Patent Application
20120224977
NONE
1. Field of the Invention
The present invention pertains to a hydraulic pumping unit. More particularly, the present invention pertains to a hydraulic pumping unit that provides precise rod speed control with minimal maintenance requirements.
2. Brief Description of the Prior Art
Liquid-producing subterranean reservoirs all have some level of energy or potential, frequently referred to as “reservoir pressure” that will force fluid (liquid, gas or a mixture) to areas of lower energy or potential. If a well penetrates such a reservoir, and if the pressure inside such a well is decreased below the reservoir pressure, fluids will feed into the well from said formation. However, depending on the depth of the reservoir and density of the fluid(s), the reservoir may not have sufficient reservoir pressure to push the fluid to the surface. The deeper the well, or the heavier the fluid(s), the higher the reservoir potential that is required to push such fluid(s) to the surface.
Many hydrocarbon producing reservoirs have sufficient potential to naturally produce oil and gas (which are relatively light, compared to water) during the early stages of production. However, as a well continues to produce, reservoir pressure will often decrease as a reservoir depletes. Further, in many reservoirs, formation water will eventually encroach into the wellbore, causing the lifting requirements to be much greater than for just oil and/or gas. Either or both of these conditions can cause production from a well to decline, or possibly even cease entirely.
As a result of the foregoing, artificial means are often used to continue or increase the flow of liquids (such as crude oil, water or a mix of oil and water) from subterranean reservoir(s) to the earth's surface. As noted above, such “artificial lift” can be required when insufficient reservoir pressure exists to lift produced fluids to the surface in a well. Artificial lift can also be employed in flowing wells to increase the flow rate above what would occur naturally.
Although numerous different means of artificial lift exist, one common type involves the use of a mechanical device known as a “rod pump” inside a well. Such rod pumps, which are well known to those having skill in the art, are typically elongate cylinders with both fixed and moveable elements. Such rod pumps are designed to be installed down-hole inside of wells, at or near the depth of the reservoir(s) from which production is obtained, to gather fluids from below and lift said fluids within the wells to the surface. In many instances, such down-hole pumps have a barrel equipped with two ball check valves: a stationary valve near the bottom of said barrel, and a traveling valve that moves up and down. As reservoir fluids enter a well from a down-hole reservoir(s), the down-hole pump lifts such fluids from said subterranean reservoir(s) to the surface within said well.
Rod pump systems generally comprise a reciprocating down-hole pump situated within a well at or near a subterranean reservoir, an above-ground drive mechanism at the earth's surface, and a length of elongate cylindrical rods (frequently referred to as “sucker rods”) connecting said down-hole pump to said surface drive mechanism in said well. In many conventional installations, said surface drive mechanism comprises a pump-jack (also sometimes referred to as a pumping unit, horsehead pump, rocking horse, beam pump, or jack pump) that converts rotary motion (from an electric motor or internal combustion engine, for example) to a reciprocating vertical motion in order to drive a reciprocating down-hole pump via the sucker rods. Such pump-jacks generally exhibit a characteristic nodding motion.
Although very common, conventional pump-jacks and other types of surface drive mechanisms suffer from a number of significant shortcomings. Said surface drive mechanisms can be large, cumbersome and difficult to install in many instances. Further, such conventional surface drive mechanisms are typically complicated, and expensive to manufacture, operate and maintain.
Thus, there is a need for a pumping apparatus having a surface drive mechanism that is relatively inexpensive, durable and simple to operate. The hydraulic pumping apparatus should provide precise rod speed control with minimal maintenance requirements, while permitting stroke speed to be easily and quickly adjusted without the need for expensive, troublesome or complicated electronic equipment.
The present invention comprises a hydraulic pumping apparatus having an improved surface drive mechanism. By way of illustration and not limitation, the present invention is described herein as a hydraulic pumping apparatus installed on a well for pumping fluids from subterranean formations. However, it is to be observed that the hydraulic pumping apparatus of the present invention, and components thereof, can be used in many different applications involving the pumping of fluid(s) beyond the particular embodiment described herein.
In a preferred embodiment, the hydraulic pumping apparatus of the present invention comprises an elongate tower assembly that can be mounted at the surface of a well. Said tower assembly provides a rigid frame for supporting at least one hydraulic cylinder assembly that is oriented substantially parallel to said tower assembly. In the preferred embodiment, said elongate tower assembly (and the at least one hydraulic cylinder assembly supported therein) are mounted in substantially axial alignment over said well at the earth's surface. Said at least one hydraulic cylinder assembly is connected to a bridle assembly attached to a polished rod; said polished rod is, in turn, connected to a length of interconnected sucker rods that extend into said well. A down-hole pump mechanism is mounted near the bottom of said well and is attached to the distal end of said sucker rods.
Said at least one hydraulic cylinder assembly can be beneficially mounted to said elongate tower assembly using a self-centering pivot mounting assembly. Said self-centering pivot mounting assembly ensures that said at least one hydraulic cylinder assembly finds the center of gravity, thereby preventing unwanted side loading on said at least one cylinder assembly.
A prime mover assembly provides hydraulic fluid used to actuate said at least one hydraulic cylinder assembly. Hoses or other conduits connect said prime mover to a wedge spool valve disposed between said prime mover and said at least one cylinder assembly. Said wedge spool valve can be used to control the stroking of said at least one hydraulic cylinder assembly and, in turn, the reciprocation of said sucker rods in and out of said well.
The hydraulic pumping apparatus of the present invention is inexpensive, durable and simple to operate. Further, the hydraulic pumping apparatus of the present invention has a small footprint and can be directly mounted to wells having shallow to medium depths or, alternatively, skid supported for wells extending to deeper depths. The hydraulic pumping apparatus of the present invention further provides for precise rod speed control with minimal maintenance requirements. Stroke speed can be easily and quickly adjusted without the need for expensive, troublesome or complicated electronic equipment.
The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, the drawings show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed. Further, dimensions, materials and part names are provided for illustration purposes only and not limitation.
Referring to the drawings,
As depicted in
Spreader bar or bridle assembly 310 is connected to the distal end of each piston rod 302. Said bridle assembly 310 is attached to polished rod 320 using clamp member 321. Polished rod 320 is, in turn, connected to a length of interconnected sucker rods 322 that extends into a well (not shown in
Tandem cylinder assemblies 300 are mounted within support tower assembly 200. Each of said hydraulic cylinder assemblies 300 has a barrel 301 and an extendable piston rod 302 movably disposed in said barrel 301. Cylinder barrels 301 are attached to upper plate member 201 with fasters 303, while the distal ends of piston rod members 302 are connected to bridle assembly 310.
Support base assembly 210 has a plurality of adjustable leg members 211. Each of said leg members 211 further has a substantially planar foot pad 212 to ensure stability of said support base assembly. Support base assembly 210 can be used to provide additional stability and support to tower assembly 200 when said tower assembly 200 is mounted on a well. In such instances, support base assembly 210 prevents all loading from being placed on a well equipped with hydraulic pumping apparatus 10, and instead transfers much of said loading (especially axial loading) to support base assembly 210. Although said support base assembly is depicted as having three leg members 211 (i.e., a tripod), it is to be observed that configurations having different numbers of leg members can also be used. Further, tie rods or other similar structural supports can be added as may be required.
Tandem cylinder assemblies 300 are mounted within support tower assembly 200 in substantially parallel orientation. Each of said hydraulic cylinder assemblies 300 has a barrel 301 and an extendable piston rod 302 movably disposed in said barrel 301. As depicted in
Polished rod 320 is movably disposed through dynamically sealing stuffing box 220 situated over well 20, and extends into wellhead 22 in a manner known to those having skill in the art. Although not shown in
As hydraulic cylinder assemblies 300 are actuated, bridle assembly 310 can be raised and lowered within tower assembly 200. Such raising and lowering of bridle assembly 310 imparts a reciprocating motion to polished rod 320 (and attached components) within well 20. Stuffing box 220 provides a dynamic seal against polished rod 320, causing pumped well fluids to exit said well via flow lines 21, rather than out the top of wellhead 22. Upper electrical switch 350 and lower electrical switch 340 are disposed within said tower assembly at predetermined locations.
Cylinder barrel 301 is attached to upper plate member 201 with fastener 303, while the distal end of piston rod member 302 is connected to bridle assembly 310. Bridle assembly 310 is attached to polished rod 320 using clamp member 321. Bridle assembly 310 has push plate 311 that extends outward from said bridle assembly 310. Polished rod 320 is movably disposed through dynamically sealing stuffing box 220 situated over well 20, and extends into wellhead 22 in a manner known to those having skill in the art. Hydraulic fluid supply line 410 provides a conduit for receiving hydraulic fluid from a hydraulic pump, such as included within a prime mover assembly (for example, prime mover assembly 400 depicted in
As depicted in
Wedge spool control valve assembly 100 comprises spool valve body 101 defining central flow bore 102 and bypass flow bore 103. In the preferred embodiment, central flow bore extension 104 extends below central flow bore 102. Upper flow channel 105 extends from said central flow bore 102 to bypass flow bore 103, while lower flow channel 106 extends from flow bore extension 104 to bypass flow bore 103. Check valve assembly 120 is disposed within bypass flow bore 103, and is beneficially positioned between upper flow channel 105 and lower flow channel 106.
Elongate spool member 110 having upper surface 110a is slidably received within bearings 107 which, in turn, are disposed within central flow bore 102. In this manner, elongate spool member is slidably received within said central flow bore 102 extending through spool valve body 101. It is to be observed that additional bearings 107 can be installed within central flow bore 102 to exceed the number of such bearings as shown in the figures.
In the preferred embodiment, elongate wedge spool member 110 extends through aligned apertures 113 in substantially parallel bottom plate member 111 and upper stroke stop member 112. Elongate spool member 110 has stroke stop collar 114 having increased diameter that is greater than the diameter of aperture 113 in upper stroke stop member 112; said stroke stop collar 114 limits upward movement of elongate spool member 110. The distance between upper stroke stop member 112 and spool valve body 101 (and, thus, the travel of elongate spool member 110) can be adjusted using stroke stop tie rods 115 and adjustment nuts 116.
A variable frequency drive (“VFD”), typically included as part of a prime mover assembly (such as the alternate embodiment skid packages described in
In operation, wedge spool control valve assembly 100 of the present invention controls the actuation of hydraulic cylinder assemblies and, thus, stroking of a down-hole pump. Reference is made to
Hydraulic fluid is pumped through a line from the hydraulic pump of the prime mover to the wedge spool control valve assembly 100. Hydraulic fluid enters said wedge spool control valve assembly 100 through bypass bore 103. Simultaneously, check valve assembly 120 opens, allowing fluid to continue flowing through bypass bore 103. Fluid flowing through bypass port 103 continues through line(s) or hose(s) (see, line 411 in
Hydraulic fluid passes through lower flow channel 106 and bore extension 104, into central flow bore 102, forcing wedge spool member 110 in an upward direction. Said hydraulic cylinder assemblies continue to retract, until upper electric switch (see, switch 350 in
With the pumping stopped and the hydraulic cylinder assemblies retracted a predetermined amount, the down stroke portion of the cycle commences. As the down stroke portion of the cycle commences, fluid is forced (by the weight of the rod string load) down through bypass bore 103. Check valve assembly 120 closes, thereby diverting hydraulic fluid through upper flow channel 105 and central flow bore 102, as well as bore extension 104 and lower flow channel 106. Said fluid then flows out of wedge spool control valve assembly, and through a conduit back to a hydraulic fluid reservoir in prime mover skid.
As the piston rods of said hydraulic cylinder assemblies extend, push plate 311 connected to bridle 310, contacts the upper surface of elongate spool member 110, driving it downward. Said elongate spool member 110 will gradually restrict the flow of fluid while simultaneously decreasing the rate of speed until the motion is almost stopped. The weight of the rod string acts on said wedge spool member 110 which, in turn, eliminates loading on the pump and motor.
If the pumping unit is not equipped with an electrical regeneration unit, the motor will be turned off until the down stroke cycle is complete. However, when an electrical regeneration unit is installed, the motor is switched into reverse until the down stroke cycle is complete.
The process repeats itself with bottom switch being actuated, thereby triggering the VFD to slowly ramp up the electric motor. In this position, most of the well load is exerted on the wedge spool. As a result, start up loading on the electric motor is reduced, thereby reducing electric consumption and shock on the entire system. From this position, the up stoke portion of the cycle begins, and the process is repeated.
The critical variable for operation of the wedge spool control valve of the present invention is distance (i.e., the stroke distance of hydraulic cylinders), rather than time as in with other conventional hydraulic pumping units. As such, the pumping apparatus of the present invention is not affected by the rate of speed on the down stroke cycle. When the push plate 311 (see
During normal operating functions, when wedge spool member 110 reaches around (adjustable) the 98% closed position within bore 102 and bore extension 104, push plate 311 has triggered the VFD to start the up stroke cycle. In the event of a power failure, or if the unit shuts down for any reason, the spool valve will continue down until the piston rods of the hydraulic cylinder assemblies come in contact with rod end caps of said cylinder assemblies, which in turn bleeds hydraulic pressure from the entire system. This function adds a significant safety feature to the hydraulic pump apparatus of the present invention while also reduces the likelihood of fluid leaks.
The hydraulic pumping assembly of the present invention can be adjusted to speeds to as little as 1 stroke per hour. On the down stroke cycle, electricity supply is turned off. The present invention virtually eliminates parted rods caused by stuck pump or rod string due to the constant monitoring of incoming electric power supply and instantaneous shutdown on low voltage. The present invention constantly monitors down hole conditions, and promptly shuts down if an overload occurs thereby greatly reducing tubing and rod wear. The present invention further adjusts to the well feed in rate thereby eliminating the need for a timer. The present invention will automatically restart when the power supply returns to normal. The rod clamp is adjustable as with conventional units,
Both the up and down stroke speeds can be independently adjusted by the simple turning of a knob or valve which provides for infinite variable speed control. An optional clean electrical power regeneration package can be provided. The present invention is specifically designed to be well tender friendly and simple to operate; as a result, limited computer skills are required for operation of said invention
The double sealing assembly 150 of the present invention eliminates problems associated with such conventional assemblies. The double sealing assembly of the present invention can be utilized in connection with hydraulic cylinder assemblies, and also with the wedge spool control valve of the present invention. Referring to
Chamber drain channel 154 extends from said chamber 153 to a waste container (not pictured); in the preferred embodiment, said waste container is maintained at ambient (typically atmospheric) pressure which in turn lets contaminants flush out of said drain channel 154 and into said waste container (instead of, as with conventional systems, leaking past the outer rod seals). As a result, internal high pressure seal 155 is kept free of most contaminants which in turn prevents contaminants from migrating inside. This, in turn, greatly increases the life of the cylinder or valve spool and also the time between servicing. The double sealing assembly 150 of the present invention allows operations to continue much longer, even with the main seal worn because the fluid is captured instead of leaking onto the surroundings. The double seal system of the present invention lasts many times longer than standard systems.
It is to be observed that double sealing assembly 150 of the present invention can also be utilized in connection with a wedge spool control valve of the present invention. Specifically, said double sealing assembly can be utilized in connection with seals associated with tapered wedge spool member 110, thereby increasing the life of such seals and, accordingly, the operating life of wedge spool control valve of the present invention.
On the down stroke cycle, the regeneration unit and the VFD are programmed to reverse the electric motor to 0 cycles. The weight of the well string forces hydraulic fluid back through the pump, turning the motor in reverse and generating electricity which, in turn, goes back into the electrical grid. As fluid flows through port 83, fluid pressure will close ball 82 and open ball 84, which allows fluid to pass through a cooler and/or filter (not shown on
Referring to
381—Electrical regenerative mounted with VFD. On the down stroke cycle, the flow control 387 (below) is used as a back up so the down speed is controlled in the event that the unit fails. Fluid is forced through the pump; turning it in reverse so the pump now acts as a hydraulic motor that in turn drives the electric motor in reverse thereby sending electrical current back into the electrical grid. Fluid is diverted by zero restriction check valve assembly (396), also shown in detail in
382—Electric motor
383—Hydraulic pump
384—Check valve to keeps the pump and motor from turning in reverse.
385—Hydraulic line to the tower
386—Control wire from the tower to the VFD
387—Flow control valve. Controls the down stroke speed from max.
389—Cooler
390—Filter
391—Reservoir
392—Desiccant
393—Air line to the top of the cylinders
394—Base (tank)
395—Base drain
396—Zero Restriction Check Valve and Electrical Regeneration (See,
Referring to
362—Electric motor
363—Hydraulic pump
364—Check valve to prevent the pump and motor from turning in reverse
365—Hydraulic line to the tower.
366—Control wire from the tower to VFD
367—Flow control valve to control the down stroke speed from max. to stop.
368—Electric valve. Said electric valve opens on the down stroke so fluid from the cylinders feeds back into the reservoir and closes on the up stroke so fluid from the pump retracts the cylinders.
369—Cooler
370—Filter
371—Reservoir
372—Desiccant
373—Air line to the top of the cylinders
374—Base (tank)
375—Base drain
Actuation of said switch ramps up the engine governor. Simultaneously, valves 278 and 286 slowly close, controlled by a timer mechanism that eliminates any shock on the up start. The up speed is controlled by predetermined setting of the governor. When the stroke gets close to the top, a switch (350 in
Now continuing the down stroke, as in above, the down stroke continues until the wedge spool control valve 110 ramps down the speed and the down stroke length is reached. Hydraulic pressure can still be maintained as to prevent a sudden shock of pressure at the start of the up cycle. On the down stroke cycle, check valve 274 keeps pressure off valve 278 and pump 273. Valve 277 is depicted as a redundant check valve that isolates any back pressure on the pump. Valve 278 beneficially allows the engine to idle free of any pressure.
Electric valves 278 and 286 are normally open. In case of engine failure, on either the up or down stroke, at any position, the stroke will automatically go down, such that the spool push plate 311 comes contacts wedge spool 110, thereby gently ramping down the speed. The process continues until the end of the wedge spool valve's stroke is reached and all the hydraulic pressure is bled from the system, with hydraulic cylinders fully extended down. This process eliminates any danger of accidently causing injury from high hydraulic pressure.
Referring to
271—Enclosure for engine governor, timer, relays and valve controls
272—Internal Combustion engine
273—Hydraulic pump
274—Check valve
275—Hydraulic line to the tower
276—Control wire from the tower to the VFD
277—Check valve
278—Hydraulic fluid and pressure unloading valve
279—Cooler
280—Filter
281—Reservoir
282—Desiccant
283—Air line to the top of the cylinders
284—Base (tank)
285—Base drain
286—Downstoke cycle return valve
287—Flow control valve
In addition to the embodiments depicted in
The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention.
| Number | Date | Country | |
|---|---|---|---|
| 61449273 | Mar 2011 | US |
