Piston-type water pump

Abstract

A pump apparatus is provided comprising: a housing; a water chamber in the housing; an hydraulic chamber in the housing; a rod member extending at least partially into each of the water chamber and the hydraulic chamber; a first piston member mounted on the rod member and contained within the hydraulic chamber; a second piston member mounted on the rod member and contained within the water chamber; hydraulic means for alternatively forcing the first piston member in first and second directions; fluid inlet means extending through the housing adjacent an end of the water chamber; and fluid outlet means extending through the housing adjacent the end of the water chamber; wherein when the hydraulic means force the first piston member to move in the first direction, the second piston member is forced to move in the first direction, and fluid is drawn through the fluid inlet means into the water chamber; and wherein when the hydraulic means force the first piston member to move in the second direction, the second piston member is forced to move in the second direction, and fluid is forced through the fluid outlet means.

Description

FIELD OF THE INVENTION

The present invention relates to water pumps, and more particularly to water pumps that can be employed in the petroleum industry.

BACKGROUND OF THE INVENTION

Water pumps are currently used in the petroleum industry for a variety of purposes, for example dewatering applications in coalbed methane wells. Coalbed methane gas is a form of natural gas that is trapped in naturally-fractured coal seams, a low pressure, water-saturated environment. Removing the water trapped in the coal seams reduces the formation pressure and accordingly allows the trapped gas to desorb from the coal seams and flow to the wells. Typically, large volumes of water are produced during the early stages of production and the initial gas produced from the coalbed wells is modest, a period which can last up to three years in some cases. The dewatering period depends on such factors as coal seam permeability and well spacing, but in-well pumping can also affect the dewatering period. As the dewatering of the coal continues, the gas rates typically increase, so dewatering of the coal seams is crucial for production operations.

Standard water pumps used in the petroleum industry for coalbed dewatering applications pump the water up like a common water pump, using sucker rods on the surface to push and pull the plunger. Standard water pumps commonly used for such purposes require a service rig for installation, and they can take approximately 1-1½ days to fit the unit. A standard unit also requires the presence of a cement pad base and the use of a crane truck to load and unload the unit onsite, as well as an additional separate well casing to extract the water to the surface. Common screw-type pumps have a drive on the surface with a drive line from surface to the screw-type pump at the bottom of the well, to perform the required functions. In addition to these service and installation disadvantages, there are associated disadvantages regarding control of the standard pump unit. Depending on the speed of movement, the plunger can sometimes buckle inside the well. Also, there is limited control of speed and volume as the system has to be closely monitored to prevent plug-ups and component damage. Further, manufacture of the joints in the inner casing and also the joints on the sucker rods for pushing/pulling is relatively costly.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a pump apparatus comprising: a housing; a water chamber in the housing; an hydraulic chamber in the housing; a rod member extending at least partially into each of the water chamber and the hydraulic chamber; a first piston member mounted on the rod member and contained within the hydraulic chamber; a second piston member mounted on the rod member and contained within the water chamber; hydraulic means for alternatively forcing the first piston member in first and second directions; fluid inlet means extending through the housing adjacent an end of the water chamber; and fluid outlet means extending through the housing adjacent the end of the water chamber; wherein when the hydraulic means force the first piston member to move in the first direction, the second piston member is forced to move in the first direction, and fluid is drawn through the fluid inlet means into the water chamber; and wherein when the hydraulic means force the first piston member to move in the second direction, the second piston member is forced to move in the second direction, and fluid is forced through the fluid outlet means.

In preferred embodiments of the present invention, the hydraulic means comprise: a first hydraulic tube in fluid communication with the interior of the hydraulic chamber on a first side of the first piston member; and a second hydraulic tube in fluid communication with the interior of the hydraulic chamber on a second, opposite side of the first piston member; wherein when hydraulic fluid is forced through the first hydraulic tube, the first piston member is forced to move in the first direction; and wherein when hydraulic fluid is forced through the second hydraulic tube, the first piston member is forced to move in the second direction.

In further preferred embodiments, this fluid outlet means comprise a fluid exhaust passage within the housing; the fluid inlet means and fluid outlet means comprise check valves to control fluid flow; and the fluid inlet means comprise an aperture opening in a downstream direction, such that when the fluid is drawn through the fluid inlet means into the water chamber, the fluid is drawn in an upstream direction to avoid undue fines and gals build-up in the fluid inlet means. The unit is also preferably made of stainless steel.

The present invention therefore seeks to provide a piston-type water pump that can more effectively perform the same type of work for which the standard water pump is currently employed, with greater control and decreased manufacturing costs.

A pump apparatus in accordance with the present invention can be installed using a coiled tubing rig, taking approximately ½ to 1 day to fit the unit, an installation time savings of approximately 40% over the standard pump units. A pump apparatus according to the present invention can also be used with a self-contained power unit, which can be gas-powered or electric depending on what is available onsite. In addition, a pump apparatus according to the present invention can be delivered on a one-ton flatbed truck and can be loaded and unloaded onsite using the crane on the tubing truck where a coil tubing installation is employed.

The pump apparatus is preferably suspended by three endless tubes from the surface to the pump, the apparatus being set at the bottom of a well. Two of the tubes would then contain hydraulic oil, which hydraulic oil drives the piston, one of the tubes forcing the piston up and then the other tube forcing the piston down. When the piston is forced down, water is drawn in through a check valve in the water chamber. When the rod is at the end of its stroke a pressure signal is sent to the power unit, the piston is forced up by means of the other tube, the suction check valve closes, and water is pushed through a fluid exhaust tube to the surface until a pressure signal is received and the piston is once more forced down to refill the water chamber.

Due to the fact that this unit is preferably made of stainless steel, and there are few internal parts, there is less chance for contamination and breakdowns when compared to the standard pump units currently in operation. In terms of control, a pump apparatus according to the present invention can provide greater control of the system speed and volume, with little stress to the pump unit. The slower the speed, the less water is pumped, while increasing the speed results in a greater volume of water being pumped.

A detailed description of an exemplary embodiment of the present invention is given in the following. It is to be understood, however, that the invention is not to be construed as limited to this embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which illustrate an exemplary embodiment of the present invention:

FIG. 1 is a top plan view of a pump apparatus according to the present invention, showing the positioning of the water exhaust tube and hydraulic supply tubes;

FIG. 2 is a side elevation view of the downstream end of a pump apparatus according to the present invention, showing the connectors for the hydraulic supply tubes;

FIG. 3 is a side elevation view of the next section of the pump apparatus of FIG. 2, connected to the upstream end of the section of FIG. 2, showing the water intake and exhaust means;

FIG. 4 is a side elevation view of the next section of the pump apparatus of FIG. 2, connected to the upstream end of the section of FIG. 3, showing the piston in the water chamber; and

FIG. 5 is a side elevation view of the upstream section of the pump apparatus of FIG. 2, connected to the upstream end of the section of FIG. 4, showing the piston in the hydraulic chamber.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

Referring now in detail to the accompanying drawings, there is illustrated an exemplary embodiment of a pump apparatus according to the present invention, generally referred to by the numeral 10. The pump apparatus 10 comprises a housing 12, which houses a water chamber 14 (shown in FIGS. 3 and 4) and an hydraulic chamber 16 (shown in FIG. 5). In the preferred embodiment, the water chamber 14 is adjacent and downstream of the hydraulic chamber 16, although other configurations are possible.

Referring now in detail to FIGS. 4 and 5, a stainless steel rod 18 extends partially into the water chamber 14 at one end, and its opposite end extends partially into the hydraulic chamber 16. Mounted on the rod 18, within the water chamber 14, is a water piston 22 (which is stainless steel and may be provided with molded urethane), secured by means of a lock nut 66 and in contact with an oil-impregnated bronze wear ring 70, which water piston 22 reciprocates within the water chamber 14 in response to movement of the rod 18. Mounted on the rod 18, within the hydraulic chamber 16, is an hydraulic piston 22, secured by means of a lock nut 68, which reciprocates within the hydraulic chamber 16 in response to the influence of the hydraulic system (discussed below), driving the movement of the rod 18.

First and second hydraulic supply tubes 28, 30 (shown in FIG. 1) are housed within a hollowed out section of the housing 12. First and second hydraulic supply tubes 28, 30 pass along the length of the housing 12 until they connect with the downstream side of connectors 40 on the housing 12, as can be seen in FIG. 2, and pass from the upstream side. The hydraulic supply tubes 28, 30 are threaded into the connectors 40 for stability, and they are preferably held against the housing 12 exterior by means of hose clamps (not shown). The sections of the hydraulic supply tubes 28, 30 upstream of the connectors 40 pass down to the upstream section of the pump apparatus 10, as can be seen in FIG. 5. The first hydraulic supply tube 28 is threaded into connector 42, with a final section of first hydraulic supply tube 28 being threaded between connectors 44 and 46. The result is that first hydraulic supply tube 28 can supply hydraulic fluid (not shown) into a portion of the hydraulic chamber 16 downstream of the hydraulic piston 20, driving the hydraulic piston 20 in an upstream direction. The second hydraulic supply tube 30 passes parallel to the first hydraulic supply tube 28 until it reaches the upstream section of the pump apparatus 10. The second hydraulic supply tube 30 is threaded into a connector 48, and is used to supply hydraulic fluid to a portion of the hydraulic chamber 16 upstream of the hydraulic piston 20, driving the hydraulic piston 20 in a downstream direction. By alternating supply of hydraulic fluid to the first and second hydraulic supply tubes 28, 30, the hydraulic piston 20 can be selectively forced in upstream and downstream directions within the hydraulic chamber 16.

As the hydraulic piston 20 is mounted on the rod 18, movement of the hydraulic piston 20 drives the rod 18 in the same direction. This causes the same movement to occur with respect to the water piston 22 in the adjacent water chamber 14, which water piston 22 is also mounted on the rod 18. In other words, manipulation of the hydraulic supply means to force the hydraulic piston 20 in a first direction causes that force to be transmitted to the water piston 22 by means of the connecting rod 18, resulting in the water piston 22 being forced in the first direction an equal distance.

The water chamber 14, as can best be seen in FIG. 3, comprises a water inlet 24 through the housing 12. This section of the housing 12 is preferably but not necessarily a machined, stainless steel manifold block. The water inlet 24 comprises an aperture 52 which opens in a downstream direction; this allows water to be drawn into the water inlet 24 in an upstream direction, which assists in preventing the ingress and build-up of fines and methane gas. The water inlet 24 is also provided with a check valve 36, comprising a stainless steel check ball 50, which ensures that water can be drawn into the water chamber 14 by means of the water inlet 24 but cannot be forced out through the water inlet 24.

The water chamber 14 also comprises a water outlet 26 which connects to a water exhaust tube 32 (see FIGS. 1, 2 and 3) extending downstream from the water chamber 14 through the horsing 12. As can be seen in FIG. 2, a downstream segment of the water exhaust tube 32 is provided with an exhaust check valve 34, comprising a stainless steel check valve insert 54 and check ball 38. As was the case with the check valve 36, exhaust check valve 34 is to control fluid flow direction. While water can be drawn downstream through the exhaust check valve 34, it cannot be drawn in an upstream direction. The downstream section of the pump apparatus 10 that houses the exhaust check valve 34 and connectors 40 is provided with a pin connector 56 for connection to a box connector 58 on the housing 12 section containing the water and hydraulic chambers 14, 16.

The section of the housing 12 just upstream of the water inlet 24 and water outlet 26 is provided with an O ring seal 60 and back-up ring 62.

The water chamber, as can be seen in FIG. 4, is provided with water cooling vents 64. This allows cooling water into the area of the rod 18 on a single-acting configuration, but the water cooling vents 64 can be converted for use with a double-acting configuration.

Referring to FIGS. 4 and 5, the pump apparatus 10 is also provided with various seals 72, a back-up ring 74, a wiper ring 76, wear rings 78, and an anti-extrusion ring 80. The hydraulic chamber 16 is also provided with a stainless steel rod end gland 82 (with a built-in cushion), a rod end piston cushion 84, and an upstream end oil piston cap 86 (with built-in cushion). The hydraulic piston 20 is provided with tapered ends so that, upon the hydraulic piston 20 nearing the end of its stroke, hydraulic fluid squeezes out of the space adjacent the tapered end and cushions the hydraulic piston 20.

The embodiment of the present invention is used as follows. When it is desired to use the pump apparatus 10 to pump unwanted fluids such as water out of a well, first hydraulic supply tube 28 is used to inject hydraulic fluid into the portion of the hydraulic chamber 16 downstream of the hydraulic piston 20, driving the hydraulic piston 20 in an upstream direction. This movement causes the rod 18 to move in an upstream direction, causing the water piston 22 to also move in an upstream direction. Fluid is drawn through the water inlet 24 due to the pressure change inside the water chamber 14 when the water piston 22 moves upstream, filling the area within the water chamber 14 downstream of the water piston 22. Fluid cannot be drawn into the water chamber 14 through the water outlet 26 due to the presence of the exhaust check valve 34.

To exhaust the fluid contained within the water chamber 14, hydraulic fluid is then injected through the second hydraulic supply tube 30 and into the portion of the hydraulic chamber 16 upstream of the hydraulic piston 20, driving the hydraulic piston 20 in a downstream direction. Forcing the hydraulic piston 20 in a downstream direction causes the rod 18 to also move in a downstream direction, and the water piston 22 accordingly is forced in a downstream direction. The downstream movement of the water piston 22 exerts pressure on the fluid within the water chamber 14, which pressure is released by the ejection of fluid through the water outlet 26 and water exhaust tube 32. As the water inlet 24 is provided with a check valve 36, the fluids cannot escape by the means. The fluids are then moved through the water exhaust tube 32 toward the surface and out of the well (not shown).

While a particular embodiment of the present invention has been described in the foregoing, it is to be understood that other embodiments are possible within the scope of the invention and are intended to be included herein. It will be clear to any person skilled in the art that modifications of and adjustments to this invention, not shown, are possible without departing from the spirit of the invention as demonstrated through the exemplary embodiment. The invention is therefore to be considered limited solely by the scope of the appended claims.

PARTS LIST

• 1 STAINLESS STEEL CHECK BALL—1⅞″ DIAMETER
• 1A STAINLESS STEEL CHECK VALVE INSERT
• 2 STAINLESS STEEL CHECK BALL— 15/16″ DIAMETER
• 3 568-244 O'RING SEAL 90 DURO
• 4 575-244T BACK UP RING
• 5 568-246V O'RING SEAL 90 DURO
• 6 575-246T BACK UP RING
• 7 1¼″ NF LOCK NUT
• 8 RDH45-5007 STAINLESS STEEL 1-PIECE PISTON w/MOLDED URETHANE
• 9 PS1850-72 BRONZE FILLED PTFE SEAL w/RUBBER O'RING ENERGIZER
• 10 568-222V SEAL w/VITON LOADER
• 11 612T-050B NYLON WEAR RING
• 12 HW1500V URETHANE WIPER RING
• 13 DPU-37-3-75-62V HEAVY DUTY PISTON SEAL
• 14 568-222V O'RING SEAL VITON
• 15 612T-050B NYLON WEAR RING
• 16 DURA BAR HYDRAULIC PISTON
• 17 1⅛″ NF LOCK NUT
• 18 1½″ STAINLESS STEEL ROD
• 19 4½″ ID×5¼″ OD STAINLESS STEEL MICRO HONED TUBE
• 20 OIL IMPREGNATED BRONZE WEAR RING
• 21 STAINLESS STEEL ROD END GLAND w/CUSHION BUILT IN
• 22 ROD END PISTON CUSHION
• 23 BOTTOM END OIL PISTON CAP w/CUSHION BUILT IN
• 24 WATER CHAMBER—COOLING BOTH WATER & HYD. ROD SEALS PLUS LUBRICATING ROD
• 25 WATER COOLING VENT
• 26 STAINLESS STEEL SOLID MANIFOLD BLOCK-MACHINED
• 27 U25-1-50-37BV ANTI-EXTRUSION RING 1½×2×0.070 GLASS FILLED TEFLON 0.475 GROOVE WIDTH

Claims

1. A pump apparatus comprising:

a housing;

a water chamber in the housing;

an hydraulic chamber in the housing;

a rod member extending at least partially into each of the water chamber and the hydraulic chamber;

a first piston member mounted on the rod member and contained within the hydraulic chamber;

a second piston member mounted on the rod member and contained within the water chamber;

hydraulic means for alternatively forcing the first piston member in first and second directions;

fluid inlet means extending through the housing adjacent an end of the water chamber; and

fluid outlet means extending through the housing adjacent the end of the water chamber;

wherein when the hydraulic means force the first piston member to move in the first direction, the second piston member is forced to move in the first direction, and fluid is drawn through the fluid inlet means into the water chamber; and

wherein when the hydraulic means force the first piston member to move in the second direction, the second piston member is forced to move in the second direction, and fluid is forced through the fluid outlet means.

2. The pump apparatus of claim 1 wherein the hydraulic means comprise:

a first hydraulic tube in fluid communication with the interior of the hydraulic chamber on a first side of the first piston member; and

a second hydraulic tube in fluid communication with the interior of the hydraulic chamber on a second, opposite side of the first piston member;

wherein when hydraulic fluid is forced through the first hydraulic tube, the first piston member is forced to move in the first direction; and

wherein when hydraulic fluid is forced through the second hydraulic tube, the first piston member is forced to move in the second direction.

3. The pump apparatus of claim 1 wherein the fluid outlet means comprise a fluid exhaust passage within the housing.

4. The pump apparatus of claim 1 wherein the fluid inlet means and fluid outlet means comprise check valves to control fluid flow.

5. The pump apparatus of claim 1 wherein the fluid inlet means comprise an aperture opening in a downstream direction, such that when the fluid is drawn through the fluid inlet means into the water chamber, the fluid is drawn in an upstream direction to avoid undue fines and gas build-up in the fluid inlet means.