GB2111134A

GB2111134A - Oil well pump assembly

Info

Publication number: GB2111134A
Application number: GB08234175A
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: JPS58150081A; FR2526496B1; DE3244822C2; GB2111134B; FR2526496A1; CA1205327A; DE3244822A1

Abstract

An oil pump assembly having a facility to adjust the production rate and stroke length comprises a reciprocating pumping rod in a well hole, a counterbalancing mechanism for reducing the power needed to pump oil by the pumping rod, a driving mechanism, including a first cable (32) and a second cable (34), to drive the reciprocating pumping rod and the counterbalancing mechanism, respectively, a speed control (41) for the driving mechanism, and a dwell mechanism 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 to 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 specification of United States Patents 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 reference 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 unit 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 its preferred form, the present invention has an object of eliminating side loads imposed by the sucker rods to extend the life of the unit.

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 product rate can be monitored by a main computer by monitoring the sampling and the motor amperage to consistently 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 its preferred form can provide 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 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 provided 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.

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

According to the 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 comprising a rotatable element and a first cable associated with said rotatable element; means for driving said counterbalance means comprising a rotatable element and a second cable operably associated with such rotatable element; means for engaging said motor means alternately with said reciprocating driving means and said counterbalance driving means and comprising an oil shear clutch operable for raising said reciprocating means, and an oil shear clutch for raising said counterbalance means; and dwell means for stopp ing both said reciprocating means and said counterbalance means in a selected position for a selected amount of time comprising an oil shear brake.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevational view of a counterbalanced pump embodying the present invention; Figure 2 is an enlarged elevated view of the drive unit of the pump of Fig. 1; Figure 3 is an elevated side view of the pump of Fig. 1; and Figure 4 is a horizontal sectional view taken along the line 4-4 of Fig. 1.

Referring to Fig. 1, a pump assembly 10 is illustrated using a bull gear 1 2 rotatable on a shaft 14 and secured to the shaft 1 4 by suitable key (not shown). The shaft 1 4 is mounted in a housing 18, including a base member 20, referring to Fig. 3, lower shaft support members 22 and 23, upper shaft support members 24 and 25, and drive support member 26. The bull gear 12 rides on the shaft 14 within the housing 1 8 intermediate two drive pulleys 28 and 30 which are also operabiy mounted on the shaft 14 by suitable keys, such as key 31 (Fig. 1). Cables 32 and 34 are wrapped around the drive pulleys 28, 30. Cable 32 is wrapped around drive pulley 28 in the opposite direction to cable 34 wrapped around drive pulley 30.

Drive pulley 28 will be referred to hereinafter as the raising pulley and drive pulley 30 will be referred to hereinafter as the lowering pulley (although the relationship of the pulleys is merely relative and can be selected or reversed as desired in the installation of the unit). A pair of idler pulleys 36 and 38 are mounted to the housing 1 8 on a rotational axis parallel to that of the drive pulleys 28, 30. In the described embodiment, the rotational axis of the idler pulleys is disposed along the intersection of a horizontal line which also intersects the rotational axis of the drive pulleys 28, 30.The cable from the raising pulley 28 comes from the top of the raising pulley 28 over the idler pulley 36 and down to the counterbalanced weights in a hole adjacent the pump assembly 1 0. The lowering pulley 30 has its cable directed upwardly from the bottom of the pulley 30 over the top of idler pulley 38 and downwardly into operable association with a sucker rod in the well hole. The operable association of the cables 32 and 34 with the sucker rod in the well hole and the weights in the counterbalance hole is done conventionally and need not be discussed in detail here. A motor 40 and motor control 41 are mounted onto the drive support member 26 of the housing 18. A belt 42 from the motor 40 is operably associated with a fly wheel pulley 44 mounted on a shaft 46 of a pump drive unit 48 also mounted on the drive support member 26.

Referring to Fig. 4, the input shaft 46 of the drive unit 48 is mounted in a housing 50, with suitable bearing assemblies 52 and 54.

A pinion gear 56 is mounted on the shaft 46 at an intermediate location thereof. Two clutches, a raising clutch 58 and a lowering clutch 60 are mounted in parallel to the input shaft 46 and to one another within the housing 50. The clutches 58 and 60 comprise a series of discs 59 and plates 61 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 62 into engagement and disengagement. The plates 61 are cooperably associated to move with the external housing 63 or 64 of the clutches 58 or 60, respectively.

The discs 59 are splined to the movable shafts 66 or 68 of the clutches 58 or 60, respectively. Reduction gears, 70 and 72 are fixedly secured to the housings 62 and 64 respectively, and intermesh with one another so that the gears are driven in opposite directions. The pinion gear 56 of the input shaft 46 meshes with the housing gear 70 of the clutch 58 to drive the mechanism via gears 70 and 72. The housings 63 and 64 are rotatably mounted to the housing 50 by suitable bearing mechanisms 54 and 74. A pinion gear 76 is mounted on shaft 66 and a second pinion gear 78 is mounted on shaft 68 to operably mesh with the drive bull gear 1 2 of the pump assembly 10.Thus, when the plates and the discs of clutch 58 are operably engaged, the pinion gear 76 will rotate in one direction to drive the bull gear 1 2 to raise the sucker rod vertically in the well hole. Clutch 58 then is disengaged and clutch 60 is engaged to drive pinion gear 78, 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 80 is also mounted on the shaft 68 of the lowering clutch 60. The brake mechanism 80 also comprises a series of plates 81 and discs 82 with the plates 81 operably splined with a stationary external housing 83 and the discs 82 operably splined to the shaft 68, to be actuated by piston actuating means 84 into engagement and brake the assembly 10. One end 86 of the shaft 68 extends through the brake unit 80.

The end 86 of the shaft 68 is used as a sensor to which a transducer is attached to determine the stroke drive speed and position of the unit. The brake unit 80 has been attached to the shaft 68 of the lowering clutch 60 but may, if space considerations allow, be attached to shaft 68 of the raising clutch 58 just as readily and be within the scope of the present invention.

Thus, the clutches 58 and 60 are alternately engaged and disengaged to provide the lowering and the raising of the sucker rod in the well hole. The brake 80 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 58 and 60 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 80 is engaged. Also the speed of the unit may be readily controlled by the automatic control that presents oil to the clutches 58 and 60 of the unit and the speed control of the drive motor 40. 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 63 or 64 may also be used to maintain the brake in all operable unreleased positions until the oil pressure in the clutch is at a predetermined level in order to control against a falling runaway condition.

The monitoring of several of the units 10 of the present invention may be performed at a single station or by a central computer. Plugin 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 inter fering 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 recipro cating means comprising a rotatable element and a first cable operably associated with said rotatable element; means for driving said counterbalance means comprising a rotatable element and a second cable operably associ ated with such rotatable element; means for engaging said motor means alternately with said reciprocating driving means and said counterbalance driving means and comprising an oil shear clutch operable for raising said reciprocating means, and an oil shear clutch for raising said counterbalance means; and dwell means for stopping both said reciprocat ing 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 said oil shear brake is opera bly 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 said clutches with said reciprocating means and said counterbalance means.

6. A pump assembly in accordance with claim 5, wherein said gear means for intercon necting said drive shafts of said clutches com prises a pinion gear on each of said drive shafts and a bull gear disposed in meshing engagement with both of said pinion gears and drivingly engaged to both said reciprocat ing means and said counterbalance means.

7. A pump assembly in accordance with any preceding claim, wherein said reciprocat ing means includes a cable, said pump assem bly further comprising means for minimizing side loads imposed on said pumping rod.

8. 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; 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; said reciprocating driving means including a rotatable element and a first cable operably associated with said rotatable element and said counterbalance driving means including a rotatable element and a second cable operably associated with said rotatable element.

9. 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 rate of said pump assembly comprising means for controlling the speed of said electric motor and means for dwelling said pump assembly a selected amount of time between reciprocations of said pumping rod by said reciprocating means, said reciprocating driving means including a rotatable element and a first cable operably associated with said rotatable element and said counterbalance driving means including a rotatable element and a second cable operably associated with said rotatable element.

1 0. A pump assembly in accordance with claim 9, 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.

11. A pump assembly in accordance with claim 10 further comprising means for adjusting the time of dwell provided by said dwelling means in response to the output of said monitoring means.

1 2. A pumping assembly in accordance with claim 9, 10 or 11, wherein said dwelling means includes an oil shear brake unit.

1 3. A pumping assembly in accordance with claim 12, further comprising means to 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.

14. A pumping assembly in accordance with claim 9, 10, 11, 12 or 13, further comprising means for controlling the acceleration and deceleration of the pumping means as a ramp function.

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