GB2111135A

GB2111135A - Oil well pump assembly

Info

Publication number: GB2111135A
Application number: GB08234176A
Authority: GB
Inventors: Gordon Maurice Sommer
Original assignee: Petroleum Recovery Systems Inc
Current assignee: Petroleum Recovery Systems Inc
Priority date: 1981-12-04
Filing date: 1982-12-01
Publication date: 1983-06-29
Also published as: DE3244868C2; JPS58150080A; CA1208977A; FR2517752B1; GB2111135B; DE3244868A1; FR2517752A1

Abstract

An oil pump assembly having an adjustable production rate and stroke length comprises a reciprocating pumping rod (45) in a well hole (47), a counterbalancing mechanism (34) for reducing the power needed to pump oil by the pumping rod, a driving mechanism to drive the reciprocating pumping rod and the counterbalancing mechanism, including a cable (30) to drive the reciprocating pumping rod and the counterbalancing mechanism, a speed control (46) for the driving mechanism, and a dwell mechanism (102) for the driving mechanism. <IMAGE>

Description

SPECIFICATION Oil well pump assembly The present invention relates generally to the pumping of wells such as oil wells, and in particular to an oil well pump assembly having an adjustable production rate capable of long stroke, low stroke per minute pumping rates.

Oil wells have been pumped for many years with a walking beam pump having a relatively large crank and arm assembly providing a sharp acceleration and deceleration of a pump rod. The walking beam arrangement needed a number of reversals per minute of the pump along with a short stroke pumping rod to provide sufficient production. With a walking beam pump, the pumping rod had to be larger than desired since the end of the rod never catches up with the pump in the pumping process and the effective stroke of the rod due the elasticity of the rod was always less than the actual length of the rod. Also, the crank had to be physically changed in order to change the production rate of the pump.

Improvements were made to the walking beam pumping arrangement by those systems described in the specifications of United States Patent Nos. 3,744,567, 3,793,904, and 3,807,902, where long stroke pumping assemblies were devised which had counterbalanced weights reciprocally attached to the well pump to move the pumping mechanism and aid the pumping mechanism by the force of gravity on its return stroke. Several disadvantages have presented themselves with the use of the prior art reciprocal well pumps as disclosed in the above referenced patents.

First, each of the pumps uses a direct current motor on a spiral (a varying diameter spool) with a hydrostatic drive. The hydrostatic drive does not have a great deal of longevity and requires a complex set of controls in order to operate the unit. The device as represented by the referenced prior art patents also only controls the speed of the unit. Furthermore, side loads are imposed on the sucker rods of the above-referenced patents.

The present invention has the object of using an oil shear clutch mechanism and brake mechanism to control the operation of a counterbalanced well pump. Such an arrangement permits an alteration in the speed of the unit and also in the dwell time of a uriit at the top and the bottom of each stroke, to allow the rod to catch up with the unit and have an effective stroke of the length of the rod.

Furthermore, in the preferred form, the present invention has an object of eliminating side loads imposed by the sucker rods to extend the life of the unit, while also providing the capability of using a fairly compact housing and substituteable parts associated with that housing to optimize the loading condition of the sucker rods for various stroke lengths and minimize the side loads on the sucker rods in each desired load condition or stroke length.

Each of the above advantages may be included with a pump assembly that has an adjustable production rate readily adjustable externally of the pump assembly. The production rate can be monitored by a main computer by monitoring the sampling and the motor amperage to consistenly provide an optimum condition in the performance of the pump. This same computer may be monitoring a number of the pump assemblies.

The prior art units also had an energy disadvantage due to the rough acceleration of the unit taking power away from the operation of the unit. The present invention in the preferred form has an energy advantage over the prior art due to the provision of a controlled ramp for acceleration and deceleration of the pump assembly.

The present invention also has the object of providing a pump assembly which is potentially ecologically aesthetic for areas that find objection to large observable well pumps. The present invention may be constructed to have an effective physical size which may extend to less than two metres above ground level, and which, in a commercial or residential setting, could permit the unit to be located underneath a parking lot, to be concealed by a fence or hedge, to be within a small attractive housing structure, or to be in another ecologically aesthetic surrounding. Such a use would also permit the surface real estate to be utilized for something else other than a mere well pumping station.A small pump assembly may also be more amenable to protection against vandalism and the pumps may be situated more closely together, as a series of directional wells to obtain a higher density than prior art well pumps. The present invention also has a much lower weight than the prior art units, which may provide an advantage particularly for off-shore wells where a number of the pumps may have to be attached to a vehicle rig. In addition, the pump assembly of the present invention has the advantage providing a compact housing assembly for its drive mechanism to contribute to the overail aesthetically appealing compact size of the pump assembly.

The present pump assembly also has the advantage of minimizing both service and original manufacture and installation costs by minimizing the number of parts. The present invention utilizes a single continuous cable extending between the reciprocating pumping means and the counterbalance means, which cable is looped around a single drum element driven by the driving means in alternate directions, driving forces being maintained between the drum and the cable.

Essentially, the present invention provides a simplified, more compact, and potentially more ecologically appealing unit than the prior art.

According to the present invention there is provided an oil well pump assembly including means for pumping oil from an oil well through a well hole, comprising a pumping rod; means for reciprocating said pumping rod in the well hole; counterbalance means for reducing the power needed to pump said oil; motor means; means for driving said reciprocating means; means for driving said counterbalance means; means for engaging said motor means alternately with said reciprocating driving means and said counterbalance driving means comprising oil shear clutch for raising said reciprocating means, and oil shear clutch for raising said counterbalance means; and dwell means for stopping both said reciprocating means and said counterbalance means in a selected position for a selected amount of time comprising an oil shear brake.

A further aspect of the invention provides an oil well pump assembly including means for pumping oil from an oil well through a well hole comprising a pumping rod; means for reciprocating said pumping rod in said well hole; counterbalance means for reducing the power needed to pump said oil; means for driving said reciprocating means and said counterbalance means; means for engaging said driving means alternately with said reciprocating means and said counterbalance means; and dwell means for stopping both said reciprocating means and said counterblance means in a selected position for a selected amount of time.

An illustrative embodiment of the invention is illustrated in the accompanying drawings, wherein: Figure 1 is a side elevational view of a counterbalanced pump assembly embodying the present invention; Figure 2 is an elevated plan view of the drive unit of the pump assembly of Fig. 1; Figure 3 is an elevated side view of the pump of Fig. 1; and Figure 4 is a horizontal sectional view along the line 4-4 of Fig. 1.

Referring to Figs. 1 and 2, a pump assembly 10 is illustrated using a bull gear 1 2 rotated on a shaft 1 4 within a housing 1 5 forming an oil chamber 16, and secured to the shaft 14 by suitable key (not shown). The shaft 14 is mounted in a support housing 18, including a base member 20, lower shaft support members 22 and 23, upper shaft support members 24 and 25, and drive support member 26. A drive drum element 28 rides on the shaft 1 4 within the housing 1 8 and is operably mounted on the shaft 1 4 by suitable key elements.A continuous cable 30 is wrapped around the drive element 28 and releases from drive element 28 in one direction to associate with a pumping means 32 and in a second opposite direction to associate with a counterbalancing means 34.

The drum element 28 has a series of grooves 35 disposed thereon to guide the cable 30 onto the drum element 28 and maintain some separation between the rows of the cable 30 as it is wrapped around or taken from the drum element 28. A curved plate 33 (Fig. 1) is disposed below and adjacent to the drum 28 with a very small clearance between the drum element 28 and the plate 33 to further guide the cable 30 into one of the grooves 35 and maintain the position of the cable 30 within each respective groove 35 as the drum element 28 is rotated.

A pair of idler pulleys 36 and 38 are mounted to outriggers 37 and 39 which are, in turn, removeably mounted to the main housing 1 8 on a rotational axis parallel to that of the drive element 28. In the described embodiment, the rotational axes of the idler pulleys 36 and 38 are disposed in a plane disposed above and not intersecting the rotational axis of the drive element 28. The cable 30 forms substantially a horizontal line connecting the top point of the drive element 28 and idler pulleys 36 and 38.The cable portion 40 associated with the counterbalance means 34 comes from the top of the driving element 28 over the idler pulley 36 and down to the counterbalance means 34 comprising weights 41 in a hole 43 adjacent the pump assembly 1 0. The cable portion 42 is directed upwardly from the bottom of the drive element 28 over the top of idle pulley 38 and downwardly into operable association with pumping means 32 comprising a sucker rod 45 in the well hole 47. The operable association of the cable portions 40 and 42 with the sucker rod 45 in the well hole 47 and the weights 41 in the counterbalance hole 43 is done conventionally and need not be discussed in detail here. The outriggers 37 and 39 are removable to facilitate servicing either the pumping means 32 or the counterbalance means 34.

A motor 44 and motor control 46 are mounted onto the drive support mernber 26 of the housing 1 8. A belt 48 from the drive shaft 49 motor 44 is operably associated with a fly wheel pulley 50 mounted on a shaft 52 of a pump drive unit 54 also mounted on the drive support member 26.

Referring to Fig. 4, the input shaft 52 of a power engaging unit 55 is mounted in a housing 56, via suitable bearing assemblies 58 and 59. A pinion gear 60 is mounted on the shaft 52 at substantially one end 61 thereof, axially opposite the drive engagement end 62 of the shaft 52. Two clutches, a raising clutch 64 and a lowering clutch 66 are mounted in parallel to the input shaft 52 and to one another within the housing 56. The clutches 64 and 66 comprise a series of plates 68 and discs 70 in a bath of oil similar to those oil shear clutches described by United States Patent Specification No.

3,696,898, actuatable by an externally controlled piston 72 into engagement and disengagement. The plates 68 are cooperably associated to move with an external clutch housing 74 or 76 of the clutches 64 or 66, respectively, disposed within the drive housing 52. The discs 70 are splined to moveable shafts 78 or 80 of the clutches 64 or 66, respectively. Reduction gears 86 and 88 are fixedly secured to outside of the clutch housings 74 and 76, respectively, and intermesh with one another so that the gears 86 and 88 are driven in opposite directions. The clutch housings 74 and 76 are rotatably mounted to the shafts 78 and 80 by suitable bearing mechanisms 90 and 92 on both housing 74 and housing 76 (not shown). The pinion gear 60 of the input shaft 52 meshes with the clutch housing gear 86 of clutch 64 to drive the mechanism (in turn meshing with gear 88).A pinion gear 98 is mounted on shaft 78 and a second pinion gear 100 is mounted on shaft 80 to operably mesh with the drive bull gear 12 of the pump assembly 10. Thus, when the plates and the discs of clutch 64 are operably engaged, the pinion gear 98 will rotate in one direction to drive the bull gear 1 2 to raise the sucker rod 45 vertically in the well hole 47. Clutch 64 then is disengaged and clutch 66 is engaged to drive pinion gear 100, which in turn drives the bull gear 1 2 in the opposite direction to lower the sucker rod in the well hole.

A brake mechanism 102 is also mounted on the shaft 80 of the lowering clutch 66.

The brake mechanism 102 also comprises a series of plates 104 and discs 106 with the plates 104 operably splined with a stationary external housing 108 and with the discs 106 operably splined to the shaft 80, to be actuated by piston actuating means 110 into engagement to brake the assembly 1 0. The brake unit 102 as illustrated has been attached to the shaft 80 of the lowering clutch 66 but may, if space considerations allow, be attached to shaft 78 of the raising clutch 64 just as readily and be within the scope of the present invention.

A sensor is also provided at the engagement end 62 of the drive shaft 52 to which a transducer is attached to determine the stroke drive speed and position of the unit.

Oil is circulated through the power engaging unit 55 by a pump 112 (Fig. 2). Drive shaft 49 of the motor 44 extends axially in both directions from the motor 44, with one end 114 driving the oil pump 11 2 and the other end 11 6 driving the belt 48. Actuation oil is fed from the pump 11 2 to the clutches 64 and 66 and brake 102 via inlet ports 118 and 1 20. Cooling oil is fed to clutches 64 and 66 and brake 102 via inlet ports 122 and 1 24 at the opposite side of the unit 58 from the actuating oil ports 11 8 and 1 20. Cooling oil inlet ports 1 22 and 1 24 are disposed within housing 1 5. Brake housing 108 has an outlet portion 1 26 that communicates with the oil sump in housing 1 5.

Thus, the clutches 64 and 66 are alternately engaged and disengaged to provide the lowering and the raising of the sucker rod in the well hole. The brake 102 is engaged at the end of each stroke to provide a dwell setting to permit the sucker rod to catch up with the unit and permit its effective length to be used without any wasted length. The engagement and disengagement of the clutches 64 and 66 is performed by an oil control mechanism with a ramp acceleration and deceleration of the clutch engagement.

It must be noted that the denomination of the clutches as "raising" and "lowering" is relative. The clutches may be oppositely denominated if set up in a manner wherein the sucker rod is controlled by the opposite drive pulley.

It can be readily seen that the dwell time of the unit 10 may be readily altered to any selected dwell time based upon the amount of time that the brake 102 is engaged. Also the speed of the unit may be readily controlled by the automatic control that presents oil to the clutches 64 and 66 of the unit and the speed control of the drive motor 44. In the present construction, a forty to fifty foot stroke may be used. A four second dwell between reversals has been found to be sufficient to permit a ten foot sucker rod to catch up at each stroke reversal. This dwell, of course, may be changed over the lifetime operation of the well as the flow rate changes. It is believed, however, that only discrete changes will be necessary, with no need for automatic feedback controls nor for minute variance alterations of the dwell setting.

An adjustable production rate is also readily available from the above-described pump assembly 10, since the pump speed and dwell time are so easily controllable as desired without the complexities of a hydrostatic drive. A flow rate sampling and the motor amperage can be monitored by conventional means while the sucker rod travels upwardly and speed and dwell can be adjusted so that optimum conditions may be consistently maintained. One example of a monitor means for the motor current on the upward portion of the pumping stroke may be an ammeter with adjustable contacts connected to the electric drive motor. The distance between the contacts will then be the dwell time that the brake will operate and adjustment of the distance between the contacts may be a means of adjusting the amount of dwell time. An oil sensor in the clutch housings 74 or 76 may also be used to maintain the brake 102 actuated in all operable unreleased positions until the oil pressure in the clutch is at a predetermined level permitting actuation of the clutch in order to control against a falling runaway condition.

The monitoring of several of the units 10 may be performed at a single station or by a central computer. Plug-in monitors may also be readily implemented for monitoring individual units without interfering with or stopping the operation of the unit 10, since motor amperage, dwell time, and sampling can be performed without interfering with or stopping the operation of the unit.

Claims

1. An oil well pump assembly including means for pumping oil from an oil well through a well hole, comprising a pumping rod; means for reciprocating said pumping rod in the well hole; counterbalance means for reducing the power needed to pump said oil; motor means; means for driving said reciprocating means; means for driving said counterbalance means; means for engaging said motor means alternately with said reciprocating driving means and said counterbalance driving means comprising oil shear clutch for raising said reciprocating means, and oil shear clutch for raising said counterbalance means; and dwell means for stopping both said reciprocating means and said counterbalance means in a selected position for a selected amount of time comprising an oil shear brake.

2. A pump assembly in accordance with claim 1, wherein said engaging means further comprises gear means for interconnecting said driving means with each of said oil shear clutches.

3. A pump assembly in accordance with claim 2, wherein each of said oil shear clutches is operably associated with a drive shaft.

4. A pump assembly in accordance with claim 3, wherein the oil shear brake means is operably disposed on the drive shaft of one of the oil shear clutches.

5. A pump assembly in accordance with claim 4, further comprising gear means for interconnecting the drive shafts of the clutches with said reciprocating means and said counterbalance means.

6. A pump assembly in accordance with claim 5, wherein said gear means for interconnecting the drive shafts of the clutches comprises a pinion gear on each of the drive shafts and a bull gear disposed in meshing engagement with both of the pinion gears and drivingly engaged to both said reciprocating means and said counterbalance means.

7. A pump assembly in accordance with any preceding claim, wherein said reciprocating means includes a cable, said pump assembly further comprising means for minimizing sideloads imposed on the pumping rod.

8. A pump assembly in accordance with any preceding claim, wherein said counterbalance means includes a cable, said pump assembly further comprising means for minimizing sideloads imposed on said counterbalance means.

9. A pump assembly in accordance with claims 7 and 8, wherein the cable of the counterbalance means and the cable of the reciprocating means is comprised by one continuous cable.

10. An oil well pump assembly including means for pumping oil from an oil well through a well hole comprising a pumping rod; means for reciprocating said pumping rod in said well hole; countarbalance means for reducing the power needed to pump said oil; means for driving said reciprocating means and said counterbalance means; means for engaging said driving means alternately with said reciprocating means and said counterbalance means; and dwell means for stopping both said reciprocating means and said counterbalance means in a selected position for a selected amount of time.

11. An oil well pump assembly including means for pumping oil from an oil well hole comprising a pumping rod and means for reciprocating said pumping rod in said hole; counterbalance means for reducing the power needed to pump said oil; means including an electric motor for driving said reciprocating means and said counterbalance means, and means for adjusting the production of rate of said pump assembly comprising means for controlling the speed of said electric motor and means for dwelling said pump assembly selected amount of time between reciprocations of said pumping rod by said reciprocating means.

1 2. A pump assembly in accordance with claim 11, further comprising means for monitoring the amperage of said electric motor and means for monitoring the flow rate of said oil pumping means, said adjusting means including means for controlling the speed of the motor in response to the output of the monitoring means.

1 3. A pump assembly in accordance with claim 12, further comprising means for adjusting the time of dwell provided by said dwelling means in response to the output of said monitoring means.

14. A pumping assembly in accordance with claim 11, 1 2 or 13, wherein said dwelling means includes an oil shear brake unit.

1 5. A pumping assembly in accordance with claim 14, further comprising means tQ control against all runaway of said pumping rod including means for sensing the oil pressure in said driving means and means for engaging said brake unit until a selected oil pressure is obtained.

16. A pumping assembly in accordance with claim 11, further comprising means for controlling the acceleration and deceleration of the pumping means as a ramp function.

17. An oil well pump assembly, including means for pumping oil from an oil well through a well hole, comprising a pumping rod and means for reciprocating said pumping rod in said well hole, counterbalance means for reducing the power needed to pump said oil, and means for driving said reciprocating means and said counterbalance means comprising a rotatable driving element, motor means, means for engaging said motor means with said driving element to alternately drive said rotatable driving element in opposite directions, and a continuous cable operably associated with said rotatable driving element, said counterbalance means and said reciprocating means each being operably associated with said continuous cable, whereby said rotatable driving element alternately drives said reciprocating means and said counterbalance means.

1 8. An oil well pump assembly, including means for pumping oil from an oil well through a well hole, comprising a pumping rod and pumping means for reciprocating said pumping rod in said well hole, counterbalance means for reducing the power needed to pump said oil, and means for driving both said reciprocating means and said counterbalance means comprising a single rotatable drum element, means for rotatably driving said drum element in alternating directions, means for dwelling said drum element at each change of direction of rotation, and a continuous cable operably associated with said single rotatable drum element and both said counterbalance means and said reciprocating pumping means.

1 9. An oil well pump assembly constructed and arranged to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.