US3070344A - Plunger actuated well control - Google Patents

Description

G. H. TAUSCH PLUNGER ACTUATED WELL CONTROL Dec. 25, 1962 Filed Feb. 20, 1961 United States Patent Oflhce 3,070,344 Patented Dec. 25, 1962 3,070,344 PLUNGER ACTUATED WELL CONTROL Gilbert H. Tausch, Houston, Tex., assignor to Cameo, Incorporated, Houston, Tex., a corporation of Texas Filed Feb. 20, 1961, Ser. No. 90,430 Claims. (Cl. 251-65) This invention relates to a gas lift system by which liquid slugs are intermittently raised to the surface ahead of a free piston being elevated through a well eduction tubing by pressure gas accumulation below the piston, and more particularly to an improved well control responsive to piston arrival at a given point in its travel stroke.

Devices which sense or detect lift piston arrival at the wellhead are common for eifecting automatic control of various instrumentalities including the control of energy transmission to or from working mechanisms for regulating operation of well systems. As heretofore proposed, such devices have been mechanically contacted by or magnetically attracted to the piston for either opening or closing a fluid :ilow valve or a swtich in electric circuitry by which piston arrival signals a responsive operation.

An object of the present invention is to provide an improved magnetic arrival signal involving a few simple and low cost parts for ready assembly as a compact unit and in relationship substantially free from heavy work force and wear and which unit affords a rapid responsive controlling action.

A further object of the invention is to provide a sealed chamber having a movable closure wall Whose movement controls a working operation and depends on travel response of a shiftable magnet sealed within the chamber along with a co-operating body of liquid mercury.

Another object is to provide a normally closed valve assembly comprising a liquid suspended bar magnet reciprocably guided between a biased valve closing relation and a magnetically attracted position for a valve opening relation.

Other objects and advantages will be apparent from the following specification and the accompanying drawing wherein FIG. 1 is a fragmentary side elevation with parts in section of a well installation embodying a free piston and a wellhead arrival signal arrangement and FIG. 2 is a vertical section of the piston arrival responsive device shown in FIG. 1 but on a larger scale.

As typical of a high gas-oil ratio producing well system, FIG. 1 diagrams a simple cycling arrangement for alternately closing and opening a motor valve 1 in the outflow pipe 2 leading from the wellhead end of an eduction tubing string 3 which extends downwardly to a production stratum and through the usual well bore casing 4. In the shut-off interval when the valve 1 closes the outflow pipe line 2, a free piston 5 closely and slide. bly fitted within the eduction tube 3 will be at the bottom of its stroke with its upwardly seating check valve 6 opened for the rise or accumulation of well fluids above the piston. Timed actuation of the motor valve 1 to open the outflow pipe line 2 vents the top of the eduction tube or effects a reduction in pressure throughout the length of the eduction tube above the piston 5 and in response to higher pressure below the piston, its valve 6 will close and seal the piston against fluid passage thereby in either direction, thereby trapping against back flow any liquid above the piston, and the piston itself Will be elevated to raise the liquid toward the surface and for ejection into the outflow line 2. With arrival of the piston 5 at the wellhead, a striker abutment is contacted by and shifts the piston check valve 6 to its open position, thereby conditioning the piston for a gravity return down stroke, and desirably the motor valve 1 should close at approximately the same time and minimize gas escape.

For present purposes, the motor valve 1 may be considered as being normally held closed by a spring Whose elastic force can be overcome by the application of .pressure gas above a flexible diaphragm operatively connected with the valve and formed as a part of a motor assembly 7. To cycle valve operation through alternate on and off intervals, a conventional controller 8 operates automatically to charge or deliver a shot of pressure gas to the motor diaphragm chamber to hold the valve open for a predetermined time as controlled by a regulated bleed down of the pressure charge. To eliminate need, especially if well production is erratic, for frequent attention and accurate adjustment of bleed down time, there is her involved a secondary vent for quickly relieving and fully dumping the pressure charge in the motor coincidently with piston arrival at the wellhead so as to end immediately the motor valve opening phase of the operating cycle.

In a preferred embodiment of the arrival responsive vent valve unit as seen in FIG. 2, a permanent magnet in the form of a cylindrical bar 9 is enclosed for limited longitudinal reciprocation within a hollow housing or casing comprising a pair of separately machined parts of brass or other nonmagnetic material. One of the parts is a cupped member 10 having an elongated tubular wall closed at one end by a solid transverse wall constituting the base of the cup and the other of which parts is a removable cap member or end piece 11 having a relatively shallow internal annular recess on its inner face peripherally surrounded by a short length cylindrical skirt and which cap 11 covers the opposite end of the cupped elongated casing 10. The cylindrical skirt of the cup 11 and the elongated tubular wall of the cupped member 10 are axially aligned and detachably secured in face to face end clamping relation by a series of screw bolts 12 and hold between the clamped together end faces the rim portion of an impervious flexible diaphragm 13 of neoprene or the like extending across the hollow casing as a movable wall or partition sealed peripherally to the casing and subdividing its interior into separate chambers in end to end succession.

On one side of the diaphragm 13, the bar magnet 9 is contained within the hollow chamber of the casing and its length is slightly less than the distance between the diaphragm 13 and the base end wall of the cup 10 for accommodating magnet reciprocation. The bore through the casing 10 intermediate the length thereof has a guide portion whose diameter slightly exceeds the external diameter of the bar magnet and on both sides of this intermediate portion the internal bore is diametrically enlarged, as at 14 and 15, for longitudinal distances surrounding the opposite ends of the magnet. In the relative position of the parts as viewed in FIG. 2, the central region of the diaphragm 13 affords a sealing seat in stopped abutment with the inner face of a frusto-conical boss 16 projecting inwardly from the end cap 11 at the recessed area thereof and in coaxial relation with the hollow casing. This boss 16 surrounds or has a drilled passageway 17 communicating with an enlarged and tapped opening through the cap piece 11 and is for coupled connection with a fitting forming a part of a fluid flow conduit 18 which is in communication with the pleasure chamber of the motor 7. The inner end of the passage 17 is thus valved and is normally closed by the diaphragm 13. Diaphragm deflection away from the boss 16 uncovers the flow passage 17 and in the particular arrangement shown, the passage 17 is vented through the annular chamber space within the hollow end .ber volume.

face of the cap member 11 and a drilled port 19 opening to the surrounding atmosphere.

Adjacent the flexible partition wall 13, the end of the bar magnet 9 has a peripheral enlargement or head 20 and terminates in a reduced diameter centrally disposed and flat nosed boss 21 whose end face is for concentrated force transmitting contact with the central area of the flexible diaphragm on the side thereof opposite the face portion which seats on the flat end of the frusto-conical boss 16. The enlarged head 29 of the bar magnet operates within the counterbore 15 of the elongated casing 10 and constitutes a seating abutment for the free end of a compressed coil spring 22 sleeved on the bar magnet and grounded at its opposite end on the shoulder at the bottom of the counterbore, whereby the bar magnet is yieldably biased toward the casing end cap 11 and normally seats the diaphragm 13 on the boss 16 as a travel limit stop and to close the passage 17. Movement of the magnet for diaphragm deflection away from the boss to uncover the vent port 17 will occur against spring force whenever a piece of magnetic material is presented adjacent the base of the casing 10 and within the magnetic field whose force will draw the magnet toward the base and overcome the spring bias.

For installation at the wellhead, the base end of the cupped casing 10 is peripherally screw threaded into a side opening in an adapter fitting 23 forming an extended part of the reduction tubing string 3. Accordingly, direction of magnet travel is laterally of the travel path of the free piston. It follows that whenever and so long as a wall portion of magnetic material carried by a free piston is presented to the casing 16 at the top of the piston stroke, the bar magnet will be drawn toward the piston and away from valve closing relation. The result will be that the pressure charge in the motor 7, which then holds the outflow valve 1 open, will be relieved by the full opening of the vent tube 18 as controlled by the arrival valve unit.

An important aspect of the valve unit is that the impervious partition wall 13 seals the casing chamber containing the movable magnet 9 and the closed chamber eliminates entrance thereto of dirt and minimizes wear and lubrication problems. More particularly, a body of mercury 24 or other similar heavy fluid partially fills or occupies the enclosed chamber space around the magnet 9 with any remainder of the space being either void or containing air at or below atmospheric pressure for accommodating diaphragm deflection and decrease in cham- The body of liquid mercury and the bar magnet in relation to one another afford a degree of buoyancy or magnet floating tendency with little or no frictional bearing on the casing wall. Only a short range of magnet travel is needed for valving action and very little endwise displacement of liquid occurs upon magnet movement. However, the casing bore enlargements 14 and at the opposite ends of the magnet, serve to reduce restriction to liquid displacements in the end regions between the terminal faces of the casing and magnet. A reduction if friction enables an effective snapping action and minimizes wear for prolonged life and dependable operation.

The magnetic valve assembly is adapted to the control of systems in various different arrangements from that here disclosed for exemplary purposes and the invention is unlimited as to details such as come within the scope of appended claims.

What is claimed is:

1. In a magnetic valve assembly of the character described, a chambered casing of nonmagnetic material having a flexible diaphragm in sealing relation to one end of the casing chamber, a body of liquid mercury entrapped within the chamber casing on one side of said diaphragm, a permanent bar magnet fioatingly suspended by said body of mercury for reciprocation toward and from said diaphragm and controlling flexure thereof, means mounting said casing to present an end thereof adjacent the path of a movable magnetic body whose presence within the field of the magnet will induce movement of the bar magnet toward the last mentioned end of the casing and an abutment seat postioned on the other side of the flexible diaphragm for contact thereby as a limit to diaphragm flexure in one direction and provided with a fluid passage to be opened and closed by flexure of the diaphragm away from and into contact with said seat.

2. In a magnetic valve assembly of the character described, an axially reciprocable permanent bar magnet arranged for endwise travel in one direction upon arrival of a magnetic member in juxtaposed relation to one end of the magnet and within the field thereof, a chambered casing of nonmagnetic material enclosing the bar magnet and guiding reciprocation thereof, means for mounting the casing to present one wall adjacent the path of said magnetic member, spring means interposed between the casing and the bar magnet normally urging the bar magnet in the direction opposite to the aforesaid one direction, a chamber end wall having a passage for fluid to be valved and an inwardly extending boss surrounding the passage and terminating in an abutment seat for co-operation with the bar magnet as a limit stop to its movement in one direction and for valving said passage, an imperforate partition wall within the casing and between said abutment seat and the bar magnet and co-operating with the casing to seal off the bar magnet enclosing chamber and a body of liquid mercury entrapped within the chamber by said partition wall and buoyantly suspending the bar magnet.

3. In a magnetically actuated valve, a cup shaped casing having a nonmagnetic wall, a shiftable permanent magnet enclosed within the casing, spring means interposed between the casing and the magnet and active to bias the magnet away from the base end of the cup shaped casing, mounting means for positioning said base end with the field of said magnet projected into intersecting relation with the path of a movable magnetic body whose presence within the field attracts the magnet against the bias of said spring means, a flexible diaphragm fitted to the opposite end of the cup shaped casing for contact by an adjacent end of the magnet under bias of said spring means, a body of liquid mercury sealed within the casing by said diaphragm and an end member fixed to said opposite end of the casing and provided with a fluid flow passage and with an annular seat at the inner end of the passage with which the flexible diaphragm has passage closing abutment in the absence of magnet response in opposition to said spring means.

4. For use with a gas lift well installation having an eduction tubing portion for travel therein of a free piston having a magnetic wall portion, a magnetic valve assembly including a chambered casing of nonmagnetic material adapted to be mounted on a well eduction tubing, a flexible partition Wall subdividing the casing chamber into a sealed space on one side of the wall and a fluid flow space on the opposite side of the wall, an abutment formation in said fluid space having a passage therethrough and providing an annular seat around the inner end of the passage for passage closing contact with said partition and toward and away from which said partition may flex, a liquid body of mercury contained within the sealed space, a laterally movable permanent magnet bar bearing in the mercury and having an end face in bearing contact with the flexible partition and spring means acting on the magnet to bias the same toward the partition, said magnet upon presentation within the field thereof and adjacent its opposite end face of the magnetic wall portion of the piston, being magnetically attracted in the direction to overcome the bias of said spring means.

5. In a magnetically controlled assembly, a hollow casing of nonmagnetic material, a movable end wall therefor having sealed relation with the nonmagnetic casing, a body of liquid mercury entrapped by the movable wall within the hollow casing, a permanent bar magnet floatingly suspended in the body of mercury for reciprocation within the casing, casing mounting means for presentation of the field of the magnet within the path of a movable magnetic body whose presence within the field attracts 5 the permanent magnet in one direction, means active to bias said permanent magnet in the other direction, force transmitting means between the magnet and the movable wall to control wall movement and work regulating means operatively related to said wall and responsive to move- 10 ment thereof.

References Cited in the file of this patent UNITED STATES PATENTS Goepfrich Dec. 2, 1952 Booth July 8, 1958 Bauerlein June 28, 1960 Binford Dec. 27, 1960 FOREIGN PATENTS Germany Feb. 6, 1923

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