US 3285081 A
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Nov. 15, 1966 Filed April 15, 1965 /3 /80 /8b I817 /80 I8 I80 I I80 J. P. KUHNS ETAL.
WELLPUMPING APPARATUS 5 Sheets-Sheet 1 TYPE-.- 2A.
JOHN P. MICHAEL 4 J IN l/EN 70/?8. KUHA/S an d L. R/ZZO/VE A r rorney 5 Sheets-Sheet 2 INVENTORS. JOHN P. KUH/VS and MICHAEL L. R/ZZO/VE BY )mzww Aflorney Nov. 15, 1966 J. P. KUHNS ETAL WELL-PUMPING APPARATUS Filed April 13, 1965 w M. iwrlrm M//\\ //N LP FT r o 1 w E Nov. 15, 1966 .J. P. KUHNS ETAL 3,285,081
WELL-PUMPING APPARATUS Filed April 13, 1965 3 Sheets-Sheet 5 I80 I80 I80 0 INVE/V TORS.
JOHN R KUH/VS and MICHAEL L. R/ZZO/VE Attorney United States Patent 3,285,081 WELL-PUMPIN G APPARATUS John P. Kuhns, Fort Worth, and Michael L. Rizzone,
Dallas, Tex., assignors to United States Steel Corporation, a corporation of Delaware Filed Apr. 13, 1965, Ser. No. 447,740 Claims. (Cl. 7489.22)
This invention relates to an improved long-stroke pumping unit for oil wells or the like.
A conventional beam-type pumping unit has a maximum stroke length of about 16 feet. The string of sucker rods to which the unit is connected accelerate from the beginning of each stroke to the middle and decelerate from there to the end. A stroke of greater length and uniform slower speed would be advantageous, but previous long-stroke units have been ineflicient and require an excessive number of parts and auxiliary devices. Usually they are driven by hydraulic mechanisms.
An object of our invention is to provide an improved long-stroke pumping unit which operates efficiently and is of simpler construction than the usual hydraulic type.
A further object is to provide an improved mechanically operated long-stroke pumping unit which utilizes momentum of moving parts advantageously to increase its operating efiiciency.
A more specific object is to provide a pumping unit of the foregoing type in which the weight of the sucker rod string is counterbalanced, and the power source is disconnected before the end of each stroke and connected only after the unit reverses and the next stroke is under way, relying on momentum of the parts to finish each stroke and weight distribution to start the next.
In the drawings:
FIGURES 1a and 1b together are a side elevational view of our pumping unit;
FIGURES 2a and 2b together are an elevational view of our unit taken from the right of FIGURES 1a and 1b;
FIGURE 3 is a schematic view showing the relation of the rods and counterbalance as they approach the end of a downstroke of the rods;
FIGURE 4 is a view similar to FIGURE 3, but showing the relation at end of the downstroke;
FIGURE 5 is another similar view but showing the relation approaching the end of an upstroke; and
FIGURE 6 is another similar view, but showing the relation at the end of the upstroke.
Our pumping unit includes a tower 10 which is formed of metal structural members and is of considerable height, preferably 60 feet or more. The tower has a skid base 12 at the bottom which rests on a concrete foundation 13 otfset from the center line of a well head, indicated at 14 (FIGURES lb and 2b). We attach guy lines 15 to the upper portion of the tower and suitably anchor them at the bot-tom to hold the tower in an upright position. The upper end of the tower has aligned bearings 16 in which we journal a horizontal shaft 17 otfset toward the side adjacent the Well head (FIGURES 1a and 2a). The shaft carries two drums 18 located between the bearings 16 and a sheave 19 at one end.
We also mount a reversible drive mechanism hereinafter described on the skid base 12 alongside the tower. The drive mechanism includes a drive sheave 23 aligned with sheave 19 on shaft 17 at the top of the tower. A flexible power-transmitting means connects sheaves 23 and 19. We illustrate this power-transmitting means as including two wire lines 24 which are wrapped around the sheaves and attached thereto with anchor means 25. Each wire line has a respective turnbuckle 26 for regulating the tension therein. Thus rotation of the drive sheave 23 in either direction also rotates sheave 19, shaft 17 and drums 18 in the same direction.
Each drum 18 has a respective pair of flexible cables 27 and 28 wrapped therearound and suitably anchored thereto. The drums have helical grooves in their circumferences to accommodate the cables. When the drums turn counterclockwise as viewed in FIGURE 2a, cables 27 unwind and cables 28 wind. When the drums turn clockwise, the reverse action takes place. Cables 27 extend downwardly outside the tower to a carrier bar 29, to which they are attached with adjustable eye-bolt assemblies 38. The carrier bar travels up and down along vertical tracks 31 fixed to the outside of the tower. We attach a polished rod 32 to the carrier bar 29, as with a clamp 33. The polished rod leads to a conventional sucker rod string (not shown) which extends into the well along the center line 14. Cables 28 extend downwardly inside the tower to a counterbalance 34, to which they are attached with adjustable eye bolts 35. The counterbalance travels up and down along vertical tracks 36 fixed to the inside of the tower.
Each drum 18 has a concentric mid-portion 18a and inner and outer eccentric end portions 18b and 18c of smaller radii then the concentric portion. During most of each upstroke and downstroke of the rods, cables 27 and 28 meet the drums at their concentric portions 18a. Hence both the polished rod 32 and the counterbalance 34 have equal moment arms. When the rod string approaches the end of a downstroke, as FIGURE 3 shows, cables 27 commence to unwind from the inner eccentric portion 18b of the drums. At this stage we automatically disconnect the power from the drive sheave 23, as hereinafter explained. The stroke is completed by momentum alone, and the parts coast to a stop, as FIGURE 4 shows. While cables 27 unwind from the inner eccentric portions 181) of the drums, the moment arms of the rod string 32 becomes progressively shorter and reaches a minimum at the end of the downstro-ke. Since cables 28 continue to meet the concentric portions 18a of the drums, the counterbalance 34 overbalances the rod string 32 and Starts an upstroke under its own weight. Presently we re-apply power to the drive sheave 23, but in the reverse direction, and the rods make their upstroke. Near the end of the upstroke cables 28 commence to unwind from the outer eccentric portions of the drums, as FIGURE 5 shows. Again we automatically disconnect the power source and complete the stroke by momentum alone. Now the rod string 32 overbalances the counterbalance 34 to start a downstroke, as FIGURE 6 shows. In this manner we utilize natural forces to move the rod string through a substantial portion of each stroke and conserve on power requirements.
Numerous forms of reversible drive are suitable for operating our pump. By way of example, we show a synchronous A.C. motor 40 and a speed reducer 41, the input and output shafts of which are connected to the motor and to the drive sheave 23 respectively. This type of motor has the characteristic that it operates in either direction, depending on which way an initial torque is applied. We mount upper and lower limit switches 42 and 43 in tower 10 in positions to be operated by the counterbalance 34 near its top and bottom positions. Preferably the positions of these switches are adjustable to control reversals of the rod string. When the rod string approaches the end of each downstroke (FIGURE 3), the counterbalance opens the upper limit switch 42 to deenergize motor 40. After the rod string begins its upstroke, the counterbalance closes this limit switch to energize the motor. Since the rod string applies a torque to the motor in the reverse direction from before, the motor continues to run in the opposite direction and propels the rod string through the remainder of its upstroke. A
similar action takes place at the end of the upstroke to produce the next downstroke. We have not shown the electric circuit since it follows Well-known principles.
From the foregoing description it is seen that our invention aifords a long-stroke pump of relatively simple construction. We take advantage of the kinetic energy of the moving parts to complete each stroke and start the next. Thus we save on power requirements, as well as performing an efiicient pumping operation. The rod string travels at a uniform Speed during the greater part of each stroke. As pointed out, we do not wish to be limited to any particular drive mechanism, since there are many which can be deenergized or disconnected temporarily and started in the reverse direction, as required at the end of each pumping stroke.
While we have shown and described only a single embodiment of our invention, it is apparent that modifications may arise. Therefore, we do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.
1. A pumping unit comprising a tower, rotatable means on said tower, flexible transmitting means connected to said rotatable means, a rod string and a counterbalance suspended from said rotatable means by said flexible transmitting means for movement in opposite directions through upstrokes and downstrokes, said rotatable means applying force to both said rod string and said counterbalance through equal moment arms during most of each stroke but providing a shorter moment arm for the rod string near the end of a downstroke thereof and a shorter moment arm for the counterbalance near the end of an upstroke of the rod string, reversible drive means operatively connected with said rotatable means, and means for disconnecting said drive means near the end of each stroke and reapplying the drive means in the reverse direction after the next stroke is underway, whereby each stroke is finished by momentum of the parts, and weight distribution starts the next stroke.
2. A pumping unit comprising a tower, a drum journaled at the top of said tower and having a concentric portion and eccentric portions of smaller radii than said concentric portion at each end thereof, first and second cables connected to said drum for winding and unwinding as said drum rotates in opposite directions with each cable winding while the other unwinds, a rod string connected to said first cable and movable through upstrokes and downstrokes, a counterbalance connected to said second cable to move in the opposite direction from said rod string, said cables meeting the concentric portion of said drum during most of each stroke, said first cable meeting one of the eccentric portions as said rod string nears the end of each downstroke, said second cable meeting the other eccentric portion as said rod string nears the end of each upstroke, reversible drive means operatively connected with said drum, and means for disconnecting said drive means near the end of each stroke and reapplying the drive means in the reverse direction after the next stroke is underway, whereby each stroke is finished by momentum of the parts, and weight distribution starts the next stroke.
3. A pumping unit comprising a tower, a shaft journaled at the top of said tower, a pair of drums mounted on said shaft and each having a concentric portion and eccentric portions of smaller radii than said concentric portion at each end thereof, first cables and second cables connected to each of said drums for winding and unwinding as said shaft rotates in opposite directions with the first cables winding while the second cables unwind, a rod string connected to said first cables and movable through upstrokes and downstrokes, a counterbalance connected to said second cables to move in the opposite direction from said rod string, said cables meeting the concentric portions of the respective drums during most of each stroke, said first cables meeting one of the eccentric portions as said rod string nears the end of each downstroke, said second cables meeting the other eccentric portions as said rod string nears the end of each upstroke, reversible drive means operatively connected with said shaft, and means for disconnecting said drive means near the end of each stroke and reapplying the drive means in the reverse direction after the next stroke is underway, whereby each stroke is finished by momentum of the parts, and weight distribution starts the next stroke.
4. A pumping unit as defined in claim 3 in which said drive means is located at the bottom of said tower and includes a driving sheave, and further comprising a sheave mounted on said shaft and aligned with said first-named sheave, the flexible power-transmitting means connecting said sheaves.
5. A pumping unit as defined in claim 3 in which said shaft is offset toward one side of said tower, said first cables extend downwardly outside the tower, said second cables extend downwardly within the tower, said counterbalance is located within the tower, the further comprising a track on the outside of the tower and a carrier bar riding on said track, said first cables and said rod string being attached to said carrier bar.
References Cited by the Examiner UNITED STATES PATENTS 868,844 10/ 1907 Conner 254-174 1,970,596 8/1934 Coberly. 2,926,000 2/ 1960 Allen. 3,207,329 9/ 1965 Bevard 254174 X FRED C. MATTERN, JR., Primary Examiner.
D. H. THIEL, Assistant Examiner.