pair. Frictional contact with the gripping members allows the weight of the casing string to move the pivot arms downward. As the pivot arms move downward, the gripping members move downward and inward into engagement with the casing string. The parallel linkages ensure that gripping surfaces of the gripping members remains vertical, in alignment.

Abstract: A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A seal is formed between the second end portion and the tubular member. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

Abstract: A tubing hanger apparatus includes a tubing hanger with a plurality of segments thereon that engage an annular groove of a tubing head thus preventing the tubing hanger from sliding down a well. The internal diameter wellhead bore is consistent from the master valve downward to the production casing. The tubing hanger has a plurality of annular seals which are expandable after insertion into the tubing head. A plurality of lock screws both expand the seals as well as prevent any further movement of the tubing hanger. The tubing hanger apparatus is situated below a master valve. Thus, coiled tubing or jointed tubing can be run down the well and landed below the master valve. The tubing hanger contains a back pressure valve, thus the master valve can be opened without releasing the formation pressure within the live well.

Abstract: An apparatus operatively coupled to a well having a production casing positioned therein, the apparatus including a first device having and internal bore, a second device having an internal bore, and a fracture isolation sleeve disposed at least partially within the internal bores of the first and second devices, wherein the fracture isolation sleeve has an internal diameter that is greater than or equal to an internal diameter of the production casing.

Abstract: A support structure for a rig above a wellhead, such as a snubbing unit, is provided which directs loads from the rig into the ground to minimize stress on the wellhead components. The support structure generally comprises a support plate to be secured onto a wellhead and onto which the rig is secured and at least three ground engaging members distributed around and connected to the support plate, with the ground engaging members accepting the load placed on the support plate. The ground engaging members can be independently vertically adjustable, such as jack stands, for distributing the load between the ground engaging members. The support structure can also be adapted to be movable between a compact shipping position and a deployed operating position.

Abstract: A hybrid wellhead system is assembled using a plurality of threaded unions, such as spanner nuts or hammer unions, for securing respective tubular heads and a flanged connection for securing a flow control stack to a top of a tubing head spool. The tubing head spool is secured by a threaded union to an intermediate head spool. The intermediate head spool is secured by another threaded union to a wellhead. Each tubular head secures and suspends a tubular string in the well bore. The hybrid wellhead system is capable of withstanding higher fluid pressures than a conventional independent screwed wellhead, while providing a more economical alternative to a flanged, or ranged, wellhead system because it is less expensive to construct and faster to assemble.

Abstract: A C-plate assembly for use in a cable-guided fishing assembly is disclosed. The disclosed invention provides a C-plate assembly in which a closure member is slidable from an open position, which allows a wellbore tubular or other item to be positioned in the cut-out section of the C-plate base, to a closed position, which closes the opening to the cut-out section and thereby prevents the wellbore tubular or other item from being unintentionally knocked free from the cut-out section during a fishing operation. The closure member is locked in place in the closed position by inserting the ends of a movable handle extending off of one side of the C-plate base into openings in the C-plate base. The ends of the movable handle are spring loaded to allow for the ends to be pulled out of the openings in the C-plate base such that the closure member can be “unlocked” and moved from a closed position to an open position during operation.

Abstract: A tubing rotator assembly that attaches to a casing head to suspend and rotate a tubing string in an oil well. The tubing assembly includes a rotation surface, such as a bearing, in which a tubing mandrel rests and allows one to rotate the tubing manually above the wellhead, and a mandrel bowl that rests inside the casing head. A tubing mandrel is partially contained within the mandrel bowl with one end exiting the bowl and attached to the tubing string, and the opposite end exiting the top of the bowl. A ledge of the tubing mandrel is supported on the bearing, which bearing rests on the interior ledge of the mandrel bowl. The assembly provides a low profile reducing the distance between the casing head and the pumping tee to eliminate the need to raise the pumping unit to fit on the rotator.

Abstract: An outer tubing hanger is secured to an outer string of tubing and landed in a wellhead housing. A Christmas tree is connected to the wellhead housing. While in a first mode, an isolation tube extends between the tree and the outer tubing hanger for conveying well fluid flowing up the outer string of tubing. The isolation tube is removed while in a second mode, and an inner tubing hanger secured to an inner string of tubing lands in the outer tubing hanger production passage. An upper portion of the inner tubing hanger extends into sealing engagement with the tree production passage for flowing well fluid up the inner string of tubing while in the second mode.

Abstract: A full bore support system for a hanger or other equipment in a wellhead features a support groove in the wellhead that can be integrally made or on an insert. A support ring can have a variety of configuration and features an energizing surface and a limit surface that ultimately share the load. The receiving groove is configured to guide the support ring as it expands to minimize bending and distortion. The support ring is recessed and protected until it is actuated outwardly into a supporting position. A high strength low modulus material is preferred to withstand the radial expansion and the applied loads and environmental conditions. Various shapes for the ring are contemplated including a C-ring and a ring made from segments movable with respect to each other.

Abstract: A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

Abstract: A wedge device (1) for clamping of pipes (24) and tools during petroleum production, the wedge device (1) comprising an annular mounting element (4) arranged for connection to a deck (2) or a rotary table, where a plurality of main wedges (6), with associated clamps (22) and displaceable with respect to the annular mounting element (4), encircle the vertical central axis (8) of the wedge device (1), and where the clamp (22) is located on an auxiliary wedge (18) displaceably or rotatably coupled to the main wedge (6).

Abstract: A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

Abstract: A tubing hanger lands in a tubular outer wellhead member and supports a string of production tubing. The tubing hanger has a production passage for communicating with the interior of the production tubing and an annulus passage for communicating with a tubing annulus on the exterior of the production tubing. An access port leads from the annulus passage to an exterior portion of the body for communicating the tubing annulus with the annulus passage. A valve stem is movable along an axis of the annulus passage between a closed position, blocking the access port, and an open position, exposing the annulus port. A pressure equalizing passage extends from the annulus passage above the valve stem to the annulus passage below the valve stem.

Abstract: A wellhead assembly for an injection tubing string is provided which allows a master valve to be closed without damaging the injection tubing string while still allowing for the use of a back pressure valve to isolate the tree. Wellhead assemblies and related methods of the present invention include a flange adapted to be connected between a wellhead and a Christmas tree. The assembly also includes a mandrel adapted to being inserted into the longitudinal bore of the flange, the mandrel having a port for communicating with an injection port which extends radially through the flange. The assembly further includes a hanger adapted to connect to the upper end of the injection string, wherein the hanger is further adapted to land in the longitudinal bore of the mandrel. The hanger includes a communication passageway for facilitating fluid communication between the port of the mandrel and the injection tubing string.

Abstract: A hybrid wellhead system is assembled using a plurality of threaded unions, such as spanner nuts or hammer unions, for securing respective tubular heads and a flanged connection for securing a flow control stack to a top of a tubing head spool. The tubing head spool is secured by a threaded union to an intermediate head spool. The intermediate head spool is secured by another threaded union to a wellhead. Each tubular head secures and suspends a tubular string in the well bore. The hybrid wellhead system is capable of withstanding higher fluid pressures than a conventional independent screwed wellhead, while providing a more economical alternative to a flanged, or ranged, wellhead system because it is less expensive to construct and faster to assemble.

Abstract: Slips (1, 21, 41) for engaging any jointed, coiled or flexible tubular with substantially no scoring, gouging or scraping, such as when supporting a drill string in a borehole or gripping a tubular (2, 22) during the connection or disconnection of a tool joint or pulling a cable or pipeline; additionally, applying a pre-determined minimum gripping force in order to avoid rotary slippage when the weight of the string is insufficient to achieve a conventional slips action; additionally, including a coarse wedge (30, 50) to take up the extra travel of a worn tool joint or a tubular of smaller diameter, with a means to ensure that the coarse wedge acts before the fine wedge (29, 49) does and a means to ensure that the wedging action remains if the actuating force is removed; additionally, including a secondary slips (40) to interfere with the upset on the tool joint to avoid relying on friction to support the string and a means of integrating this with the gripping slips and ensuring that the secondary slips act

Abstract: A tubing hanger suspension assembly for an oil and gas well completion system and a method of installing same. The tubing hanger suspension assembly includes a tubing hanger housing which is positioned in the wellhead housing. The tubing hanger assembly includes a sealing and lockdown mechanism capable of providing sealing and load support of the production tubing in the production casing string. A stab sub assembly connected to the upper end of the tubing hanger suspension assembly and lower end of the Christmas tree assembly provides downhole hydraulic and electric functionality and annulus access to the production tubing.

Abstract: A wellhead seal assembly forms a metal-to-metal seal between the inner and outer wellhead members. A metal seal ring has inner and outer conical walls separated by a tapered slot. An energizing ring has inner and outer annular members that are separated by an annular cavity. When the energizing ring is moved further into the slot, the cavity width decreases but remains to provide a preloaded radial force to the seal ring.

Abstract: A safety valve system for removing down-hole tools from a coal-bed methane well. The system includes first and second horizontally opposed stuffer-blocks, a stuffer-box housing for housing the stuffer-blocks, a means for attaching said stuffer-box housing to a coal-bed methane wellhead, and a means for delivering fluid to move the stuffer-blocks between an open position and a closed position. In one embodiment, the safety valve system further includes a controller, at least one methane sensor, a stuffer-box position sensor, and a stuffer-block activation system. A control algorithm is stored on or in communication with the controller enabling the controller to control the position of the stuffer-blocks, moving the stuffer-blocks between an open and closed configuration, wherein the stuffer-blocks are maintained in an open configuration if the methane level is below a predetermined threshold level. The valve system may further comprise a free-rotating stripper-diverter atop of the valve system.

Abstract: A self-tightening safety tubular clamp for suspending a casing string or other tubular member within a well. In one embodiment, a base has an opening for receiving the casing string. A first gripping member and an opposing second gripping member are each adapted to frictionally engage the casing string. First and second pivot arms include parallel linkages for supporting the gripping members. Each parallel linkage is pivotally secured to the base at one pivot pair, and pivotally secured to one of the gripping members at an upper pivot pair. Frictional contact with the gripping members allows the weight of the casing string to move the pivot arms downward. As the pivot arms move downward, the gripping members move downward and inward into engagement with the casing string. The parallel linkages ensure that gripping surfaces of the gripping members remains vertical, in alignment.

Abstract: A hanger flange includes an annular body having a circumferential inner surface defining a central passage and a circumferential outer surface. Ram alignment apertures are provided within the body spaced radially about the passage. Each of the apertures has a first portion with a non-circular first cross-sectional dimension extending radially outwardly from the inner surface and a second portion with a second cross-sectional dimension extending radially inwardly from the outer surface. A ram is positioned in each of the apertures. Each ram has a first portion having a first cross-sectional dimension corresponding with the first cross-sectional dimension of the apertures, and a second portion having a second cross-section dimension corresponding with the second cross-sectional dimension of the apertures.

Abstract: A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A seal is formed between the second end portion and the tubular member. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

Abstract: An apparatus operatively coupled to a well having a production casing positioned therein, the apparatus including a first device having and internal bore, a second device having an internal bore, and a fracture isolation sleeve disposed at least partially within the internal bores of the first and second devices, wherein the fracture isolation sleeve has an internal diameter that is greater than or equal to an internal diameter of the production casing.

Abstract: The present invention is directed to an apparatus and method for reverse circulation cementing a casing in an open-hole wellbore. The apparatus includes a surface pack-off device, which has a housing defined by an upper section and lower section. A load bearing plate is secured to the housing between the upper and lower sections. The load plate and lower section of the housing cooperate to prevent sloughing of the earth at the surface of the wellbore via a section of casing string. The surface pack-off device also includes a casing hanger, which couples to the casing in the wellbore. Fluid inlets allow the cement to be pumped into the wellbore in the annulus formed between the casing and wellbore sidewall. The method includes the steps of installing the surface pack-off device and operation on reverse circulation of the cement down the annulus.

Abstract: A blast joint swivel for use in a wellhead isolation tool includes a blast joint hanger mounted to a top of the wellhead isolation tool and a swivel body rotatably received in the blast joint hanger. The swivel body threadedly connects to a blast joint, which in turn threadedly connects to a top end of a tubing string suspended in a well. The blast joint swivel can also be displaced vertically over a limited range between upper and lower abutments.

Abstract: The spider, arranged for support on a drilling rig, is fitted with a plurality of slips peripherally distributed about a slip bowl. Each slip has a plurality of pipe gripping dies distributed vertically and resting on individual abutment surfaces on the slip. Each slip has a generally vertical slide way to receive mating surfaces on the die for radial constraint of the dies.

Abstract: A hybrid wellhead system is assembled using a plurality of threaded unions, such as spanner nuts or hammer unions, for securing respective tubular heads and a flanged connection for securing a flow control stack to a top of a tubing head spool. The tubing head spool is secured by a threaded union to an intermediate head spool. The intermediate head spool is secured by another threaded union to a wellhead. Each tubular head secures and suspends a tubular string in the well bore. The hybrid wellhead system is capable of withstanding higher fluid pressures than a conventional independent screwed wellhead, while providing a more economical alternative to a flanged, or ranged, wellhead system because it is less expensive to construct and faster to assemble.

Abstract: A method and apparatus for facilitating the connection of tubulars using a top drive which, in one aspect, the apparatus includes a body connectable to said top drive. The body includes at least one gripping element radially displaceable by hydraulic or pneumatic fluid to drivingly engage a tubular to permit a screw connection between said tubular and a further tubular to be tightened to the required torque.

Abstract: An apparatus for retaining two strings of tubulars characterized in that the apparatus comprises body parts of a device for retaining a single string of tubulars and a converting member. A device for retaining a string of tubulars, the device comprising at least one body part having a curved tapered surface upon which inserts are located for engagement with the string of tubulars characterised in that the curved tapered surface comprises a recess for the passage of cables.

Abstract: A clamp for clamping two concentric tubes, typically two concentric tubes in an oil or gas well. The clamp has two axially movable tapered components which can be pulled over one another in an axial direction to provide a contraction of internal diameter which grips the smaller diameter tube. In one embodiment, a spacer is fitted to allow the tapered components to be held apart until the tubes have been correctly positioned. The spacer is then removed, and the tapered components are drawn together to effect the clamping. A hydraulic ram can be provided to separate the tapered components should readjustment be required. In another embodiment, the larger diameter tube is made with a relatively thin wall, so that it can be distorted inwards to grip the smaller tube.