US2982100A - Pumping unit - Google Patents

Description

A. C. SINCLAIR May 2, 1961 PUMPING UNIT 4 Sheets-Sheet 1 Filed Oct. 17, 1958 r J m c m J C m F A, 7.,

awf lzeu'uAd-tz'adm m M A. C. SINCLAIR May 2, 1961 PUMPING UNIT 4 Sheets-Sheet 2 Filed Oct. 17, 1958 A/freo C. J? C/o/r INVENTOR. v 9. Aim-1&4. BY am MAW A TTOR/VfK! May 2, 1961 A. c. SINCLAIR PUMPING UNIT Filed Oct. 17, 1958 4 Sheets-Sheet 3 M9: 43% BY M m AW ATTOR/VL'VJ y 1961 A. c. SINCLAIR 2,982,100

PUMPING UNIT Filed Oct. 17, 1958 4 Sheets-Sheet 4 7 BY MAM ,4 ITO/PA/E ya I entire load.

United States atene 4 Claims. 2 (CI. 60-51) This invention relates to pumping units and, more particularly, relates to hydraulic pumping equipment particularly used for pumping oil wells wherein a string of sucker rods is used as a means of linking the piston of a submerged well pump with the lifting mechanism for lifting the oil to the surface.

' Hydraulic pumping units have been proposed by others but there have been certain disadvantages to these pumping units mainly in their lack of efficiency particularly in pumping relatively deep holes. Two radically different types of hydrauli'c pumping units are predominant at this time. In one of these'types counterbalancing is ignored and thepowerunit utilized must be of suflicient capacity string load. At the end of the lifting stroke the motor and the power pump continue to operate at full speed but the hydraulic liquid is by-passed to the supply tank, either directly or through a cooling radiator. The power re quired per thousand feet of lift is equal to the sum of .the weight of the fluid load plus that of the sucker rods or string. For example, in pumping from a depth of 5,000 feet and using /a' diameterrods, the rod load to; lift and accelerate the entire pump string or sucker including bottom hole pump is a minimum of 4,500

lbs. The fluid load, using l t' diameter working barrel, is 1,900 lbs., assuming that the fluid pumped is 50% water.

Thus, this type unit lifts 4,500 lbs. plus 1,900 lbs. equaling 6,400 lbs. which is unbalanced or, in any event, lifts the In the present invention, the pump provides working fluid sufficient to with only about one-half the fluid load,

or, as in the above example, only, half of 1,900 lbs. which is 950 lbs. In other words, the pump power required to operate the-hydraulic pumping unit of the present invention is 950/6400 or 14.6% of the abovementioned type .unit. a

, Inthe second type ofhydraulic pumpingunit, referred to'above, the load is partiallybalanced by pressure in ,an accumulator but a relatively large pump is required to handle allof the hydraulic, liquid involved. In this case, the volume handled is equal to the volumepumped butthe power requirements are much lessv than in the type firstfreferred to' before. 'Inthe-hydraulic pumping I unit of; the present invention ,Oxilysufficiem hydraulic liquid, is;pumped:toj liftone-halfof the fluid, 950 lbs., compared with 6,400 lbs. in. the foregoing example. ,Thus,

therpowerpump "in thelast-mentioned eirampl'e must deliver ;640Q/.950 or 6,7 timesas muehhydraulic liquid as 11 -that ofathegpresentinvention:r f Accordingly, the present-invention {constitutes an inn ,provernent inhydraulic;pumping.;units-by oyercomingtlie above-mentioned. disadvantages .of-fl pres/i603}: hydraulic pumping units and provides ,a, hydraulic pumping unit "11 new and-fer ide p w whichis efiiciently effectlve in operationp both f has the;piston rod l7secured to its lower portion which effect,-forms .a part of the. sucker rods which are re- .ciprocatedto provide the lifting force for pumping the well.

' the working" str'o Still a further object of the present invention is the provision of a relatively simple hydraulic pump unit of greatly increased efficiency effected by hydraulically over;- balancing the entire well string load (both fluid and sucker rods) so that very little, hydraulic force is'requiredfor the pumping action thereby greatly increasing efficiency of the pumping unit.

Yet a further object of the present invention. is a provision of a relatively simple hydraulic pumping unit of greatly increased efliciency made possible by hydraulically overbalancing the entire well string load (including both fluid and sucker rods) by means of an accumulator whereiin suitable hydraulic liquid is maintained under pressure by compressed inert gas or air whereby the pumping ac tion is effected readily and efi'iciently.

Still a further object of this invention is the provision of a pneumatic-hydraulic pumpingsystem in which the entire well string load is overbalanced by an amount sub stantially equal to one-half the fluid load and which in cludes means for reversing the flow of hydraulic liquid for effecting the pumping action.

Still a further object of the present invention is the provision of a hydraulic pumping system which eliminates the need for relief valves and the like.

Yet a further object of this invention is the provision of a hydraulic pumping unit which includes a piston or ram having work surfaces on opposite sides so that a relatively small differential in hydraulic pressure applied against these work areas effect the pumping action.

Other and further objects, features and advantages will be apparent from the following description of presently preferred embodiments of the invention, given for the purpose of disclosure, and taken in conjunction with the accompanying drawings, where Figure 1 is an elevational view, partly in section, illustrating a hydraulic pumping unit according to the invention, and with the parts in position at the upper portion of the stroke,

- Figure 2 is a fragmentary view, similar to Figure 1 illustrating the piston and stroke,-

Figure 3 is a fragmentary view similar to that of Figure 2 illustrating another embodiment of the invention.

Figure 4 is a quarter sectional view illustrating a preferred pack off arrangement, a Figure 5 is aplan view taken along the line 55 of Figure l, a

Figure 6 is a sectional view of a presently-preferred reversing valve, and a Figure 7 is a view similar to that of Figure 6 with the valve rotated to provide reverse flow.

Referring now to the drawings, and particularly to Figure 1, the hydraulic pumping unit includesa hydraulic well head 13, such as by bolting or otherwise securing. the

flanges 14 and15.

- Disposed within the cylinder 10 is a. piston 16 which extends down into the well and isconnec'ted to andfin' 1 The sucker rod, and pump elements down hole, connections, fittings and thelike' may ,all be of any..d;--

sired designv and, accordingly, no detailed, description thereofisdeemednecessary. R a The, piston; 1. 6 is provided with-th ram in a lower portion of the v face 46 so that hydraulic pressure applied'against these faces overbalances the working load of the pumping unit in an upward direction. 7

Preferably, the upper end of the cylinder. is provided ,with a cylinder extension 20 which receives the.r am119 and which is connected to the cylinder 10 by meansof the coupling element 21. The cylinder extension serves as a closure for the ram 19 to prevent injury or weathering of the ram 19. It may be omitted if desired. The coupling element 21 serves as a fixed'bearing including the packing (see Figure 4) 23 which is compressed between the gland rings 24 by means of the nuts and bolts, generally indicated by the reference numeral 25, securing the flanges26 and 27and 28 and 29 together. 7

Thus, the coupling element 21 serves as a packing adjustment ringZl to make certain that the packing 23 is compressed into sealing engagement with the outer surface of the ram 19 throughout the stroke. f Turning again to Figure 1,.an accumulator 30 is provided which isconnected to the upper and lower ends of the cylinder 10 by the lines 31 and 32, respectively. It is noted that the fluid pressure from the accumulator 30 may be applied by the lines 31 and 32 on opposite sides of the piston 16.

Inorder to pump hydraulic liquidfrom and to the upper portion of the cylinder 10 to obtain reciprocation of the piston 16, a pump 33 is driven by any suitable prime mover, such as illustrated at 33' in Figure 5, by means of the belt drive 34'. Referringagain to Figure l, the pump 33 is here shown-to be supported by the support 34 and is connected through the direction valve 45 to the hydraulic line 32 for pumping hydraulic liquid to and from the upper end of the cylinder 10.

A connection 36 is provided in the line 35 leading to the accumulator 30 and to the small accumulator 36' for applying inert gas or air to the accumulator 30 for providing sufficient pressure to the hydraulic liquid 37 in .the accumulator 30 to overbalance the working load of the pumping unit. Any suitable compressor'or means to apply inert gas or air under the required pressures may be used. V a

,It is of utmost importance to prevent the inert gas or air from mixing with the hydraulic liquid 37 within the :accumulator 30 to prevent absorption of theair or gas by the liquid beneath. This is necessary to prevent froth- -ing and foaming at the interface. For this purpose, a float separator 38 is provided which includes the upper float member 39 and the lower float member 40 secured together by the spacer rod 41. The float maybe made of any preferred materials which will stand the pressures and prevent the gas or air from coming into contact with 'the upper surface'of the hydraulic'liquid 37. -If desired, the float may be made of a solid material, such as :wood, or be hollow and made of metal, in which event, ;there should be means provided to permit an equalization of pressure from within and without the float.

Disposed in 'the hydraulic lines 31 and 32 are the shut off valves 42 and 43, respectively, and in line 31, there is provided an adjustment valve 44 with a bypass line 44'. for the purpose: of raising the piston 16 to the desired height-for'adjusting the position of the piston 16 .when replacing packing at the upper end of the stroke.

a 'The small accumulator 36' is for the purpose of receiving and returning surplus fiuid'provided at thestroke ends by the pump33 whichoperates at a constant speedwhereas the piston 16 slows down'to zero speed, then 'ireverses at stroke ends and accelerates to normalstroke. This advantageously eliminates a relief valve and conseguent heating. "l 'hesrnall accumulator 36 drains into the:

pump 33 by m'eans of the line 35'.

. :The directional control'valve' 45 may be ofgany pre-L i ferredtyp e forexample a" steam. engine piston type whichprovides }rapid, acceleration. and deceleration; If

1 preferred, howev'erfa'rotarytype valve which" provides .16 to raise the sucker rods and lift liquid to the surface. j fAt th e predetermined end f'thelift stroke,-the direction f valve 45 reverses and the flowqf hydraulicflliquidisf'ndw fror'n'th'e accumulator'jgto the, 'r33 and is then pumped into the annular space hetween'thepist ori'16ahd 4 Y slower acceleration and deceleration may be used to reverse the flow of hydraulic liquid.

Referring now to Figures 6 and 7, a rotary type valve 45 is shown which includes the generally tubular valve body 76 into which the valve 47 is rotatably journaled. The body 76 includes the end plates 48 and 49 bolted or otherwise secured to the body 76. The end plate 48 includes an opening into which is placed a valve shaft bushing. 50 which rotatably receives the valve shaft 51 which is suitably packed off by the chevron type packing 52 sealingly urged against the valve shaft 51 by the gland nut 53. The other end plate 49 includes a discharge'line 54 to the pump.

As best seen in Figure 7,- the valve body 76 includes the inlet 55 from the pump 33, the high pressure outlet 56 to the working cylinder and the discharge from the accumulator, inlet 57. v w

Referring again to Figure 6 it is noted that the valve is completely balanced and no thrust bearings are required, although they may be used, if desired. This is accomplished by providing a flange portion 58 to the valve 47 so that the pressure is equalized.

I It is noted that the valve element 47 may be cast and includes the central bore to receive the valve shaft 51 which vis pinned to the valve by the pins 59, although it may be secured in other ways. Also, the valve face 60 is arranged sothat in one position (Figure 7) the discharge fromthe accumulator 30 in inlet 57 is in communication with'the discharge to pump line 54 and inlet 55 from the pump 33 is in communication with the outlet 56 to the working cylinder 10. Similarly, when the valve element 47 has been rotated (Figure 6) a passage is provided about the central portion 61 of the valve 47 so that the discharge to the accumulator 30 is in fluid communication, with the pump line 55. Thus, as the valve 47 is rotated, hydraulic liquid is pumped from the accumulator 30 out the valve outlet 56 to the upper dead center with the discharge ports closed, a by-pass arrangement is provided by, providing the by- pass ports 62 and 63 in the valve flange 64 which align with the ports 65 and 66 and 67 and 68 at each one-half revolution of the valve 47.

V .The rotation of the valve 45' is reduced eonsiderably by any suitable gear reduction device. Since the gear 'reduction, as such, does not form the present invention,

it is diagrammatically shown as a gear case 69 (Figures 1 'and 5) to which the valve shaft 51 is connected. The

pump shaft 70, on which the belt-driven wheel 71 is provided serves as the drive for the gear reduction train by which. greatly reduced rotation is imparted to the valve shaft 51. Thus, rotation of the driving wheel 72 by the .prime mover 33, drives the belt 34', which in turn drives "the driven wheel 71, which in turn drives the pump 33 and through the gear reduction69 slowly drives the valve 45 7 .In operation, sufficient pressuremust be applied to the accumulator 30 so that the pressure acting on the lower face of the piston l is sufficient to raise the entire well load and sucker rod string load. In order to avoid'unrestrained upward movement of the rods and fluid load itis necessary to provide 'an opposing pressure'on the exposed upper annular face 46'of the piston ram 19. g'Ihus, the pressure is balanced on each side ,ofthe piston :16. j To permit a lifting of the sucker rods, the pump 33 transferstheliquid in the annular space above the piston 16 to the accumulator thereby allowing the lifting piston the upper end of cylinder to act against the annular face 46 of piston 16 thereby forcing the sucker rods downwardly.

The average pump pressure required to pump the oil contained in the annular space between the piston extension 9 and the upper end of cylinder 10 into the accumulator is substantially equal to the average pump pressure in the annular space required to force the unloaded sucker rods downwardly. This is accomplished by the correct relationship of the areas of the upper and the lower acting faces of the lifting unit which are so related that pressure-volume product required is equal to one-half the weight of the fluid lifted plus an allowance for friction and acceleration losses.

Thus, the pressure in the accumulator 30 must be sufficient to lift the rod string, the piston ram including the extension or ram 19, the piston rod '17, the sucker rods and the entire fluid load. In addition, it is'necessary to provide for acceleration sufficient to lift the entire mass throughout the complete stroke. The pressure on the upper reduced area surface 46 of the piston is insignificant because the pump eliminates this pressure by pumping the fluid involved into the accumulator 30.

Example In the present example it is assumed that a pumping unit such as illustrated in Figure 1 is provided with a6 inch diameter piston and a 10 foot stroke to lift oil I from a depth of 6,000 feet. That area of the lifting surface of the piston is 25.89 square inches and of the upper working annular surface 46 is 6.62 square inches.

When the lifting piston 16 reaches the upper end of the lifting stroke, the dead load remains unchanged until the fluid load is transferred to the standing valve, not shown. At this point it is desirable that the pressure in the accumulator 30 be just sufiicient to balance the dead weight, including the fluid weight.

On the downstroke, the actual load consists of the piston and rod string but since the pressure on the lifting face of the piston .16 is still sufficient to support the entire dead load, including the fluid load, the power pump 33 with the aid of the accumulator pressure, must deliver suflicient pressure, acting on the small area of the piston 16, to return the piston 16 and load to the lower end of the stroke.

This is accomplished by the single acting piston-ram which includes the piston 16, which may be of normal design, and the extension or piston ram 19 of less diameter than the piston and of a length in excess of the total stroke of the piston-ram. The difference in area between the ram and the cylinder provides the work area which when subjected to sufficient pressure causes the ram -19 to move downwardly or, upon removal of such fluid pressure, permits the ram 19 to move upwardly thereby providing the pumping action.

Referring now to Figure 3, an alternate arrangement is illustrated. In this arrangement, the reference letter "a has been added to similar parts of the other figures to designate like parts.

It is noted, that the main difference here is that the cylinder extension 20a is of reduced diameter and forms a continuation of the piston 10a and that the fluid pressure line 32a has been moved above the box or pack off connection 21a so that hydraulic pressure is applied against the upper face or end 46a of the ram 19a. Also, a drain line 47 has been added to permit liquid leakage to drain from the cylinders 10a and 20a during operation of the unit.

All other parts and the mode of operation is the same as previously described above, except that pressure is applied to the upper end 46a of the piston ram 19a rather than the annular'face 46 (Figure l) as in the previous description.

Thus, in its broader aspects the present invention provides a pumping unit which utilizes hydraulic pressure to overbalance the pump load so that there is a tendency of the working string to rise to efiect the pumping action. Suitable means are provided to overcome this overbalance so that the working string will lower so that it will again be in position to rise as the pump load is again overbalanced. While a hydraulic system has been illustrated for this purpose; obviously, other means may be employed, such as, pneumatic or mechanical.

The present invention, therefore, is well suited and adapted to attain the objects and ends set forth and has the advantages mentioned as well as others inherent therein. While only presently-preferred embodiments of this invention have been given for purposes of the disclosure, numerous changes in details of construction and arrangement of parts and in uses may be made which are within the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. The improvement in a fluid system for operating a hydraulic motor including a piston having first and second sides in a cylinder for moving a load comprising, a

fluid accumulator, first and second lines leading from the accumulator, said first line connected to the cylinder on a first side of the piston and the second line connected to the cylinder on the second side of the piston, said second side of the piston being connectable to the load and being larger than the first side of the piston, means for applying pressure to fluid in the accumulator, a pump in fluid communication with said first line, and a directional valve in said first line in fluid communication with said pump for reversing flow of fluid in the first line between the accumulator and said cylinder for reciprocating the piston in the cylinder thereby reciprocating the hydraulic motor.

2. The invention of claim 1 in which the means for applying pressure comprises means for applying gas under pressure to the hydraulic liquid in the accumulator, and includes a separator constructed and arranged to float on and cover the upper surface of the hydraulic liquid in the accumulator for preventing mixture of the gas with the hydraulic liquid.

3. The invention of claim 2 including a second smaller accumulator connected to said first accumulator arranged to receive and return surplus fluid built up at the end .of each stroke of the piston.

4. The improvement in a fluid system for operating a hydraulic motor including a cylinder and a piston re ciproc-ally mounted therein comprising, a piston rod extending from the first side of the piston and exteriorly of the cylinder, a ram extending from the second side of said piston and exteriorly of the cylinder, said ram being larger in cross-section than said piston rod thereby providing the second side of the piston with less surface area than the first side, an accumulator containing hydraulic liquid, first and second hydraulic flow lines connected to the accumulator and connected one each to the cylinder, said first line in direct fluid communication with the first side of said piston and said second line in fluid communication with said second side of said piston for applying hydraulic pressure against said first and second sides of the piston thereby balancing a load connected to the piston rod, means for applying gas pressure to the hydraulic liquid in the accumulator, a pump connected in said second line, and a directional valve in said second line connected to the pump for reversing the flow of hydraulic liquid to and from the second side of said piston.

References Cited in the file of this patent UNITED STATES PATENTS 1,460,586 Howse July 3, 1923 1,826,363 Miedbrodt Oct. 6, 1931 2,016,654 Shippy et al. Oct. 8, 1935 2,141,703 Bays Dec. 27, 1938 2,355,669 Moser Aug. 15, 1944 2,402,300 Shimer June 18, 1946 2,555,427 Trautrnan June 5, 1951

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