Integrated pump and compressor and method of producing multiphase well fluid downhole and at surface

Abstract

An integrated system is disclosed to handle production of multiphase fluid consisting of oil, gas and water. The production stream is first separated into two streams: a liquid dominated stream (GVF<5% for example) and a gas dominated stream (GVF>95% for example). The separation can be done through shrouds, cylindrical cyclonic, gravity, in-line or the like separation techniques. The two streams are then routed separately to pumps which pump dissimilar fluids, such as a liquid pump and a gas compressor, and subsequently recombined. Both pumps are driven by a single motor shaft which includes an internal passageway associated with one of the pumps for reception of the fluid from the other pump, thereby providing better cooling and greater overall efficiency of all systems associated therewith. A method for providing artificial lift or pressure boosting of multiphase fluid is also disclosed.

Claims

1. A system comprising: a separator configured to separate a multiphase fluid into a first single-phase dominant stream and a second single-phase dominant stream; a first pumping device configured to receive and pump the first single phase-dominant stream of the multiphase fluid; a second pumping device configured to receive and pump the second single phase-dominant stream of the multiphase fluid, wherein the first single phase-dominant stream and the second single phase-dominant stream flow together in the multiphase fluid towards the first pumping device and the second pumping device; a drive shaft common to the first pumping device and the second pumping device, each of the first pumping device and the second pumping device configured to be simultaneously driven on the drive shaft, the drive shaft comprising: a solid portion located within the first pumping device, and a hollow portion located within the second pumping device, the hollow portion configured to receive the first single phase-dominant stream pumped by the first pumping device; and an electric motor or fuel engine coupled to the drive shaft and configured to drive the drive shaft.

2. The system of claim 1, wherein the first single phase-dominant stream is a liquid phase-dominant stream, wherein the first pumping device comprises a liquid pump.

3. The system of claim 2, wherein the second single phase-dominant stream is a gas phase-dominant stream, wherein the second pumping device comprises a gas compressor.

4. The system of claim 1, further comprising an outlet tube attached to an outlet end of the second pumping device, the outlet tube configured to receive the second single phase-dominant stream from the second pumping device.

5. The system of claim 4, wherein the outlet tube is configured to receive the first single phase-dominant stream from an outlet end of the first pumping device and mix the first single phase-dominant stream with the second single-phase dominant stream.

6. The system of claim 4, wherein the system is configured to be positioned within a wellbore, wherein an outer surface of the system and an inner wall of the wellbore define an annulus, and wherein the system further comprises a packer positioned within the annulus.

7. The system of claim 1, wherein the first single phase-dominant stream is a gas phase-dominant stream, wherein the first pumping device comprises a gas compressor.

8. The system of claim 7, wherein the second single phase-dominant stream is a liquid phase-dominant stream, wherein the second pumping device comprises a liquid pump.

9. The system of claim 1, further comprising a gearbox positioned between the first pumping device and the second pumping device, the gearbox configured to operate the first pumping device or the second pumping device at different pumping speeds.

10. A system comprising: a first pumping device configured to receive and pump a first single phase-dominant stream of a multiphase fluid; a second pumping device configured to receive and pump a second single phase-dominant stream of the multiphase fluid; an outlet tube attached to an outlet end of the second pumping device, the outlet tube configured to receive the second single phase-dominant stream from the second pumping device, wherein the outlet tube is configured to receive the first single phase-dominant stream from an outlet end of the first pumping device and mix the first single phase-dominant stream with the second single-phase dominant stream; a drive shaft common to the first pumping device and the second pumping device, each of the first pumping device and the second pumping device configured to be simultaneously driven on the drive shaft, the drive shaft comprising: a solid portion located within the first pumping device, and a hollow portion located within the second pumping device, the hollow portion configured to receive the first single phase-dominant stream pumped by the first pumping device; and an electric motor or fuel engine coupled to the drive shaft and configured to drive the drive shaft.

11. A system comprising: a first pumping device configured to receive and pump a first single phase-dominant stream of a multiphase fluid; a second pumping device configured to receive and pump a second single phase-dominant stream of the multiphase fluid; an outlet tube attached to an outlet end of the second pumping device, the outlet tube configured to receive the second single phase-dominant stream from the second pumping device; a drive shaft common to the first pumping device and the second pumping device, each of the first pumping device and the second pumping device configured to be simultaneously driven on the drive shaft, the drive shaft comprising: a solid portion located within the first pumping device, and a hollow portion located within the second pumping device, the hollow portion configured to receive the first single phase-dominant stream pumped by the first pumping device; and an electric motor or fuel engine coupled to the drive shaft and configured to drive the drive shaft; and wherein the system is configured to be positioned within a wellbore, wherein an outer surface of the system and an inner wall of the wellbore define an annulus, and wherein the system further comprises a packer positioned within the annulus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments of the invention are disclosed hereinbelow with reference to the drawings, wherein:

(2) FIG. 1 is an elevational view, partially in cross-section, of a combination liquid pump/gas compressor arrangement constructed according to the present invention, the arrangement shown in a vertical orientation and adapted to flow fluids upwardly from a well location downhole;

(3) FIG. 2 is an enlarged elevational cross-sectional view of a liquid pump and gas compressor similar to FIG. 1, the arrangement shown in a horizontal orientation, and the single motor shown in schematic format for convenience of illustration;

(4) FIG. 3 is an enlarged elevational cross-sectional view of an alternative embodiment of the liquid pump/gas compressor arrangement similar to FIGS. 1 and 2, with the positions of the liquid pump and gas compressor being respectively reversed, the pump portion of the shaft being hollow to provide a flow path for the gas discharged from the compressor; and

(5) FIG. 4 is an elevational cross-sectional view of a combination liquid pump/gas compressor similar to the previous FIGS., and particularly of FIG. 1, but including an optional gearbox positioned between the liquid pump and gas compressor to facilitate operation of each unit at respectively different speeds.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) One preferred embodiment of the present invention is illustrated in FIG. 1, which is an elevational view, partially in cross-section, of a combination liquid pump/gas compressor 10 shown downhole in a vertical orientation. A typical portion of a well 12 contains a liquid/gas mixture 14, and is provided with a suitable casing sleeve 16 which extends downhole to where the liquid/gas mixture 14 exists.

(7) Downstream of the liquid/gas supply is liquid/gas separator 18, which is shown schematically in FIG. 1, and which may be any one of several known types of separators, such as those which utilize gravity, shrouds, centrifugal or rotary gas separation, or gas-liquid cylindrical cyclonic, in-line separation technology, or the like.

(8) Downstream of separator 18 is drive motor 20, encased in cooling jacket 22. The motor 20 can be powered from the surface by known means, including electric power or the like delivered to drive motor 20 by power cable 24. Production fluids are directed to cooling jacket 22 from separator 18 via feed line 19 if needed.

(9) In FIG. 1, seal 26 provides an interface between drive motor 20 and liquid pump 28, which is supplied with liquid medium separated by separator 18 from the liquid/gas mixture 14, and is directed via liquid feed line 30 to pump intake 27, and then to liquid pump 28. Gas feed line 34 directs gas separated by separator 18 from the liquid/gas mixture 14 directly to compressor intake 36, and then to gas compressor 38, as shown. Both feed lines 30 & 34 are optional.

(10) The drive shaft 40 of the drive motor 20 extends through, and drives both the liquid pump and the gas compressor, as will be shown and described in the description which follows.

(11) The portion 40A of shaft 40 is associated with liquid pump 28, and the portion 40B of shaft 40 is associated with compressor 38. The shaft 40 is commonly driven in its entirety by motor 22.

(12) In FIG. 1, the portion 40A of the shaft 40 associated with liquid pump 28 is solid as shown, and the portion 40B associated with gas compressor 38 is hollow to receive the flow of the liquid discharged from the pump 28 so as to provide cooling to the gas compressor 38. This cooling effect enhances compressor efficiency and reduces the horsepower requirement for operating the compressor. The flow of gas 37 from the gas compressor 38 is discharged into the outlet tube 42, where it may be combined with the liquid component as shown. As can be seen, outlet tubing 42 is surrounded by deep packer 41 positioned within the annulus 43 formed by outlet tube 42 and casing 16. In particular, FIG. 1 shows how the present invention can be effectively deployed downhole to provide artificial lift.

(13) In FIG. 1, liquid pump blades 44 and gas compressor blades 46 are shown in a single stage format for illustration purposes. In practice, such blades may be provided in multiple stages, sometimes numbering in tens of hundreds of such stages of blades.

(14) Referring now to FIG. 2, an enlarged elevational cross-sectional view of the liquid pump 28 and gas compressor 38 of FIG. 1 is shown, in a horizontal orientation.

(15) Separator 18 is shown schematically in FIG. 2, but can be of any desired type as noted previously, i.e., cylindrical cyclonic, gravity, in-line, or the like. Motor 20 is shown in schematic format in FIG. 2, and is arranged to drive the common shaft 40, comprised in part of liquid pump portion 40A and gas compressor portion 40B, similar to the arrangement shown in FIG. 1.

(16) After the separation process which takes place at separator 18, the liquid dominant stream 48 is directed via liquid feed line 30 to pump intake 27 of liquid pump 28 as shown, and then directed from liquid pump 28 to the hollow portion 40B of shaft 40 associated with gas compressor 38.

(17) The gas dominant stream 50 is in turn directed from separator 18 via gas feed line 34 directly to compressor intake 36 and then to gas compressor 38, where it is compressed, pumped and directed to outlet tube 42 to be combined with the liquid dominant stream flowing through the hollow shaft portion 40B of gas compressor 38.

(18) In FIGS. 1 and 2, liquid feed line 30 and gas feed line 34 are shown schematically, but can be representative of any known system to convey the respective dominant liquid or dominant gas medium from one place to another. As will be seen, the dominant liquid medium and dominant gas medium may be transferred from place to place to facilitate better heat transfer between the components of the system.

(19) Referring now to FIG. 3, there is shown an enlarged elevational cross-sectional view of an alternative embodiment 51 of the liquid pump/gas compressor arrangement of FIGS. 1 and 2, with the respective positions of the gas compressor 52 and the liquid pump 54 in respectively reversed positions and configurations. Liquid pump blades 31 and gas compressor blades 33 are shown.

(20) In FIG. 3, motor 56 is shown schematically to rotatably operate the drive shaft 58 which is common to both gas compressor 52 and liquid pump 54. In this embodiment the shaft portion 58A associated with gas compressor 52 is solid, and gas is pumped through the gas compressor 52 in the annular zone surrounding the solid shaft portion 58A. The gas dominant stream 61 is directed from separator 60 via gas feed line 62 shown schematically, to compressor intake 64, and then to gas compressor 52.

(21) The liquid dominant stream 69 from separator 60 is directed via liquid feed line 66 to liquid pump intake 68, and then to liquid pump 54 where it is pumped as liquid dominant stream 69 toward outlet tube 65 to be recombined with the gas dominant stream 61 from hollow shaft portion 58B associated with liquid pump 54. It can be seen that the simultaneous flow of gas dominant stream 61 through hollow shaft portion 58B and the liquid dominant stream 69 through liquid pump 54 provides a stabilizing heat exchange between the various components, which are commonly driven by a single motor 56. This feature significantly improves the efficiency of all working components. The respective streams are combined in outlet tube 65 in FIG. 3.

(22) As noted previously, the pump and compressor systems shown in the FIGS. respectively depict a single stage of blades, for convenience of illustration. In reality, the pump and compressor systems according to the invention incorporate multiple stages of such blade systems, occasionally numbering tens of hundreds of blade stages, sometimes including an impeller and diffuser.

(23) Referring now to FIG. 4, there is shown an alternative embodiment 71 similar to the structural arrangement of FIG. 1, with the addition of gearbox 70 positioned between liquid pump 28 and gas compressor 38 to facilitate operation of each component at respectively different speeds so as to accommodate specific conditions for any specific environment, such as well conditions, fluid viscosity and other flow conditions.

(24) In all other respects, the structural and functional arrangement in 4 is the same as the arrangement shown in FIG. 1.

(25) While the invention has been described in conjunction with several embodiments, it is to be understood that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications and variations which fall within the spirit and scope of the appended claims.

LIST OF NUMERALS

(26) 10 Combination Liquid Pump/Gas Compressor 12 Well 14 Liquid/Gas Mixture 16 Casing Sleeve 18 Liquid/Gas Separator 19 Feed Line 20 Drive Motor 22 Cooling Jacket 24 Power Cable 26 Seal 27 Liquid Pump Intake 28 Liquid Pump. 30 Liquid Feed Line 31 Liquid Pump Blades 32 Liquid. Pump 33 Gas Compressor Blades 34 Gas Feed Line 36 Compressor Intake 37 Flow of Gas from Compressor 38 38 Gas Compressor 40 Drive Shaft 40A Liquid Pump Portion of Drive Shaft 40B Hollow Shaft Portion 41 Deep Packer 42 Outlet Tube 43 Annulus 44 Liquid Pump Blades 45 Flow of Liquid from Pump 28 46 Gas Compressor Blades 48 Liquid Dominant Stream 50 Gas Dominant Stream 51 Alternative Embodiment 52 Gas Compressor 54 Liquid Pump 56 Motor 58 Drive Shaft 58A Solid Shaft Portion of Compressor 58B Hollow Shaft Portion of Compressor 60 Separator 61 Gas Dominant Stream, FIG. 3 62 Gas Feed Line 64 Compressor Intake 65 Outlet Tube 66 Liquid Feed Line 68 Liquid Pump Intake 69 Liquid Dominant Stream, FIG. 3 70 Gearbox 71 Alternative Embodiment