Abstract:
An improved hydraulic downhole oil recovery system may incorporate an above ground hydraulic pumping unit and a submersible, bidirectional, reciprocating downhole hydraulic slave cylinder-based pumping unit. Water, rather than hydraulic fluid, may be responsible for actuating the reciprocating downhole pump unit. The water may be transferred through the system using seamless, coil tubing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of PCT/US2005/045305, filed Dec. 13, 2005, which is a continuation-in-part of U.S. application Ser. No. 11/010,641, filed Dec. 13, 2004, now U.S. Pat. No. 7,165,952, and this application is a continuation-in-part of U.S. application Ser. No. 10/945,562, filed Sep. 20, 2004, which is a continuation-in-part of U.S. application Ser. No. 10/945,530, filed Sep. 20, 2004, which is a continuation-in-part of U.S. application Ser. No. 10/884,376, filed Jul. 2, 2004, the disclosures of all of which are incorporated herein by reference. 
     
    
     FIELD  
       [0002]     The system described herein generally relates to an improved hydraulic downhole oil recovery system.  
       BACKGROUND  
       [0003]     Conventional oil recovery systems are hampered by limitations on both the depth and volume of oil that can be recovered. In fact, known oil recovery systems can generally recover 400 barrels of oil per day, at a depth of 1000 feet, using full-sized standard surface pumps.  
         [0004]     Conventional oil recovery systems are relatively short-lived and require a high level of maintenance. Current systems rely on large, cumbersome parts that are prone to leaking and causing wear and tear of standard production tubing. In the past, fitting system components and power fluid tubing within coil tubing has proven to be too difficult.  
         [0005]     A large portion of the problems associated with known oil recovery systems come from the secured-production tubing configuration of those systems. Specifically, reciprocation of the sucker rod within the production tube causes wear and tear of the tubing. As a result, leaks often originate within the tubing at the secured reciprocation location. This leads to both inefficiency and environmental contamination. Such problems are exaggerated in the common case of deviated oil wells.  
         [0006]     Common oil recovery systems also present significant problems at the surface. Surface pumps are loud, cumbersome, visually offensive, dangerous, and environmentally unfriendly. As such, restrictions are placed on both where and when these systems can be used. Prohibitive zoning restrictions are often based on the way the pumps look, how they sound, and the inconvenience they cause to people in their proximity. Further, it is widely known in the art that conventional surface pumps are prone to leaking both oil and hazardous fumes. As such, environmental concerns are very high and periodic maintenance is required, while the cost of operation increases and efficiency decreases.  
         [0007]     Surface pumps are also dangerous; each year, there are several injuries and deaths that result from the operation of such pumps. These casualties often involve children who make their way to the pumps, drawn by curiosity, only to get caught in the moving parts.  
         [0008]     There is a narrow range of hydraulically operated oil recovery systems known in the art. For instance, Schulte (U.S. Pat. No. 5,494,102) discloses a downhole operated pump having a power piston reciprocated by alternating pressurized hydraulic fluid flow controlled at the surface by a hydraulic power control system which quickly reverses the flow direction.  
         [0009]     In view of the limitations and hazards associated with traditional oil recovery systems, and the defects in those systems, a great need exists for a system that can operate efficiently and safely.  
       EXAMPLES AND SUMMARY  
       [0010]     The present system does away with the limitations of the prior art. Some embodiments of Applicant&#39;s system will be able to recover 1500 barrels per day, using a fraction of the energy consumed by conventional systems. Particular embodiments of the present system may be maintained on solar energy, which is not feasible with known downhole oil recovery systems. Some embodiments of Applicant&#39;s system provide a much smaller surface unit, with fewer moving parts, and incorporate coil tubing. As such, the maintenance and the risk of leaks are reduced. As will be further discussed, various embodiments of Applicant&#39;s system eliminate the common problems of the prior art through the novel use of coil production tubing.  
         [0011]     Applicant&#39;s system provides a refreshing solution to the problems mentioned above and avoids the worst characteristics associated with known surface pumps. Various embodiments of the present system use only a fraction of the energy required for standard surface pumps. As such, the present system is much smaller and quieter, is easily housed and insulated, and greatly reduces the likelihood of leaks and the need for maintenance. Further, the present system eliminates the dangers associated with surface pumps as there are no large, cumbersome moving parts.  
         [0012]     Applicant&#39;s system is distinguished from Schulte specifically in a number of ways. While Schulte teaches an apparatus having a power piston above the production piston, some embodiments of the present system provide for a power piston below the production piston. Such configuration provides greater efficiency and allows the present system to be operated on much less energy.  
         [0013]     Schulte teaches a power piston that runs along the well bore itself. However, some embodiments of the present system provide for a power piston/production piston configuration whereby each piston is actuated within a removable tube housing located within the well bore. This feature provides for a straightforward maintenance or replacement scheme that is simply not available with devices known in the art.  
         [0014]     Applicant&#39;s system also provides a scheme whereby either the volume of the power piston or the volume of the production piston may be changed with respect to one another. As such, the power piston/production piston ratio may be manipulated to vary the power fluid/output fluid ratio for different situations. For example, the size of the power piston may be increased with respect to the production piston. This scheme will allow the present system to be operated on an extremely small amount of power. In fact, some embodiments are thought to operate within the range of solar power sources. This feature is not available with any known products. Alternatively, the size of the production piston could be increased with respect to the power piston. This scheme will allow the present system to achieve rates of oil production not generally possible. For example, the present system will be able to produce approximately 1,500 barrels of oil per day while accepted limitations fall around 400 barrels of oil per day. As mentioned, the components are housed in a removable tubing; as such, the power piston/production piston ratio may be changed in accordance with changing amounts and depths of available oil.  
         [0015]     Applicant&#39;s system further provides a tremendous improvement in oil production efficiency. Traditional oil well pump devices can only pump oil to the surface during an upstroke. However, some embodiments of the present system, through employment of a double acting pump and a novel component configuration, allow for oil to be continuously pumped to the surface. That is, oil is sent to the surface during both the upstroke and the downstroke. Perhaps of even greater importance, this “double action” is achieved with no greater expenditure of power. While production is double, energy consumption remains constant.  
         [0016]     Certain embodiments of the present system incorporate the use of coil tubing throughout the system. Coil tubing is known in the industry and is typically used to clean sand from well bores; however, no known products have been able to incorporate such tubing to transfer power fluid and provide housing for system components. Some embodiments of Applicant&#39;s system, however, provide for the novel use of such tubing to transfer power fluid and house components. This feature makes such embodiments of Applicant&#39;s system particularly useful in deviated oil wells when compared to presently available products. Through use of coil tubing, water-based fluid rather than hydraulic fluid, and a unique combination of system components, various embodiments of Applicant&#39;s system eliminate problems associated with known recovery systems and provide tremendous progress in view of those systems.  
         [0017]     Certain embodiments of the present system are further distinguished over the prior art in general, and the Schulte patent in particular, by the use of water-based fluid rather than hydraulic fluid to actuate the downhole reciprocating pump unit. The substitution of water-based fluid for hydraulic fluid may appear to be a subtle distinction at first glance. Nevertheless, the use of water-based fluid in the present system has virtually eliminated the most common problems associated with presently proposed but impractical hydraulic recovery systems, including: the compression of production fluid circulated though the system, inflexible fluid transfer lines, fluid friction during downhole and return flow cycles, and fluid viscosity.  
         [0018]     In view of the foregoing, some embodiments of the present system provide an oil recovery system that pumps oil to the surface during both its upstroke and its downstroke.  
         [0019]     Various embodiments of the present system provide an oil recovery system that has a favorable oil production to energy consumption ratio.  
         [0020]     Various embodiments of the present system provide an oil recovery system that eliminates conventional tubing wear and tear.  
         [0021]     Various embodiments of the present system provide an oil recovery system that eliminates weak tubing link unreliability.  
         [0022]     Various embodiments of the present system provide an oil recovery system that eliminates surface leaks.  
         [0023]     Various embodiments of the present system provide an oil recovery system that eliminates pumping unit liability.  
         [0024]     Various embodiments of the present system provide an oil recovery system that eliminates submersible pump inefficiencies.  
         [0025]     Various embodiments of the present system provide an oil recovery system that may be exceptionally useful in deviated oil wells.  
         [0026]     Various embodiments of the present system provide an oil recovery system that produces and maintains relatively high volume lift in relatively low production wells.  
         [0027]     Various embodiments of the present system provide an oil recovery system that may be used in environmentally sensitive locations.  
         [0028]     Various embodiments of the present system provide an oil recovery system that may be safely used in urban environments.  
         [0029]     Various embodiments of the present system provide an oil recovery system that may be used in corrosive environments.  
         [0030]     Various embodiments of the present system provide an oil recovery system that may be used in remote locations.  
         [0031]     Various embodiments of the present system provide an oil recovery system that contains a surface adjustable lift capacity.  
         [0032]     Various embodiments of the present system provide an oil recovery system that may be used to recover particularly deep oil deposits.  
         [0033]     Various embodiments of the present system provide an oil recovery system that may be powered by solar energy or other alternative power sources.  
         [0034]     Various embodiments of the present system provide an oil recovery system that employs the use of coil production tubing.  
         [0035]     Various embodiments of the present system provide an oil recovery system that maintains its power piston below its production piston.  
         [0036]     Various embodiments of the present system provide an oil recovery system that employs the use of pressure controlled surface pumps.  
         [0037]     Various embodiments of the present system provide an oil recovery system that requires an exceptionally low amount of service.  
         [0038]     Various embodiments of the present system provide an oil recovery system that has an exceptionally long running life.  
         [0039]     As will be discussed in the specification to follow, some embodiments of the present system involve a pressure-type pump surface unit. This surface unit is modified to read and react to pressure measurements during pump cycles so that when pressure builds past a certain point at the completion of a cycle, the unit “switches” to begin the next cycle. As mentioned, the surface unit of the present system is of a pressure-type, and therefore is much smaller, quieter, and cleaner than standard oil well surface units.  
         [0040]     The surface unit of the present system is connected to a downhole apparatus by a pair of hydraulic powerlines. Some embodiments of the downhole unit of the present system primarily consist of a power piston, a production piston, a connecting rod, and a series of inlets, valves, and reservoirs. Operation of the system is initiated when power fluid is alternatingly pumped through each powerline, thereby actuating a downhole power piston between a top position and a bottom position. Specifically, as fluid is pumped through the upstroke powerline, the fluid volume of the reservoir below the power piston expands, thereby forcing the power piston upward. During the following downstroke, fluid is pumped through the downstroke powerline, and the fluid volume of the reservoir above the power piston expands, thereby forcing the power piston downward.  
         [0041]     A connecting rod extends from the power piston to the production piston. In holding the power piston and production piston fixed with respect to one another, the connecting rod traverses both a hydraulic power fluid reservoir and an oil reservoir. Importantly, the connecting rod, in combination with the pump barrel, forms a fluid-tight seal between the power fluid reservoir and the oil reservoir. This feature allows the connecting rod to actuate between a top position and a down position while keeping the “dirty” oil environment separate from the “clean” power fluid environment.  
         [0042]     In some embodiments, the production piston rests along the top surface of the connecting rod and is actuated between a bottom position just above the power fluid reservoir and a top position just below a one-way valve. These one-way valves may be standard “check” valves as known in the art. That is, each valve may consist of a loosely seated bearing that rests above a grooved slot. Each bearing may become unseated, thereby allowing fluid to flow in a given direction, yet returns to a seated position to prevent backflow of any fluid.  
         [0043]     In some embodiments, as the production piston is actuated from a bottom position to a top position, oil is cycled from a first inlet, positioned below the production piston, to a first reservoir, positioned between the power fluid reservoir and the production piston. During this stage, production oil located in a second reservoir, positioned between the production piston and a one-way check valve, is forced through the check valve and to the rest of the system. Specifically, the production piston forces oil through the check valve. As the production piston begins to lower, the check valve returns to the seated position, preventing fluid from returning. This action also creates the vacuum that is responsible for sucking oil through a second oil inlet into a second oil reservoir. This process is repeated through a series of valves until the oil is cycled to the surface.  
         [0044]     In some embodiments, as the production piston is actuated from a top position to a bottom position, oil is cycled from a second inlet, positioned above the production piston at the completion of a downstroke, into a second reservoir, positioned between the production piston and a one-way check valve. During this stage, production oil located in the first reservoir, positioned between the production piston and the power fluid reservoir, is forced through an adjacent shaft leading from the first reservoir to a location above the second reservoir and separated from the first reservoir by a check valve. Said adjacent shaft also contains its own one-way valve so that fluid only flows through the shaft during the downstroke, and no backflow is permitted.  
         [0045]     It is important to note that the general operation and effectiveness of the present system do not depend on the exact arrangement of the component parts. Specifically, in some embodiments, the power piston may be placed below or above the production fluid reservoirs. It is easily seen that production oil may still be pumped on both an upstroke and a downstroke, with only minor changes needed in the arrangement of the system. In each arrangement, the efficiency of the present system is preserved.  
         [0046]     As mentioned, some embodiments of Applicant&#39;s system circulate a water-based fluid, rather than hydraulic fluid, throughout the system. This substitution promotes both the novel design and great efficiency of the present system. More specifically, the use of water-based fluid provides for a much greater operating efficiency. That is, typical hydraulic fluid is compressible and therefore requires significantly more pump strokes to “pressure up” than a column of water-based fluid. As a result, the efficiency of hydraulic fluid decreases over any appreciable distance as its compression causes wasted pump strokes, which directly translates to lost power. Because some embodiments of the present system use incompressible water-based fluid, problems associated with fluid compressibility have been eliminated. Specifically, power loss is avoided as there is no appreciable loss in efficiency due to the compression of the circulated production fluid.  
         [0047]     Other useful embodiments of the present system are thought to utilize additives that may increase the viscosity of the water-based hydraulic fluid. Such may involve the use of “oils” to form emulsions. These embodiments are thought to be particularly useful in further reducing fluid friction and further improving operating efficiency.  
         [0048]     However, the benefits associated with the present system do not end with use of water-based fluid. Further benefits of the present system may lie in the placement and action of the downhole pump. In some embodiments, the downhole pump is placed below the production oil; as such, the surface unit is in a mechanically superior alignment. That is, the surface unit is responsible for actuating only the downhole pump, rather than cycling the entire production string through the production tube. This feature alone, in conjunction with an efficient surface unit, provides for an extreme decrease in the energy used during production.  
         [0049]     Devices of the past have not been successful in using coil tubing, as it has proven too difficult to incorporate such tubing within the production tube itself. However, Applicant has overcome that obstacle. Some embodiments of the present system provide for coil, flexible tubing contained within the production tube that allows circulation of water-based fluid from the surface to the downhole pump unit. This feature alone, and particularly in combination with coil production tubing, allows some embodiments of the present system to be useful in deviated wells that would otherwise be inaccessible. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0050]     Applicant&#39;s system may be further understood from a description of the accompanying drawings, wherein unless otherwise specified, like reference numerals are intended to depict like components in the various views.  
         [0051]      FIGS. 1A-1B  are cross-sectional views of one embodiment of a downhole unit of a hydraulic downhole oil recovery system.  
         [0052]      FIGS. 2A-2B  are cross-sectional views of one embodiment of a downhole unit of a hydraulic downhole oil recovery system.  
         [0053]      FIG. 3  is a cross-sectional schematic view of one embodiment of a downhole oil recovery system as used in connection with an oil well.  
         [0054]      FIG. 4  is a perspective view of one embodiment of a downhole unit of a downhole oil recovery system.  
         [0055]      FIGS. 5A-5B  are cross-sectional views of the downhole unit of  FIG. 4 .  
     
    
     DETAILED DESCRIPTION  
       [0056]     With reference to  FIG. 3 , a hydraulic downhole oil recovery system is identified generally by the reference numeral  10 . In some embodiments, system  10  is primarily made of alloy metal and coil tubing.  
         [0057]     Referring to  FIGS. 1A-1B ,  FIGS. 2A-2B ,  FIG. 3 ,  FIG. 4  and  FIGS. 5A-5B , system  10  includes surface pump unit  12 . Surface pump unit  12  sends power fluid  14  through upstroke powerline  16  during one cycle and sends power fluid  14  through downstroke powerline  18  in a following downstroke cycle. Surface pump unit  12  reversibly engages with powerlines  16  and  18  so as to form a fluid-tight seal, such seal being formed by standard tube fittings as known in the art. In some embodiments, surface pump unit  12  is a pressure pump, modified to contain a “switch off pressure sensor”  13  which reads the pressure at surface pump unit  12  on both the upstroke and the downstroke. At the point each stroke is carried out, pressure increases beyond a preset “switch off” point where sensor  13  sends a signal to surface pump unit  12  to begin the next stroke. Further, surface pump unit  12  transfers power fluid  14  by alternating pressure on both powerline  16  and powerline  18 , and such pressure change may be carried out in a number of ways. Finally, in some embodiments, power fluid  14  may be a water-based fluid. As previously discussed in the specification, the use of water-based fluid in conjunction with system  10  provides its user with a number of advantages.  
         [0058]     Both upstroke powerline  16  and downstroke powerline  18  may extend from surface pump unit  12  to a downhole unit  11  and follow along the length of removable production tube  20 . Production tube  20 , in some embodiments, reversibly slides along outer shaft  21 . In some embodiments, upstroke powerline  16  and downstroke powerline  18  are comprised of coil production tubing. As previously discussed in the specification, powerlines made of this material allow some embodiments of the present system to be particularly useful in deviated oil wells. Perhaps more importantly, powerlines made of this material avoid the problems otherwise associated with the use of particularly long, jointed tubes in a hydraulic powerline context.  
         [0059]     Upstroke powerline  16  leads to upstroke reservoir  22  and is connected thereto by upstroke fitting  24 . Downstroke powerline  18  leads to downstroke reservoir  26  and is connected thereto by downstroke fitting  28 . In some embodiments, both fitting  24  and fitting  28  are standard tube fittings as known in the art.  
         [0060]     As surface pump unit  12  sends power fluid  14  through upstroke powerline  16 , power fluid  14  fills upstroke reservoir  22  such that its fluid volume increases, thereby actuating power piston  30  in an upward direction so that the fluid volume of downstroke reservoir  26  decreases. Likewise, as surface pump unit  12  sends power fluid  14  through downstroke powerline  18 , power fluid  14  fills downstroke reservoir  26  such that its fluid volume increases, thereby actuating power piston  30  in a downward direction, so that the fluid volume of upstroke reservoir  22  decreases.  
         [0061]     Referring to  FIGS. 1A-1B ,  FIGS. 2A-2B ,  FIG. 4  and  FIGS. 5A-5B , power piston  30  is actuated between a top position and a bottom position, where power piston  30  reaches a position just above upstroke fitting  24  at the completion of the downstroke in the bottom position; and where power piston  30  reaches a position just below downstroke fitting  28  at the completion of the upstroke in the top position. The pressure change in powerlines  16  and  18 , and resulting fluid volume change in reservoirs  22  and  26 , respectively, is the mechanism responsible for actuating power piston  30 . In some embodiments, power piston  30  is a “spray metal” plunger, or made of some suitable alloy, and is shaped so as to form a fluid-tight fit with removable production tube  20 .  
         [0062]     Connecting rod  32  is attached to power piston  30  and extends therefrom. Connecting rod  32  is of such length that connecting rod  32  extends beyond pump barrel seal  38  during both the downstroke and the upstroke. Rod  32  is actuated between a top position and a bottom position (power piston first and second position, respectively) where its top portion rests just above pump barrel seal  38  in a bottom position, at the completion of a downstroke; and where its bottom portion rests just below pump barrel seal  38  in a top position, at the completion of an upstroke.  
         [0063]     The combination of rod  32  and pump barrel seal  38  form a fluid-tight seal; as such, downstroke reservoir  26  in the embodiments shown in  FIGS. 1A-1B  and  FIGS. 5A-5B , or upstroke reservoir  22  in the embodiment shown in  FIGS. 2A-2B , remains completely sealed from first reservoir  40  and second reservoir  42  during both the upstroke and downstroke. In some embodiments, connecting rod  32  and pump barrel seal  38  are fitted so that a 1/1000th inch gap is found on either side of rod  32 . This fit is thought to be most beneficial in that it allows rod  32  to freely move between its top and bottom position while preventing production oil from flowing between rod  32  and pump barrel seal  38 . Such a fluid tight seal is particularly beneficial in that it separates the clean environment of power fluid  14  from the dirty environment of the oil  62  cycled by system  10 . As previously discussed in the specification, this has not been possible with known hydraulically-driven systems. More typical gasket materials, with their erosion in such harsh conditions as are typically found “down hole,” are avoided.  
         [0064]     In the alternative, a slightly “looser” fitting may be selected, whereby power fluid  14 , by design, is ejected in some measure as a means for insuring lack of invasion of outside, possibly corrosive, fluids into the power piston and cylinder assembly. Such an alternative arrangement may be appropriate in situations where particulates might score the tighter, substantially fluid-tight, metal-to-metal seal. Also, some form of corrosives-resistant “boot” through which connecting rod  32  extends, by which it is “wiped” as it cycles, may be provided to protect seal  38  from particulate contamination.  
         [0065]     Production piston  46  is connected to and rests just above rod  32  in the embodiments shown in  FIGS. 1A-1B  and  FIGS. 5A-5B , and just below rod  32  in the embodiment shown in  FIGS. 2A-2B , and is of a generally solid cylindrical form. Production piston  46  is actuated between a top position and a bottom position where production piston  46  rests just above pump barrel seal  38  at the completion of a downstroke in a bottom position; and piston  46  reaches just below one-way valve  52  at the completion of an upstroke, in a top position in the embodiments shown in  FIGS. 1A-1B  and  FIGS. 5A-5B . In the embodiment shown in  FIGS. 2A-2B , production piston  46  is actuated between a top position and a bottom position, where production piston  46  rests just below seal  38  at the completion of an upstroke and just above valve  45  at the completion of a downstroke. As previously mentioned in the specification, the volume of both production piston  46  and power piston  30  may be changed with respect to one another. This change in ratio between production piston  46  and power piston  30  has particular applicability in a low production energy context. Immediately above pump barrel seal  38  is first reservoir  40 , into which extends the production piston end rod of connecting rod  32 , which is in turn connected to production piston  46  and the cylinder assembly portion of the downhole pumping unit.  
         [0066]     Immediately above pump barrel seal  38  in the embodiments shown in  FIGS. 1A-1B  and  FIGS. 5A-5B , and immediately above oil inlet  41  in the embodiment shown in  FIGS. 2A-2B , is first reservoir  40 . Adjacent to first reservoir  40  is first inlet  41 . In one embodiment, first inlet  41  may have a one-way valve  45  that allows oil  62  to flow into first reservoir  40  during an upstroke, but does not allow backflow. During an upstroke, oil  62  (oil from a standard type as known in the production zone of the subject well) is drawn into system  10  through first inlet  41  where it travels through and fills first reservoir  40 . During a downstroke, oil  62  is pushed from first reservoir  40  by production piston  46 , and flows through adjacent shaft  48 , through one-way valve  49 , and into upper reservoir  53  (upper reservoir  53  is not shown in  FIGS. 5A-5B ). Importantly, with this configuration, production of oil is precisely doubled, yet there is no increase in energy consumption in view of some systems that only pump oil during the upstroke.  
         [0067]     Second reservoir  42  is positioned between production piston  46  and one-way valve  52 . Adjacent to second reservoir  42  is second inlet  43 . In some embodiments, second inlet  43  may have a one-way valve that allows oil  62  to flow into second reservoir  42  during a downstroke, but does not allow backflow. During a downstroke, oil  62  is drawn into system  10  through second inlet  43  where it travels through and fills second reservoir  42 . During an upstroke, oil  62  is pushed from second reservoir  42  by production piston  46 , and flows through valve  52 , through adjacent shaft  48  and into upper reservoir  53 . This pumping of production oil during the upstroke compliments pumping of oil to the surface during the downstroke so that oil travels to the surface in a continuous manner. Again, by virtue of pumping oil  62  to the surface during both the upstroke and downstroke, production of oil  62  is precisely doubled, yet there is no increase in energy consumption in view of some systems that only pump oil during the upstroke.  
         [0068]     While some embodiments shown in  FIGS. 1A-1B  and  FIGS. 5A-5B  show first reservoir  40  and second reservoir  42  as being positioned above power piston  30 , other useful embodiments are envisioned where first reservoir  40  and second reservoir  42 , and their respective inlets, are positioned below power piston  30  such as the embodiment shown in FIGS.  2 A- 2 B. In such cases, the general relationship between the components remains the same, and the effectiveness of system  10  remains the same. In fact, system  10  is still able to pump twice the amount of oil while expending the same amount of energy.  
         [0069]     In some embodiments, valve  52  is of a standard type as known in the art. That is, a loosely seated bearing  51  rests upon a grooved slot. Referring specifically to the embodiments shown in  FIGS. 1A-1B  and  FIGS. 2A-2B , during an upstroke, bearing  51  becomes unseated and allows oil  62  to flow from second reservoir  42 , through valve  52 , and into upper reservoir  53 . Oil  62  easily flows into reservoir  53  as bearing  51  becomes unseated and oil  62  is pushed into reservoir  53 . During a downstroke, bearing  51  remains seated as fluid flows into reservoir  53  from adjacent shaft  48 . As system  10  completes a pumping cycle, oil  62  is continuously pushed through reservoir  53  and adjoining reservoirs, separated by other one-way valves, until oil  62  reaches the surface.  
         [0070]     While alternatives may be employed, one-way valves depicted in some embodiments are a standard ball valve type as are known in the art. These essentially consist of a loosely-seated metal ball or bearing resting upon a complimentarily contoured orifice. When the ball is fully seated, little or no fluid may pass through the orifice. When pressure is exerted from below the ball or bearing, it is unseated, and fluid may pass through the orifice. However, when pressure is exerted from above the ball, it is forced even more into a sealed configuration, and little or no fluid may pass.  
         [0071]     Although the foregoing specific details describe certain embodiments of this invention, persons reasonably skilled in the art will recognize that various changes may be made in the details of this invention without departing from the spirit and scope of the invention as defined in the appended claims and considering the doctrine of equivalents. Therefore, it should be understood that this invention is not to be limited to the specific details shown and described herein.