US 3374746 A
Description (OCR text may contain errors)
United States Patent Ofiice 3,374,746 Patented Mar. 26, 1968 This invention relates to improved hydraulically operated subsurface motor and pump combination.
Hydraulically operated subsurface pumps are used in some oil wells in lieu of the more common sucker rod pumps. The motor is driven by a stream of power oil pumped down the well from the surface. The motor includes a reciprocable piston and a valve arrangement which alternately directs power oil against opposite ends of the piston, thereby propelling the motor and pump parts through upstrokes and downstrokes. Exhaust power oil returns to the surface along with oil pumped from the well. My earlier Patent No. 2,191,369, dated Feb. 20, 1940, shows a motor and pump combination in which the motor valves are housed entirely within the motor piston. This arrangement affords a highly practical advantage in that it avoids longitudinal passages in the walls of the motor barrel. Another of my earlier Patents No. 2,679,- 806, dated June 1, 1954, shows a motor and pump combination which embodies a similar motor, but in which the pump is single-acting and avoids longitudinal passages in the walls of the pump barrel as well as the motor barrel. The cross-sectional areas of the motor and pump parts are proportioned according to a formula which provides balanced loads on upstrokes and downstrokes.
An object of the present invention is to provide a motor and pump combination which has the advantages of those shown in my earlier patents, along with further advantages of greater capacity for a given diameter and of using lower ratios of power oil to pumped oil.
A more specific object is to provide a motor and pump combination in which the pump has two barrels and two reciprocating elements arranged in tandem and driven by a single hydraulic motor, and in which the cross-sectional areas of the parts are proportioned to provide balanced loads on upstrokes and downstrokes.
In the drawing:
FIGURES 1 and la together are a diagrammatic vertical sectional view of a motor and pump combination constructed in accordance with the present invention; and
FIGURE 2 is a diagrammatic sectional view showing a modification.
FIGURES 1 and 1a together show a conventional well casing or tubing and a power oil tube 12 which extends down the tubing, leaving an annular passage 13 therebetween. An assembly formed of a hydraulic motor 14, a spacer 15 and a pump 16 is fixed to the lower end of the power oil tube 12. A packing element 18 surrounds the assembly between the spacer 15 and pump 16 and engages the inside of the tubing 10, closing the bottom of the annular passage 13.
Motor 14 includes a barrel 19 joined at opposite ends to the power oil tube '12 and spacer 15. Upper and lower cylinder heads 20 and 21 are fixed to the respective ends of the motor barrel. A reciprocable piston 22 is housed within the motor barrel. Upper and lower tubular piston rods 23 and 24 are attached to piston 22 and extend through the respective cylinder heads 20 and 21. Piston 22 contains a main valve and a pilot valve which are similar in construction and operation to those shown in my aforementioned Patent No. 2,191,369; hence I have not repeated the showing. The upper piston rod 23 has a plurality of inlet openings 25 for admitting power oil from the power oil tube 12 into piston 22. The lower piston rod 24 has an outlet port 26 for discharging exhaust power oil from the motor (and also oil pumped from the well) into a chamber 27 within the spacer 15. The spacer has outlet ports 28 through which this oil discharges into the annular passage 13 and thence to the surface. During a downstroke the valve within piston 22 direct the power oil to the space within the motor barrel '19 above the piston and relieve the space below to the bore of the lower piston rod 24. During an upstroke the valves reverse this relation.
Pump 16 includes an upper barrel 29 joined at its upper end to the lower end of spacer 15. Cylinder heads 30 and 31 are fixed to the upper and lower ends respectively of the pump barrel 29. The lower piston rod 24 from the motor piston 22 extends through the cylinder head 30 and is fixed to a reciprocable piston 32 within the barrel 29. Piston rod 24 has two sections 24a and 24b, which may be of different outside diameters, as hereinafter explained. Another tubular piston rod 33 extends downwardly from piston 32 through the cylinder head 31. Piston 32 has an axial passage 34 which affords communication between the bores of piston rods 33 and 24. This passage contains a traveling valve 35. The piston rod 33 has ports 36 located just below piston 32. The upper end of the pump barrel 29' has relief ports 37 beneath the packing element 18.
Pump 16 also includes a lower barrel 38 joined at its upper end to the lower end of barrel 29. The bottom of barrel 38 contains a standing valve 39. The barrel contains a reciprocable piston 40 joined to the lower end of the piston rod 33. Piston 40 has an axial passage 41 which affords communication with the bore of piston rod '33. Preferably the passage contains a second traveling valve 42. The upper end of barrel 38 has relief ports 43.
FIGURE 2 shows a modification in which the exterior of the assembly of motor, spacer and pump carries a sleeve 44 joined to the assembly opposite the cylinder head 30. The sleeve is spaced from the lower portion of the assembly, leaving an annular relief passage 45. The relief ports 37 and 43 communicate with this passage. The lower end of the sleeve is of reduced diameter and carries a packing element 46 which engages the inside of the tubing '10. This modification is particularly useful for installations in which it is necessary to use a pump of the largest possible diameter, and there is not sufficient room for a packing element at the location shown in FIG- URES 1 and 1a. In all other respects the modification is similar, hence I have not repeated the description.
In operation, power oil pumped down tube 12 propels the motor piston 22, pump pistons 32 and 40, and piston rods 23, 24 and 33 through upstrokes and downstrokes, as already explained. During an upstroke the volumes of the spaces within the two pump barrels-29 and 38 below the respective pistons continuously increase. The standing valve 39 and second traveling valve 42 open, while the traveling valve 35 closes. Thus fluid from the well is drawn into the two pump barrels. As already pointed out, exhaust power oil from the upper portion of the motor barrel 19 discharges into chamber 27 and from there into the annular passage 13. In the construction illustrated the lower section 24]) of piston rod 24 has a larger cross-sectional area than the upper portion 24a. As the larger section of the piston rod replaces the smaller section within chamber 27, additional fluid is forced from the chamber into the annular passage 13.
Durin a downstroke the standing valve 39 closes, while the two traveling valves 35 and 42 open. Fluid is forced from the two pump barrels 29 and 38, through the bore of the piston rod 33, passage 34, bore of the piston rod 24 and out port 26 into chamber 27. Exhaust power oil from the lower portion of the motor barrel 19 also discharges through port 26 into this chamber, The smaller 3 section 24b of piston rod 24 now replaces the larger section within the chamber, whereby some of this fluid remains in the chamber to occupy the increased volume thereof. The remainder of the fluid, which is a blend of fluid from the well and exhaust power oil, discharges through ports 28 into the annular passage 13.
The lower traveling valve 42 is not essential in normal operation, since it opens on both strokes. However, I prefer to include it, as it increases the pumping efliciency for gassy or highly volatile well fluids. It isolates any gas which has been set free in piston 40, piston rod 33 and pump barrel 29 and prevents this gas from entering the lower pump barrel 38. Thus there is a better chance of I filling the lower pump barrel with oil during each upstroke. Under gassy conditions valve 42 does not open during an upstroke until pressure above the valve is reduced to the intake pressure.
To attain a balanced load on upstrokes and downstrokes it is necessary that a number of critical diameters and cross-sectional areas be properly proportioned. These diameters and areas are as follows:
D and A outsidediameter and cross-sectional area respectively of piston rod 23;
D and A outside diameter and cross-sectional area of the'upper section 24a of piston rod 24;
D and A outside diameter and cross-sectional area of the motor piston 22;
D and A outside diameter and cross-sectional area of the upper pump piston 32;
D and A outside diameter and cross-sectional area of the lower section 24b of piston rod 24;
D and A outside diameter and cross-sectional area of the lower pump piston 40; and 7 D and A outside diameter and cross-sectional area of piston rod 33.
The foregoing designations are indicated on FIGURE 1.
During a downstroke the effective area on which the power oil acts is A the total cross-sectional area of the motor piston 22, since the power fluid acts downwardly against the top of piston rod 23, aswell as against the actual end of the piston. The displacement area from the motor 14 is A minus A the cross-sectional area of the motor piston 22 less that of the section 24a of piston rod 24. The displacement area from the upper pump barrel 29 is A, minus A the cross-sectional area of the upper pump piston 32 less that of piston rod'33. The displacement area from the lower pump barrel 38 is A the crosssectional area of the lower pump piston 40. The displaceferences between the cross-sectional areas of the two 'secment area is also diminished by A minus A the diftions 24a and 24b of piston rod 24.
During an upstroke the effective area on which the power'oil acts is A minus both A and A the crosssectional area of the motor piston 22 less the cross-sectional areas of both piston rod 23 and the upper section 24a of piston rod 24. The power oil in tube 12 continues to act downwardly on the topof rod 23, thus diminishing the effective piston area 'by this further area A besides the loss caused by the presence of the piston rod 24. The displacement area from the motor is A minus A the cross- 7 sectional area of the motor piston 22 less that of piston rod 23. The pump itself offers no displacement area, but the effective area is increased by A minus A the difference between the cross-sectional areas of the two sections 24a and 24b of piston rod 24.
To attain a balance, the ratio of power piston area to e displacement area must be the same during both down- A3-A1+ (A5'1lg) in which the quantity at the left represents the ratio during a downstroke and the quantity at the right the ratio' during an upstroke. One example of dimensions which furnish a balanced load is as follows:
D =1.375 in. A =1.48 sq. in. D =.l.7S0in. A =2.41 sq. in. D =3.750 in. A '=1l.05 sq. in.. D =3.750 in. A =11.05 sq. in. D =3.02 in. A =7.15 sq. in. D =3.750 in. A =11.05 sq. in. Dq=2.226 in. A =3.89 sq. in.
Volume discharged by motor during an upstroke =A A stroke length=9.57 stroke length.
Volume discharged by motor during a downstroke =(A -A stroke length=8.64 stroke length.
Total motor displacement per cycle =(9.57+8.64) stroke length=18.21' stroke length.
Volume discharged by pump per cycle (A,A7+A6) stroke length=18.21 stroke length.
From the foregoing description it is seen that my invention affords a fully balanced, high capactiy hydraulically operated pump which requires a minimum volume of power oil. It should be pointed out that the present showing is strictly diagrammatic and that the actual parts of the combination are constructed like corresponding parts shown in FIGURES 2 to 2d ofmy aforementioned Patent No. 2,679,806, with the addition. of the second pump barrel and piston. V
While I have shown and described certain preferred embodiments of my invention, it is apparent that other modifications may arise. Therefore, I do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.
1. In a hydraulically operated subsurface motor and pump combination, the motor of which includes a barrel, cylinder heads at the ends of said barrel, a Ieciprocable piston within said barrel, and tubular upper and lower" piston rods attached to said .piston and extend ing through said cylinder heads, an improved pump spaced below said motor and comprising upper and lower pump barrels arranged in tandem, cylinder heads fixed to the upper and lower ends a of said upper .pump barrel, a standing valve carried by' said lower pump barrel at its lower end, respective upper and lower reciprocable elements within said' pump barrels; the lower piston rod' of said motor being attached to said upper reciprocable element, and a travel ing valve in said upper reciprocable element, said com- =bination including a spacer connecting the barrel of said motor and said upper pump barrel and through which the lower piston rod of said motor extends, said thirdnamed piston rod having a port for fluid to enter and leave said upper pump barrel, the lower piston rod of 1 said motor having a port for discharging fluid from said motor and pump into said spacer, said spacer having a port for discharging fluid from the combination, the cross-sectional areas of the parts of said motor and pump being proportioned to provide the same ratio of power piston area to displacement area on both upstrokes and downstrokes of said piston and reciprocable elements,
thereby achieving a balanced load.
2. A combination as defined in claim 1 in which the parts are proportioned according to the formula:
. A, Y a 2)+( 4- 1)+ G( 5 2) wherein A is the cross-sectional area of the upper piston rod of said motor, A the cross-sectional area of the upper portion of the lower piston rod of Said motor, A the cross-sectional area of said motor piston, A, the cross-sectional area of said upper reciprocable element, A; the cross-sectional area of the lower portion of the lower piston rod of said motor, A the cross-sectional area of said lower reciprocable element, and A, the crosssectional area of said third-named piston rod.
3. A combination as defined in claim 2 in which the ratio of power oil to operate said motor to pumped fluid from a well is aproximately 1 tol.
4. A combination as defined in claim 1 in which said pump further comprises a second traveling valve in said lower reciprocable element.
5. A combination as defined in claim 1 in which said combination includes a packing element on the outside of said spacer.
6. A combination as defined in claim 1 in which said combination includes a sleeve carried by said spacer and extending downwardly therefrom in spaced relation to said pump, and a packing element carried by said sleeve below said pump.
References Cited UNITED STATES PATENTS 2,679,806 6/1954 Chenault 103-46 2,813,489 11/1957 Deitrickson 103-46 ROBERT M. WALKER, Primary Examiner.
UNITED sTATEs PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,374,746 March 26, 1968 Roy L. Chenault It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:
Column 2, line 5, "valve" should read valves Column 3, lines 49 to 52, cancel "The displace-ferences between the crosssectional areas of'the two secment area is also diminished by A minus A thediftions 24a and 24b of piston rod 24." and insert The displacement area is also diminishedby -A minus A the differences between the cross-sectional areas of the two sections 24a and 24b ofm-pistonrodm24h 4 Column 4 line 19 "=A -A should read =(A -A Signed and sealed this 29th day of July 1969. (SEAL) Attest:
Edward M. Fletcher, Jr. J
Attesting Officer Commissioner of Patents