US3150596A

US3150596A - Free piston well pump device

Info

Publication number: US3150596A
Application number: US144231A
Authority: US
Inventors: Donald G Knox
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-10-10
Filing date: 1961-10-10
Publication date: 1964-09-29
Anticipated expiration: 1981-09-29

Description

Sept. 29, 1964 D. e. KNOX FREE PISTON WELL PUMP DEVICE F l G. 3.

DONALD s. KNOX INVENTOR.

ATTORNEYS.

mx wdw w. -l{l M A z 1/ Jl lZ IIV/l/l/ V J 5 .1 4 F niuwmanuww4mmr e o M .l o w 2 m w 2 F I AW I V 0 I aw W 3/ 2 w m w m3 m m United States Patent 3,150,596 FREE PISTON WELL PUMP DEVICE Donald G. Knox, Box 458, Rolling Hills, Calif. Filed Oct. 10, 1961, Ser. No. 144,231 7 Claims. (Cl. 103-52) This invention relates to a free piston pump apparatus for raising fluid from a well by means of fluid pressure acting on said piston which travels the length of the eduction tube. This invention is more particularly directed to improvements in devices of the type shown in my Patent No. 2,642,002 dated June 16, 1953.

One of the difficulties encountered in the operation of these pumping devices is the frequent inability of the free piston or plunger to reach the bottom of the well with sufficient speed. This is especially true at depths of 10,000 feet or more. The plunger is required to descend in the eduction tube under the forces of gravity. However when a high viscosity well fluid is encountered, the plunger may descend so slowly that it may not make the required cycles per day to obtain maximum production. The result is a reduction in amount of formation fluid raised to the surface.

It is the principal object of this invention to provide a free piston pumping device employing a novel form of weighted element or sinker bar to aid the free piston or plunger in descending in the eduction tube through high viscosity well fluid.

Another object is to provide such a Weighted element with an external helical fin to promote rapid descent of the plunger through such well fluid.

It is more specifically an object of this invention to provide a free piston pumping device having a weighted element which can be articulated to allow its easy passage through sections of the eduction tube which are not straight, said element being of suflicient mass to speed the descent of the piston in a highly viscous fluid medium.

It is also the object of this invention to provide a free piston with a Weighted element so that the piston can descend against a large volume of gas, such as in freecycling both in oil and gas wells Other important features and advantages which are believed to be novel are set forth in the appended claims. The invention itself, and further advantages thereof, may be more readily understood when read in connection with the accompanying drawings, in which:

FIGURE 1 is a partial sectional side elevation of a well installation having an eduction tube and an improved embodiment of the free piston device therein.

FIGURE 2 is a partial sectional side elevation of the free piston or plunger taken substantially along line 22 of FIGURE 1.

FIGURE 3 is a sectional plan view of the sinker bar taken along line 33 of FIGURE 2.

Referring now to the drawings, the free piston assembly generally designated is positioned within a sectional eduction tubing 11 which extends into a well bore 12. The bore may be provided with the usual casing 13. Gas under pressure may be admitted through valve 14, if desired to supplement formation gas, and passes downwardly in the annulus 15 between the casing 13 and eduction tubing 11 and acts upon the well fluid 16 causing it to pass upwardly into the footpiece assembly 17 at the bottom of the eduction tubing 11. The well fluid 16 is thereby caused to rise up the eduction tubing. The free piston assembly 10 descends by gravity in the eduction tubing until it strikes the bumper 18 supported by the spring 19 in the footpiece assembly 17. A valve in the piston assembly closes and the gas pressures below it causes it to move upwardly through the eduction tubing, raising a load of well fluid above it.

3,150,596 Patented Sept. 29., 1964 ice The well fluid thus raised is discharged through restriction valve 20 attached to the bumper housing 21.

When the free piston assembly or plunger 10 moves upward into the bumper housing 21, reaching the upper limit of its movement, a mechanical valve opener (not shown) is received within the central bore 22 of the plunger 10, striking the valve element 23, moving it downwardly to open the valve. The plunger 10 is then free to make another descent through the eduction tubing 11. A locking pin 24 with a spring 25 is provided to hold the valve in the open or closed position as said pin engages one or the other of annular grooves 26 in valve stem 27. The magnitude of the force supplied by spring 25 is not heavy, and the locking pin 24 is easily disengaged from the grooves 26 by an axial force applied to said valve element 23.

This piston assembly 10 has a body 28 which houses the valve 23 and which has a number of inlet passages 29 communicating with the central bore 22 adapted to be closed off by said valve. The upper portion of the piston body may also be provided with expansible ring segments 30 to form a sealing contact with the eduction tubing. To the lower edge of the piston body 28 is threadably attached a connector 31 having a bore 32 which receives valve stem 27. The upper portion of connector 31 has a shoulder 33 which supports valve 23 when the same is in the open position as shown in FIG- URE 2.

To the lower portion of connector 31 is threadedly attached an extension tube 34 having a central cavity 35 adapted to receive a rod 36 having an enlarged head 37. The upper portion of rod 36 is slidably positioned in bore 32 and is adapted to abut the lower end of the valve stem 27 to disengage the valve from its open position when said rod 36 is moved upward. A coil spring 38 is positioned in central cavity 35 to maintain the rod 36 normally in the downward position so that it is spaced from the valve stem 27.

A sinker bar 39 is attached to the lower end of extension tube 34 by a flexible or articulated coupling 40. The flexible coupling is provided to allow the free piston assembly to bend in the event the eduction tubing 11 is not straight. The top portion of sinker bar 39 has an interior cavity 41 receiving a coil spring 42, the top of which provides upward support for rod 36 as it abuts head 37. The sinker bar 39 is normally longer than the plunger body 28.

The lower portion of sinker bar 39 has an axial bore 43 receiving the push rod 44 which projects below said sinker bar 39 at 45 and has an enlarged head 46 at the other end thereof. The spring 42' is supported by this head 46. The exterior dimension of sinker bar 39 is made smaller at 47 to facilitate the descent of the free piston through the viscous well fluid. A helical fin 43 is provided on this smaller diameter section and extends substantially the length thereof. The purpose of the helical fin 48 is to impart to the free piston assembly a rotating motion as it descends in the eduction tubing. This rotating motion, together with the increased weight of the assembly, allows the piston to fall more rapidly through the highly viscous well fluid which is often encountered. When the piston reaches the bottom of the well the projection 45 of push rod 44 strikes the bumper 18. The force is transmitted up the rod 44 compressing spring 42 until it pushes on head 37, whence rod 36 travels upward striking valve stem 27, disengaging the lock pin 24 from the upper groove 26 and the valve seals the bottom of central bore 22. The lock pin engages lower groove 26 holdingthe valve shut. The gas pressure below it then forces the plunger 10 upward carrying a load of well fluid above it to the surface.

While particular embodiments of the present invention have been shown and described it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. In a free piston pumping device for use in a well tubing, the combination of: a plunger having a passage therethrough closed by an upward closing valve, the plunger having a body provided with means for slidably contacting the interior of the tubing, whereby the plunger may be raised in the well tubing by fluid pressure below it, a sinker bar fixed against axial movement relative to the body and extending downward therefrom, and a helical fin on the sinker bar.

2. In a free piston pumping device for use in a well tubing, the combination of: a plunger having a passage therethrough closed by an upward closing valve, the plunger having a body provided with means for slidably contacting the interior of the tubing, whereby the plunger may be raised in the well tubing by fiuid pressure below it, a sinker bar, and means attaching the upper end of the sinker bar to the lower end of the body, said means permitting universal tilting movement of the sinker bar relative to the body.

3. In a free piston pumping device for use in a well tubing, the combination of: a plunger having a tubular body provided with a passage extending therethrough, upward closing valve means in the body for closing said passage, sealing means on the plunger slidably engageable with the well tubing, whereby the plunger may be raised in the well tubing by fluid pressure below it, a sinker bar fixed against axial movement relative to the body and extending downward therefrom, and a helical fin on the sinker bar.

4. In a free piston pumping device for use in a well tubing, the combination of: a plunger having a tubular body provided with a passage extending therethrough, upward valve means on the body for closing said passage, sealing means in the plunger slidably engageable with the well tubing, whereby the plunger may be raised in the well tubing by fluid pressure below it, a sinker bar, means attaching the upper end of the sinker bar to the lower end of the body, said means permitting universal tilting movement of the sinker bar relative to the body, and means including an element extending through the interior of the sinker bar for closing said valve means.

5. In a free piston pumping device of the class having a plunger provided with a valve and adapted to travel from the lower end of an eduction tube to a well head, the combination with said plunger of: a valve actuating means, a sinker bar having a central cavity adapted to receive the valve actuating means, means for attaching the sinker bar to the plunger, means resiliently supporting said valve actuating means in said cavity, said valve actuating means having a portion thereof projecting below said sinker bar, said sinker bar having an external helical fin.

6. In a free piston pumping device of the class having a plunger provided with a valve and adapted to travel from the lower end of an eduction tube to a well head, the combination with said plunger of: an extension tube fastened to said plunger and having an axial bore, a valve actuating rod received in said bore, resilient means supporting the valve actuating rod, a sinker bar fastened to said extension tube by a flexible coupling, said sinker bar having a central cavity in the upper portion thereof and an axially extending bore communicating therewith, a resilient supporting member received in said central cavity and abutting said valve actuating rod, a push rod positioned in said axially extending bore and projecting into said central cavity and abutting said resilient member, the lower portion of said push rod projecting below said sinker bar, and said sinker bar having an external helical fin.

7. In a free piston pumping device of the class having a plunger provided with a valve and adapted to travel from the lower end of an eduction tube to a well head, the combination of: a plunger body having a valve therein, an extension tube attached to said body and having an axial bore, a valve actuating rod slidably mounted in said bore and positioned to abut the stem of said valve, said actuating rod having an enlarged lower head, a resilient member supported on said head and positioned between the bottom of said body and said head, a sinker bar attached to said extension tube and having a central cavity communicating with the bore of said extension tube, a second resilient member positioned in said cavity and abutting the lower side of the aforementioned head, an axial bore in said sinker bar communieating with said cavity and having a push rod positioned in said bore having an enlarged upper head supporting said second resilient member, said push rod projecting below the said sinker bar, said sinker bar having a lower cylindrical portion the diameter of which is less than that of said extension tube, and a helical fin on said lower cylindrical portion extending substantially the entire length thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,516,479 Strong Nov. 18, 1924 1,943,533 Ricker Jan. 16, 1934 1,947,587 Fletcher Feb. 20, 1934 2,172,636 Coberly Sept. 12, 1939 2,267,902 Eddins Dec. 30, 1941 2,642,002 Knox et al. June 16, 1953 2,970,547 McMurry Feb. 7, 1961 3,044,414 Chancellor et al. July 17, 1962