| Hydraulic pump jack sytem for reciprocating oil well sucker rods -> Monitor Keywords |
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Hydraulic pump jack sytem for reciprocating oil well sucker rodsRelated Patent Categories: Pumps, Motor Driven, Fluid Motor, With Motive Fluid Generator, Fluid PumpHydraulic pump jack sytem for reciprocating oil well sucker rods description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060171821, Hydraulic pump jack sytem for reciprocating oil well sucker rods. Brief Patent Description - Full Patent Description - Patent Application Claims
REFERENCE TO PENDING APPLICATIONS [0001] This application is based on Provisional Patent Application 60/562,207 filed April 13, 2004 entitled PUMP APPARATUS AND METHOD FOR OIL WELL PRODUCTION. REFERENCE TO MICROFICHE APPENDIX [0002] This application is not referenced in any microfiche appendix. FIELD OF THE INVENTION [0003] This invention relates to a system for reciprocating an oil well pump located in the bottom portion of a string of tubing in which the pump is reciprocated by sucker rods extending from the pump to the earth's surface. BACKGROUND OF THE INVENTION [0004] 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 to the earth's surface. For this reason some system must be devised for pumping the crude oil from the producing formation to the earth's surface. The most common system for pumping an oil well is by the installation of a pumping unit at the earth's surface that vertically reciprocates a string of sucker rods extending within tubing to a subsurface pump. [0005] Traditionally sucker rod strings have been reciprocated by a device known as a pump jack which operates by the rotation of an eccentric crank driven by a prime mover which may be an engine or an electric motor. Such mechanical drive mechanism has been utilized extensively in oil production industry for decades and continues to be a primary method for extracting oil from a well. However, such mechanical systems suffer from a number of inherent disadvantages or inefficiencies that include their substantial size and weight that makes them expensive to produce, difficult to transport and expensive to install. The mass of such units also requires significant structural support elements at the wellhead which adds to the complexity and expense of the overall drive mechanism. Furthermore, mechanical drive systems have components that are physically linked or connected in some form by way of connecting rods, cams and gear boxes. For a variety of different reasons it often becomes necessary to adjust the travel of the pump rod. Mechanical linkages, as have been previously used, present difficulties in adjusting the travel or displacement of the pumping rods. With most mechanical pumping systems in present use adjusting the rod displacement or pumping speed requires the drive system to be shut down, wasting valuable production time and increasing labor costs. Mechanical drive pump jacks are also limited in their ability to control acceleration and deceleration of the pump rod during its reciprocation. [0006] To combat these limitations in mechanical pump jack drive systems, others have provided a variety of different pneumatic and hydraulic drive mechanisms that have met varying degrees of success. Most hydraulic drive systems in use today are mounted above a stuffing box through which a polished rod extends. Below the stuffing box is a T-fitting so that produced oil is diverted from upward flow within the well tubing to a gathering line that connects to the stuffing box. Stuffing boxes require frequent lubrication. If not constantly lubricated, the packing in stuffing boxes soon wear out resulting in leakage that can spread crude oil to the environment. The invention herein provides an improved hydraulic operated pumping unit that, among other advantages, eliminates the need for a stuffing box. [0007] For additional information relating to pumping units employed in the oil industry for reciprocating sucker rod strings, reference may be had to the following previously issued U.S. patents. TABLE-US-00001 Pat. No. Inventor Title 2,645,900 Hutchinson Hydraulic Type Fluid Transmission 2,651,914 Joy Pumping Head and Operating Mechanism For Wells 2,699,154 Smith Oil Well Pumping Apparatus 2,729,942 Billings et al. Manually Controllable Pumping Jack 2,838,910 Bacchi Hydraulic Pumping Jack 2,982,100 Sinclair Pumping Unit 4,320,799 Gilbertson Oil Well Pump Driving Unit 4,448,110 Polak et al. Hydraulic Pump 4,480,685 Gilbertson Oil Well Pump Driving Unit 4,490,097 Gilbertson Hydraulic Pump Driving Unit For Oil Wells 4,637,459 Roussel Anti Rotational Device For Down Hole Hydraulic Pumping Unit 4,646,517 Wright Hydraulic Well Pumping Apparatus 5,996,688 Schultz et al. Hydraulic Pump Jack Drive System For Reciprocating An Oil Well Pump Rod BRIEF SUMMARY OF THE INVENTION [0008] The hydraulic pump jack drive system for reciprocating a down hole oil well pump by means of a sucker rod string, that is the subject of this invention, includes a vertically positioned hydraulic cylinder having a reciprocated piston therein. A cylindrical, polished, piston rod extends from a lower end of the piston and through a bottom seal that closes the lower end of the hydraulic cylinder. The hydraulic cylinder preferably sits above a wellhead that has the lower end thereof connected to a tubing string that extends from the earth's surface downward to a subterranean oil producing formation. The wellhead has an upper end that is connected to the lower end of the hydraulic cylinder. Further the wellhead includes at least one side orifice that is adapted to be connected to a collection line by which crude oil produced by the well can be conveyed to a collection system. This arrangement eliminates the expense of providing a stuffing box that is typically employed with the systems currently used by the oil industry for pumping reciprocated bottom hole pumps. Not only does the system herein eliminate the stuffing box but eliminates the time and expense encountered in keeping a stuffing box properly lubricated and the packing replaced. [0009] The invention herein provides a hydraulic system in which the stroke action can be significantly varied. By controlling the application of hydraulic fluid pressure the sucker rod strings can be raised at a selected rate from a lower to an upper position. At the upper positions the sucker rod strings may be held briefly in a steady state so that if the bottom hole pump is of the type designed to release gas trapped within the pump, ample opportunity is given for the gas release. Thereafter, the hydraulic system may be controlled so that sucker rod string is dropped rapidly to recharge the bottom hole pump and to restart the pumping cycle. [0010] The present invention addresses and solves many of the problems involved in fluid extraction from oil and gas wells with current art pumping systems. The loss of pump capacity due to rod stretch is eliminated. Full stroke of the pump plunger on each stroke prevents debris accumulating in the normally unused upper section of the pump barrel and therefore allows the pump to be unseated without sticking the plunger in the pump barrel. The repair of pumps is reduced when the plunger and barrel can be reused. Well pulling costs are reduced when the pump can be unseated and the tubing flushed without sticking the plunger in the pump barrel. Well pulling rig costs are reduced due to the ability of the invention to long stroke the pump. When needed the rods can be dropped at a velocity equal to a method only possible in current art pumping systems when a pulling rig is used. The present invention makes possible full control of the reciprocating action of the pump including the ability to stop at the peak of the upstroke or any position in the cycle. The present invention can prevent pipeline damage by adjusting or stopping the rate of the sucker rod fall on the down stroke cycle. [0011] In many wells, and stripper wells in particular, the walking beam pumping system cannot run at a slow enough rate. Well pulling and well tubing, rod and pump repair expense is reduced by slowing the rate to four strokes per minute or less in most wells. Electrical power use and maintenance is reduced. Horse power demand is less and power is only needed on the upstroke of the pump. Elimination of the cyclic load created by a walking beam pumping unit on the electric motor results in reduced power factor penalties from electrical utility companies. In stripper wells in particular which produce ten barrels or less per day, the cost of daily operations are reduced. Reduced risk of pipe line leaks, the elimination of stuffing box leaks and no mechanical maintenance reduces the cost of field equipment and employees required to operate wells. [0012] The present invention provides a pumping system which is easily installed on existing wells and is cheaper to operate and maintain. The productive life of all oil and gas wells depend on the economics involved in extracting and delivering the well bore fluids. The apparatus of the present invention includes (a) a hydraulic cylinder connected to the pumping tee; (b) a pump spacing adaptor attached to the cylinder rod; (c) a sucker rod string attached to the spacing adaptor; (d) a hydraulic pump of pre-determined pressure and rate to raise the rod string and load the down hole pump; (e) a means to control the hydraulic flow at the top of the upstroke of the down hole pump; (f) a means to hold the pump at the top of the stroke for a pre-determined time; (g) a means to release fluid back to the hydraulic reservoir and allow the gravity fall of the sucker rod string; (h) a means to regulate the speed of the gravity fall of the sucker rod string on the down stroke; and (i) a means to restart the pumping cycle at a pre-determined time. [0013] The method of the present invention is an improved method using the above described apparatus for oil and gas well fluid extraction, which comprises, hydraulic fluid pumped into the hydraulic drive cylinder at sufficient pressure to raise the cylinder rod and sucker rod to load the down hole pump. When the pull rod of the down hole pump reaches the maximum stroke length of the pump barrel, pressure increases above what is required to lift the rods. An adjustable pressure switch stops the flow of drive fluid at a pre-determined pressure above the string weight, but less than the pressure required to unseat the pump. This insures full stroke of the pump regardless of the rod stretch. The gas venting pump is held at the peak of the up stroke for a pre-determined time to vent gas out of the fluid chamber and facilitate maximum fluid pump efficiency. After a pre-determined time an adjustable time delay opens a solenoid valve and fluid is allowed to flow from the drive cylinder back to the hydraulic reservoir. Gravity and fluid column pressure in the well tubing allow the rods and pump to return to the down stroke position. A variable orifice valve adjusts the speed of the down stroke by holding back pressure on the drive cylinder. The pressure on the drive cylinder is adjusted to remain above the well tubing pressure with an adjustable back pressure valve. This insures that well fluids cannot dilute hydraulic drive fluid. An adjustable electric time delay restarts the hydraulic pump for the next cycle at a pre-determined time. [0014] Another important advantage of the present invention is the provision of a unique system for adjusting the length of the sucker rod string for more efficient actuation of the bottom hole pump. [0015] A better understanding of the invention will be obtained from the following detailed description of the preferred embodiments taken in conjunction with the drawings and the attached claims. BRIEF DESCRIPTION OF THE DRAWINGS [0016] FIG. 1 is an elevational diagrammatic view of a pumping unit according to this invention showing a system for producing hydraulic fluid pressure flow for the actuation of a piston within a cylinder. [0017] FIG. 2 is an elevational view of the hydraulic cylinder with a piston rod extending therefrom. [0018] FIG. 3 is an elevational view of the components of the system used to adjust the length of the sucker rod string to more effectively accommodate a bottom hole pump. Continue reading about Hydraulic pump jack sytem for reciprocating oil well sucker rods... 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