Abstract:
Systems and methods for providing a hydraulic lift device for use in producing a subterranean well. In some cases, the hydraulic lift device includes a hydraulic cylinder having a first cylindrical sleeve slidably coupled to a second cylindrical sleeve, wherein the first and second sleeves define a hollow channel to accommodate passage of a polished rod. In some cases, the first cylindrical sleeve includes a surface for securing a portion of the polished rod. Additionally, in some cases, the lift device includes a port in fluid communication with the hollow channel, wherein the port is configured to receive an inlet line from a hydraulic pump. In some cases, the lift device also includes a guidance system disposed at least partially outside the hydraulic cylinder, wherein the guidance system is configured to prevent axial rotation of the first cylindrical sleeve with resect to the second cylindrical sleeve. Other implementations are described.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an efficient, compact system for lifting a product from a subterranean well. In particular, the present invention relates to systems and methods for providing a hydraulic lift which drives a down hole pump configured to produce a subterranean well. 
     2. Background and Related Art 
     Oil wells typically vary in depth from a few hundred feet, to several thousand feet. In many wells there is insufficient subterranean pressure to force the oil and water to the earth&#39;s surface. For this reason, some system must be used to pump the crude oil, hydrocarbon gas, produced water and/or hydrocarbon liquids of the producing formation to the earth&#39;s surface. The most common system for pumping an oil well is by the installation of a pumping unit at the earth&#39;s surface that vertically reciprocates a travelling valve of a subsurface pump. 
     Traditionally, subsurface pumps have been reciprocated by a pumping device called a pumpjack which operates by the rotation of an eccentric crank driven by a prime mover which may be an engine or an electric motor. A horse head of the pumpjack is attached to a first end of a polished rod which passes through a stuffing box and is further coupled to a sucker rod attached to a traveling valve positioned deep in the well. A walking beam of the pumpjack is oscillated which in turn raises and lowers the horse head thereby oscillating the traveling valve within the subsurface pump. This motion results in a desired liquid being lifted and produced from the well. 
     While traditionally effective in oil well production, pumpjack units are exceptionally large and heavy pieces of equipment. Pumpjack units are typically built onsite and require a substantially large plot of land on which to construct and install the unit. Pumpjack units further require a prime mover, a gear reducer, a crank and counter arm to provide the necessary speed and oscillating motion for the unit. 
     Thus, while techniques currently exist that relate to the production of a well, challenges still exist. A need, therefore, exists for a lift system that overcomes the current challenges. Accordingly, it would be an improvement in the art to augment or even replace current techniques with other techniques. 
     SUMMARY OF THE INVENTION 
     The present invention relates to an efficient, compact system for lifting a product from a subterranean well. In particular, the present invention relates to systems and methods for providing a hydraulic lift which drives a down hole pump configured to produce a subterranean well. 
     Implementation of the present invention takes place in association with an artificial lift system for recovery of oil and/or gas from a subterranean well. In some implementations, a hydraulic lift device is providing which includes a hydraulic piston having a first piston sleeve slidably coupled to a second piston sleeve, the first and second piston sleeves further having a hollow channel to accommodate passage of a polished rod connected to a sucker rod associated with a subterranean well, the first piston sleeve further including a surface for securing a portion of the polished rod, the device further including a port in fluid communication with the hollow channel, the port being configured to receive an inlet line from a hydraulic pump. Some implementations further include a sensor for determining a position of the first piston sleeve relative to a position of the second piston sleeve. 
     In some implementations, the first piston sleeve is slidably inserted within the second piston sleeve. In other implementations, a sensor is provided which includes a piston rod having a first end coupled to a first end of the first piston sleeve, and a second end comprising an object. The sensor further includes a first sensor positioned at a first height relative to the second piston sleeve, and a second sensor positioned at a second height relative to the second piston sleeve, wherein the object is detectable by the first and second sensors when the object is positioned within proximity to the respective sensors. 
     The position of the first and second sensors determines a stroke length of the hydraulic lift. In some implementations, the object is a magnet or other object that is detectable by the first and second sensors. In other implementations, a computer device is provided for receiving and sending signals from the first and second sensors to a hydraulic pump. For some implementations of the present invention, an expansion chamber is provided between the first piston sleeve and the second piston sleeve whereby to move the first piston sleeve within the second piston sleeve. 
     For some implementations, the second piston sleeve further includes an inner tube concentrically positioned within an interior of the second piston sleeve. As such, the expansion chamber is defined by a space between an outer surface of the inner tube and an inner surface of the piston sleeve. Some implementations further include a plurality of seals formed between an outer surface of the first piston sleeve and the inner surface of the second piston sleeve, and further seals provided and formed between an inner surface of the first piston sleeve and the outer surface of the inner tube. 
     Some implementations of the present invention further include methods for manufacturing a hydraulic lift device in accordance with the present invention, the method including steps for providing a hydraulic piston having a first piston sleeve slidably coupled to a second piston sleeve, the first and second piston sleeves further having a hollow channel to accommodate passage of a polished rod connected to a sucker rod associated with a subterranean well, the first piston sleeve further comprising a surface for securing a portion of the polished rod, providing a port in fluid communication with the hollow channel, the port being configured to receive an inlet line from a hydraulic pump, and providing a sensor for determining a position of the first piston sleeve relative to a position of the second piston sleeve. The method may further include a step for slidably inserting the first piston sleeve within the second piston sleeve. 
     Still further, methods in accordance with the present invention provide steps for attaching a first end of a piston rod to a first end of the first piston sleeve, followed by attaching an object to the second end of the piston rod. Additional steps include steps for coupling a first sensor to a first portion of the second piston sleeve, and coupling a second sensor to a second portion of the second piston sleeve, wherein the object is detectable by the first and second sensors when the object is positioned within proximity to the respective sensors. 
     Some implementations of the present invention provide a hydraulic lift apparatus which includes a hydraulic cylinder having a stationary portion and a moving portion, the moving portion being slidably coupled to the stationary portion, the moving portion further having a surface for retaining a polished rod coupled to a sucker rod of a subterranean well, a sensor system having a stationary base coupled to the stationary portion of the hydraulic cylinder, the system further including a rod having a first end attached to the moving portion of the hydraulic cylinder, a second end of the rod being positioned within the stationary portion of the system, an object attached to the second end of the rod, a plurality of sensors attached to at least one of the stationary portion of the hydraulic cylinder and the stationary base, the sensors being capable of detecting the object, a distance provided between the plurality of sensors, the distance being equal to a desired stroke length of the hydraulic cylinder; and a hydraulic pump in fluid communication with an expansion chamber of the hydraulic cylinder, the expansion chamber being interposedly positioned between the stationary portion and the moving portion of the hydraulic cylinder. 
     While the methods, modifications and components of the present invention have proven to be particularly useful in the area oil and/or gas production, those skilled in the art will appreciate that the methods, modifications and components can be used in a variety of different artificial lift applications. 
     These and other features and advantages of the present invention will be set forth or will become more fully apparent in the description that follows and in the appended claims. The features and advantages may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Furthermore, the features and advantages of the invention may be learned by the practice of the invention or will be obvious from the description, as set forth hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the manner in which the above recited and other features and advantages of the present invention are obtained, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. Understanding that the drawings depict only typical embodiments of the present invention and are not, therefore, to be considered as limiting the scope of the invention, the present invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1 , shown in parts A-C, shows various views of a hydraulic lift in accordance with various representative embodiments of the present invention; 
         FIG. 2  is a cross-sectional view of a hydraulic lift in accordance with a representative embodiment of the present invention; 
         FIG. 3  is a cross-sectional view of a hydraulic lift in accordance with a representative embodiment of the present invention; 
         FIG. 4  is a cross-sectional view of a hydraulic lift in accordance with a representative embodiment of the present invention; and 
         FIGS. 5A-5B  show perspective views of a hydraulic lift having an alignment channel in accordance with representative embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to an efficient, compact system for lifting a product from a subterranean well. In particular, the present invention relates to systems and methods for providing a hydraulic lift which drives a down hole pump configured to produce a subterranean well. 
     It is emphasized that the present invention, as illustrated in the figures and description herein, may be embodied in other forms. Thus, neither the drawings nor the following more detailed description of the various embodiments of the system and method of the present invention limit the scope of the invention. The drawings and detailed description are merely representative of examples of embodiments of the invention; the substantive scope of the present invention is limited only by the appended claims recited to describe the many embodiments. The various embodiments of the invention will best be understood by reference to the drawings, wherein like elements are designated by like alphanumeric character throughout. 
     Referring now to  FIGS. 1A-1C , an implementation of a hydraulic lift system  10  is shown. In general, system  10  comprises a hydraulic lift  20  which is coupled to a well head  50  having an outlet line  52 . A product lifted from an associated subterranean well  60  flows through outlet line  52  and is retained in a storage tank  62 . In some embodiments, outlet line  52  is coupled to a pipeline (not shown) wherein a lifted product is placed directly into the pipeline. 
     Hydraulic lift  20  generally comprises a hydraulic cylinder or piston having an outer piston sleeve  22  and an inner piston sleeve  24 . In some embodiments, inner piston sleeve  24  is slidably positioned within outer piston sleeve  22 , wherein inner piston sleeve  24  translates inwardly and outwardly within an interior space  126  of outer piston sleeve  22 . O-ring seals  32  and  34  are interposedly positioned between outer wall surface  36  of inner piston sleeve  24 , and inner wall surface  38  of outer piston sleeve  22 , thereby isolating the hollow interior  136  of hydraulic lift  20  from the exterior environment. In some embodiments, inner piston sleeve  24  is moved outwardly relative to a stationary position of outer piston sleeve  22  as hydraulic pressure is increased within the interior space of outer piston sleeve  22 . In other embodiments, hydraulic lift  20  comprises an outer piston sleeve slidably positioned over an inner, stationary piston sleeve, wherein the outer piston sleeve translates upwardly and downwardly over the inner piston sleeve&#39;s outer surface (not shown). Thus, the teachings of the present invention may be implemented with any hydraulic piston or cylinder configuration. 
     In some embodiments, lift system  10  further comprises a hydraulic pump  70  in fluid communication with the interior space  126  of outer piston sleeve  22 . In some embodiments, hydraulic pump  70  is remotely located from hydraulic lift  20 , wherein a hydraulic line  72  is used to provide fluid communication between the two components. Hydraulic pressure is increased within the interior space of outer piston sleeve  22  as fluid is delivered to the interior space  126  from hydraulic pump  70 . In some embodiments, hydraulic pump  70  is computer controlled, wherein the direction, timing, pressure and duration of hydraulic pressure being delivered to hydraulic lift  20  is automated or otherwise controlled by a first computer device  74 . In some embodiments, a user remote is provided whereby a user may adjust various operating perimeters of hydraulic pump  70  to achieve a desired rate of productivity for subterranean well  60 . In other embodiments, hydraulic pump  70  comprises a computer controlled valve (not shown), wherein the computer device digitally controls flow of hydraulic fluid though the valve. Thus, in some embodiments one or more computer devices are used to control the rate of speed and productivity of subterranean well  60 . 
     In some embodiments, outer and inner piston sleeves  22  and  24  comprise a hollow interior channel  26  within which a polished rod  54  is housed, wherein a first end  56  of rod  54  is attached to a sucker line  66  which in turn is attached to the valve  82  of a subsurface pump  80 , and wherein a second end  58  of rod  54  is attached to inner piston sleeve  24 . In some embodiments, a portion of second end  58  of rod  54  is positioned externally to hollow channel  26  of inner piston sleeve  24 , a portion of the second end  58  being coupled to inner piston sleeve  24  by a fastener  46 , such as a compression fitting. In other embodiments, inner piston sleeve  24  comprises a solid cross-section (not shown), wherein second end  58  is attached to a solid portion of inner piston sleeve  24 . 
     In some embodiments, hydraulic lift  20  further comprises a gland retainer  42  comprising a dripless seal  44  which forms a seal against the outer surface of polished rod  54 . In some embodiments, gland retainer is coupled to outer piston sleeve  22  and wellhead  50  via fasteners, such as lag bolts. In other embodiments, gland retainer  42  is an integrated feature of outer piston sleeve  22  (not shown). 
     Dripless seal  44  may include any seal compatible with oil and gas applications. In some embodiments, dripless seal  44  comprises a gland seal. In other embodiments, dripless seal is a mechanical face seal. In other embodiments dripless seal  44  comprises a lip seal. Further, in some embodiments dripless seal  44  comprises a plurality of seals. Still further, in some embodiments dripless seal  44  comprises a carbon or polytetrafluoroethylene material. 
     The translating motion and interaction between gland retainer  42  and polished rod  54  creates a positive pressure within wellhead  50  created by the up and down action of pump  80  thereby lifting a product from the subterranean well. The product is then collected in a storage tank or pipeline  62  via outlet line  52 . In some embodiments, polished rod  54  further comprises a hollow rod string  158  that is directly attached to valve  82  of pump  80 . Hollow rod string  158  further comprises a lumen  164  which is coupled to outlet line  52 , as shown in  FIG. 1C . A lifted product is thereby passed through lumen  164  and collected in a storage tank or pipeline  62  via outlet line  52 . In some embodiments, dripless seal  44  prevents passage of gases lifted from well  60  from leaking into hollow interior  136  of hydraulic lift  20 . Accordingly, in some embodiments lifted gas products are collected within an interstitial space  166  of well  60  and removed from well  60  via a gas outlet port  160 . 
     Some embodiments of the present invention further include a sensor system  90  for controlling a stroke length of hydraulic lift  20 , as shown in  FIGS. 1A-4 . In general, sensor system  90  comprises a series of sensors which detect the position of inner piston sleeve  24  relative to outer piston sleeve  22 . In some embodiments, a second computer device  100  receives input from the series of sensors and communicates the sensor input to computer device  74  (e.g., first computer device). Computer device  74  then processes the sensor input to control the flow of hydraulic fluid to hydraulic lift  20 . 
     For example, in some embodiments system  90  comprises a piston rod  92  having a first end coupled to a rod end assembly  94 , and a second end being slidably positioned within a non-cushion tube  96 . Tube  96  further comprises a maximum insertion sensor  102  adjustably coupled to the outer surface of the tube&#39;s base at a desired position, and a maximum height sensor  104  adjustably coupled at a desired position on the tube&#39;s outer surface. The second end of piston rod  92  further comprises a magnet  110  or another object that is detectable by sensors  102  and  104 . 
     In some embodiments, the stroke length of hydraulic lift  20  is equal to a distance  120  between adjustable sensor  102  and adjustable sensor  104 , wherein the position of sensor  102  indicates maximum insertion of inner piston sleeve  24  within outer piston sleeve  22 . Therefore, a user may increase the stroke length of hydraulic lift  20  by increasing distance  120  between sensors  102  and  104  by repositioning  106  at least one of the sensors. Conversely, a user may decrease the stroke length of hydraulic lift  20  by repositioning  106  at least one of sensors  102  and  104  to decrease distance  120 . 
     In some embodiments, magnet  110  exerts a magnetic field on sensors  102  and  104  thereby communicating the relative position of inner piston sleeve  24 . In some embodiments, sensors  102  and  104  convert the sensed magnetic field of magnet  110  into an electronic signal or pulse that is detected by computer device  100 . Compute device  100  processes the signal and then sends instructions  112  to computer device  74  which in turn controls the function of hydraulic pump  70 . In some embodiments, a signal from adjustable sensor  104  indicates a maximum extended position of inner piston sleeve  24 , as shown in  FIGS. 1 and 2 . This signal is processed and sent to computer device  74  within instructions to cease flow of hydraulic fluid to hydraulic lift  20 . In some embodiments, the weight of sucker rod  54  and valve  82  are great enough that inner piston sleeve  24  is drawn into outer piston sleeve  22  by gravitational force alone. In other embodiments, the operation of hydraulic pump  70  is reversed whereby a negative hydraulic pressure is provided within hydraulic lift  20  to draw sleeve  24  within sleeve  22 . 
     A signal from terminal sensor  102  indicates a maximum insertion depth of inner piston sleeve  24  within outer piston sleeve  22 , as shown in  FIG. 3 . This signal is processed and sent to computer device  74  with instructions to resume flow of hydraulic fluid to hydraulic lift  20 . The repetition of signals from sensors  102  and  104  provide an oscillating motion of polished rod  54 , which motion is characteristic of that achieved by a traditional pumpjack unit. In some embodiments, computer device  100  is computer device  74 . 
     Referring now to  FIG. 4 , an exploded view of a representative commercial embodiment of a hydraulic lift is shown. In some embodiments, hydraulic lift  200  further comprises a plurality of O-ring seals and wipers to control the flow of hydraulic fluid within hydraulic lift  200 . In some embodiments, O-ring seals  150  are provided on the outer surface of inner piston sleeve  24  so as to provide a seal between the outer surface of sleeve  24  and the inner surface of outer sleeve  22 . Additional O-ring seals  152  are provided on the inner surface of sleeve  22  so as to further provide a seal between the outer surface of sleeve  24  and the inner surface of outer sleeve  22 . Additional seals may be provided as necessary control the flow of hydraulic fluid within the system. 
     In some embodiments, outer piston sleeve  22  further comprises a concentric, inner tube  222  positioned within sleeve  22  so as to provide an annular expansion chamber  224  between the outer surface of tube  222  and the inner surface of sleeve  22 . Expansion chamber  224  is in fluid communication with hydraulic pump  70  via inlet line  72  and inlet port  28 . The width  226  of expansion chamber  224  is configured to compatibly receive a distal end  30  of inner piston sleeve  24 , wherein O-rings  150  provide a seal between distal end  30  and the inner wall surface of sleeve  22 , and O-ring  154  provides a seal between the inner surface of sleeve  24  and an outer surface of tube  222 . As such, hydraulic fluid pumped into expansion chamber  224  is prevented from bypassing O-rings  150  and  154  thereby displacing inner piston sleeve  24  in an outward direction. In the event that O-rings  150  leak thereby permitting hydraulic fluid to flow into a space between the outer surface of sleeve  24  and the inner surface of sleeve  22 , an auxiliary port  128  is provided whereby the trapped hydraulic fluid may be drained and collected in a container  130 . In some embodiments, auxiliary port  128  and port  28  are coupled to hydraulic pump  70  via a valve block (not shown) wherein hydraulic pressure is alternated between the two ports to provide a double action hydraulic lift. Alternatively, in some embodiments auxiliary port  128  is coupled to a second hydraulic pump (not shown) to provide a double action hydraulic lift device. 
     In some embodiments, inner piston sleeve  24  further comprises a concentric, centering tube  234  positioned within sleeve  24 , having a diameter configured to slidably insert within the inner diameter of inner tube  222 . Centering tube  234  is provided to further stabilize the oscillating motion of inner piston sleeve  24  within outer piston sleeve  22 . In some embodiments, centering tube  234  further prevents dust and debris from exiting hollow channel into the interface between inner surface of sleeve  24  and outer surface of inner tube  222 . 
     Referring now to  FIGS. 5A and 5B , in some embodiments hydraulic lift system  10  further comprises a guidance system  40 , whereby to prevent axial rotation of inner piston sleeve  24  relative to outer piston sleeve  22  during operation of the unit. In some embodiments a structural brace  42  is provided which supports an alignment track  44  having a channel in which a cleat  48  translates along the stroke distance of the hydraulic lift  20 . Thus, alignment track  44  prevents axial rotation of sleeve  24  within sleeve  22 . 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.