Abstract:
A hydraulic oil well pumping apparatus, preferably includes a hydraulic cylinder having a rod that is movable between a upper and lower rod positions; a pumping string that extends downwardly from the rod, the string being configured to extend into an oil well for pumping oil from the well; a prime mover; a hydraulic pump that is powered by the prime mover, said pump having a compensator that regulates pump flow and pump pressure; a directional control valve that moves between open flow and closed flow positions; an accumulator in fluid communication with the pump and directional control valve; a flow line connecting the pump and the accumulator, the directional control valve being positioned in the flow line so that it can control flow between the accumulator and hydraulic cylinder; a proportioning valve; a hydraulic fluid reservoir for containing hydraulic fluid to be supplied to the hydraulic pump; a flow line that transmits hydraulic fluid from the hydraulic cylinder to the reservoir via the proportioning valve; and an electronic control system that controls movement of the rod as it moves between the upper and lower positions by controlling the control valve and the proportioning valve, wherein the control system includes an electrical signal that opens or closes the proportioning valve so that a control of rod movement is enabled when the rod changes direction at the lower position of the rod, and wherein the proportioning valve is choked to lower flow through it as the rod is descending from the upper toward the lower position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Priority of U.S. Provisional Patent Application Ser. No. 61/119,160, filed 2 Dec. 2008, incorporated herein by reference, is hereby claimed. 
         [0002]    Priority of U.S. Provisional Patent Application Ser. No. 61/024,020, filed 28 Jan. 2008, incorporated herein by reference, is hereby claimed. 
         [0003]    U.S. Provisional Patent Application Ser. No. 60/764,481, filed 1 Feb. 2006, is incorporated herein by reference. 
         [0004]    U.S. Provisional Patent Application Ser. No. 60/824,123, filed 31 Aug. 2006, is incorporated herein by reference. 
         [0005]    U.S. patent application Ser. No. 11/670,239, filed 1 Feb. 2007, is incorporated herein by reference. 
         [0006]    PCT Patent Application Serial No. PCT/US2007/061478, filed 1 Feb. 2007, is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0007]    Not applicable 
       REFERENCE TO A “MICROFICHE APPENDIX” 
       [0008]    Not applicable 
       BACKGROUND OF THE INVENTION 
       [0009]    1. Field of the Invention 
         [0010]    The present invention relates to oil well pumps and more particularly to an improved hydraulic oil well pump that is electronically controlled using limit or proximity switches to control a valving arrangement that eliminates shock or excess load from the pumping string or sucker rod during pumping, and especially when changing direction of the sucker rod at the bottom of a stroke. 
         [0011]    2. General Background of the Invention 
         [0012]    Several patents have issued that relate generally to the pumping of oil from an oil well. Examples of those patents are contained in the following table, wherein the order of listing has no significance other than chronological. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 
               
               
                   
               
               
                   
                   
                 ISSUE DATE 
               
               
                 PATENT DOC. NO. 
                 TITLE 
                 MM-DD-YY 
               
               
                   
               
             
             
               
                 3,726,093 
                 Variable displacement pump control assembly 
                 03-02-1976 
               
               
                 4,503,752 
                 Hydraulic Pumping Unit 
                 03-12-1985 
               
               
                 4,631,918 
                 Oil-well pumping system or the like 
                 12-30-1986 
               
               
                 4,761,120 
                 Well Pumping Unit and Control System 
                 08-02-1988 
               
               
                 5,143,153 
                 Rotary Oil Well Pump and Sucker Rod Lift 
                 09-01-1992 
               
               
                 5,390,743 
                 Installation and Method for the Offshore 
                 02-21-1995 
               
               
                   
                 Exploitation of Small Fields 
               
               
                 6,017,198 
                 Submersible well pumping system 
                 01-25-2000 
               
               
                 6,394,461 
                 Pressure Compensated Stuffing Box for 
                 05-28-2002 
               
               
                   
                 Reciprocating Pumping Units 
               
               
                 2003/0085036 
                 Combination Well Kick Off and Gas Lift Booster 
                 05-08-2003 
               
               
                   
                 Unit 
               
               
                 6,595,280 
                 Submersible Well Pumping System with an 
                 07-22-2003 
               
               
                   
                 Improved Hydraulically Actuated Switching 
               
               
                   
                 Mechanism 
               
               
                 2005/0155758 
                 Well Tubing/Casing Vibrator Apparatus 
                 07-21-2005 
               
               
                   
               
             
          
         
       
     
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    The present invention provides a hydraulic oil well pumping apparatus. The system of the present invention utilizes a hydraulic cylinder having a piston or rod that is movable between upper and lower piston positions. A pumping string or sucker rod extends downwardly from the piston, the pumping string or sucker rod being configured to extend into an oil well for pumping oil from the well. 
         [0014]    A prime mover such as an engine is connected to a compensating type hydraulic pump. 
         [0015]    A directional control valve moves between open flow and closed flow positions. A hydraulic flow line connects the pump and the hydraulic cylinder. 
         [0016]    Electronic controls are provided that control movement of the piston as it moves between the upper and lower positions. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0017]    For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
           [0018]      FIG. 1  is a schematic diagram of an embodiment of the apparatus of the present invention; 
           [0019]      FIG. 2  is a schematic diagram of another embodiment of the apparatus of the present invention; 
           [0020]      FIGS. 3-4  are elevation views of a preferred embodiment of the apparatus of the present invention showing an alternate construction for the pump cylinder, wherein lines A-A are match lines and  FIG. 4  is taken along lines  4 - 4  of  FIG. 3 ; 
           [0021]      FIG. 5  is a fragmentary, sectional elevation view of a preferred embodiment of the apparatus of the present invention taken along lines  5 - 5  of  FIG. 3 ; 
           [0022]      FIG. 6  is a partial sectional elevation view of the preferred embodiment of the apparatus of the present invention and showing the alternate construction for the pump cylinder; and 
           [0023]      FIG. 7  is a schematic diagram of another alternate embodiment of the apparatus of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]      FIG. 1  shows an embodiment of the apparatus of the present invention, designated generally by the numeral  150 . Oil well pump  150  provides a pump (e.g. hydraulic piston pump)  153  that receives hydraulic fluid via a reservoir  151  and intake flow line/filter  152 . The hydraulic piston pump  153  is driven by a prime mover (e.g. engine or electric motor). A manifold assembly  154  is shown surrounded by dotted lines in  FIG. 1 . The manifold assembly  154  includes various flow lines as shown in  FIG. 1 , directional valve  165 , proportional flow control valve  171 , relief valve  175 , and valves  174 ,  176 . A discharge flow line  155  extends from the discharge side of pump  153  to internal manifold tee  157 . Check valve  156  can be placed in discharge flow line  155 . Valves  161 ,  171 ,  174 ,  175 ,  176  can be a part of (e.g. internal) manifold  154 . 
         [0025]    At internal manifold tee  157 , flow lines  158 ,  159  communicate with discharge flow line  155 . The flow line  159  extends through flow control valve  164  and to accumulator  160 . The accumulator  160  has an oil containing portion  161  and a gas containing portion  162 . In  FIG. 1 , arrow  163  indicates schematically the level of oil  161  in accumulator  160 . 
         [0026]    Hydraulic cylinder  166  is connected to both accumulator  160  and pump  153  via flow line  158 . Hydraulic cylinder  166  includes a cylinder body  167  and an extendable pushrod  168 . The pushrod  168  is movable between retracted upper and extended lower positions. The pushrod  168  provides a rod end  169  that is fitted with a coupling (e.g. coupling 20 of the embodiments of FIGS. 1-42 in Publication No. US 2007/0261841A1, published 15 Nov. 2007, and in Publication No. WO 2007/090193 A2, published 9 Aug. 2007, both of which are hereby incorporated by reference) which connects the pushrod  168  to a well string such as the pumping string 21 (e.g. sucker rods) shown in FIGS. 1-42 in Publication No. US 2007/0261841A1, published 15 Nov. 2007, and in Publication No. WO 2007/090193 A2, published 9 Aug. 2007. Flow line  170  extends from internal manifold tee  177  through proportional flow control valve  171  to reservoir  178 . Reservoirs  151 ,  178  can be a common reservoir. The flow line  170  can be provided with an oil cooler  172  and filter  173 . Excess pressure in the system can be relieved using relief valve  175 . Valve  176  is a valve that controls flow of fan/cooler  172 . 
         [0027]    In operation, the prime mover (e.g. engine or electric motor) is started which operates hydraulic pump  153 . The hydraulic pump  153  initially rotates at a speed of about 1800 rpm&#39;s and is destroked. The hydraulic pump  153  can be a Parker Model P1075XS (01SRM5AEY0T00CPB). A pumping cycle begins by giving the hydraulic piston pump  153  a command using a controller (such as the controller 39 described herein in reference to FIGS. 1-42), stroking it to charge accumulator  160 . When accumulator  160  is fully charged, the directional valve  165  is energized, while maintaining the command to the pump  153 . Oil  161  is then directed from the charged accumulator  160  through the flow control valve  164  and from the pump  153  into the rod end  168  of the hydraulic cylinder  166 . Valve  164  enables free flow in and restricted flow out to control speed of upstroke of cylinder  166 . Pushrod  168  will then retract lifting the pumping string until a proximity switch is actuated by a coupling that is mounted on the rod end  169 . 
         [0028]    The controller 39 then de-energizes the directional valve  165  and activates the proportional control valve  171  forcing it to open until the pushrod  168  begins to fall at a desired velocity. The degree of opening of the proportional control valve  171  controls how fast fluid leaves the cylinder body  167  and flows via flow lines  158 ,  170  through the proportional flow control valve  171  and into reservoir  178 . 
         [0029]    Eventually, the coupling on the rod end  169  reaches a second proximity switch which is positioned a short distance (e.g. approximately one foot) from the bottom of the travel of the pushrod  168 . When the coupling reaches the second proximity switch, a current signal to the proportional control valve  171  is decreased, forcing the pushrod  168  to decelerate until the coupling 20 on the rod end  169  of the pushrod  168  reaches a third proximity switch. The electrical signal from the controller 39 will then be removed from the proportional control valve  171 , with a voltage signal then being sent by controller 39 to the directional valve  165  while maintaining the command to the pump  153  to continue pumping. Oil  161  returning from the cylinder body  167  through the proportional control valve  171  passes through an oil cooler  172  and filter  173  before reaching reservoir  178 . 
         [0030]    During the time that the pushrod  168  is extending with respect to the cylinder body  167 , oil  161  is being pumped by the pump  153  to the accumulator  160 , charging the accumulator  160  for use in the next cycle. The accumulator  160  will thus have a pressure change of between about five hundred (500) psi depending on sucker rod string load when it has been discharged by transmitting fluid to the cylinder  166  and a maximum pressure value of about three thousand (3,000) psi depending on sucker rod string load when it is fully charged by the pump  153  during that time that the pushrod  168  is extending and cylinder  166  is draining. 
         [0031]      FIG. 2  shows another embodiment of the apparatus of the present invention designated generally by the numeral  180 . Oil well pump  180  is somewhat similar to the embodiment of  FIG. 1 , with the elimination of bypass valve  174 , that function now being taken care of by pump  184 . The pump  184  is an electronically controlled variable volume pressure compensated positive displacement piston pump such as is available from Parker® (www.parker.com). Pump  184  receives hydraulic fluid via intake flow line/filter  185  and from reservoir  182 . As with the embodiment of  FIG. 1 , a manifold  186  contains various valves  198 ,  204 ,  207 ,  208  that can be internally of manifold  186 . Discharge flow line  187  transmits pressurized oil from pump  184  to tees  188 ,  189 . A check valve  190  can be positioned in between the tees  188 ,  189  in discharge line  187 . At internal manifold tee  183 , discharge flow line  187  communicates with flow lines  191 ,  192 . 
         [0032]    Flow line  192  communicates with accumulator  193 . As with the embodiment of  FIG. 1 , the accumulator  193  has an oil containing portion  194 , a gas containing portion  195 , and wherein arrow  196  indicates the level of oil  194  contained within accumulator  193 . 
         [0033]    Flow control valve  197  can be the same as the valve  164  of  FIG. 1 . The directional valve  198  of  FIG. 2  can be the same as the directional valve  165  of  FIG. 1 . 
         [0034]    Hydraulic cylinder  199  provides a cylinder body  200  that includes a pushrod  201  that can be raised or lowered. The pushrod  201  has a rod end  202  that can be coupled to a pumping string such as a plurality of sucker rods  228  connected end to end. Pushrod  201  (and sucker rods  228 ) rises and falls during operation as illustrated by arrow  18  in  FIG. 2 . 
         [0035]    Flow line  203  connects to flow line  191  at internal manifold tee  210 . Flow line  203  communicates with proportional flow control valve  204 , oil cooler/fan  205 , filter  206  and reservoir  182 . 
         [0036]    Relief valve  207  is placed in flow line  211  that extends between tee  189  and reservoir  182 . The relief valve  207  enables excess pressure to be vented from the discharge flow line  187  via flow line  211  to reservoir  182 . 
         [0037]    Valve  208  is a fan control valve that controls the flow of hydraulic fluid via flow line  209  to the fan/oil cooler  205 . Flow from line  209  discharges into reservoir  182 . The embodiment of  FIG. 2  operates in much the same fashion as the embodiment of  FIG. 1 , but for the elimination of bypass valve  174 , that function now taken care of by the pump  184 . 
         [0038]      FIGS. 3-6  show an alternate construction for the hydraulic cylinder and its connection to the well string, pumping string or sucker rod string  228 . In  FIGS. 3 and 4 , hydraulic cylinder  212  provides a cylinder body  213  and a pushrod  214  that moves between upper and lower positions. Pushrod  214  is affixed to piston  237  and travels therewith. At the lower end portion of pushrod  214  is provided female connector  215  to which is connected elongated polished rod  216 . 
         [0039]    Frame  217  forms an interface between cylinder body  213  and a wellhead tree  220 . The frame  217  has an upper end portion  218  to which cylinder body  213  is mounted using its flange  231 . The frame  217  has a lower end portion  219  that attaches to the wellhead tree  220 . 
         [0040]    Flange  231  can be mounted to upper end portion  218  of frame  217 . Rod gland  232  is connected to and extends downwardly from flange  231 . Head  233  forms an interface between cylinder body  213  and flange  231  as shown. Flushing box  221  is mounted to the lower end portion of gland  232 . The flushing box  221  has an influent port  222  and an effluent port  223 , enabling a flushing fluid to be pumped from a source to the flushing box interior  239  and then discharged. A continual stream of flushing fluid (for example hydraulic fluid) continuously cleans the polished rod  216  which is attached to the lower end portion of pushrod  214  at female connector  215 . 
         [0041]    Cylinder body  213  provides an upper port  234  and a lower port  235 . The upper port  234  can be a part of cap  236  which is fastened to the upper end portion of cylinder body  213  as shown.  FIG. 4  illustrates a condition wherein the piston  237  is being elevated in the direction of arrows  241 . Lower port  235  is receiving inflow of hydraulic fluid as indicated schematically by the arrow  240  in  FIG. 4 . Fluid above piston  237  is evacuated via port  244  illustrated in  FIG. 5 , the arrows  229  indicate schematically the flow direction of oil as the piston  237 , pushrod  214 , and polished rod  216  are elevated. Coupling  227  is also elevating as illustrated in  FIG. 5 . 
         [0042]    In  FIG. 6 , the piston  237  is being lowered. Fluid escapes cylinder  212  via flow line  243  as illustrated by arrow  247  in  FIG. 6 . Port  244  is simply a vent at the top of the cylinder  212  as indicated by arrow  246  in  FIG. 6 . String pot  238  is mounted upon cap  236 . String pot  238  is a measuring apparatus that is commercially available from Parker (www.parker.com). The String pot  238  has a cable or wire  248  that attaches at  249  to piston  237  or pushrod  214 . As the piston  237  raises and lowers, the cable or wire  248  pays out or is retrieved by string pot  238 . The string pot  238  is interface with suitable instrumentation with the programmable logic controller or PLC  39 . Thus, the string pot  238  replaces the limit switches of FIGS. 1-42. 
         [0043]    A flow tee  224  can be mounted upon wellhead tree  220  below frame  217 . The flow tee  224  enables oil that is being pumped from the well to be transmitted to tankage via flow line  225  as indicated schematically by arrow  230 . Flow line  225  can be a vent line from top of wellhead  220 . Blowout preventer  226  can be positioned below flow tee  224 . Polished rod  216  can be for example about 25-30 feet in length. Thus, the polished rod enables a very long pump stroke to be provided for pumping oil. Because the polished rod  216  extends through the flushing box  221  and into the wellhead tree  220 , coupling  227  can be placed below blowout preventer  226  for connecting the polished rod  216  to sucker rods or pumping string  228 . The pumping cylinder arrangement of  FIG. 3  enables the frame  217  to be relatively short such as for example about three feet in height. 
         [0044]      FIG. 7  shows another alternate embodiment of the apparatus of the present invention, designated generally by the numeral  250 . Oil well pump  250  provides a pump (e.g. hydraulic piston pump)  253  that receives hydraulic fluid via a reservoir  251  and intake flow line/filter  252 . The hydraulic piston pump  253  is driven by a prime mover (e.g. engine or electric motor). A manifold assembly  254  is shown surrounded by dotted lines in  FIG. 7 . The manifold assembly  254  includes various flow lines as shown in  FIG. 7 , directional valve  265 , proportional flow control valve  271 , relief valve  275 , and valves  274 ,  276 . A discharge flow line  255  extends from the discharge side of pump  253  to internal manifold tee  257 . Check valve  256  can be placed in discharge flow line  255 . Valves  265 ,  271 ,  274 ,  275 ,  276  can be a part of (e.g. internal) manifold  254 . 
         [0045]    At internal manifold tee  257 , flow lines  258 ,  259  communicate with discharge flow line  255 . The flow line  259  extends through flow control valve  264  and to accumulator  260 . The accumulator  260  has an oil containing portion  261  and a gas containing portion  262 . In  FIG. 7  arrow  263  indicates schematically the level of oil  261  in accumulator  260 . 
         [0046]    Hydraulic cylinder  266  is connected to both accumulator  260  and pump  253  via flow line  258 . Hydraulic cylinder  266  includes a cylinder body  267  and an extendable pushrod  268 . The pushrod  268  is movable between retracted upper and extended lower positions. The pushrod  268  provides a rod end  269  that is fitted with a coupling (e.g. coupling 20 of the embodiments of FIGS. 1-42 in Publication No. US 2007/0261841A1, published 15 Nov. 2007, and in Publication No. WO 2007/090193 A2, published 9 Aug. 2007, both of which are hereby incorporated by reference) which connects the pushrod  268  to a well string such as the pumping string 21 (e.g. sucker rods) shown in FIGS. 1-42 in Publication No. US 2007/0261841A1, published 15 Nov. 2007, and in Publication No. WO 2007/090193 A2, published 9 Aug. 2007. Flow line  270  extends from internal manifold tee  277  through proportional flow control valve  271  to reservoir  278 . Reservoirs  251 ,  278  can be a common reservoir. The flow line  270  can be provided with an oil cooler  272  and filter  273 . Excess pressure in the system can be relieved using relief valve  275 . Valve  276  is a valve that controls flow of fan/cooler  272 . 
         [0047]    In operation, the prime mover (e.g. engine or electric motor) is started which operates hydraulic pump  253 . The hydraulic pump  253  initially rotates at a speed of about 1800 rpm&#39;s and is destroked. The hydraulic pump  253  can be a Parker Model P1075XS (01SRM5AEY0T00CPB). A pumping cycle begins by giving the hydraulic piston pump  253  a command using a controller (such as the controller 39 described herein in reference to FIGS. 1-42), stroking it to charge accumulator  260 . When accumulator  260  is fully charged, the directional valve  265  is energized, while maintaining the command to the pump  253 . Oil  261  is then directed from the charged accumulator  260  through the flow control valve  264  and from the pump  253  into the rod end  268  of the hydraulic cylinder  266 . Valve  264  enables free flow in and restricted flow out to control speed of upstroke of cylinder  266 . Pushrod  268  will then retract lifting the pumping string until a proximity switch is actuated by a coupling that is mounted on the rod end  269 . 
         [0048]    The controller 39 then de-energizes the directional valve  265  and activates the proportional control valve  271  forcing it to open until the pushrod  268  begins to fall at a desired velocity. The degree of opening of the proportional control valve  271  controls how fast fluid leaves the cylinder body  267  and flows via flow lines  258 ,  270  through the proportional flow control valve  271  and into reservoir  278 . 
         [0049]    Eventually, the coupling on the rod end  269  reaches a second proximity switch which is positioned a short distance (e.g. approximately one foot) from the bottom of the travel of the pushrod  268 . When the coupling reaches the second proximity switch, a current signal to the proportional control valve  271  is decreased, forcing the pushrod  268  to decelerate until the coupling 20 on the rod end  269  of the pushrod  268  reaches a third proximity switch. The electrical signal from the controller 39 will then be removed from the proportional control valve  271 , with a voltage signal then being sent by controller 39 to the directional valve  265  while maintaining the command to the pump  253  to continue pumping. Oil  261  returning from the cylinder body  267  through the proportional control valve  271  passes through an oil cooler  272  and filter  273  before reaching reservoir  278 . 
         [0050]    During the time that the pushrod  268  is extending with respect to the cylinder body  267 , oil  261  is being pumped by the pump  253  to the accumulator  260 , charging the accumulator  260  for use in the next cycle. The accumulator  260  will thus have a pressure change of between about five hundred (500) psi depending on sucker rod string load when it has been discharged by transmitting fluid to the cylinder  266  and a maximum pressure value of about three thousand (3,000) psi depending on sucker rod string load when it is fully charged by the pump  253  during that time that the pushrod  268  is extending and cylinder  266  is draining. 
         [0051]    A second, optional, accumulator  279  is shown in  FIG. 7 , connected to flow line  258  via flow line  283 . As with accumulator  260 , the accumulator  279  has oil at  280  and gas at  281 . The arrow  282  shows the surface of oil  280 . Accumulator  279  is used to remove surge or shock in the operation of hydraulic cylinder  266  to help protect cylinder  266 . Accumulator  279  is in the discharge line of the pump. Accumulator  279  may have a capacity of, for example, around one quart, while accumulator  260  may have a capacity of around 15 gallons. 
         [0052]    Accumulator  260  my be, for example, an integrated accumulator with a capacity of around 15 gallons, or it may be an accumulator with a capacity of around 5 to 7.5 gallons, for example, with a gas bottle having a capacity of around 10 gallons, to give it a total capacity of around 15 to 17.5 gallons, for example. 
         [0053]    Also, multiple smaller capacity accumulators  260  could be used instead of one larger capacity accumulator  260  (due to space constraints, for example). 
         [0054]    In all accumulators, the oil can be, for example, hydraulic oil such as Exxon Humble Hydraulic H68 brand hydraulic oil or equivalent, biodegradable oil, Sea Blue Hydraulic Oil  68  by Industrial Oils Unlimited of Arkansas; the gas can be, for example, nitrogen, carbon dioxide, or any other preferably non-toxic and non-flammable commercially available compressed inert gas. 
         [0055]    Valve  274  is optional, though preferred. 
         [0056]    The following is a list of parts and materials suitable for use in the present invention. 
       PARTS LIST 
     Part Number Description 
       [0000]    
       
         
           
               150  oil well pump 
               151  reservoir 
               152  intake flow line/filter 
               153  hydraulic piston pump 
               154  manifold assembly 
               155  discharge flow line 
               156  check valve 
               157  internal manifold tee 
               158  flow line 
               159  flow line 
               160  accumulator 
               161  oil 
               162  gas 
               163  arrow 
               164  flow control valve 
               165  directional valve 
               166  hydraulic cylinder 
               167  cylinder body 
               168  pushrod 
               169  rod end 
               170  flow line 
               171  proportional flow control valve 
               172  oil cooler/fan 
               173  filter 
               174  bypass valve 
               175  relief valve 
               176  valve 
               177  internal manifold tee 
               178  reservoir 
               180  oil well pump 
               181  reservoir 
               182  reservoir 
               183  internal manifold tee 
               184  pump 
               185  intake flow line/filter 
               186  manifold 
               187  discharge flow line 
               188  tee 
               189  tee 
               190  check valve 
               191  flow line 
               192  flow line 
               193  accumulator 
               194  oil 
               195  gas 
               196  arrow 
               197  flow control valve 
               198  directional valve 
               199  hydraulic cylinder 
               200  cylinder body 
               201  pushrod 
               202  rod end 
               203  flow line 
               204  proportional flow control valve 
               205  oil cooler/fan 
               206  filter 
               207  relief valve 
               208  valve 
               209  flow line 
               210  tee 
               211  flow line 
               212  hydraulic cylinder 
               213  cylinder body 
               214  pushrod 
               215  female connector 
               216  polished rod 
               217  frame 
               218  upper end portion 
               219  lower end portion 
               220  wellhead tree 
               221  flushing box 
               222  influent 
               223  effluent 
               224  flow tee 
               225  flow line 
               226  blowout preventer 
               227  coupling 
               228  suckerrod 
               229  flow line 
               230  arrow 
               231  flange 
               232  rod gland 
               233  head 
               234  upper port 
               235  lower port 
               236  cap 
               237  piston 
               238  string pot 
               239  interior 
               240  arrow 
               241  arrow 
               242  arrow 
               243  flow line 
               244  flow line 
               245  arrow 
               246  arrow 
               247  arrow 
               250  oil well pump 
               251  reservoir 
               252  intake flow line/filter 
               253  hydraulic piston pump 
               254  manifold assembly 
               255  discharge flow line 
               256  check valve 
               257  internal manifold tee 
               258  flow line 
               259  flow line 
               260  accumulator 
               261  oil 
               262  gas 
               263  arrow 
               264  flow control valve 
               265  directional valve 
               266  hydraulic cylinder 
               267  cylinder body 
               268  pushrod 
               269  rod end 
               270  flow line 
               271  proportional flow control valve 
               272  oil cooler/fan 
               273  filter 
               274  bypass valve 
               275  relief valve 
               276  valve 
               277  internal manifold tee 
               278  reservoir 
               279  accumulator 
               280  oil 
               281  gas 
               282  arrow 
               283  flow line 
               319  flow line 
           
         
       
     
         [0189]    All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. 
         [0190]    The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.