Abstract: An apparatus for controlling fluid flow between a wellbore tubular and a wellbore annulus includes a passage between a bore of the wellbore tubular and the wellbore annulus. The passage causes cavitations in a flowing fluid made up of mostly water. The cavitations activate a flow control device that controls fluid flow into the wellbore tubular. In one method, the flow control device includes a pressure chamber pressurized by high-pressure fluid associated with the cavitations. The pressure in the pressure chamber actuates a piston assembly coupled to a closure element that restricts fluid flow into the wellbore tubular. Alternatively, a power generator generates an electrical signal in response to the cavitations and transmits the electrical signal to the flow control device. In response to the electrical signal, the flow control element activates one or more devices that move a closure element to restrict fluid flow into the wellbore tubular.

Abstract: An annular choke mechanism is incorporated into a flow path within the outer housing of the sleeve valve to the interior flow ports of the sliding sleeve member. As the sliding sleeve member is moved axially within the housing, the lateral fluid ports of the sliding sleeve member are aligned within particular bore portions so that the size of the annular space between the fluid ports in the housing and the fluid ports in the sleeve is varied. The annular flow area through the annular space governs the rate of fluid flow through the valve.

Abstract: Methods and devices are provided for treating multiple interval well bores. More particularly, an isolation assembly may be used to allow for zonal isolation to allow treatment of selected productive or previously producing intervals in multiple interval well bores. One example of a method for treating a multiple interval well bore includes the steps of: introducing an isolation assembly to a well bore, the isolation assembly comprising a liner, one or more sleeves and a plurality of swellable packers, wherein the sleeves and swellable packers are disposed about the liner; deploying a shifting tool inside the liner, where the sleeves are configured so as to provide open, closed and open to screen positions when actuated by the shifting tool. An open position allows for treatment of the well bore while an open to screen position allows for receiving fluid from the well bore. A closed position re-establishes zonal isolation.

Abstract: Systems and methods for opening and/or closing sliding sleeve valves while preventing significant stress upon and damage to the fluid seals that are disposed between the outer housing and the sleeve member elements of the valve. A shifting tool carries a latching device and a fluid closure portion with sacrificial seals. In operations the shifting tool is secured to the sleeve member with the latching device as the closure portion seals off across the fluid flow port of the sleeve member. The shifting tool is then moved to slide the sleeve member between open and closed positions.

Abstract: The invention relates to a device for control of the flow through a production tube placed in an oil well. The device comprising a portion of the production tube provided with through orifices and protection equipment for providing resistance to wear by erosion. The protection equipment comprises several add-on sectors assembled around the portion of the tube. Each add-on sector provided with an associated inner stiffener penetrating into the portion of the production tube through at least one through orifice. At least one of the add-on sectors provided with at least one opening extending through the sector and its associated inner stiffener.

Abstract: A valve for use in a downhole tool The valve has an inlet communicating with the work string from which it is anchored. The inlet provides a flow path of a first cross-sectional area. A sealing assembly comprising a spring biased seal cap moves within an outer tubular body to open and close a number of ports arranged through the body. The ports provide a flow path of a combined cross-sectional area greater than the first cross-sectional area and the valve is arranged such that fluid flow through the inlet moves the seal cap to open the valve and create an unimpeded flow path between the inlet and the ports with negligible pressure drop. An embodiment including a shear ring is described to facilitate pressure testing above. A further embodiment includes a load adjuster to assist in closing the valve. The valve can be a high lift injection valve.

Abstract: A hydraulic sleeve valve is disclosed that comprises a bypass relief system that provides an indication that the valve has reached a predetermined position, such as, for example, the fully opened or fully closed condition. The bypass relief may also provide a valve control fluid circulation function to filter or otherwise manipulate the control fluid. Also disclosed are flow port alignment systems that maintain the valve flow ports in predetermined relationships.

Abstract: A downhole releasable swivel joint comprises a mandrel and a housing. A resilently deformable retaining device maintains the components in the illustrated first relative axial position until downward movement of the housing is stopped and a sufficient load is applied to the mandrel to overcome the retaining force of the retaining device whereupon the mandrel is able to move downwardly relative to the housing to adopt a second relative axial position. Apertures are provided in the wall of the mandrel and apertures are provided in the wall of the housing. When the mandrel is in the illustrated first relative axial position the apertures and are isolated from each other by a seal. When the mandrel is in the second relative axial position the apertures communicate with each other to permit flow from the interior of the mandrel to the exterior of the housing.

Abstract: The present invention relates to apparatus and methods for remotely actuating a downhole tool. In one aspect, the present invention provides an apparatus for activating a downhole tool in a wellbore, the downhole tool having an actuated and unactuated positions. The apparatus includes an actuator for operating the downhole tool between the actuated and unactuated positions; a controller for activating the actuator; and a sensor for detecting a condition in the wellbore, wherein the detected condition is transmitted to the controller, thereby causing the actuator to operate the downhole tool. In one embodiment, conditions in the wellbore are generated at the surface, which is later detected downhole. These conditions include changes in pressure, temperature, vibration, or flow rate. In another embodiment, a fiber optic signal may be transmitted downhole to the sensor. In another embodiment still, a radio frequency tag is dropped into the wellbore for detection by the sensor.

Abstract: A valve that is usable with a well includes an indexer and a closing mechanism. The indexer includes a profile to establish a sequence of open settings for the valve, and the indexer is adapted to respond to first control stimuli to transition the valve through the settings according to the sequence. The closing mechanism is adapted to operate independently of the sequence in response to a second control stimulus to close the valve.

Abstract: Systems and methods for operating a circulation valve such that the valve will automatically close without the need for a ball to be dropped or other intervention from the surface. The circulation valve is autonomous and will preferably be actuated from an open to a closed position by a motive force such as a power screw. The valve includes an actuator that causes the valve to close in response to particular conditions, such as the passing of a predetermined amount of time, or wellbore conditions, such as pressure, temperature or position.

Abstract: A material that reacts to produced hydrocarbons acts as a latch to retain a stored potential energy force. In a specific application, a sliding sleeve valve is held away from a circulating port to allow drilling mud to be circulated out. Later, when the well is put on production, the lock that holds collets in a groove releases as exposure to produced hydrocarbons at a retaining sleeve makes it get soft. This, in turn, allows a spring force to run the collets out of their groove and straddle the circulation port between two o-rings on the shifting sleeve to close the port. The closure of the port directs produced hydrocarbons to screens that had been bypassed when mud was circulated out due to ports being the path of least resistance.

Abstract: A well packing system and method for operating a well packing system wherein an isolation string assembly has a lower circulation valve with lateral flow ports that are operated to an open position without the use of shifters on a wash pipe. The isolation string assembly is incorporated into a well packing assembly within a wellbore and includes an upper sleeve tool that provides selective production of fluids through the frac pack assembly. In addition, the isolation string includes a lower circulation valve having a sliding sleeve that is shiftable from an open position to a closed position upon receipt of a suitable pressure differential. This configuration is particularly valuable for permitting monitoring of pressure or other conditions in the annulus of the wellbore portion being packed during packing operations. Further, the lower circulation valve tool can be used to selectively allow fluid returns during the packing operation.

Abstract: An improved seal assembly for use in sliding sleeve valves. The seal assembly incorporates a number of annular, chevron-shaped seal elements that are in a stacked configuration and preferably formed of a thermoplastic material to provide a fluid seal between the outer housing and the inner sleeve member of the sliding sleeve valve. In addition, the seal assembly preferably includes a pair of annular metallic seal members that have a C-ring cross-section (a “C-seal”). On opposite axial sides of each metallic C-seal are a C-seal support ring and an end adapter that are shaped and sized to assist the metallic C-seals to be axially compressed and uncompressed to resiliently seal against both the inner sleeve member and the outer housing.

Abstract: Sliding sleeve mechanisms including protective sheaths for debris protection are disclosed. Protective sheaths can be formed from materials such as composites, metal, foil, rubber, plastic, glass, ceramic, wire mesh, tape, etc. The protective sheaths can be substantially cylindrical shells (having one or more pieces), plugs in the flow ports, and/or tape or wire wrappings. The protective sheaths can be retained by recesses in the sliding sleeve or mechanical fasteners such as screws, pins, rivets, snap rings, bands, and buckles. The protective sheath can be outside or inside the sliding sleeve. The protective sheath can protect the sliding sleeve from debris by retaining grease that has been packed into the sliding sleeve for that purpose or positively preventing entry of debris into the sliding sleeve. The protective sheath can be cleared by permitting fluid flow through the sliding sleeve, which can act to destroy and/or wash away the protective sheath.

Abstract: A well system comprising an improved cross-over tool is provided. The tool may comprise a debris shield for substantially preventing sand, proppant or other well debris from fouling a flow port closing sleeve located below the cross-over tool fracture ports; a return port cover adapted to close or open a return port upon contact with a designated downhole surface regardless of tubing movement caused by stretching or contracting under stress or other induced pipe movement from downhole conditions; or a collet-type circulation valve adapted to mechanically indicate the position or flow status of the cross-over tool.

Abstract: A pin connector with a seal assembly using a unique wet connect assembly. The pin connector is formed from a tubular having an upper tubular portion and a lower tubular portion. The lower tubular portion has an upper tubular body and a lower tubular body with a lower tubular body face. A first pin engages the wet connect assembly. The first pin has a first pin outer surface, which can be connected to the wet connect assembly.

Abstract: A method and apparatus for sealing a tool for use in a wellbore is provided. The seal is configured to be disposed in a tool comprising a ported sliding sleeve and a ported housing. The tool may be actuable between a closed and an open position. The seal is configured so that one side of the seal acts as a flow restrictor to protect the other side of the seal from damage during actuation of the tool under pressurized conditions.

Abstract: An apparatus for use in a wellbore comprises a flow control device having an open position, a closed position, and at least one intermediate position. The apparatus further comprises a chamber and a movable member for actuating the flow control device, where the movable member is movable inside the chamber. The movable member causes a characteristic in the chamber to change in response to movement of the movable member to actuate the flow control device. A sensor detects the change in the characteristic inside the chamber that is indicative of actuation of the flow control device.

Abstract: A downhole apparatus which can be used as multi-cycle circulating subs utilized in downhole drilling operations, includes a piston (242) slidably mounted in a body between positions in which at least one aperture in the body is opened and closed. Movement of the piston (242) is controlled by a pin (86), secured to one of the body and a control member, and a control groove (52) formed in the other of the body and control member for receiving a portion of the pin. An arrangement of elements (232, 276) respectively connected to the control member and body is such as to normally resist axial movement of the control member from a first axial position to a second axial position. A spring (44) is located in a chamber for biasing the piston (242). The chamber is vented by an opening in the body.

Abstract: Methods and systems for operating a sliding sleeve valve or other downhole well tool that is axially shiftable among a finite number of increments between two extreme configurations such as open and closed configurations. A metering device is described having a pair of piston metering assemblies that operate in parallel fluid flow paths. The first piston metering assembly moves the sleeve of the well tool from a fully closed position to the zero position. The second piston metering assembly can be repeatedly pressurized and depressurized to meter predetermined amounts of fluid from an actuator sequentially to move the sleeve of the sleeve valve in consecutive increments toward a fully open position.

Abstract: A technique is provided for actuating devices deployed in a wellbore. The technique utilizes an actuator that cooperates with a downhole device, such as a well tool. The actuator has a phase change material that can be caused to undergo a phase change upon an appropriate input. The phase change of the material is used to provide the force necessary for actuation of the downhole device.

Abstract: Methods and apparatus are provided for reducing surge pressure while running casing into a wellbore. The apparatus includes a running string for running casing having a diverter tool therein. The diverter tool has one or more bypass ports between its upper and lower end which are normally closed. In operation, the diverter tool is automatically cycled between the open and closed positions of the bypass ports during a casing running operation. A pressure event inside the diverter tool deactivates the cyclic opening and closing function of the bypass port.

Abstract: A frac pack system and method for operating a frac pack system wherein an isolation string assembly has a lower circulation valve with lateral flow ports that are operated to an open position without the use of shifters on a wash pipe. The isolation string assembly is incorporated into a frac pack assembly within a wellbore and includes an upper sleeve tool that provides selective production of fluids through the frac pack assembly. In addition, the isolation string includes a lower circulation valve having a sliding sleeve that is shiftable from an open position to a closed position upon receipt of a suitable pressure differential. This configuration is particularly valuable for permitting monitoring of pressure or other conditions in the annulus of the wellbore portion being packed during frac pack operations. Further, the lower circulation valve tool can be used to selectively allow fluid returns during the frac pack operation.

Abstract: A method and apparatus for controlling inflation and deflation of spaced inflatable packer elements of a straddle stimulation tool within a well casing of a well. A straddle stimulation tool is positioned by tubing at a desired location within the well casing. Fluid is pumped through the tubing and tool at a rate inflating the spaced inflatable packer elements within the well casing and establishing an annulus interval. The inflation control retains pressure within the inflated packer elements and permits the flow of stimulation fluid into the annulus interval for stimulation of the formation. After completion of well stimulation, the packer element pressure control is moved to a packer equalizing position by tension applied via the tubing to equalize packer pressure with casing annulus pressure, deflating the packer elements and permitting conveyance of the straddle stimulation tool within the well casing by the tubing string.

Abstract: A hydraulic tool assembly for a downhole tool comprises a body (12), first and second members (14, 16) mounted for independent movement with respect to the body, and first and second control fluid chambers (24, 26) associated with the respective first and second members. Movement of the first member (14) between a first position and a second position in response to an applied force displaces control fluid from the first chamber (24) into the second chamber (26), to move the second member from a first position towards a second position to execute a tool function.

Abstract: An aquifer recharge valve assembly comprises a valve movable along the interior of a pipe section to open and close aquifer recharge openings through the pipe section. The position of the valve controls the extent to which the recharge openings are available for delivery of recharge water into the aquifer. The valve may be a seamless resilient cylinder which expands due to well head pressure to assist in sealing the recharge openings when the valve is closed.

Abstract: Methods and apparatus for filling a tubing string as it is lowered into a subterranean hydrocarbon well. In one embodiment, an apparatus to fill a tubular with fluid in a wellbore comprises a housing defining a central bore. An aperture formed in the housing provides fluid communication between the central bore and the ambient environment of the tubing string. A piston valve slidingly disposed in the housing is selectively pressure actuatable relative to the housing to control fluid communication between the central bore and the ambient environment.

Abstract: A tubing string assembly for fluid treatment of a wellbore includes substantially pressure holding closures spaced along the tubing string, which each close at least one port through the tubing string wall. The closures are openable by a sleeve drivable through the tubing string inner bore.

Abstract: A bi-directional seal assembly can be used in various types of cartridge valves including dirty fluid valves and a variety of other valves. The present seal assembly utilizes a seal spool, two O-rings and opposing seal cups. Back-up rings are provided to engage the O-rings to control deformation of the O-rings. The O-rings are compressed during manufacture of the seal assembly and the valve more than typically recommended by O-ring manufacturers. Because of this compression, the O-rings serve a dual function. At lower pressures, the O-rings act as a spring causing the seal cups to contact the opposing seal plates and at higher pressures they act as seals between the seal assembly and the valve.

Abstract: A pressurized sealing arrangement suited for providing a seal between a valve stem and a valve body is provided. The sealing arrangement includes a piston that is restrained in and statically sealed to the valve body and which surrounds the valve stem. Contained within the piston is an annular seal packing that includes two sealing elements spaced apart by a spacer element. The piston includes a face acted upon by a process fluid flowing through the valve body in such a manner that the piston exerts pressure upon a lubricant cavity. The lubricant cavity is in fluid communication with the seal packing such that lubricant contained therein forms a lubricant ring around the stem. Lubricant is also thereby supplied to sealing elements of the packing seal. To prevent contamination of the seal packing, a removable cover is provided that encloses the piston and seal packing.

Abstract: A downhole tool is provided for use within a casing. The tool includes a collector tool that has a cylindrical body having an external diameter smaller than the casing diameter so as to form an annular gap between the body and the casing. A first downhole fluid passage is provided in the body, which has an upper inlet and a lower outlet. At least one secondary fluid passage extends between the first downhole fluid passage and the annular gap, with a filter arranged between the at least one secondary fluid passage and outlet. A first sleeve member is provided on the body and adapted to move between a first position in which the at least one secondary fluid passage is closed, and a second position in which the at least one secondary fluid passage is open.

Abstract: A valve assembly connects into a drill string for opening and closing a passage within the drill string. The valve assembly has an inner valve member for opening and closing an inner passage of the drill string. The valve member moves between the open and closed positions in response to axial movement of the drill string. Lifting the drill string causes the upper portion to move upward relative to the lower portion, bringing along with it the valve member, while the valve sleeve remains stationary with the lower portion, opening the valve. The valve assembly can include an annular valve assembly for opening and closing an annular passage located around the inner passage. The annular valve assembly is opened and closed by increasing the pressure in the annular passage above the annular valve assembly.

Abstract: The present invention provides a return port cover that can close and open a return port separate from tubing movement caused by stretching or contracting under stress or other induced pipe movement from downhole conditions. For example, the return port cover can assist in preventing pack “fluffing” by preventing unintended fluid communication through an associated downhole tool regardless of the position of a circulating valve means. The return port cover can be biased, so that in one position it closes the port and in another position opens the port based on relative tubing placement at different portions of the fracturing operation or other well treatment operations.

Abstract: A valve assembly to control the intake of fluid. The valve assembly has a valve body and a valve choke disposed therein. The valve choke has a choke bore through the interior of the valve choke. The valve choke has a plurality of orifices to the choke bore spaced at intervals along the valve choke. A seal is disposed between the valve body and valve choke. The valve system is operable to position the valve choke so that the seal is positioned between the valve body and the valve choke at the intervals between the plurality of orifices.

Abstract: A valve assembly to control the intake of fluid. The valve assembly has a valve body and a valve choke disposed therein. The valve choke has a choke bore through the interior of the valve choke. The valve choke has a plurality of orifices to the choke bore spaced at intervals along the valve choke. A seal is disposed between the valve body and valve choke. The valve system is operable to position the valve choke so that the seal is positioned between the valve body and the valve choke at the intervals between the plurality of orifices.

Abstract: An indexing mechanism is disclosed that can put a tool in a variety of positions while downhole in the face of high static and dynamic loads. In the preferred application, the mechanism controls a movable sleeve on a downhole choke. It contains an indexing feature comprising a pin movable in a series of slots. A piston restrained to move longitudinally engages and rotates an index sleeve to allow the pin to advance into the next J-slot track. A separate lug on the piston engages a radial face on the index sleeve to take the shock load and position the choke instead of allowing the pin to load against the closed end of the slot.

Abstract: A method is disclosed that allows for sequential treatment of two zones in a single trip while isolating the zones. A fluid loss valve prevents the column of fluid in the tubing from flowing into the lower formation until activated. Zone isolation is accomplished by manipulation of a port on a wash pipe attached to the crossover assembly.

Abstract: An apparatus for reducing pressure surges in a wellbore comprising a body having a bore therethrough, the bore providing a fluid path for wellbore fluid between a first and second end of the body, at least one fluid path permitting the wellbore fluid to pass between the bore and an annular area formed between an outer surface of the body and the walls of a wellbore therearound, and a number of closure mechanisms whereby the at least one fluid path is selectively closable to the flow of fluid.

Abstract: A fluid flow switching device for a drill string comprises a tubular member having a port (4). A sleeve member is slidable within the tubular member between a first position in which a port (3) thereof is in alignment with the port (4) and a second position in which the port (4) is obstructed. A plurality of fingers are connected to the sleeve member (2). Each finger defines one segment of a closure member that is closed when the fingers are pivoted inwardly and open when the fingers are pivoted outwardly. An operating surface is positioned within the tubular member, and the fingers are axially slidable thereover as the sleeve member is moved between the first and second positions to close and open the segmented closure.

Abstract: A sliding sleeve valve and method for assembly is disclosed. The valve comprises a segmented main body that is assembled from a top, middle and bottom segments. The middle segment has flow apertures. A closing sleeve is co-axially mounted in the assembled main body. The closing sleeve has flow apertures that are intended to communicate with the flow apertures of the middle section when the valve is open. The closing sleeve is sealed by seal means within the main body to prevent undesired fluid flow across the valve. The seal means comprise primary, secondary and tertiary seals acting in cooperative combinations. The seals comprise O-Ring and Vee-stack seals located within the body of the valve. The sliding sleeve valve has a fluid pressure equalization means to permit equalization of fluid pressure across the valve before it is fully opened or fully closed in order to reduce wear on the seals.

Abstract: A choke valve assembly is disclosed for controlling the flow of fluid through a production tubing. The valve assembly includes a housing having a plurality of axially aligned apertures and a ported sleeve disposed in the housing. The ported sleeve has a plurality of rows of fluid ports. Each row of ports has at least one port in selective fluid communication with a respective aperture. In the full open position, each aperture is in fluid communication with a port from each row. To choke the flow, the ported sleeve is rotated relative to the housing to reduce the number of ports in fluid communication with the housing. To close the valve, axial force is applied to move the ported sleeve axially relative to the housing.

Abstract: Downhole apparatus comprises a body for mounting on a tubular string, the body defining an internal bore. A fluid pressure actuated valve member is movable relative to the body and a normally closed flow port is provided in the valve member. With the valve member in a first position relative to the body the port is closed, and with the valve member in a second position the port is open to permit fluid communication therethrough between the body bore and the exterior of the body. The valve member is biassed towards the first position. A fluid pressure actuated latch arrangement releasably retains the valve member in the first position, the latch arrangement being releasable on application of a predetermined cracking pressure to allow the unlatched valve member to move to the second position in response to a valve opening pressure lower than the cracking pressure. The latch is resettable to relatch the valve member on return of the valve member to the first position.

Abstract: A downhole choke in the form of a sliding sleeve valve operable in a plurality of positions including fully open, fully closed, and positions in between, is disclosed. It features a hydraulic control system that, in one embodiment, provides the motive force to move the sliding sleeve a predetermined amount for a given applied control pressure. Further increments in applied pressure result in further predetermined movements of the sliding sleeve. In another embodiment, the sliding sleeve lands in a series of grooves in the surrounding housing depending on the degree of pressure applied to the control system.

Abstract: A bi-directional seal assembly can be used in various types of cartridge valves including dirty fluid valves and a variety of other valves. The present seal assembly utilizes a seal spool, two O-rings and opposing seal cups. The O-rings are compressed during manufacture of the seal assembly and the valve more than typically recommended by O-ring manufacturers. Because of this compression, the O-rings serve a dual function. At lower pressures, the O-rings act as a spring causing the seal cups to contact the opposing seal plates and at higher pressures they act as seals between the seal assembly and the valve.

Abstract: A crossover tool is disclosed that permits access through to the wash pipe below after the conclusion of a known gravel packing operation. A ball is trapped to a sleeve after shifting it so as to allow flow through the crossover for acid treatment in the screen area and a reversing out procedure to remove excess acid. Alternatively, pressure delivered through the wash pipe can operate packers, as part of a gravel packing procedure as outlined in two steps in U.S. Pat. No. 6,311,772 is a single trip. The acid treating or other downhole operation through the wash pipe can also be accomplished in a single trip with the gravel packing assembly.

Abstract: The present invention provides for dynamic sealing in a flow control device. In an embodiment, the flow control device comprises a closure sleeve adapted to slide over the tubing hole. The closure sleeve has a front edge having a wave-like surface. One or more seals are mounted downstream of the tubing hole. The one or more seals cooperate in a fluid-tight manner with the closure sleeve. A protective sleeve is mounted in alignment with the closure sleeve and proximate to the one or more seals. The protective sleeve has a top edge adapted for mating engagement with the wave-like surface of the front edge of the closure sleeve. A return mechanism is provided for automatically returning the protective sleeve to a covering position in which the protective sleeve covers the first seal when the first seal is not covered by the closure sleeve.

Abstract: A device for providing surge pressure reduction with volume compensation and methods of use are presented. Surge pressure reduction and volume compensation are accomplished by pressure-actuated release of the compensation device.

Abstract: A tubing hanger to facilitate production tubing annulus access including a tubing hanger body having a central bore, a shuttle valve slidably mounted to the tubing hanger body, and at least one annulus access bore through the tubing hanger permitting fluid communication between the central bore and an annulus defined between a production tubing string and a wellbore or casing via the tubing hanger body and the shuttle valve. The shuttle valve may be slidingly movable between an open and a closed position. The tubing hanger may further include a groove enclosed by a filler, the groove providing communication between a plurality of small annulus access bores and a large annulus access bore.

Abstract: A by-pass tool to be incorporated in a drill string, in combination with an activating ball assembly operative to adjust the tool between an activated mode and a de-activated mode. The tool has a valve seat engageable by the activating ball assembly to move its sleeve to a by-pass mode which diverts drilling mud from flowing through the housing to a by-pass flow through the by-pass port. The activating ball assembly has a deformable ball of a size sufficient to engage and to be held captive by the salve seat and a weight attached to the ball and operative to assist in movement of the assembly under the action of gravity to engage the ball with the valve seat. The weight has smaller transverse dimensions that the ball so that it moves downwardly through the valve seat and pulls the ball into engagement with the valve seat.