Abstract:
A system to provide mechanical energy to well-head equipment by directing pressurized gas existing in nearby pipelines to an engine. The engine is a linearly reciprocating piston in a closed cylinder driven by pressure differentials between the gas on either side of its piston, the differential being controlled by a switching valve which directs higher and lower pressured gas to the appropriate side of the piston, and which recirculates spent gas from the lower pressure side of the piston back to the pipeline. The system is a closed system, and avoids venting or flaring gas used in the engine.

Description:
[0001]    The present application claims the benefit of the filing date of Canadian patent no.  2 , 357 , 533 , filed Aug. 29, 2001.  
         FIELD OF THE INVENTION  
         [0002]    The present invention relates to the field of providing gas drive to mechanical devices such as pumps and injectors at well-heads, using pressurized gas in a pipeline system, without the necessity of flaring or venting “spent” gas.  
           [0003]    In particular, the present invention relates to a linear gas-driven system powered by pressure differential from produced gas to well-head gas without venting the gas spent or used in driving the system.  
           [0004]    The invention has particular application (but is not thereby limited) in the field of gas production in the oil and gas industry, where it is often useful to provide power to energize well production equipment without resorting to externally (or remotely) supplied energy sources such as electrical power, and without using produced gas in internal combustion or other power-generating engines where waste products, heat, and maintenance are issues. The gas used is recirculated to the production line; the system is in that way a closed system.  
         BACKGROUND OF THE INVENTION  
         [0005]    It is well known to provide for generation of mechanical power (such as powered reciprocal motion by reciprocating piston/cylinder/valve means or rotary motion by turbine, fan, or combined reciprocal piston/crank means) utilizing pressure differentials between produced gas well-head pressure and atmosphere; likewise between produced well-head gas pressures and sales line pressures. Engines in which power is derived from partially expanding pressurized fluid to drive an output shaft are generally preferred over internal combustion. See U.S. Pat. Nos. 3,801,230, US 4,369,373, US 4,896,505, and US 6,113,357, which each provide means of harnessing either fluid flow or differential pressure to provide mechanically available power for other purposes.  
           [0006]    The use of valves and pistons in combination with a fluid operated pressure-powered system is also known. See U.S. Pat. Nos. 4,439,114 and 4,616,981, which describe the use of pistons in combination with valves and fluid pressure in a pumping system.  
           [0007]    It is also well known to provide for the injection of chemicals into a well bore to assist in the production of desired hydrocarbons or the protection of the well&#39;s equipment. See, for example, U.S. Pat. Nos. 3,901,313 and 4,776,775. Of course, the injection of material into a well (which is typically at higher than atmospheric pressure) requires the use of mechanical or pressure-providing power sources.  
           [0008]    It is known in the art that such power sources may be provided by the use of pressure-differential between well-head produced gas pressures and atmosphere, with the spent gas (that is, once it is relieved to atmospheric pressures after powering the devices required) being released to atmosphere or flared. At current prices for hydrocarbons, in particular natural gases, and with current constraints on pollution of the atmosphere, these techniques are not ideally suited for today&#39;s use.  
           [0009]    Engines that derive power from partially expanding pressurized fluid to drive equipment are preferred over internal combustion engines because of the absence of the involvement of volatile combustible fluids and the resulting exhaust gas which gives rise to pollution and safety concerns.  
           [0010]    Several innovations have arisen due to those problems, such as the devices offered for sale and installation by ABI Oil Tools e-tronics Corp. under the trade name “Zero Emission Blair Air System”, which powers a traditional venting glycol pump replacement with a closed-loop system in a containment device, depending upon the differential between well-head pressures and sales line pressures, which may be very high pressures, and may be very different pressures, and may be pressurized gases including corrosive or dangerous substances the release of which at high pressures could be problematic.  
           [0011]    Another example of a similar containment device system is provided by the “Enviro Drive—the Environmental Alternative” system, which is a similarly powered, closed loop (that is, no escaping gases), production-to-sales line pressure-drop-driven injection pump (see “envirodrive.com” web page as at March 1, 2001).  
           [0012]    It is therefore desirable to provide a source to energize equipment at the wellhead in the form of reciprocating motion without venting or flaring exhaust gas. It is further desirable to provide such energizing motion without use of internal or other combustion of produced gas or fluids and without resort to externally provided power sources such as electricity, and without expensive external containment devices.  
         SUMMARY OF THE INVENTION  
         [0013]    It is an object of this invention to overcome limitations in the prior art using internal or external combustion of fuel or sweet gas to drive pumps and to address safety and environmental issues related to such use. The existing prior art inadequately addresses the need for a recirculating linear gas drive system that utilizes pressurized gas, a simple closed valve and a piston drive system to drive a mechanical device, such as a pump, and that eliminates the need to routinely flare or release “spent” gas to atmosphere. None of the prior art discloses an invention that utilizes pressurized gas from a pipeline well-head, which is directed through a switching valve to drive a power unit with a piston to operate a pump.  
           [0014]    This Invention relates to a system for providing drive to a mechanical wellhead device by utilizing pressurized gas existing in a pipeline to power a unit containing a piston. This system provides for the use of pressurized gas within a pipeline system to provide gas drive to mechanical devices.  
           [0015]    The invention is a system comprising:  
           [0016]    produced gas;  
           [0017]    a pipeline with gas at a lower pressure;  
           [0018]    a manifold with flow control valve;  
           [0019]    a reciprocating power unit;  
           [0020]    a drive connection from power unit to a powered unit; and  
           [0021]    a flow-directing switching means which, in time with the drive&#39;s reciprocating movement to the end-point positions, switches communication of produced gas and pipeline with the appropriate sides of the power unit which returns spent gas to the pipeline  
           [0022]    In particular, this invention in one embodiment is a system that provides the gas drive to a device using the pressurized gas in a pipeline, such as from the well-head, by directing that gas through a switching valve to a power unit containing a piston within a cylinder. The pressurized gas works against the piston, driving it through the length of the cylinder. When the piston reaches the end of the stroke, the switching valve reverses the flow in the valve manifold, so that the piston is driven back in the opposite direction. At the end of the reverse stroke, the switching valve changes the flow direction and drives the piston forward to the end of the stroke. This process may be continuously maintained by an adjustable flow control means, and may be turned on or off or have its speed or power varied by the flow control means.  
           [0023]    The Invention has particular application (but is not thereby limited) in the field of gas production in the oil and gas industry, where it is often useful to provide power to energize well production equipment without resorting to externally (remotely) supplied energy sources such as electrical power, and without using produced gas in internal combustion or other power-generation engines where waste products, heat, and maintenance are issues. The use of pressurized gas also assists in preventing the system from stalling and will cure difficulties overcoming the friction of the driver.  
           [0024]    These and other objects and advantages of the Invention are apparent in the following descriptions of the preferred embodiments of the Invention, which are not intended to limit in any way the scope or the claims of the Invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    Preferred embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein:  
         [0026]    [0026]FIG. 1 is a schematic representation of valve-states, gas flow and drive motion directions  
         [0027]    [0027]FIG. 2 is a similar schematic representation showing the valve-states and drive motions in its reciprocal state  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]    The preferred embodiment of the Invention is comprised of high pressurized gas supplied from a pipeline well-head, pipe, a switching valve c/w manifold system for directing the gas flow, a power unit with piston and a driven injection pump.  
         [0029]    [0029]FIGS. 1 and 2 illustrates a preferred embodiment of the Invention comprised of:  
         [0030]    [0030] 1 —manifold  
         [0031]    [0031] 2 —high pressure gas source  
         [0032]    [0032] 3 —high pressure gas (produced gas)  
         [0033]    [0033] 4 —low pressure gas outlet  
         [0034]    [0034] 5 —low pressure gas  
         [0035]    [0035] 6 —engine cylinder (double-acting) or power unit  
         [0036]    [0036] 7 —engine or power unit piston  
         [0037]    [0037] 8 —engine or power unit cylinder body  
         [0038]    [0038] 9 —engine or power unit piston rod  
         [0039]    [0039] 10 —switching valve,  
         [0040]    [0040] 11 —switching valve piston  
         [0041]    [0041] 12 —switching valve cylinder  
         [0042]    [0042] 13 —switching valve body  
         [0043]    [0043] 14 —switching valve manifold  
         [0044]    [0044] 15 —driven pump or similar equipment  
         [0045]    [0045] 16 —control valve  
         [0046]    In FIG. 1:  
         [0047]    The high-pressure or produced gas  3  is obtained from a high-pressure gas source  2 , typically a conventional well-head with fittings and valves, blowout preventers and the like.  
         [0048]    The high-pressure or produced gas  3  flows through the manifold  1  to the switching valve  10  and is directed by the body  13  of the switching valve  10 , to one of the sides of the engine piston  7  in the double acting cylinder  6  of the engine or reciprocating power unit  6 .  
         [0049]    The produced gas  3  pushes the power unit piston  7  contained within the power unit cylinder body  8 , transmitting the piston&#39;s  7  powered stroke through the engine piston rod  9  to the driven pump equipment  15 .  
         [0050]    At the same time, spent gas  3 , contained in the opposite side of the double acting driver cylinder  6  is exhausted through the manifold and the switching valve  10  to the low-pressure outlet  4 .  
         [0051]    During approximately the same time, high-pressure gas  3  flows through the control valve  16  to one of the switching valve&#39;s cylinders  12  and pushes the switching valve piston  11  toward one end position.  
         [0052]    The switching valve&#39;s piston  11  movement is transferred to the switching valve&#39;s body  13 . The body  13  moves linearly within the switching valve&#39;s ported cylinder  14  closing one flow path and opening another, and thus reversing the flow of both spent and high pressure gas through the manifold  1 .  
         [0053]    Once the flow direction is reversed, the process may be continuously repeated.  
         [0054]    In FIG. 2:  
         [0055]    The high-pressure or produced gas  3 , obtained from a high-pressure gas source  2 , flows through the manifold  1  to the switching valve  10  and is directed by the body  13  of the switching valve  10 , through its ported cylinder  14  to the opposite side of the double acting cylinder of the engine or power unit  6 .  
         [0056]    The high-pressure or produced gas  3  pushes the engine piston  7  transmitting the piston&#39;s powered stroke through the engine piston rod  9  to the driven pump equipment  15 .  
         [0057]    At the same time, spent gas  3 , contained in the opposite side of the double acting engine cylinder  6 , is exhausted through the switching valve  10  to the low-pressure gas outlet  4  to pipeline at lower pressure than the produced gas.  
         [0058]    During approximately the same time, high-pressure gas  3  flows through the switching valve  16  to the second of the switching valve&#39;s cylinder bodies  12  which pushes the switching valve piston  11 .  
         [0059]    The switching valve piston  11  movement is transferred to the body  13 . The body  13  moves linearly within the switching valve&#39;s ported cylinder  14  closing the flow path and opening another, altering the flow of high pressure gas and of spent gas.  
         [0060]    The speed, power and time delays of the operation are controlled using adjustable flow control  16  and the stroke of the engine&#39;s piston  7  may be optimized by using variable length piston sleeves.  
         [0061]    In one embodiment, the system comprises:  
         [0062]    produced gas  3   
         [0063]    a pipeline with gas at a lower pressure  5   
         [0064]    a manifold  1  with flow control valve  16   
         [0065]    a reciprocating power unit  6   
         [0066]    a drive connection  9  from power unit  6  to a driven pump or other powered unit  15 ; and  
         [0067]    a flow-directing switching means  10  which, in time with the drive&#39;s reciprocating movement to the end-point positions, switches communication of produced gas  3  and pipeline  5  with the appropriate sides of the power unit  6 .  
         [0068]    The switching means in one embodiment comprises:  
         [0069]    two opposed pistons  11  tightly fitted and moveable in a linear fashion within closed cylinders  12   
         [0070]    each opposed piston  11  connected to the other via a body  13  between them which is itself tightly fitted and slideable within a fourth cylinder  12  fixed to both of said opposed piston&#39;s cylinders  
         [0071]    said body  13  having cavities which match with and form different conduits between five ports in said fourth cylinder  12  at different orientations of said body  13  within said fourth cylinder&#39;s  12  wall, each port communicating with said manifold  1   
         [0072]    two flow control valves  16  deployed in the manifold  1 , each control valve  16  to control the rate of gas flow between one side of the power unit&#39;s piston  7  and one side of the matching one of said opposed pistons  11  versus the other side of said opposed piston, to control the speed of reciprocation of said opposed pistons  11  and said body  13 .  
         [0073]    In that embodiment:  
         [0074]    when said opposed pistons  11  are substantially at one extreme of their linear travel within their respective cylinders  12 , said cavities and manifold  1  form the following communications paths:  
         [0075]    produced gas  3  to the first side of said power unit piston  7  and directly to one side of a matching one of said opposing pistons  11 , and through flow-control valve  16  to the other side of said one opposing piston  11   
         [0076]    the other side of said power unit piston  7  and directly to one side of the matching second of said opposing pistons  11  and, through the second flow-control valve  16  from the other side of said second opposing piston  11 , to pipeline  5   
         [0077]     such that the power unit piston  7  is pushed in a direction from the produced gas side toward the pipeline side of its cylinder  6 , providing power through its connecting rod  7  to the driven pump or other powered unit  15 , and such that:  
         [0078]    the opposing piston  11  communicating with pipeline  5  is moved from its directly communicating side toward its flow-control communicating side and spent gas from the power unit piston  7  then flows to pipeline  5   
         [0079]    essentially simultaneously, the other opposing piston which is communicating with produced gas is pushed from its directly communicating side toward its flow-control communicating side which until then had contained gas at lower pipeline pressures, and  
         [0080]    said body  13  is moved toward one direction in relation to said ports to alter in a timed way the conduits thus formed within the manifold  1  and ported cylinder  12  and body  13  so that at the other extreme of their linear travel within their respective cylinders is caused the communications paths as follows:  
         [0081]    produced gas to the second side of said power unit piston  7  and directly to one side of the matching second opposing piston  11  and through the second flow-control valve  16  to the other side of the second opposing piston  11  -the first side of said power unit piston  7  and directly to one side of the matching first opposing piston  11  and through the first flow-control valve  11  to the other side of the first opposing piston  11 , and to pipeline  5   
         [0082]    such that the power unit piston  7  then is pushed in the other direction, providing repeatable reciprocating linear powered motion of said drive connection, and said reversed gas-flows provide realignment of said switching valve&#39;s internal body&#39;s cavities with said ports to cause the further repeated redirection of gas through the manifold.  
         [0083]    In the same embodiment, the first and second flow-control valves  16  may be independently adjusted to vary the timing of the reciprocation, each such valve  16  controlling the rate of gas flow required to reach equilibrium between a produced gas side and a pipeline side of the power unit&#39;s piston  7  for a different direction of said reciprocation.  
         [0084]    All components of the Invention may be comprised of any device and material suitable.  
         [0085]    In the foregoing Description, the Invention has been described in its preferred embodiments. However, it will be evident that various modifications and changes may be made without departing from the broader scope and spirit of the Invention. Accordingly, the present specifications and embodiments are to be regarded as illustrative rather than restrictive.  
         [0086]    The descriptions here are meant to be exemplary and not limiting. It is to be understood that a reader skilled in the art will derive from this descriptive material the concepts of this Invention, and that there are a variety of other possible implementation; substitution of different specific components for those mentioned here will not be sufficient to differ from the Invention described where the substituted components are functionally equivalent.  
         [0087]    The above-described embodiments of the invention are intended to be examples of the present invention. Alterations, modifications and variations may be effected the particular embodiments by those of skill in the art, without departing from the scope of the invention which is defined solely by the claims appended hereto.