US3397643A - Submerged motor reciprocating well pump - Google Patents

Description

Aug. 20, 1968 H. E. JEPSEN SUBMERGED MOTOR RECIPROCATING WELL PUMP Filed March 13, 1967 llnhliiiiifi TL 4 17% l a? P.

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I ul H INVENTOR. BY M ,4 r roe/v5 Y5 United States Patent 3,397,643 SUBMERGED M0 CR RECIPROCATING WELL PUMP Henry E. Jepsen, 10902 S. La Serna Drive, Whittier, Calif. 90604 Filed Mar. 13, 1967, Ser. No. 622,492 8 Claims. (Cl. 10346) ABSTRACT OF THE DISCLOSURE A submersible electric motor-screwshaft driven reciprocable pump having single inlet and discharge ports, a charging chamber and a pumping chamber so related that the load is approximately equal during both strokes of the pump.

Summary of invention Typical prior art directed to submersible motor oper ated reciprocable well pumps is represented by the fol lowing patents: Scharpenberg, 1,428,300; Schmidt, 1,736,094; Arutunolf, 2,377,743.

The present invention is intended to eliminate some of the problems previously encountered in the operation of well pumps of this type; accordingly, the objects of this invention include:

First, to provide a reciprocable well pump wherein the drive motor is subjected to an essentially uniform load; that is, the load is substantially the same during the up-stroke of the pump and during its down-stroke. This is accomplished by drawing well fluid into a charging chamber while simultaneously discharging a like quantity of well fluid from a pumping chamber into the well tubing during the up-stroke of the pump; then transferring the well fluid from the charging chamber to the pumping chamber against the back pressure of well fluid in the well tubing during the down-stroke of the pump.

Second, to provide a screwthread-traveler nut drive means contained within a chamber which is isolated from the well fluid, but which is subjected to well fluid pressure so as to maintain essentially zero pressure difference across the sealing means through which the operating shaft of the drive means extends for connection to the pump.

Description of figures FIGURE 1 is a fragmentary view, partially in elevation and partially in section, showing the lower portion of the well pump.

FIGURE 2 is a fragmentary, partial elevational, partial sectional, view thereof, continuing from FIGURE 1 and showing the upper portion of the well pump, with the parts in the position assumed at the beginning and during the up-stroke.

FIGURE 3 is a fragmentary, partial elevational, partial sectional view, corresponding to FIGURE 2, but showing the parts in the positions assumed at the beginning and during the down-stroke of the pump.

FIGURE 4 is a transverse sectional view, taken through 44 of FIGURE 1.

FIGURE 5 is an enlarged fragmentary sectional view, taken within Circle 5 of FIGURE 1.

FIGURE 6 is an enlarged fragmentary sectional view, taken within Circle 6 of FIGURE 3.

FIGURE 7 is an enlarged fragmentary sectional view, taken within Circle 7'of FIGURE 3.

The submerged motor reciprocating well pump is joined at its upper end to a length of well tubing 1, which in turn is connected to a tubing string, not shown. The well tubing 1 is joined by a connecting fitting 2, through a pump housing structure 3, of uniform external diameter. The housing structure is joined to the upper end 3,397,643 Patented Aug. 20, 1968 of a motor unit 4, which for the purposes of this invention may be considered as conventional. The motor unit includes a gear reduction assembly, not shown, and is connected in a conventional manner to an electric cable 5, which extends upwardly along the outside of the well tubing 1, and along the outside of the tubing string above. Suitable conventional means is provided for reversing the motor periodically.

The motor output shaft, indicated by 6, is suitably connected to a thrust bearing 7, held between retainer rings 8 in the lower portion of the housing structure 3.

Extending upwardly from the thrust bearing is a drive screw 9, on which is mounted a traveler nut 10. The drive screw and traveler nut are, per se, conventional. The traveler nut is preferably of the ball bearing type to minimize friction. Secured to the upper end of the traveler nut .10 is a drive sleeve 11 which encloses the drive screw 9. A bearing 12 is provided at the top of the drive screw which maintains the drive screw and drive sleeve in coaxial relation.

The upper end of the drive sleeve 11 extends through a sealing gland 13 in the form of a restriction within the housing structure 3, containing a suitable seal ring 14, and sleeve wiper 15, as shown in FIGURE 5. The seal ring and sleeve wiper are omitted from FIGURE 1 due to the necessarily small scale of the drawing.

The upper end of the drive sleeve 11 is connected by an adapter fitting 16 to a coaxially extending pump rod 17. The adapter fitting and adjacent end of the pump rod is provided with a pressure equalizing passage 18, the upper end of which is exposed to the pressure of the surrounding well fluid and is covered by a strainer sleeve 19. The lower end of the passage communicates with the interior of a pressure equalizing bellows 20, suspended from the lower end of the adapter fitting 16.

The interior of the housing structure 3, between the sealing gland 13 and the motor 4, is completely sealed from the surrounding well fluid and is filled with a lubricating oil. The bellows not only equalize the pressure, but also to such a dimension as to compensate for the change in lubricant space within the housing as the drive sleeve 11 is extended and retracted through the sealing gland 13.

A length of the housing structure 3, above the sealing gland 13, is provided with a series of pump inlet ports 21, either covered or lined internally by a strainer 22. At the upper end of the pump inlet chamber 23 thus formed, is a constriction which forms an inlet 24 at an upwardly facing shoulder which forms a valve seat 25, above which is formed an inlet valve chamber 26, containing an inlet or standing valve 27.

The pump rod 17 projects upwardly through the inlet valve chamber 26, and through the inlet or standing valve 27. That is, the valve 27 is annular and provided internally with seal rings 28, permitting axial movement of the pump rod 17, while maintaining a seal between the pump rod and the inlet or standing valve 27.

Immediately above the inlet or standing valve chamber 26, and forming the upper wall thereof, is a collar 29. The collar is held in place by a spacer sleeve 30, which lines a section of the housing structure 3, extending above the collar. Resting on the upper end of the sleeve 30, is a top collar 31. The two collars, 29 and 31, are joined by a charging chamber sleeve 32, and the collar 29 is provided with a charging chamber inlet port 33, communicating with the interior of the sleeve 32.

The charging chamber sleeve 32 forms with the surrounding spacer sleeve 30 and housing structure 3, a surge chamber 34. The spacer sleeve 30 and housing structure are provided near the lower end of the surge chamber with a set of surge ports 35, whereas the charging chamber sleeve 32 is provided near its upper end with a set of surge ports 36.

Fitted within the charging chamber sleeve 32 is a piston 37, having a depending tubular stem 38, which is joined to the upper end of the pump rod 17. The stem 38 is provided with a transfer port 39. Formed within the piston 37 is a traveling valve seat 40, engaged by a traveling or discharge valve 41. Secured to or formed integrally with the piston 37, is an upwardly extending pumping chamber sleeve 42, which extends through the collar 31, and a suitable sealing gland, such as that shown in FIG- URE 5, surrounds the upper end of the pumping chamber sleeve.

The space within the sleeve 42 forms a pumping chamber 43, and the space between the sleeve 42 and the sleeve 32, below the piston 37, forms a charging chamber 44. The transfer port 39 communicates between the pumping chamber 43 and the charging chamber 44.

The upper portion of the housing structure 3 projecting above the collar 31, is provided with a spacer sleeve 45, which extends to the fitting 2, so that When the fitting 2 is screwed in place, the spacer sleeve 45, collar 31 and spacer sleeve 30, and collar 29, are secured in position. The space between the collar 31 and the connecting fitting 2, forms a receiving chamber 46.

The connecting fitting 2 is provided with an outlet passage 47, terminating at it upper end in a valve seat 48, which receives a backflow preventing check valve 49. Extending upwardly from the connecting fitting 2 is a perforated sleeve 50, closed at its upper end, as indicated by 51. The space betwen the sleeve 50 and the well tubing 1, forms a sand collecting or trapping chamber 52.

Operation of the submerged motor reciprocating well pump is as follows:

The motor unit 4 is adapted to rotate a predetermined number of revolutions in one direction, and then a predetermined number of revolutions in the opposite direction, by conventional control means located within the motor housing or at the discharge end of the well. Operation of the motor in this manner causes the traveler nut to reciprocate on the drive screw 9 and causes the drive sleeve 11 and pump rod 17 to reciprocate. The piston 37 and pumping chamber 42 are moved between the positions shown in FIGURES 2 and 3. During the up-stroke, that is during movement between the position shown in FIGURE 2 and the position shown in FIGURE 3, well fluid enters through the standing valve 27 and fills the charging chamber 44 below the piston 37. Simultaneously, a previous charge of well fluid is lifted by the pumping chamber sleeve 42, but remains within the sleeve.

During the down-stroke, that is movement from the position shown in FIGURE 3 to the position shown in FIGURE 2, the charge of Well fluid collected in the charging chamber 44 is delivered through the transfer port 39, and traveling valve 41, into the pumping chamber sleeve 42, displacing the previous charge of well fluid into the receiving chamber 46.

It should be noted that the effective areas of the pumping chamber 43 and charging chamber 44 are the same, and thus the load on the motor is uniform during both the up-stroke and the down-stroke.

While a particular embodiment of this invention has been shown and described, it is not intended to limit the same to the details of the construction set forth, but instead, the invention embraces such changes, modifications and equivalents of the various parts and their relationships as come within the purview of the appended claims.

I claim:

1. A reciprocable well pump, comprising:

'(a) a pumping unit including a sleeve forming a pumping chamber open at its upper end, a transfer port at its lower end, and a traveling valve above said transfer port;

(b) a charging unit including a fixed sleeve surrounding said pumping unit sleeve, and forming therewith a charging chamber communicating with said pumping chamber through said transfer port; a piston carried by said pumping unit sleeve and forming the upper end of said charging chamber; an inlet communicating with the lower end of said charging chamber; and a standing valve for said inlet located below said transfer port;

(c) and means for reciprocating said pumping chamber sleeve to cause simultaneous flow of a charge of well fluid into said charging chamber and elevation of a previous charge of well fluid in said pumping chamber during up-stroke of said pumping sleeve and simultaneous transfer of said charge of well fluid from said charging chamber into said pumping chamber and discharge of said previous charge of well fluid from said pumping chamber.

2. A reciprocable well pump, as defined in claim 1,

wherein:

(a) said charging chamber is provided above the range of movement of said piston with a surge port exposed to surrounding well fluid to permit surging flow of well fluid into the region above said piston as said piston reciprocates.

3. LA reciprocable well pump, as defined in claim 2,

which further comprises:

(a) an outer tubular shell encasing said charging chamber sleeve and secured to the ends thereof, said shell projecting axially above and below said sleeve and said inlet, the lower projecting portion of said shell being perforated for entrance of well fluid to said inlet.

4. A reciprocable well pump, as defined in claim 1,

which further comprises:

(a) a tubular means extending above said pumping unit to receive well fluid therefrom;

(b) a. check valve intermediate the extremities of said tubular means to prevent back flow of well fluid; (c) and a perforated sleeve projecting above said check valve, said sleeve forming with the surrounding tubular means and annular sand trapping chamber.

5. A reciprocable well pump, as defined in claim 1,

wherein said reciprocating means includes:

(a) a reversible and submergible electric motor;

(b) a screw shaft rotated by said motor;

(c) a traveling nut for said screw shaft;

(d) a drive sleeve secured to said traveling nut and connected to said pumping sleeve;

(e) a housing for said screw shaft, traveling nut and drive sleeve;

(f) a sealing gland through which said drive sleeve extends;

(g) yieldable means subject to pressure of the surrounding well fluid and movable to compensate for displacement of said drive sleeve as said drive sleeve reciprocates thereby to maintain the pressure within said housing essentially equal to the well fluid pressure and maintain an essentially zero pressure differential across said sealing gland.

6. A reciprocable well pump, comprising:

(a) an elongated tubular housing structure having a perforated section for admission of surrounding well fluid, and a standing valve port above said perforated section;

(b) a standing valve controlling said port;

(c) a fixed sleeve located above said standing valve for receiving well fluid passing said standing valve, said fixed sleeve being perforated adjacent its upper end for communication with the surrounding well fluid;

(d) a reciprocable sleeve within said fixed sleeve and forming a pump chamber; said reciprocable sleeve being open at its upper end and having a traveling valve port adjacent its lower end and a transfer port below said traveling valve port;

(e) a fixed sealing gland at the upper end of said fixed sleeve slidably receiving said reciprocable sleeve; (f) a piston reciprocable with said reciprocable sleeve and dividing the space between said sleeves into an upper surge chamber and a lower charge chamber; said charge chamber communicating with the interior of said inner sleeve through said transfer port;

(g) and means for reciprocating said reciprocable sleeve to cause a charge of well fluid to flow into said charge chamber, then into said pump chamber and then discharge therefrom.

7. A reciprocable well pump, as defined in claim 6,

wherein:

(a) said housing structure encloses said fixed and reciprocable sleeves and projects thereabove for connection to a tubing string;

(b) a check valve is located in the upwardly projecting portion of said housing structure;

(c) and a perforated tube extends upwardly from said check valve and forms, with the surrounding portion of said housing structure, an annular sand trap.

8. A reciprocable well pump, as defined in claim 6,

wherein said reciprocating means comprises:

(a) reversible and submersible motor joined to said housing structure beyond one end of said reciprocable sleeve;

(b) a screw shaft connected to said motor;

(c) a traveling nut reciprocal-ble on said shaft as said shaft is turned first in one direction then in the opposite direction;

(d) a drive member connected to said traveling nut and to said reciprocable sleeve;

(e) a sealing gland for said drive means, said sealing gland being fixed to said housing structure and forming with the portion thereof extending to said motor, a sealed chamber encasing said screw shaft, traveling nut and a portion of said drive means;

(f) and yieldable means for subjecting the interior of said sealed chamber to the pressure of the exterior well fluid; said yieldable means being movable to compensate for change in displacement of said drive means.

References Cited UNITED STATES PATENTS 1,830,258 11/1931 Bohnenblust 103192 2,068,729 1/1937 Basher 103-192 ROBERT M. WALKER, Primary Examiner.

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