US2985112A - Liquid pump assembly - Google Patents

Description

May 23, 1961 R. c. HENRY LIQUID PUMP ASSEMBLY eum l m n 4W United States Patent() F LIQUID PUMP ASSEMBLY Robert 'C. Henry, 14572 Jefferson St., Midway City, Calif.

Filed July 21, 1959, Ser. No. 828,588

Claims. (Cl. 10S-184) The present invention relates to liquid pumps and more particularly to an improved double check valve type pump featuring a liquid trapping chamber below the usual inlet check valve and provided with a check valve at its inlet end for automatically trapping a quantity of liquid during the downward stroke of the pump plunger and for forcibly transferring the trapped liquid into the pump chamber during the upward stroke of the plunger.

Serious operating problems are encountered particularly under low-head operating conditions in introducing a suitable quantity of liquid into the pumping chamber. The difficulties are especially serious in deep wells, such as oil wells, where it is desirable to maintain the annulus under a partial vacuum to facilitate liquid flow into the well bore. Further adding to the diiculties is the presence in some subterranean flows of constituents which gasify when relieved of the high pressures present before the ow issued from the earth formation into the well bore. The presence of gas in the lower chamber of conventional plunger-type pumps can seriously impede if not prevent the opening of the inlet check valve. This is because such gas becomes compressed under very considerable pressure during the downward stroke of the plunger and remains trapped upon the closing of the upper check valve as the plunger starts its upward stroke. Elevation of the plunger allows the trapped compressed gas to expand but if any appreciable volume of trapped gas is present, the permitted expansion may be insufficient to permit opening of the inlet valve. Under these conditions, the pump becomes totally inoperative until such time as the trapped gas is vented or the liquid head in the annulus increases sutliciently to overcome the gas pressure in the pumping chamber and permit opening of the inlet check valve. Under stripper operating conditions there is no possibility of any material rise in the liquid head and it is impossible to pump the well.

Numerous attempts have been made to provide pumps not subject to the foregoing and other shortcomings and which will continue in operation with low liquid heads and either with or without a partial vacuum on the annulus to aid liow into the well. However, these attempts have fallen far short of desirable objectives.

With the foregoing disadvantages and shortcomings of prior' pumps in mind it is an object of the present invention to provide a pump not subject to any of the above mentioned and other disadvantages of prior pumps and which operates at high efficiency irrespective of the use of a partial vacuum to induce ilow into the well, and with liquid heads on the pumping chamber appreciably below those conceivably adequate for the operation of prior plunger type pumps.

The pump of this invention achieves these objectives by the provision of a liquid trapping chamber carried by and disposed below the plunger of a conventional type pump and operable to ill automatically with liquid during downward movement of the plunger. A simple lightweight check valve opens readily to admit the liquid dur- Patented May 23, 1961 ICC ing the downstroke but closes instantly at the end of this stroke. Elevation of the liquid trapping tube forcibly unseats the check valve carried at the lower end of the pumping chamber maintaining this expanding chamber completely filled to capacity throughout the upstroke of the pump plunger. As a result the upper check valve carried by the plunger is forced to open position irnmediately upon the start of the downstroke.

This described action characteristic of the pump of this invention takes place irrespective of the presence or absence of gas in the trapped liquid. Furthermore, assurance is provided that the pumping chamber is filled to capacity during each operating stroke of the pump even though the liquid level in the well is no higher than the inlet ball valve.

Accordingly, it is a primary object of the invention to provide an improved plunger-type pump not subject yto the serious limitations and shortcomings of prior designs.

Another object of the invention is the provision of a plunger type pump designed to operate at full eiiciency with much lower liquid heads than are feasible with prior pump constructions. e

Another object of the invention is the provision of a deep well stripper pump provided with a plurality of check valves arranged in series axially of the pump and cooperable tocompletely fill the pumping chamber during each `upward* stroke of the plunger whereby, upon downward movement of the plunger, this trapped liquid is forced past the plunger valve in readiness for elevation to the top of the well during elevation of the plunger.

Another object of the invention is the provision of a stripper type pump designedto operate at full eiiciency irrespective of the degree of vacuum desired in the annulus to facilitate ow from the formation.

These and other more specific objects will appear uponl reading the following specication and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated.

Figure l is a longitudinal sectional view through a well and showing the pump of the present invention in a typical installation, parts of the pump being broken away to show interior details;

Figure 2 is a longitudinal sectional view on an enlarged scale through the pump but showing the length of the tubular components shorter than employed in actual practice, the positions of the valves being those occupied during the upstroke; and

Figure 3 is a view similar to Figure 2 but showing the position of the various valves during the downstroke of the plunger. i

Referring now more particularly to Figure l, there is shown by way of example one particularly suitable application of the pump constituting the present invention, the pump proper vbeing designated generally 10. Pump 10 would normally be firmly anchored, as by any suitable conventional pump shoe 11, to the lower end of an upper riser tube 12 extending substantially the entire length of Well bore 13. At least the upper end of the well bore is provided with a liner or casing 14 which projects above ground level and terminates in any suitable Christmas tree structure designated generally 15.

This structure seals the top of the well bore and includes a combined bushing and packing lstructure 17 having slidably mounted vertically therein a pump rod 18, the latter being arranged to be vertically reciprocated as by the Well known walking beam structure 20 pivotable about fulcrum 21 and driven by a crank and any suitable source of power. Extending laterally from the upper end 3 Y of riser 12 is a liquid discharge tube 23. Casing 14 includes a tubular connection 24 connected to any conventional auxiliaries for maintaining a desired vacuum pressure within well `annulus 25, and effective to facilitate the flow of liquid from the formation into the well.

InV a typical deep Well installation, pump assembly may be as long as 25 to 30 feet, although it will be understood that the principles of the present invention are equally applicable to constructions of much shorter length. In fact, the present pump design would be equally as effective for certain purposes if made with an overall length of a few inches. The main body and the sole stationary main component of the pump assembly comprises a barrel or lower riser tube 38 having its upper end firmly anchored and sealed to the lower end of riser 12, as by a pump shoe 11. The lower end of riser tube v3i) is provided with a high strength ring 31 having a spherical seat 32 for a ball check valve 33.

A plunger tube 35 has a close sliding tit with the interior of riser 3) and is suitably connected at its upper end to pump rod 18. Mounted in the lower end of riser tube is a high strength ring 36 formed with a spherical seat 37 for a ball check valve 38.

A liquid trapping tube 40 forms an important feature of the invention and its upper end has a close and fluid-tight sliding tit with the lower end of riser tube 3). One highly effective manner of reciprocating trapping tube 40 concurrently with plunger is illustrated in Figures 2 and 3. To this end, diametrically opposed walls of riser 30 `are provided with elongated slots 39 which accommodate radially disposed driving pins 41 rigidly secured to tube 4t), as by welding or riveting, and having their inner ends extending into an annular groove 42 formed in the exterior wall of plunger 35. It will be understood that reciprocal movement of plunger 35 operates to reciprocate liquid trapping tube 40. Plum-ger 35 and tube 4t) are so arranged and constructed as to coopera-te in preventing the escape of liquid being pumped through slots 39. It is also pointed out that the lengths of tubes 35 and 4d are of sufficient length to extend well beyond the opposite ends of slots 39 in all operating positions of the pumpy components as to prevent the leakage of liquid past the interface between the contacting surfaces of these tubes.

It is further pointed out that although liquid trapping tube is here shown as disposed in sliding contact with the exterior of riser tube 30 it is entirely feasible to support its upper end interiorly of an extension of barrel 38 below check valve 33. In such an arrangement the exterior of tube 48 would have sliding contact with the interior of the extended riser -tube 3). A suitable mode of connecting tube 4d for reciprocation with plunger 35 would include two or more connector rods extending vertically through close fitting openings in valve seating ring 31 and having their opposite ends connected respectively Ato the lower end of plunger 35 and to the upper end of tube 40.

Liquid trapping tube 481 extends sufficiently below check valve 33 as to have an internal liquid capacity equal to or of its components. Let it be assumed that at the start of operation, plunger 35 is at the upper end of its stroke in readiness to start the downstroke, as in Figure 3. While the plunger remains stationary in this position, it will be clear that each of the ygravity-closed check valves, including ball valves 33 and 38 and ap valve 45, will be closed against their respective seats. -It will also be apparent that the entire length of the pump and of the overlying riser tube 12 will be completely lled with liquid.

Let it now be assumed that plunger 35 starts to move downwardly carrying with it the liquid trapping tube 40. Check valve 33 Vvwill obviously Vremain rmly seated but the liquid trapped thereabove in pumping chamber 44 will lift upper valve 38 from its seat to permit liquid from chamber 44 to pass valve 38. Simultaneously therewith, downward movement of tube 48 will cause valve 45 to be lifted or pivoted upwardly away from its seat thereby allowing liquid to displace upwardly into chamber 56. It is pointed out that to fill chamber 56 it is unnecessary to reduce .the pressure in any way in this chamber, it merely being essential that the liquid level in the well be at least as high as the upper end of chamber 56. Accordingly, chamber 56 continues to fill with water throughout the downward stroke of the plunger leaving this chamber completely filled at the end of the downward stroke.

Referring now to Figure 2 showing the position of the parts during the -upstroke of pump rod 18, it is pointed out that at the instant the upward stroke starts each of valves 32, 38, 45 and 50 will be firmly seated. A moment after the start of the upstroke, the elevation of tube 40 carrying with it liquid-filled chamber 56 will result in this liquid forcibly lifting lower ball valve 33 from its seat as the liquid is transferred from chamber 56- into in excess of the capacity of pumping chamber 44 located y Vybetween check valves 33 and 38. The lower endV of tube 40 is provided with any simple, lightweight check valve 45 having a supporting arm 46 pivotally connected at 47 toV a suitable support. Valve 45 closes 'againstV a seat 48 formed in a sleeve 49 having a close sliding iit with tube 40. The skirted upper end 58 is normally held pressed against a iixed stop ring 51 by a spring 52 held in assemi Theoperation of the described pumping assembly willV be quite apparent from the foregoing detailed description pump chamber 44. Meanwhile, upper valve 38 remains seated under the pressure of the overlying liquid column with the result that this liquid is elevated by plunger 35 and discharged in part from outlet tube 23.

Since the volumetric capacity of chamber 56 is slightly greater than that of chamber 44, ,in the embodiment illustrated, it is not possible to transfer all of this liquid to chamber 44 without unseating valve 38. It is undesirable to unseat valve 38 in deep well pumping operations because of the very high pressure imposed on valve 38 by the overlying liquid'co'lumn and to provide for the opening of valve 38 during the upstroke would require heavy-duty connections between plunger 35 and the uppper end of tube 40. To avoid these undesirable requirements, it is preferred'to provide the pressure relief valve 50 urged closed by spring 52. so designed as to permit escape of liquid from chamber 56 through ports 54 to the well bore upon an increase in pressure in chamber 56 over and above that required to accomplish the emcient transfer of liquid to pumping chamber 44. The strength required in spring 52 will be understood to differ widely under diierent operating conditions and is somewhat greater than that required to unseat valve 33 but far less than that required to unseat valve 38. VFor example, a spring strength of 40 to 5i) pounds is found to give Vvery satisfactory results when pumping a well of medium depth. Under normal operating conditions with steady upward movement of pump rod 18, it will be recognized that skirt 50 is depressed slightly to bleed small increments of the Vtrapped'liquid through relief ports 54 while maintaining Vcontinuous flow conditions into pumping chamber 44.

lf gas is present in the liquid being pumped this circumstance intereferes in no material way with the etiicient operationof the pump. Thus, gas present in either chamber 56 or'44 simply remains there temporarily until the next pumping Vstroke when it is transferred along with liquid to the next higher chamber. it will be equally apparent that the presence of Ya vacuum in'any degree within the well bore has no influence on the operation of the present pumprand that so long as liquid is present up to the level of valve seating ring 31 or above, trapping chamber 56 un'll be filled to capacity during each downward stroke making it possible to 4till pumping chamber 44 to capacity despite the fact this chamber may be substantially entirely above the liquid level in the well bore.

While the particular liquid pump assembly herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

l claim:

l. In a liquid pump of the type comprising a barrel adapted to be connected at its outlet end to a liquid discharge tube leading to a point of discharge and supporting a iirst upwardly opening check valve at its lower end, a plunger tube concentric with said barrel slidable axially thereof and supporting a second upwardly opening check valve therein, means for reciprocating said plunger along said barrel; that improvement which comprises, a tubular member concentric of and exterior to said barrel, means interconnecting said tubular member and said plunger to reciprocate the one with the other, and a third upwardly opening check valve mounted on said tubular member at a level spaced below said rst mentioned check valve and effective during lowering of said plunger to open allowing liquid to flow into said tubular member and to be trapped therein by the closing of said third check valve at the end of the downward movement of said plunger, whereby upon upward movement of the plunger liquid trapped above said third check valve is forced past said second check valve into the chamber between said rst and second check valves.

2. In a pump assembly of the type comprising a riser tube for conveying pumped liquid to a point of discharge and having a irst check valve at its inlet end, a plunger tube having a sliding fit axially and interiorly of said riser tube and spaced inwardly from said rst check valve and having a second check valve intermediate the opposite ends of said plunger tube; that improvement which comprises, a liquid trapping tube in alignment and in sealing engagement with said riser and plunger tubes, said liquid trapping tube extending beyond the inlet end of said riser tube and having an inwardly opening check Valve operable to admit liquid thereinto during movement of the plunger in one direction and -to trap liquid for transfer beyond said first check valve upon movement of said plunger in the opposite direction, and means for reciprocating said plunger and liquid trapping tubes in unison axially of said riser tube.

3. A pump assembly as defined in claim 2 characterized in that said first and second check valves comprise ball valves and in that said inwardly opening check valve in said liquid trapping tube is a flap valve opening readily upon initial movement of the liquid trapping tube in a direction to trap liquid to be pumped.

4. A pump assembly as dened in claim 2 characterized in the provision of pressure responsive relief valve means for bleeding excess liquid from said liquid trapping tube in an amount not readily accommodated in the chamber of said pump assembly located between said first and second check thereof.

5. A liquid pump assembly suitable for use in deep wells having a low liquid head relative to the pump assembly, said pump assembly being of the type having a riser tube slidably supporting a plunger tube therewithin provided with a check valve and having a stroke terminating short of an inlet check Valve mounted inwardly of the inlet end of said riser tube; said pump assembly being characterized by the provision of a tubular extension attached to and movable with said plunger tube and disposed on the opposite side of said inlet check valve from said plunger tube, and check valve means carried at the inlet of said tubular extension operable to admit liquid thereinto during movement of said tubular extension in one direction and to trap liquid against reverse ow when said tubular extension moves opposite to said one direction.

6. A pump assembly as dened in claim 5 characterized in that said tubular extension is slidable in sealing engagement with one of the cylindrical surfaces of said riser tube and having a major portion of its length extending beyond the inlet end of said riser tube.

7. A pump assembly as defined in claim 5 characterized in that the interior wall surface of said tubular extension has sliding fluid-sealing contact with the exterior wall surface of said riser tube and having a major portion of its length extending beyond the inlet end of said riser tube.

8. A pump assembly as defined in claim 7 characterized in that said riser tube has a plurality of slots extending lengthwise through the walls thereof and terminating short of the opposite ends of the operating stroke of said plunger tube, and being further characterized in that the attachment between said plunger tube and said tubular extension comprises rigid means extending through said slots and engaged with said plunger and with said tubular extension to reciprocate the latter in unison with the plunger tube.

9. A pump assembly as dened in claim 5 characterized in that said tubular extension includes a pressure relief valve operable to release liquid therefrom automatically when the liquid pressure within said tubular extension exceeds a predetermined value.

1i). A stripper pump assembly suitable for use in liquid wells having a liquid head on the pump inadequate for the effective operation of a conventional double check valve type reciprocating plunger pump, and of the type having a check valve-carrying plunger tube reciprocably supported within and above the lower end of a liquid riser tube having an inlet check valve at its end, said stripper pump being characterized by the provision of a liquid trapping tube having an operating connection with said plunger tube and having its inlet end extending downwardly below the inlet valve of said riser tube and having a sliding iiuid seal therewithin, said liquid trapping tube being operable to discharge trapped liquid through said inlet check during upward movement of Vsaid plunger tube and having an inwardly opening check valve adjacent its lower inlet end for admitting liquid thereinto during reverse movement of said plunger tube.

No references cited.

UNITED STATES PATENT OEEICE CERTIFICATE OF CORRECTION Patent Noe 2,985,112. May 23, 1961 Robert Co Henry It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5,7 line 1.63, after "check'" insert valves Signed and sealed this 14th day of November 196] 0 (SEAL)l Attest:

Attesting Officer Commissioner of Patents USCOMM-DC

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