US3055306A

US3055306A - Magnetic valve for well plunger

Info

Publication number: US3055306A
Application number: US65029A
Authority: US
Inventors: Gilbert H Tausch
Original assignee: Camco Inc
Current assignee: Camco Inc
Priority date: 1960-10-26
Filing date: 1960-10-26
Publication date: 1962-09-25
Anticipated expiration: 1979-09-25

Description

Sept. 25, 1962 G. H TAUSCH MAGNETIC VALVE FOR WELL PLUNGER Filed 001;. 26, 1960 6. /7. 7270-3 cfi INVENTOR.

BY 2Q (AL Staes Patented Sept. 25, 1962 3,055,306 MAGNETIC VALVE FOR WELL PLUNGER Gilbert H. Tausch, Houston, Tex., assignor to Cameo, Incorporated, Houston, Tex., a corporation of Texas Filed Oct. 26, 1960, Ser. No. 65,029 Claims. (Cl. 103-52) This invention relates to the elevation of liquids through a well eduction tube under influence of pressure gas delivered to the eduction tube below its liquid level, and more particularly to a free piston plunger closely fitting thetube for rise and fall between opposite limits therein and having an upwardly seating check valve controlling a pressure equalizing passage communicating the tube space above and below the plunger.

Plunger lift systems, Whether dependent on formation pressure or outside pressure gas supplied and regulated by a surface timer, have long been in use and in general are arranged in the manner disclosed in Fletcher Patent 1,846,000, dated February 16, 1932. On plunger downstroke, an open passage across the plunger permits its gravity descent through well fluids and at the lower limit of travel a valve engages a striker land is shifted to passage closing relation, whereupon fluid pressure below the plunger raises the same and pushes any liquid thereabove to the surface. At the upper limit, a bumper engagement returns the valve to open position for a pressure equalizing action and a repeated plunger downstroke.

Satisfactory valve action is of critical importance and has been a troublesome problem and an object of the present invention is to provide :an improved valve structure which will be reliable and care free for effective operation throughout long periods of use.

A further object of the invention is to provide a simplified valve structure comprising but a few inexpensive and easy to manufacture and assemble elements and which will hold itself in closed position as well as open position without reliance entirely on fluid pressure differentials or on movable position controlling parts inclusive of latching detents, springs or other items likely to get out of order from wear, strain and the wide range of temperature change encountered in deep well installations.

Another object of the invention is to provide an improved plunger whose body adjacent its annular passage seat includes a valve cage having a valve abutment shoulder below the seat, with the shoulder and seat affording spaced apart limit stops and defining the travel range of a shiftable check valve which incorporates a longitudinally magnetized permanent magnet whose end portions and opposite poles co-operate with the limit stops and the cage wall whereby lines of magnetic force have effective valve holding action in both closed and open relationships and provide predetermined resistance to displacement of the shiftable valve from either position at which the valve has been set.

Other objects and advantages will be apparent from inspection of the accompanying drawing wherein FIG. 1 is an elevation partly in section showing a plunger having a check valve in its open position and FIG. 2 is a similar view of a modified embodiment of the invention.

In the plunger as shown in FIG. 1, there is included a hollow body member comprising an elongated central tube 1 and enlarged upper and

lower heads

2 and 3 threaded onto opposite ends of the tube 1. The uppermost tubular head 2 terminates upwardly in the usual fishing neck coupling and between it and the bottom head 3 are clamped in surrounding relation to the central tube 1, a stack of sealing assemblies which are for co-operation with the eduction tube wall in restricting fluid passage around the plunger assembly. These elements include a sleeve 4 having an alternate succession of pcripheral ribs and grooves to provide a labyrinth type seal. In addition, FIG. 1 shows a pair of

sleeves

5 and 6 in end to end succession, each having a pair of diametrically opposite windows extending longitudinally therein from adjoining edges and receiving wiping shoes 7 suitably retained in the sleeves, as by means of end tabs 8 which project above and below each window and fit the hollow sleeves to limit outward travel of the shoes under influence of laterally disposed coil springs 9. Each wiper shoe 7 has an arcuate length exceeding ninety degrees and the pair of shoes received within the window of the sleeve 5 are angularly spaced from the pair of shoes 7 fitted [to the companion sleeve 6.

The lowermost coupling head 3 is hollow and immediately below its upper screw threaded end portion it has an enlarged cylindrical chamber 10 of uniform diameter throughout its length which forms a continuation of the passageway through the hollow tube 1 and communicates with the outside of the plunger and below the sealing elements through one or more lateral ports 11. At its upper end, the chamber 10 encloses an annular and upwardly tapered valve seat 12 formed either as a part of the coupling head 3 or as the bottom end of the tube 11, as shown in the drawing.

For co-operation with the fixed annular seat 12 and slidably caged or contained within the chamber 10 is a check valve assembly for movement toward and from the seat 12. This check valve includes a central stem 13 which slidably fits and projects through a reduced diameter bore leading downwardly from the chamber 10 from an adjacent shoulder 14 at thet bottom of the chamber. A reduced diameter upper portion of the stem provides an intermediate upwardly facing shoulder thereon to which is fitted a washer 15 at the lower end of an annular magnet 16 Whose upper end is overlapped by a washer 17 threaded on or otherwise secured to the upper end of the stem 13. Peripherally enclosing the cylindrical magnet 16 and extending between the upper and

lower washers

15 and 17 is a facing sleeve 18 of brass or other suitable nonmagnetic material and preferably of uniform outside diameter throughout its length. The assembly comprising sleeve 18 and magnet 16 and the

washers

15 and 17 has a slight and uniform clearance re laden with the interior surface of the chamber 10 and is an over-all length somewhat less that the length of the chamber 10, sufficient to accommodate movement of the valve toward and from the seat 12. The upper washer 17 has an upwardly tapered rim portion to mate with and tightly engage with the tapered seat 12 when the valve is raised. Bearing on the upper face of the washer 17 is the lower end of .a longitudinally fluted or grooved rod 19 extending through the passage the tube 1 and terminating upwardly in a reduced pin portion 20 slida-bly projectable through the upper end of the coupling head 2. In the position of the parts seen in FIG. 1, the check valve is at its lower open limit for free movement of liquid by way of the ports 11 and the longitudinal grooves in the rod 19 which lead to lateral ports 21 in the coupling 2. This is the relationship of the parts which enables gravity descent of the plunger until the projecting lower tip portion of the stem 13 strikes an abutment at the lower limit of travel, whereupon the valve seat 12 and body assembly move downwardly until the seat 12 in engagement with the mating seat on the check valve assembly for closing the passage, Incident to such relative movement, the upper tip portion 20 of the fluted rod will be projected upwardly above the plunger, and with the valve seated, pressure below the plunger will elevate it until the tip 20 comes into abutment with a suitable striker at the well head and holds the check valve stationary while the main body and seat 12 rise for opening the passageway until the seating shoulder 14 engages the bottom of the check valve.

The annular magnet 16 is magnetized longitudinally of its length so that its opposite poles are spaced apart in the longitudinal direction. The wall of the cage is formed of ferrous or magnetic material and co-operates with the field of the magnet and since the radial clearance relation between the opposite poles and the cage wall is similar at both ends of valve travel, the magnetic holding force will be effective whether the valve is in open or closed position. That is to say, when the check valve is bodily moved from one position to the other, the lines of force of the permanent magnet are overcome for accommodating the movement and then act through the valve cage for resisting displacement. This holding action is of special consequence in the valve closing position under conditions in which the fluctuations in pressure, which normally tends to act upwardly on the closed valve, are of sufficiently wide variation during upward plunger travel as to allow the valve to unseat itself. The holding force is also of importance in the open position of the valve in resisting any closing forces during downward plunger travel.

The improved result obtained with the use of a permanent magnet eliminates need for locating springs and poppet devices, such as often used heretofore, and insures a positive and reliable action without wear out and breakage of parts. As previously indicated, the facing sleeve 18 is of nonmagnetic material. Its use as an optional feature is to minimize accumulation of metal debris on the valve assembly. As proposed in the embodiment disclosed, the valve stem 13 and the elongated motion transmitting rod 19 are of nonmagnetic material whereas the cage 3, containing the seating shoulder 14, and the tubular body 1, presenting the valve seat 12, are of magnetic material. Also, the end washers 15 and 17 in bottom and top face contact with the permanent magnet are of magnetic material and constitute pole pieces for extending and concentrating the magnetic field. This arrangement is preferred for an effective holding action when the shiftable valve is engaged with either the magnetic seat 14 or the magnetic seat 12. In both valve positions, the cage affords a flux path between the magnet poles with similar small gap reluctance due to uniform cylindrical clearance throughout the valve travel range.

The magnet-valve assembly and cage arrangement just described is incorporated in the modified plunger of FIG. 2 except that there is absent the long push rod 19 in the passageway in the tube 1 above its bottom valve seat 12. Instead, a dependent rod 19a is fixedly mounted in the lubricator assembly at the well head and is of such length that it will be telescopically received in the body of the plunger and project downwardly through the central passageway therethrough into striking engagement with the top of the magnetic valve at the upper limit of plunger travel. As an optional sealing arrangement for wiping engagement with the eduction tube, the peripherally ribbed sleeve 4 shown in FIG. 1 is omitted in FIG. 2 and is replaced by a second set of four wiper shoes 7 indentical in structure and arrangement to the set of shoes shown and described in connection with FIG. 1. In other words, there are two sets of four co-operating wiper shoes and locating

sleeves

5 and 6 and the two sets are arranged in tandem assembly relationship.

While the foregoing specification has been limited to specific structure, it is to be understood that various modifications can be made without departing from the invention as set forth in the attached claims.

What is claimed is:

1. A free plunger for travel through a well eduction tube and between upper and lower limit stops therein, a hollow body having a passage therethrough and a downwardly facing valve seat fixed in the passage, a check valve mounted in the body for movement longitudinally thereof toward and from said seat and between passage opening and closing positions, mechanical motion transmitting means at each end of said valve adapted to receive force for effecting valve movements at the travel limits of said plunger and means resisting valve movement from both positions-and comprising a permanent magnet mounted on the valve for movement therewith and arranged with opposite poles spaced apart in the longitudinal direction of movement, said magnet having a peripheral surface of uniform radial dimension throughout its length between its opposite poles and a body wall of magnetic material below said sea-t and surrounding the magnet in uniform spaced radial clearance relation with the magnet throughout the operating length thereof, said wall and said valve having lower terminal portions slidably fitted one to another to center and maintain said clearance relation and also having radial abutment surface for engagement at the limit of valve movement away from said valve seat.

2. In a free plunger for wells, a hollow body having a passageway and a valve seat surrounding the passageway, a movable check valve for controlling the passage through the body, a valve carried permanent magnet of uniform outside dimension and with its opposite poles spaced apart in the longitudinal direction of its movement, a valve retaining cage enclosing the valve and accommodating movement thereof to and from said valve seat, interengaging seating surfaces on the valve and the cage engageable to limit the range of valve movement away from said valve seat, means on the valve to receive valve moving forces, said cage being carried by the body and provided with a surrounding wall of magnetic material and of a uniform inside dimension and interengaging centering surfaces on the valve and body to provide substantially the same clearance relation between the wall and the magnet in all relative positions thereof.

3. In a free plunger as in claim 2, together with an outside facing of nonmagnetic material lining the outside surface of the magnet.

4. A free plunger for travel in a well eduction tube, a hollow body having a peripheral sealing formation and a passageway through the body, a downwardly facing valve seat on the body in passageway surrounding relation, a hollow valve cage having a wall of magnetic material and constituting a downward extension of the body below said seat, a movable check valve slidably mounted within the valve cage for longitudinal valve movement between an upper position in passageway closing engagement with the seat and a lower position in passageway opening relation with the seat, an upwardly facing stop shoulder carried by the cage as an extension of the wall thereof and engageable by the check valve as a limit to valve movement toward said lower position, force receiving means at opposite ends of the valve for controlling valve movement relative to the body and a permanent magnet forming a part of and movable with the check valve and having opposite poles longitudinally spaced apart and co-operating with said magnetic wall to resist valve movement away from both of said positions.

5. A free plunger for travel through a well eduction tube in the operation of producing well liquid, a body having an outside diameter for close fitment with an eduction tube and having an internal passage therethrough, an upwardly seating check valve controlling said passage, top and bottom abutment surfaces on the valve for receipt of valve shifting forces, a hollow cage on the body having an annular wall of magnetic material enclosing the valve and being of uniform internal diameter, a valve engageable seat projected inwardly on said wall and engageable by the check valve to limit shift thereof downwardly and a permanent magnet formed as a unit with the valve and arranged with longitudinally spaced apart poles of similar outside dimension for substantially the same clearance relation adjacent said poles with the interior surface of the cage Wall in all positions of the valve.

6. A well plunger for free travel in an eduction tube and comprising a body containing a fluid passage, a valve cage having a wall portion of magnetic material and constituting a fixed part of the body, a valve seat for the passage, a check valve movably housed within the cage, interengageable surfaces on the check valve and said cage engageable with one another to limit valve movement away from said valve seat, said check valve being mova ble for passage opening and closing relations with the seat and including abutment surfaces on the valve to receive valve movement force and a permanent magnet having its opposite poles spaced apart in the direction of valve movement for co-operation with the magnetic wall portion of the cage in aliording a valve holding effect.

7. A well plunger for free travel in an eduction tube, comprising a body containing a fluid passage and having a hollow portion constituting a part of the passage, said hollow portion providing a check valve enclosing chamber and having a chamber wall of magnetic material and also having a lateral port through the wall intermediate its longitudinal extent, a downwardly facing valve seat in the passage above said lateral port, an upwardly facing stop shoulder in the chamber below said port, a valve stem guide on said hollow portion extended downwardwardly below the stop shoulder, a valve stem having a lower portion slidably fitted to said guide and adapted to transmit valve moving force and having an upper portion projected into the chamber and terminated upwardly in a valve head for co-operation with said seat, a magnet mounted by the stem below said head with opposite poles longitudinally spaced apart, a stop surface at the bottom of the magnet for co-operation with said shoulder and a facing layer of nonmagnetic material overlying the peripheral surface of the magnet.

8. In a free plunger for travel within a well eduction tube, a hollow body having eduction tube engageable sealing means peripherally thereon and providing a fluid passageway in the body with communication exteriorly thereof above and below the sealing means, an upwardly seating check valve for closing said passage way, a permanent magnet carried by the valve and provided with opposite poles spaced apart longitudinally of the direction of valve travel and a valve cage of magnetic material enclosing said valve and having top and bottom stop abutments engageable alternately by the valve and the upper of which constitutes an annular valve seat for said passageway, said stop abutments being longitudinaldy spaced apart a distance greater than the longitudinal spacing between said poles and cooperating therewith whereby the magnetic holding force on the valve is efiecltive at valve engagements repectively with the top and the bottom stop abutments and force transmitting means on the check valve for the receipt of mechanical force to shift the valve in opposition to the magnetic holding force.

9. In a well plunger having a passageway therethrough, a valve cage of magnetic material forming part of said passageway and having a valve seat at one end of the cage and a valve stop longitudinally spaced from said seat, a shiftable valve engageable with said seat at one limit to close said passageway and with said stop at the other limit, valve carried means positioned for receipt of mechanical valve shifting force and a magnet carried by the valve and magnetized to present its opposite poles spaced apart in the direction of valve movement for cooperation with the seat and the stop respectively for a valve holding action.

10. In a magnetic check valve assembly, a pair of relatively shiftable elements, one of which is a body of magnetic material having a passageway and the other of which is a valve for the passageway, a pair of stop abutments of magnetic material on the body extending a mag netic flux path through the body and defining opposite limits of relative travel and alternately engageable with said valve, a magnet constituting a part of the valve and having its opposite poles spaced apart in the direction of relative travel for magnetic attraction valve holding co-operation with the magnetic abutments when either is engaged with the valve and mechanical force responsive means on one of the elements for effecting the relative shifting of said elements against opposition of magnetic attraction.

References Cited in the file of this patent UNITED STATES PATENTS