WO2006078951A1

WO2006078951A1 - Downhole well pump

Info

Publication number: WO2006078951A1
Application number: PCT/US2006/002121
Authority: WO
Inventors: Kenneth G. Johnson; William Lyons; Michael Mcgovern; Steven E. Johnson; Stephan T. Kujawa; Gloyd A. Simmons; Bojana Nikolic-Tirkas
Original assignee: Burlington Resources Oil & Gas Company Lp
Priority date: 2005-01-21
Filing date: 2006-01-23
Publication date: 2006-07-27
Also published as: CA2613232A1; WO2006079110A2; WO2006079110A3; US20060225886A1

Abstract

The pump and pump system of the present invention is designed to remove liquids and gases from gas and/or oil wells. The pump operates using pressurized gas, preferably gas produced from the well, to lift fluids from the well without any moving pump parts. One embodiment of the pump utilizes a nozzle to create an area of reduced pressure drawing well fluids to that area and a diffuser section which allows the liquids to flow to the surface for removal from the well.

Description

DOWNHOLE WELL PUMP

FIELD OF INVENTION

[0001] The present invention relates generally to a pump system for removing fluids (e.g., water and natural hydrocarbons) from a cased hole, i.e. a well bore. More particularly, the present invention relates to a novel downhole, gas-driven pump system having no moving parts, that is particularly suitable for removing fluids from hydrocarbon-producing wells.

BACKGROUND OF THE INVENTION

[0002] Increasing production demands and the need to extend the economic life of oil and gas wells have long posed a variety of problems. For example, as natural gas is produced from a reservoir, the pressure within the reservoir decreases over time and some fluids that are entrained in the gas stream with higher pressures precipitate due to lower reservoir pressures, and build up within the well bore. In time, the bottom hole pressure will decrease to such an extent that the pressure will be insufficient to lift the accumulated fluids to the surface. In turn, the hydrostatic pressure of the accumulated fluids causes the natural gas produced from the "pay zone" to become substantially reduced or maybe even completely static, reducing or preventing the gases/fluids from flowing into the perforated cased hole. In such cases, the well bore may log off and possibly be plugged prematurely for economic reasons.

[0003] The oil and gas industry has used various methods to lift fluids from well bores. The most common method is the use of a pump jack (reciprocating pump), but pump jack systems have given rise to additional problems. Pump jack systems require a large mass of steel to be installed on the surface and comprise several moving parts, including counter balance weights, which pose a significant risk of serious injury to operators. Additionally, this type of artificial lift system causes wear to well tubing due to pumping rods that are constantly moving up and down inside the tubing. Consequently, pump jack systems have significant service costs, which negatively impact the economic viability of a well.

[0004] Another known system for lifting well fluids is a plunger lift system. The plunger lift system requires bottom hole pressure assistance to raise a piston, which lifts liquids to the surface. Like the pump jack system, the plunger lift system includes numerous supporting equipment elements that must be maintained and replaced regularly to operate effectively. This adds significant costs to the production of hydrocarbons from the well. , In addition, plunger lift systems eventually become ineffective due to lower reservoir pressures than are required to lift the piston to the surface to evacuate the built up liquids.

[0005] Yet another system for lifting well fluids from a well bore is disclosed in PCT International Application No.: PCT/US02/32462, which is hereby incorporated by reference. In that system, gas from the well is used to power a downhole pump. The disclosed pump design uses pressurized gas to rotate impeller or turbine-type blades, which lift well fluids from the well. While this design does not have the above-described drawbacks inherent in the pump jack and plunger lift systems, it still includes moving parts (impeller/turbine blades) which increases the potential for wear and malfunction.

[0006] Thus, there is a need for a safe, durable and cost effective pump system that is less susceptible to mechanical failure and that effectively removes liquids from well bores that do not have sufficient bottom hole pressure to lift the liquids to the surface.

[0007] The present invention relates to a method and pump system for producing fluids from a well having a pay zone and a wellbore opening at the surface. In accordance with the method of the present invention, gas (motive gas) is supplied to a pump disposed in said well and fluids are removed from the well by the pump which is adapted for employing the motive gas for generating a force for lifting fluids from said well without any moving parts in the pump. In a preferred aspect of the invention, the pump includes a nozzle and a diffuser to lift fluids from the well. In addition, the motive gas can be pressurized by a compressor in order to obtain the required pressure to lift fluids from the well. In alternative aspects of the invention the compressor can.be a well head compressor or a central compressor.

[0008] In another aspect of the present invention, the nozzle includes at least one fluid intake port (and preferably a plurality of intake ports). In a most preferred aspect of the invention, the pump further includes means for aligning said fluid intake port to receive well fluids from the well.

[0009] In another aspect of the present invention the pump also includes a mixing chamber in which the well fluids mix with the motive gas before the removal of the fluids from said well.

[0010] In preferred embodiment of the invention, the nozzle has a throat opening at its upper end (discharge end) of between about 0.212 inches to about 0.237 inches in diameter.

[0011] In yet another aspect of the present invention a second pump is disposed in a second well, the second pump being adapted for employing the motive gas for generating a force for lifting fluids from the second well without any moving parts. In this aspect of the invention, pressurized motive gas is supplied to the first and second pumps by a common compressor or central compressor system.

[0012] In yet another aspect of the invention, the pump is disposed within the well directly adjacent a pay zone.

[0013] In yet another aspect of the present invention, the pump system includes (a) a pump disposed in the well, the pump having no moving parts and being adapted to employ pressurized gas for generating a force for lifting fluids from the well to the wellbore opening (at the surface), (b) a well casing surrounding a first tubing string, and (c) an annulus between the casing and the first tubing string, the annulus being open from the pay zone to a point upwell of the pump and the annulus being in fluid communication with a point adjacent the wellbore opening at the surface. SUMMARY OF THE INVENTION

[0014] The present invention relates to a method and pump system for producing fluids from a well having a pay zone and a wellbore opening at the surface. In accordance with the method of the present invention, gas (motive gas) is supplied to a pump disposed in said well and fluids are removed from the well by the pump which is adapted for employing the motive gas for generating a force for lifting fluids from said well without any moving parts in the pump. In a preferred aspect of the invention, the pump includes a nozzle and a diffuser to lift fluids from the well. In addition, the motive gas can be pressurized by a compressor in order to obtain the required pressure to lift fluids from the well. In alternative aspects of the invention the compressor can be a well head compressor or a central compressor.

[0015] In another aspect of the present invention, the nozzle includes at least one fluid intake port (and preferably a plurality of intake ports). In a most preferred aspect of the invention, the pump further includes means for aligning said fluid intake port to receive well fluids from the well.

[0016] In another aspect of the present invention the pump also includes a mixing chamber in which the well fluids mix with the motive gas before the removal of the fluids from said well.

[0017] In preferred embodiment of the invention, the nozzle has a throat opening at its upper end (discharge end) of between about 0.212 inches to about 0.237 inches in diameter.

[0018] In yet another aspect of the present invention a second pump is disposed in a second well, the second pump being adapted for employing the motive gas for generating a force for lifting fluids from the second well without any moving parts. In this aspect of the invention, pressurized motive gas is supplied to the first and second pumps by a common compressor or central compressor system. [0019] In yet another aspect of the invention, the pump is disposed within the well directly adjacent a pay zone.

[0020] In yet another aspect of the present invention, the pump system includes (a) a pump disposed in the well, the pump having no moving parts and being adapted to employ pressurized gas for generating a force for lifting fluids from the well to the wellbore opening (at the surface), (b) a well casing surrounding a first tubing string, and (c) an annulus between the casing and the first tubing string, the annulus being open from the pay zone to a point upwell of the pump and the annulus being in fluid communication with a point adjacent the wellbore opening at the surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] For a more complete understanding of the present invention and for further advantages thereof, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

[0022] FIGS. IA- 1C depict, respectively, a side view, perspective view and exploded cross-sectional view of the downhole pump assembly of the present invention.

[0023] FIGS. 2A-2E depict, respectively, a left end view, side view, right end view, perspective view and cross-sectional view of the pump housing section of the downhole pump assembly of the present invention.

[0024] FIGS. 3A-3D depict, respectively, a left end view, side view, right end view, and cross-sectional view of the upper flow adapter section of the downhole pump assembly of the present invention.

[0025] FIGS. 4A-4E depict, respectively, a left end view, side view, right end view, perspective view and cross-sectional view of the lower flow adapter section of the downhole pump assembly of the present .invention.

[0026] FIGS. 5A-5D depict, respectively, a side view, right end view, exploded perspective view and cross-sectional view of the diffuser section of the downhole pump assembly of the present invention. [0027] FIGS. 6A-6E depict, respectively, a side view, right end view, perspective view, first cross-sectional view and second cross-sectional view of the mixing chamber section of the downhole pump assembly of the present invention.

[0028] FIGS. 7A-7C depict, respectively, an end view, cross-sectional view and perspective view of the downhole parallel section of the downhole pump assembly of the present invention.

[0029] FIGS. 8A-8C depict, respectively, a side view, cross-sectional view and perspective view of the jet nozzle section of the downhole pump assembly of the present invention.

[0030] FIGS. 9A-9B depict, respectively, a side view and cross-sectional view of the downhole pump assembly of the present invention indicating the flow paths for motive gases and well fluids through the pump.

[0031] FIGS. 10A-10D depict, respectively, a side view, an end view, a perspective view and a cross-sectional view of the downhole diffuser of the present invention.

[0032] FIG. 11 depicts a cross-sectional side view of an alternative embodiment of the pump assembly of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033] The present invention is a novel downhole pump for use in the removal of liquids from wells, especially, but not limited to, wells that have insufficient bottom hole pressure to lift the well liquids out of the well bore and to the surface. In its typical use, the pump is disposed downhole in a well adjacent the bottom of the well or the hydrocarbon-producing formation. Referring now to FIGS. IA- 1C, there is shown a preferred embodiment of the pump assembly 10 of present invention. Pump assembly 10 includes as its main components a downhole diffuser assembly section 100, an upper flow adapter section 200, a pump housing section 300, a lower flow adapter section 400.

[0034] Referring to FIGS. 2A-2E, the pump housing section 300 shall be described. Pump housing section 300 includes an outer surface 310, a lower end 312 disposed further downhole when installed, and an upper end 314. (The use of the term "lower" herein generally refers to the portion of the pump structure positioned further downhole when the pump is installed. The term "upper" is used to refer to the opposite end of the subject pump structure positioned further up hole when the pump is installed.) Pump housing 300 is substantially cylindrical in shape and can be constructed out of any material suitable for use in a down hole wellbore environment, such as stainless steel. In the depicted embodiment, the outer diameter of the housing is about 3.5 inches, which is suitable for wells with a 5 ¹A inch casing. In many wells, however, smaller diameter casing is in place. It is very common to have 4 ¹A inch diameter casing in the well. In such cases, the outer diameter of the pump can be scaled down to accommodate the pump. For example, for a 4 ¹A inch diameter casing, the outer diameter of the pump is preferably scaled down to a 2 7/8 inches and is connected to a 2 7/8 inch tubing string, with the diffuser assembly portion 100 of the pump being connected to a 1 ¹A inch tubing string.

[0035] Still referring to FIGS. 2A-2E, pump housing 300 includes a plurality of openings 320 (for motive gas flow) that extend longitudinally through the housing from upper end 314 to lower end 312. In addition to providing a conduit for the flow of motive gas, elongated openings 320 serve to reduce gas turbulence, thereby enhancing the efficiency of the pump. Another larger opening 330 also extends longitudinally through the housing. Opening 330 is disposed in the approximate center of the housing and has a slight taper from the upper end to the lower end. A flange 340 extends around the periphery of upper end 314, creating a recess 342. A dowel pin opening 316 is also formed in the upper end 314. Still referring to FIGS. 2A-2E, housing 300 further includes a lateral opening 370 which extends from opening 330 through the outer surface 310 of the housing. During pumping operations, opening 370 is plugged with plug 380 (FIG. 1C). Lower end 312 includes a flange 350 which extends around the periphery of lower end 312, creating a recess 352. Also disposed at the lower end of the housing is tube opening 360 which extends from lateral opening 370 into recess 352. In a preferred embodiment, as shown in FIG. 2E, openings 330, 316 and 360 have chamfered edges to allow for easier mating with other pump assembly components to be described hereafter. In a most preferred embodiment of the invention, the pump housing 300 has the dimensions and specifications indicated in FIGS. 2A- 2E.

[0036] Referring to FIGS. 3A-3D, there is shown the upper flow adapter section 200 of the pump assembly. Upper flow adapter section 200 has an upper end 212 and lower end 214. Opening 220 extends longitudinally through the center of the flow adapter. The diameter of opening 220 is greater at upper end 212 and tapers down to a lesser diameter at the lower end 214 to substantially correspond to the diameter of the opening 330 in pump housing 300. A plurality of openings 230 (for motive gas flow), which surround opening 220 at lower end 214, extend longitudinally through the flow adapter. In addition to providing a conduit for the flow of motive gas, elongated openings 230 serve to reduce gas turbulence, thereby enhancing the efficiency of the pump. When the components of the pump are assembled, openings 230 will align with the motive gas openings 320 in the pump housing section 300. A dowel pin opening 240 is included at the lower end 214 and corresponds with the dowel pin opening in the pump housing, allowing for the proper alignment of the upper flow adapter section 200 with the pump housing 300. Lower end 214 has a reduced outer diameter allowing lower end 214 to be seated in recess 342 (FIG. 2E) at the upper end of the pump housing. Upper end 212 has a reduced outer diameter to allow the upper flow adapter to be connected to an outer tubing string that extends to the surface. Preferably upper end 212 includes threads and is threaded to the outer tubing string. The preferred dimensions and specifications for upper flow adapter 200 are shown in FIGS. 3A- 3D.

[0037] Referring to FIGS. 4A-4E, there is shown the lower flow adapter section 400 of the pump assembly. Lower flow adapter section 400 has an upper end 412 and lower end 414. A tube opening 410 extends longitudinally through the lower flow adapter. Upper end 412 includes a recess 420. Upper end 412 also has a reduced outer diameter, allowing upper 412 to be seated within recess 352 at the lower end of the pump housing 300. Lower end 414 has a reduced outer diameter to allow for the attachment (preferably threaded attachment) of an additional tubing section(s) below the lower flow adapter. When the pump is assembled, a tube 450 will extend through opening 410 in the lower flow adapter and will be seated within opening 360 in the pump housing (see FIGS. 1C and 9B). The preferred dimensions and specifications for lower flow adapter 400 are shown in FIGS. 4A-4E.

[0038] Referring to FIGS. 5A-5D, there is shown the diffuser assembly 100 of the pump. Diffuser assembly 100 includes a diffuser section 102, a parallel section 120, a mixing chamber section 140, and a jet nozzle 160. As shown in FIGS. 5D and 10A- 10D, diffuser section 102 has an upper end 104 and a lower end 106. In the preferred embodiment, the upper end of the diffuser section is attached to a tubing string (not shown) that extends to the surface of the well. As shown in FIGS. 5D and 10D, an opening 110 at the center of the diffuser section extends longitudinally through the section. As shown, opening_, 110 tapers outwardly (i.e., expands in diameter) from the lower end 106 to the upper end 104. Dowel pin openings 112 are provided at the lower end of the diffuser. As shown (FIGS. 5 A, 5C-5D and 7A-7C), parallel section 120 is seated on the lower end 106 of the diffuser section and has a centered opening 130 which extends longitudinally through the section. Preferably, the diameter of opening 130 is substantially the same as the diameter of the nozzle throat (i.e., the nozzle opening 166 at upper end 164 of the nozzle - see FIGS. 8A-8C). Dowel pin openings 148 extend longitudinally through the parallel section and are aligned with the dowel pin openings 112 on the diffuser when the pump is assembled. The preferred dimensions and specifications for the diffuser section are shown in detail in FIGS. 10A- 10D. The preferred dimensions and specifications for the parallel section are shown in detail in FIGS. 7A-7C.

[0039] Referring to FIGS. 5A-5D and 6A-6E the mixing chamber section 140 of the diffuser assembly 100 shall be described. Mixing chamber 140 has a lower end 142 and upper end 144. Mixing chamber 140 is generally cylindrical and tapers to a slightly smaller diameter from its upper end 144 to lower end 142. The degree of taper corresponds with the tapered opening 330 in pump housing 300 (FIG. 2E) so as to provide a metal to metal taper fit when the mixing chamber section is disposed within the pump housing. As shown in FIGS. 6D and 6E, the mixing chamber section has a centered opening 150 that extends longitudinally through the section. Opening 150 has (a) a first portion 152 adjacent lower end 142 having a substantially constant diameter and (b) a second portion 154 having a diameter which tapers downward toward the upper end 144. At the upper end 144 there are a pair of dowel openings 146 which align with the dowel openings 140 in the parallel section 120 (see e.g., FIGS. 1C and 5C). At the lower end 142 there are a plurality of lateral inlet openings 180 about the periphery of the mixing chamber section. Openings 180 extend through the mixing chamber walls into the first portion 152 of opening 150. At the lower end of the mixing chamber there is also a ledge or flange 190 on which the nozzle will seat when the pump is assembled. A notch 192 is provided about the periphery of opening 150 at the lower end 142. Seated within notch 192 is a ring 194 (e.g., a stainless steel snap ring) (FIG. 5C). When the pump is assembled, dowel pins 181 (FIG. 5C) extend into the dowel pin openings 146 (mixing chamber section), through dowel pin openings 140 (parallel section), and into dowel pin openings 112 (diffuser section). The preferred dimensions and specifications for the mixing chamber section are shown in detail in FIGS. 6A-6E and the detailed drawings corresponding to FIGS. 6A-6E.

[0040] Referring to FIGS. 5C-5D and FIGS. 8A-8C the jet nozzle 160 of the diffuser assembly 100 shall be described. Jet nozzle 160 includes a lower end 162 and upper end 164. As shown, the nozzle has a centered opening 166 that extends longitudinally through the it. Opening 166 has (a) a first portion 168 adjacent lower end 162 having a substantially constant diameter and (b) a second portion 170 having a diameter which tapers downward toward the upper end 164. A flange or ledge 172 extends about the outer periphery of the nozzle at the lower end 162. Flange 172 is designed to rest upon the ledge 190 in the mixing chamber section, thus seating the nozzle within the mixing chamber. The exterior surface of the nozzle includes (a) a first portion (adjacent the lower end 162) which is substantially untapered and (b) a second portion (adjacent upper end 164) which tapers downwardly toward the upper end 164. As depicted in the drawings, the shape of the exterior surface of the nozzle is designed to substantially correspond with the shape of the opening 150 in the mixing chamber section 140. The preferred dimensions and specifications for the mixing jet nozzle are shown in detail in FIGS. 8A-8C. Specifically, in the preferred embodiment depicted in FIG. 8B, the inlet opening adjacent the lower end 162 of the nozzle is about 0.5 inches in diameter and the outlet opening (the nozzle throat) is about 0.212 inches in diameter. In other preferred embodiment of the nozzle design, the outlet opening is larger to allow for greater fluid production at lower pressures. Particularly suitable nozzle outlet opening diameters for the preferred pump described herein range from 0.220 to 0.237 inches. A nozzle outlet opening of about 0.234 inches in diameter, as depicted in FIG. 11, has been found to be particularly suitable in operation.

[0041] When the pump 10 is fully assembled, as depicted in FIGS. IA and 9A-9B, upper flow adapter 200 is connected to pump housing 300, which is connected to the lower flow adapter 400. Any suitable means can be used to connect these components. Most preferably, these components are removably connected, such as by threaded connection.

[0042] The assembled pump and the flow of fluids within and about the pump (i.e., the operation of the pump) are depicted in FIGS. 9A-9B. In its typical use, the pump is disposed downhole in a well adjacent the bottom of the well or the hydrocarbon-producing formation. In the preferred embodiment depicted, the upper flow adapter 200 is attached to an outer tubing string 880 that extends to the surface and the diffuser 102 is attached to an inner tubing string 890 that also extends to the surface. As shown, motive gas (i.e., the gas that operates the pump) is injected into the annulus between the inner and outer tubing strings and then enters the annulus 800 between outer surface of the diffuser 102 and the inner surface of the untapered portion of opening 220 in the upper flow adapter 200. The motive gas then flows through openings 230 in the upper flow adapter 200 and into openings 320 of the pump housing 300. From openings 320, motive gas then flows into the chamber 810 created between the recess 352 (in the pump housing) and the upper end 412 of the lower flow adapter 400. Next, the pressurized motive gas enters the opening 166 in the jet nozzle 160 and passes into the opening 130 in parallel section 120. The flow of the motive gas into the parallel section 120 creates a region of reduced pressure within and adjacent opening 130, causing water and other well fluids to flow from the wellbore through tube 450, then through opening 370, then through openings 180, then through the annulus 850 between the exterior surface of the nozzle 160 and the inner surface of the opening 330 in pump housing 300, and then into the opening 130 in parallel section 120 where such well fluids mix with the motive gas. Finally, as indicated in FIG. 9B, the motive gas and water (well fluids) mixture enters the diffuser opening 110 where the pressure is such that the mixture flows to the surface through the inner tubing string 890 attached to the upper end of the diffuser.

[0043] Referring to Figure 11, there is another embodiment of the pump with an alternative diffuser assembly alignment feature, an alternative inflow tube design for the lower flow adapter section 400, and an alternative arrangement for the inflow of fluids into the mixing chamber 140. As depicted, the pump of Figure 11 is similar in most aspects to the pump design described above and depicted in the preceding drawings. As such, the same elements are indicated by the same reference numerals. As shown in Figure 11, outer tubing string 880 includes boss members 860 which protrude into the tubing string. Diffuser assembly 100 has notches 195 on its outer surface in which respective boss members 860 seat when the mixing chamber section 140 of diffuser assembly 100 is fully seated within the pump housing section 300. Notches 195 are positioned such that when the boss members 860 are seated therein the diffuser assembly 100 is properly aligned within the pump housing section 300 allowing for optimal flow of motive gas through the motive gas ports in the pump. In use, the inner tubing string (to which the diffuser assembly 100 is attached) is simply rotated until the boss members seat within notches 195.

[0044] Still referring to Figure 11, there also is shown an alternative fluid inflow tube design. Specifically, in this alternative embodiment, two fluid inflow tubes 450A and 450B are provided (instead of the single tube 450 depicted in previously described pump design). By providing dual fluid inflow tubes, the pump would still continue to operate in the event that one of the tubes becomes blocked.

[0045] Still referring to FIG. 11 , the number of lateral inlet openings 180 about the periphery of the mixing chamber section has been reduced to two larger diameter openings. More specifically, two lateral inlet openings 180 having diameters of about 0.625 inches extend through the mixing chamber walls into the fϊrstportion 152 of opening 150. [0046] Optionally attached to the bottom of the pump is a sand screen sub section to prevent large particles from entering the pump and potentially clogging it. Suitable sand screen sub designs are well known in the art, such as the Bakerweld™ Gravel Pack Screen. A preferred sand screen sub is a 40 gauge screen (0.040 inches) providing about 44 in.² of open flow area.

[0047] The motive gas needed to operate the pump can be from any source so long as the pressure and flow of gas is adequate to lift the fluids from the well. In a preferred embodiment of the invention, the pump would be driven by the natural gas produced from the well. In some cases the natural pressure of the gases produced from the well will be sufficient to effectively operate the pump without the need to compress the gas. For many wells the natural gas pressure will be insufficient. In such cases, a compressor can be utilized. Such compressor should be selected to provide pressures and motive gas flow sufficient to lift the motive gas/well fluid mixture from the wellbore through the inner tubing string. Additionally, the compressor preferably would be versatile enough to adapt to a wide range of inlet and discharge pressures. This versatility would allow the operator to adjust the discharge pressure or gas volume that feeds the pump, thereby allowing the operator to achieve optimum well bore protection and gas/fluid flow. Preferably, the pressure rating of the pump or compressor will be in excess of 1,000 PSIG. In the preferred mode of operation, motive gas is circulated continuously to keep the wellbore substantially free of fluids - thereby minimizing the hydrostatic pressure in the well - in order to maximize production of hydrocarbons from the well.

[0048] It is also preferred that the components of the pump be constructed of materials suitable for prolonged use in a well environment, such as stainless steel. In a preferred embodiment, the pump is constructed out of 316 Stainless Steel to reduce the corrosive effects of exposure to carbonic acid and to reduce erosion from formation sand particles.

[0049] The above described pump has several advantages over conventional pump systems. For example, the above describe pump is uniquely suitable for use in directional wells which often have highly deviated bores. Conventional rod pumping systems are unsuitable or very difficult and expensive to maintain in directional wells due to the wear and tear on the polished rods which inevitably contact the sidewalls of the well. In contrast, the pump of the present invention has no moving parts or other complex components that make use in deviated wells difficult or ineffective.

[0050] Another advantage of the pump of the present invention is that it is particularly suitable for use without a packer between the casing and the pump or outer tubing string to which the pump is attached. In this arrangement, the annulus between the casing and the outer tubing string is substantially open from a point adjacent the pay zone to a point adjacent the surface (i.e., a point adjacent the well head at the surface). The open casing annulus permits direct fluid communication from a point adjacent the surface to the casing perforations and pay zone, allowing for easy and effective treatment of the well bore. For example, the open annulus arrangement of the present system allows for acid treatment of the casing perforations to treat scaling without interruption of well operations and without having to release a packer. This advantage is significant because packers are frequently damaged if released or fail to reset properly, which then requires the tubing to be pulled to replace the packer.

[0051] Yet another advantage of the present pump is that the flow of gas (or other fluid or liquid) through the pump can be reversed to clean the pump or sand screen sub.

[0052] Yet another advantage of the pump of the present invention is that multiple pumps can be driven by a single compressor or centralized motive gas source without any additional valves, controllers or means to regulate motive gas flow.

[0053] The invention has been described herein to enable one skilled in the art to practice and use the invention. It is understood that one skilled in the art will have the knowledge and experience to select suitable components and materials to implement the invention. Moreover, although the present invention has been described with respect to preferred embodiments, various changes, substitutions and modifications of this invention may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes, substitutions and modifications. For example, although the diffuser assembly 100 (see FIG. 5C) is depicted and described herein as being constructed of multiple components (i.e., a diffuser section 102, a parallel section 120, and a mixing chamber section 140) that are welded or otherwise securely connected together, it is understood and intended that the assembly could be constructed as a single part (e.g., by casting the structure).

[0054] The present invention is not limited to the preferred embodiments described above, as it is understood that one ordinarily skilled in the art would be able to utilize substitutes and equivalents without departing from the present invention. Accordingly, although the present invention has been described with respect to preferred embodiments, various changes, substitutions and modifications of this invention may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes, substitutions and modifications as fall within the scope of the appended claims.

Claims

CLAIMS:

1. A method of producing fluids from a well having a pay zone and a wellbore opening at the surface, said method comprising: supplying a gas to a first pump disposed in said well; removing said fluid from said well with said first pump, said first pump adapted for employing said gas for generating a force for lifting said fluids from said well without any moving parts in said first pump for lifting said fluids.

2. The method of claim 1 wherein said first pump comprises a nozzle.

3. The method of claim 2, said first pump further comprising a mixing chamber in which said fluids mix with said gas before the removal of said fluids from said well.

4. The method of claim 3, said nozzle having a throat opening at an upper end of said nozzle, said throat opening having a diameter between about 0.212 inches to about 0.237 inches.

5. The method of claim 1 further comprising a second pump disposed within a second well, said second pump adapted for employing said gas for generating a force for lifting fluids from said second well without any moving parts in said second pump; and a compressor for supplying pressurized gas to said first pump and said second pump.

6. A downhole well pump system for producing well fluids from a pay zone within a well, said system comprising: a first pump disposed in said well, said well having a wellbore opening at the surface, and said pump adapted to employ pressurized gas for generating a force for lifting fluids from said to said wellbore opening; said first pump adapted for employing said gas for generating a force for lifting said fluids from said well without any moving parts in said first pump for lifting said fluids.

7. The pump system of claim 6 wherein said first pump comprises a nozzle.

8. The pump system of claim 7, said first pump further comprising a mixing chamber in which said fluids mix with said gas before the removal of said fluids from said well.

9. The pump system of claim 8, said nozzle having a throat opening at an upper end of said nozzle, said throat opening having a diameter between about 0.212 inches to about 0.237 inches.

10. The pump system of claim 6 further comprising a second pump disposed within a second well, said second pump adapted for employing said gas for generating a force for lifting fluids from said second well without any moving parts in said second pump; and a compressor for supplying pressurized gas to said first pump and said second pump.

11. The pump system of claim 6, wherein said pump is attached to a string of tubing disposed within said well, said tubing string having an out diameter and an inner diameter, said tubing string providing a conduit through which said gas is supplied to said pump.

12. The pump system of claims 6 - 9 further comprising a compressor to pressurize said gas.

13. A method in accordance with claims 1 or 2 wherein said pump is disposed in said well adjacent a pay zone.

14. A method in accordance with claims 1 -^' 4, further comprising compressing said gas with a compressor to produce.

15. A method in accordance with claim 14, wherein said compressor is a wellhead compressor.

16. A method in accordance with claim 15, wherein said compressor is a central compressor.

17. The pump system of claims 7 - 9, said nozzle including at least one fluid intake port, said pump further including means for aligning said fluid intake port to receive said well fluids from said well.

18. A method of producing fluids from a well having a pay zone and a wellbore opening at the surface, said method comprising: receiving pressurized gas, said pressurized gas including gas produced from said well said well including (a) a well casing surrounding a first tubing string and (b) an annulus between said casing and said first tubing string, said annulus being open from said pay zone to a point upwell of a pump disposed in said well and said annulus being in fluid communication with a point adjacent the wellbore opening at the surface; and supplying said pressurized gas to said pump, said pump having no moving parts and being adapted for employing said pressurized gas for generating a force for lifting said fluids from said well to said wellbore opening at the surface.

19. A downhole well pump system for producing well fluids from a pay zone within a well, said system comprising: a pump disposed in said well, said well having a wellbore opening at the surface, and said pump having no moving parts and being adapted to employ pressurized gas for generating a force for lifting fluids from said well to said wellbore opening, said pressurized gas including gas produced from said well, said well including (a) a well casing surrounding a first tubing string and (b) an annulus between said casing and said first tubing string, said annulus being open from said pay zone to a point upwell of said pump and said annulus being in fluid communication with a point adjacent the wellbore opening at the surface.