Abstract: Hydraulic pulses are produced each time that a pulse valve interrupts the flow of a pressurized fluid through a conduit. The pulse valve includes an elongate housing having an inlet configured to couple to the conduit to receive the pressurized fluid, and an outlet configured to couple to one or more tools. In the housing, a valve assembly includes a poppet reciprocating between open and closed positions, and a poppet seat, in which the poppet closes to at least partially block the flow of pressurized fluid through the valve. A pilot within the poppet moves between disparate positions to modify fluid paths within the valve. When the valve is open, a relatively lower pressure is produced by a Venturi effect as the fluid flows through a throat in the poppet seat, to provide a differential pressure used to move the pilot and poppet. An optional bypass reduces the pulse amplitude.

Abstract: A downhole element to isolate or complete a wellbore includes a shape memory material including polyphenylene sulfide. The polyphenylene sulfide is the cure product of being cured at a temperature of about 200° C. to about 400° C., for a total time of less than or equal to 200 hours. The shape memory material is thermally activated between an actuated and unactuated shape, and the polyphenylene sulfide in the shape memory material is a closed cell foam, open cell foam, or solid.

Abstract: A setting assembly including a settable member. A housing including a chamber and a setting material disposed in the chamber and having a first phase of matter and a second phase of matter. The setting material occupying a greater volume in the second phase than in the first phase. The setting material arranged to exert a setting force on the settable member during transition of the setting material from the first phase to the second phase. Also included is a method of setting a settable member.

Abstract: An example flow control device includes a body having an inlet and an outlet and a flow chamber extending therebetween. The flow chamber is configured to convey a fluid composition comprising a desired and an undesired fluid from the inlet to the outlet. A nozzle is arranged at the outlet and in fluid communication with the flow chamber, and at least one helical groove is defined along at least a portion of an axial length of the flow chamber. The at least one helical groove is configured to impart rotational motion to the fluid composition and thereby force at least some of the undesired fluid into the at least one helical groove and slow a progress of the undesired fluid along the axial length of the flow chamber.

Abstract: An apparatus having a shock-absorbing sleeve is disclosed. The apparatus comprises a housing, an axially moveable sleeve received in the housing and a sealed annular space having a fixed volume axially between the housing and the sleeve. A barrier axially moveable with the sleeve divides the annular space into a first and a second chambers. The first and second chambers are filled with uncompressible dampening fluid. One or more metering passages across the barrier fluidly connect the first and chambers. During the axial movement of the sleeve, the volume of the first chamber is reduced and that of the second chamber is increased, forcing the fluid in the first chamber to flow into the second chamber in a controlled manner to dampen the movement of the sleeve.

Abstract: An apparatus for controlling fluid in-flow into a wellbore tubular includes a translating flow control element having one or more fluid conveying conduits; and a reactive element that actuates the flow control element. The reactive element may be responsive to a change in composition of the in-flowing fluid. The reactive element may change volume or shape when exposed to or not exposed to a selected fluid. The selected fluid may be oil, water, or some other fluid (e.g., liquid, gas, mixture, etc.). The reactive element may slide the flow control element such that a conduit formed on the flow control element changes length, which then changes a pressure differential across the flow control element.

Abstract: A control mechanism for use with a safety valve adapted to seal a wellbore is described. The control mechanism comprises at least one valve actuator for engaging with the safety valve, the at least one actuator being moveable, in use, between a valve open position in which the safety valve is open and a valve closed position, in which the safety valve is closed. The control mechanism further comprises biasing apparatus adapted to bias the at least one valve actuator to the valve closed position, wherein, in use, the at least one valve actuator extends from the safety valve up to a wellbore wellhead. In one described embodiment, the safety valve is moved between the open and closed positions by movement of the at least one valve actuator with respect to the wellbore.

Abstract: A valve comprises a housing including a first chamber, a second chamber, and a neutral chamber. In addition, the valve comprises a stem disposed within the housing. Further, the valve comprises a first valve member at least partially disposed in the first chamber and connected to the stem and a second valve member at least partially disposed in the second chamber and connected to the stem. The first valve member has a closed position seated in a first annular valve seat and an open position spaced apart from the first valve seat. The second valve member has a closed position seated in a second annular valve seat and an open position spaced apart from the second valve seat. Moreover, the valve comprises a biasing member configured to bias the second valve member to the closed position and the first valve member to the open position.

Abstract: An apparatus is described for controlling flow of fluid in a subterranean formation based on a selected characteristic of fluid flow, such as viscosity, velocity or density, as that characteristic varies over time. A pathway-dependent resistance assembly, such as a vortex chamber having two inlets and an outlet, provides varying resistance to fluid flow based on the ratio of flow from the inlets, the direction of flow as directed by the inlets, and the characteristic of the fluid. The incoming flow ratio is preferably determined by flowing fluid through a plurality of passageways having differing flow rate responses to fluid having differing characteristics. Fluid of a selected characteristic will encounter lesser resistance to flow across the system, while fluid of an un-favored characteristic will encounter greater resistance to flow. Thus, flow of well fluids can be autonomously restricted as the fluid characteristics change over time.

Abstract: A wellbore tubular port closure system includes a mechanism to delay the opening of the port the port closure has been actuated to open. A port opening delay mechanism configured to act after actuation of the pressure responsive mechanism to delay full movement of the port-closure to the port-open position until after a selected time has lapsed.

Abstract: An inflow control device laterally insertable in a wall of a tubular, the inflow control device includes a plug shaped body having a first section and a second section, the first section having an orifice accessible to an interior of the tubular and the second section having an opening accessible to an exterior of the tubular, the orifice in fluid communication with the opening; and a selectable insert insertable into the orifice, the insert having an inner periphery providing a flow path between the exterior and interior of the tubular. Also, included is a production string and adjustable orifice inflow control device combination.

Abstract: A ball launcher system is provided. In one embodiment, such a system includes a ball launcher having a rotatable sleeve installed within an internal bore of a hollow body. The hollow body has ball chutes extending from an external surface to the internal bore. The rotatable sleeve has one or more holes that can be sequentially aligned with the ball chutes by rotation of the sleeve to enable balls within the ball chutes to pass sequentially into a well through the one or more holes. Additional systems, devices, and methods are also disclosed.

Abstract: A “passive” apparatus and method for isolating flow within a thermal wellbore wherein inflow apertures are plugged with a temporary fusible alloy plug that can be selectively removed by increasing the wellbore temperature.

Abstract: A method can include applying a magnetic field to a well screen, thereby varying sizes of pores via which fluid flows through the well screen. A well screen can include a magnetic shape memory material having a dimension which changes in response to application of a magnetic field. Restriction to flow through the well screen can vary in response to the change in dimension of the magnetic shape memory material.

Abstract: Disclosed are systems and methods of producing from multiple production zones with a single trip multi-zone completion system. One method includes arranging an outer completion string within an open hole section of a wellbore, the outer completion string having at least one sand screen disposed thereabout, extending a production tubing within the outer completion string, the production tubing having at least one interval control valve disposed thereon, communicably coupling the production tubing to the completion string at a crossover coupling having one or more control lines coupled thereto, actuating the at least one interval control valve to initiate production into the production tubing at the at least one interval control valve, and measuring one or more fluid and/or well environmental parameters external to the outer completion string with a surveillance line communicably coupled to one or more control lines at the crossover coupling.

Abstract: A smooth bore toe valve includes a first sub defining a through bore and a fluid flow path through a wall thereof; a second sub; a housing mechanically engaged with the first and second subs to define a valve cavity axially between the first and second subs and to define a chamber radially between the first and second subs and the housing, the housing further defining a plurality of openings in a wall thereof; and a sleeve disposed within the chamber between the housing and the first and second subs to close the openings and, upon application of fluid pressure horn the through bore through the fluid this path, open the openings to fluid flow from the valve cavity to the exterior of the housing. A method for using such a valve is also disclosed.

Abstract: A hydraulic anchor is coupled to a packer subassembly of a tool string. The hydraulic anchor, when actuated by fluid pressure, engages the surrounding wellbore, holding the tool string in place within the wellbore. A packer may then be actuated, held in position within the wellbore by the hydraulic anchor. In some embodiments, an inflatable packer may be held in the desired location by the hydraulic anchor. In some embodiments, a straddle packer assembly may be held in place by the hydraulic anchor. In some embodiments, a swellable packer may be held in place during the swelling process by the hydraulic anchor.

Abstract: A valve includes: a housing; a mandrel disposed in the housing; a rupture disk disposed in a passageway of the mandrel; a sliding sleeve disposed between the housing and the mandrel; and a ball seat disposed in the mandrel. A method for actuating a valve includes: flowing a fluid through the valve; dropping a ball; seating the ball in the ball seat and blocking fluid flow through the mandrel; flowing fluid through the passageway to the sliding sleeve; moving the sliding sleeve axially within the valve; and exiting fluid through the openings of the housing and mandrel. A valve includes: a housing having an opening; a mandrel disposed in the housing; a sliding sleeve disposed between the housing and the mandrel; and a ball seat disposed in the mandrel blocking fluid communication between the mandrel and the passageway.

Abstract: A down-hole tool for pressure testing production tubing within a borehole of a well returning the well to production, includes an anti-rotational device comprising a tubular housing having a first end, a second end, an outer surface, and at least one anti-rotational wing disposed on the outer surface of the tubular housing, radially extendable to engage a radial surface of the borehole to anchor the production tubing thereto; a valve for controlling the flow of down-hole fluids within the production tubing, the valve comprising a first valve member fixedly positioned within the tubular housing of the anti-rotational device and a second valve member positionable between a closed position and an open position; and a reactivation device comprising means for axially engaging an axial surface of the borehole, the reactivation device affixed to the first end of the tubular housing, wherein the production tubing may be pressure tested when the valve is in the closed position.

Abstract: An injection mandrel may include a valve controlling the flow of the injection fluid. A valve actuator operatively connected to the valve sequentially generates a first predetermined pressure and a larger second predetermined pressure in the valve. The valve actuator generates the second predetermined pressure in the valve in response to a predetermined change in a pressure at an annulus surrounding the mandrel.

Abstract: A system including a combined plug and valve device that may be precisely delivered to and inserted into an uncontrolled undersea oil well. Once positioned in the well, the device is operated in graduated fashion to anchor the plug to the well and gradually stanch the flow of oil from the well.

Abstract: In one aspect, an apparatus for controlling fluid flow between a formation and a tubular is provided, wherein the apparatus includes a retrievable communication device configured to be conveyed to a selected location in the tubular downhole. The apparatus also includes a control node configured to communicate with the retrievable communication device at the selected location, a flow control device coupled to and controlled by the control node and a sensor coupled to the control node, wherein the sensor and flow control device are downhole of the control node.

Abstract: A tubular closure assembly responsive to speed or velocity of an object. The tubular closure assembly includes at least one sensor in operable communication with an interior of a tubular. The at least one sensor sensing an object passing a first point and then a second point within the tubular. A processor receiving an output from the at least one sensor and calculating speed of the object from the first point to the second point. A control panel receiving information from the processor and a closure system movable between an open condition and a closed condition. Activatable to the closed condition by the control panel in response to the object moving from the first point to the second point at speed faster than a preset value or at a velocity outside a preset range. Also included is a method of closing a tubular of a borehole.

Abstract: A well tool having an actuator sleeve in a housing. The actuator sleeve has an internal shifting tool engaging profile. The tool has an actuator in the housing that is responsive to a remote signal to change from an unactuated state to an actuated state and shift the actuator sleeve from a first position to a second position. A collet in the housing is supported to couple the actuator sleeve to the actuator while the actuator changes from the unactuated state to the actuated state and is unsupported to allow the actuator sleeve to move relative to the actuator when the actuator is in the actuated state.

Abstract: Methods and apparatus enable reliable and improved isolation between two portions of a bore extending through a casing string disposed in a borehole. A downhole deployment valve (DDV) may provide the isolation utilizing a valve member, such as a flapper, that is disposed in a housing of the DDV and is designed to close against a seat within the housing. The DDV includes an operating mechanism for opening/closing the DDV. In use, pressure in one portion of a well that is in fluid communication with a well surface may be bled off and open at well surface while maintaining pressure in another portion of the casing string beyond the DDV.

Abstract: A flow control device can include a surface that defines a chamber and includes a side perimeter and opposing end surfaces, a greatest distance between the opposing end surfaces being smaller than a largest dimension of the opposing end surfaces, a first port through one of the end surfaces, and a second port through the surface and apart from the first port, the side perimeter surface being operable to direct flow from the second port to rotate about the first port. Another device can include a cylindroidal chamber for receiving flow through an inlet and directing the flow to an outlet, a greatest axial dimension of the cylindroidal chamber being smaller than a greatest diametric dimension of the cylindroidal chamber, the cylindroidal chamber promoting rotation of the flow based on a characteristic of the inflow through the inlet. The device can have a flow path structure in the cylindroidal chamber.

Abstract: Fluid actuated chokes include an expandable material that expands due to an undesired fluid coming in contact with the choke. The choke includes one or more passageways through which desired fluids from a well flow unimpeded. The choke is disposed in a downhole tool as part of a downhole completion. When one or more undesired fluids enters a production stream flowing through the downhole completion and, thus, the downhole tool, and contacts the choke, the expandable material expands causing fluid flow through the passageway(s) to be restricted and, in some cases, completely closed off. Thus, the choke automatically detects and reacts, i.e., restricts fluid flow through the choke, when contacted by the undesired fluid(s).

Abstract: A downhole bypass valve comprises a tubular body including a side port and a sleeve axially movably mounted in the body and normally biased to a closed position to close the side port. An activating device is configured to be pumped or dropped into the body to engage the sleeve and permit movement of the sleeve to an open position and open the side port. A latch has a part in the body and a part in the activating device, the parts of the latch configured to engage and retain the sleeve in the open position. The activating device is further operable to disengage from and translate through the sleeve and the parts of the latch are further operable to disengage and permit the sleeve to return to the closed position.

Abstract: A wellbore servicing apparatus, comprising a housing defining an axial flowbore and comprising ports, a first sleeve, a second sleeve movable relative to the housing from (a) a first position in which the second sleeve obstructs fluid communication via the ports of the housing to (b) a second position in which the second sleeve allows fluid communication via the ports of the housing, and wherein the first sleeve is movable relative to the housing from (a) a first position in which the first sleeve does not allow a fluid pressure applied to the axial flowbore to move the second sleeve from the first position to the second position to (b) a second position in which the first sleeve allows a fluid pressure applied to the axial flowbore to move the second sleeve from the first position to the second position, and an expandable seat.

Abstract: A selectively openable inflow control sub includes a sliding sleeve valve slidable within an inner bore of the sub between a closed-port position, closing the inflow port, and an open-port position, opening the inflow port to fluid flow therethrough, the sliding sleeve valve is axially moveable from the closed-port position to the open-port position by pushing the sleeve with a mill string.

Abstract: An actuation system and method, the system including a tubular having a passage, and an assembly disposed with the tubular. The assembly includes a degradable restriction, the restriction only partially blocking the passage prior to being degraded. The assembly is configured to receive and prevent further movement of a restrictor through the tubular prior to the restriction being degraded. The assembly is further configured to release the restrictor when the restriction is degraded.

Abstract: A method of servicing a wellbore comprising providing a flowable component comprising syntactic foam, and communicating the flowable component into a wellbore.

Abstract: A retrievable stimulation frac plug for a well casing, having an elongate mandrel having a fluid bore, a valve seat, adapted to receive a sealing member for selectively sealing the fluid bore, a sealing mechanism for releasably sealing between the mandrel and the casing, a slip mechanism for releasably engaging the well casing, and a valve seat bypass, moveable between a closed position and an open position, adapted to provide a bypass past the valve seat.

Abstract: Casing valves for selective well stimulation and control. A well system includes at least one valve interconnected in a casing string operable via at least one line external to the casing string to selectively control fluid flow between an exterior and interior of the casing string, and the casing string, valve and line being cemented in a wellbore. A method of selectively stimulating a subterranean formation includes: positioning a casing string in a wellbore, the casing string including spaced apart valves operable via a line to selectively control fluid flow between an interior and exterior of the casing string; and for each of multiple intervals of the formation in sequence, stimulating the interval by opening a corresponding one of the valves, closing the remainder of the valves, and flowing a stimulation fluid from the casing string into the interval.

Abstract: Systems and methods for producing from multiple zones in a subterranean formation are provided. The system can include a liner including a first frac valve, a second frac valve, and a formation isolation valve. The second frac valve can be positioned above the first frac valve, and the formation isolation valve can be positioned above the second frac valve. A completion assembly can be disposed at least partially within the liner. The completion assembly can include a valve shifting tool adapted to actuate the formation isolation valve between an open position and a closed position. The completion assembly can also include a first flow control valve in fluid communication with the first frac valve and a second flow control valve in fluid communication with the second frac valve.

Abstract: A method of propagating pressure pulses in a well can include flowing a fluid composition through a variable flow resistance system which includes a vortex chamber having at least one inlet and an outlet, a vortex being created when the fluid composition spirals about the outlet, and a resistance to flow of the fluid composition alternately increasing and decreasing. The vortex can be alternately created and dissipated in response to flowing the fluid composition through the system. A well system can include a variable flow resistance system which propagates pressure pulses into a formation in response to flow of a fluid composition from the formation.

Abstract: A production sleeve assembly for use in a wellbore comprises a wellbore tubular, a plurality of fluid pathways configured to provide fluid communication within the downhole component, a plurality of electronic actuators configured to selectively provide fluid communication through one or more of the plurality of fluid pathways, and at least one sensor coupled to the plurality of electronic actuators. One or more of the plurality of electronic actuators are configured to selectively actuate to allow or prevent fluid flow through a corresponding fluid pathway of the plurality of fluid pathways in response to the at least one sensor receiving a suitable signal.

Abstract: Zone isolation is a leading concern for operators that wish to fluidly treat a well. By utilizing a ported sliding sleeve assembly that is highly resistant to leaking after being opened and closed through multiple cycles a wellbore may be accessed at any ported sliding sleeve assembly location without plugging the wellbore below the ported sliding sleeve assembly and will allow any ported sliding sleeve assembly to be accessed in any order.

Abstract: A flow control device comprises a fluid pathway configured to provide fluid communication between an exterior of a wellbore tubular and an interior of the wellbore tubular, a flow restriction disposed in the fluid pathway, a one-way valve disposed in the fluid pathway to substantially block fluid flow from the interior of the wellbore tubular to the fluid pathway and to allow fluid flow from the fluid pathway to the interior of the wellbore tubular, and an inflatable seal disposed between an opening to the interior of the wellbore tubular and the fluid pathway, wherein the inflatable seal is configured to inflate to substantially block the fluid pathway in response to a fluid pressure differential between the interior of the wellbore tubular and the exterior of the wellbore tubular that exceeds a predefined threshold.

Abstract: An actuation ball for a downhole tool, the actuation ball includes a ball body having an outer surface defining a seating surface with a substantially circular shape in section encircling an axis of the actuation ball; and a flexible protrusion attached to the ball body and extending substantially coaxially relative to the seating surface. Another actuation ball for a downhole tool, the actuation ball includes a body having an outer surface defining a seating surface, the body having a specific gravity less than 2.6.

Abstract: A double swivel for use with a top drive power unit supported for connection with a well string in a well bore to selectively impart longitudinal and/or rotational movement to the well string, a feeder for supplying a pumpable substance such as cement and the like from an external supply source to the interior of the well string in the well bore without first discharging it through the top drive power unit including a mandrel extending through double sleeves which are sealably and rotatably supported thereon for relative rotation between the sleeves and mandrel. The mandrel and sleeves have flow passages for communicating the pumpable substance from an external source to discharge through the sleeve and mandrel and into the interior of the well string below the top drive power unit. The unit can include a packing injection system, clamp, and novel packing configuration. In an alternative embodiment the unit can include a plug or ball insertion tool.

Abstract: The present invention relates to an annular barrier (1) to be expanded in an annulus (2) between a well tubular structure and an inside wall (4) of a borehole (5) downhole, comprising a tubular part for mounting as part of the well tubular structure, said tubular part (6) having a longitudinal axis; an expandable sleeve (7) surrounding the tubular part and having an outer face (8), each end (9, 10) of the expandable sleeve being fastened to the tubular part by means of a connection part (12), where one of the connection parts is a sliding connection part sliding in relation to the tubular part when the expandable sleeve is expanded; an annular barrier space (13) between the tubular part and the expandable sleeve; an aperture (11) in the tubular part for letting fluid into the annular barrier space to expand the sleeve; and an activatable shut-off valve (14) having an open and a closed position and arranged in the aperture, wherein the annular barrier further comprises a detection device (20) for detecting whe

Abstract: Certain aspects and features of the present invention are directed to a supercapacitor device that can be disposed in a wellbore through a fluid-producing formation. The supercapacitor device can include a body that can be disposed in the wellbore, a supercapacitor disposed in the body, at least two terminals disposed at least partially outside the body, and an actuation mechanism. The supercapacitor stores energy. The terminals can be electrically connected with the supercapacitor. An electrical connection between the supercapacitor and the terminals can cause the energy to be discharged from the supercapacitor in response to a conductive material providing an electrical path between the at least two terminals. The actuation mechanism can selectively prevent a deployment of the supercapacitor device in the wellbore from causing a discharge of the energy from the supercapacitor.

Abstract: A hybrid dump bailer is disclosed herein comprising a bailer tubes for containing a material, such as cement slurry, to be dumped. The hybrid dump bailer comprises a pressure pulse piston that is accelerated by a spring causing a pressure pulse to expel the material to be dumped. The hybrid dump bailer further comprises a collet, a retaining rod, a piston, valve, and a supply of pressurized fluid which is holds the pressure pulse piston in place while the spring is compressed. Once the valve is opened, releasing the pressurized fluid, the retaining rod separates from the collet allowing the pressure pulse piston to accelerate can produce the pressure pulse to dump the material.

Abstract: A method for flow control and a self-adjusting valve or flow control device, in particular useful in a production pipe for producing oil and/or gas from a well in an oil and/or gas reservoir, which production pipe includes a lower drainage pipe preferably being divided into at least two sections each including one or more inflow control devices which communicates the geological production formation with the flow space of the drainage pipe. The fluid flows through an inlet and further through a flow path of the control device passing by a movable disc or movable device which is designed to move relative to the opening of the inlet and thereby reduce or increase the flow-through area by exploiting the Bernoulli effect and stagnation pressure created over the disc, whereby the control device, depending on the composition of the fluid and its properties, automatically adjusts the flow of the fluid based on a pre-estimated flow design.

Abstract: A check valve for a drill string fluid delivery system. The fluid delivery system allows for drilling mud to travel from a source up the drill string, through the drill string, through a downhole tool assembly, to a port located at a surface of a boring tool. The check valve rests in a socket within the downhole tool assembly, with a forward face extending into a gallery within the bit. When the ambient pressure within the fluid delivery system exceeds the ambient pressure in the borehole, mud flows through the system to the ports and into the borehole. When the ambient pressure within the borehole exceeds the ambient pressure in the fluid delivery system, the pressure is applied to the forward face, causing the check valve to close, preventing contaminants from the borehole from entering the fluid delivery system.

Abstract: Disclosed herein is a valve. The valve includes a first member having a first port therethrough, a second member in operable communication with the first member having a sealing surface thereon and a second port therethrough that is movable relative to the first member. The valve also has a seal sealingly engaged with the first member and slidably sealingly engagable with the second member, and a support member movably disposed relative to the first member and the second member. The support member has a support surface dimensioned similarly to the sealing surface, and is movable with the second member relative to the first member so that upon such movement the seal is continuously supported by at least one of the sealing surface and the support surface.

Abstract: Apparatus for controlling a downhole device in a well has a body with a control slot and pin movable in the slot. The slot has a first inactive loop in which the pin can cycle between different idling configurations, and a second active loop in which the pin can move between different configurations which correspond to active and inactive configurations of the downhole device. The pin can be switched between the first and second loops, and can cycle between the different configurations within without switching between the different loops. The slot can be provided on a piston, and the axial movement of the piston in the bore can drive the relative movement of the pin and the slot.

Abstract: An apparatus and method to control and exert a predetermined force back on the wellbore thereby controlling the hydrostatic force on the formation surrounding the well-bore, the inflow of fluids from the surrounding formation and the drilling circulating medium. The apparatus comprises and the method utilizes a pump having at least one pair of intermeshing and opposite-handed helical screws disposed within a chamber for restricting the flow of well bore returns. The speed of the pump may be varied to selectively restrict the flow of well bore returns from the well bore.

Abstract: A plunger lift control system for improving the output efficiency of an oil or gas well by a real-time reporting arrangement, the system comprising: a tubing string having an upper end and a lower end, the tubing string arranged within a well casing for receiving a plunger traveling therethrough, a plunger having a sound generating function therewith, so as to transmit a real-time lower-end location signal from the plunger to a signal sensor and processor arranged in communication with a system controller arranged at the upper end of the tubing.