GB2571135A

GB2571135A - Jet pump apparatus

Info

Publication number: GB2571135A
Application number: GB1802713.6A
Authority: GB
Inventors: Mifsud Darren; Cao Yi; Verdin Patrick
Original assignee: Cranfield University
Current assignee: Cranfield University
Priority date: 2018-02-20
Filing date: 2018-02-20
Publication date: 2019-08-21
Anticipated expiration: 2038-02-20
Also published as: GB2571135B; GB201802713D0; WO2019162649A1

Abstract

A jet pump 10 comprising a first fluid inlet 19, to receive a first fluid 33, in fluid communication with a phase separator (fig. 6; 48), with a nozzle assembly 49 comprising two concentrically arranged nozzles 16, 17, the phase separator directing a first portion of a fluid radially outwards, relative to a longitudinal axis 23 of the device, along the first nozzle and directing a second portion of the fluid along the second nozzle which lies on said axis, the flow of the nozzles converging at an entrainment chamber 18 where a second fluid 32 is received from a second fluid inlet 14 where the fluids pass through a throat 20 into a mixing chamber 21. A fluid extraction apparatus and a method of pumping a fluid using jet pumps are also claimed. The nozzles may have further ports providing fluid communication between the two nozzles.

Description

Field of invention

The present invention relates to fluid jet pump apparatus and methods of pumping a fluid from one or a plurality of sources and in particular although not exclusively, to jet pump apparatus having an internal configuration and nozzle assembly to minimise choking, reduce or eliminate the formation of intermitting/pulsating single and/or multiphase fluid jets, so as to provide smooth operation which in-turn reduces jet and/or energy loss within the device to achieve enhanced extraction of low pressure fluids within an extraction network.

Background art

Jet pumps are typically employed to facilitate fluid retrieval from low pressure oil and gas wells. Jet pumps, also known as injectors, ejectors, inductors or thermo-compressors, use energy from a high pressure (HP) fluid source to boost the pressure of a low pressure (LP) fluid typically a low pressure oil or gas well. HP and LP fluids may be liquids, gases or

-2multiphase fluids. Conventionally, the HP fluid (referred to as the motive, source, power or driving fluid) flows in high velocity through a nozzle restriction within the jet pump initiating a high speed jet. At a nozzle throat, the accelerated fluid experiences a rapid decrease in pressure and a corresponding gain in kinetic energy. The resulting HP jet creates a suction or relative low pressure zone within an entrainment/mixing chamber at a region where the ‘production’ (suction or secondary) LP fluid is introduced into the jet pump (via an induction port) so as to entrain the LP fluid. The HP and LP streams intersect at a position immediately upstream of the nozzle throat where partial mixing occurs, before entering a mixing tube. Inside the mixing tube, turbulent mixing enhances the transfer of energy and momentum between the motive and production fluids. Within the length of the mixing tube, the mixed stream undergoes a reduction of kinetic energy and travels with reduced velocity to complete the momentum exchange. The multiphase fluid then typically flows through a diffuser where the kinetic energy of the fluid is transferred to static pressure to facilitate further downstream flow.

Example jut pump devices are described in US 8,257,055; US 2013/0216352; US 8,622,715; US 2014/0346250 and US 2015/0285271. However, existing devices are disadvantageous for a number of reasons. Under certain operating conditions principally including pressure, fluid velocities and liquid-gas fluid composition, existing jet pumps are susceptible to choking, jet loss (or fluid recirculation) and frictional resistance which degrade the operation and efficiency of the pump which in turn suppresses recovery of the LP fluid. Accordingly, what is required is jet pump apparatus and method of pumping that address the above problems.

Summary of the Invention

It is a general objective of the present invention to provide fluid pumping apparatus and methods that greatly facilitate extraction or recovery of LP fluids from remote locations. It is a specific objective to provide a device capable of convenient insulation in remote locations for reliable operation to increase production entrainment performance of LP fluids relative to a HP driving fluid. It is a further specific objective to provide a jet pump device that is less susceptible to choking, vibration, jet loss (or recirculation) and frictional

-3losses that will accordingly enable a broader range of operating conditions relative to existing devices with regard to pressure, fluid mixture velocity and multiphase composition.

The objectives are achieved via a jet pump device and method of pumping a fluid in which a phase separator is positioned in a fluid flow direction upstream of a multi-nozzle arrangement that together provide and maintain a zonal separation of a liquid-enriched and a gas-enriched phase of the HP driving/motive fluid to create high velocity zonally separate jet streams for optimised entrainments of LP fluids. The creation and maintenance of phase separated flow streams through the device broadens the operating conditions with regard to pressure, mixture velocity and fluid composition whilst minimising and preferably preventing choking. The present system is also beneficial to prevent jet loss/recirculation and reduce and preferably eliminate the formation of intermitting/pulsating jets, thereby providing a smooth operation which in-tum reduces jet and energy loss within the device.

According to a first aspect of the present invention that is provided a jet pump device comprising: a first fluid inlet port to allow a flow of a first fluid into the device; a phase separator connected in fluid communication with the first inlet port to direct at least a first portion of the fluid radially outward relative to a longitudinal axis extending through the device and to allow at least a second portion of the first fluid to flow along the longitudinal axis; a nozzle assembly comprising at least one first nozzle having an inlet end and an outlet end and a radially inward facing surface that defines a fluid flow conduit, the inlet end positioned to receive the first portion of the first fluid at the radially outward position, the inward facing surface in a plane extending in a longitudinal axis direction orientated to converge towards the axis in a fluid flow direction from the inlet end to the outlet end; a second fluid inlet port to allow a flow of a second fluid into the device; an entrainment chamber provided in fluid communication to receive the first and second fluids; a mixing conduit positioned in fluid communication to receive the first and second fluids from the entrainment chamber, a junction between the mixing conduit and the entrainment chamber defining a throat of the device; wherein the nozzle assembly further comprises at least one second nozzle having an inlet end, an outlet end and a radially inward facing surface that

-4defines a fluid flow conduit, the inlet end of the second nozzle positioned radially inward relative to the inlet end of the first nozzle to receive the second portion of the first fluid at or towards the longitudinal axis, the inward facing surface in a plane extending in a longitudinal axis direction orientated to converge towards the axis in the fluid flow direction; the outlet ends of the respective first and second nozzles positioned within the entrainment chamber upstream of the throat such that the flow of the first fluid from the respective outlet ends of the first and second nozzles acts to entrain a flow of the second fluid into the device via the second fluid inlet.

Within this specification, reference to a jet pump device encompasses a device also referred to as an injector, an inductor, a thermo-compressor or an injector. Preferably, the device comprises first and second fluid inlet ports to receive respectively a HP driving (or motive) fluid and a production fluid with the LP production fluid being entrained in the HP driving fluid.

Preferably, the present jet pump device may be considered to comprise an injection body having a plurality of coaxially aligned nozzles, an entrainment body having a partial vacuum/entrainment chamber and an injection body. Preferably having the injection body comprises a Venturi-like body. The injection body may comprise multiple portions configured to at least partially separate a multiphase HP fluid whilst distributing the conditioned flow radially and axially forward within the at least one conduit of the injection body and towards a nozzle assembly and subsequently a throat of the device. The present device is configured to produce coaxially aligned jet streams of fluid in which liquid-dominant and gas-dominant high velocity jets are injected into a mixing chamber. Preferably, the injection body comprises two bodies including an outer and an inner body respectively. Partial phase separation is provided by a phase separator configured to provide radially outward flow of a liquid-dominant phase that is preferably configured to be directed to the nozzle assembly by swirling rotation at the radially outer perimeter (inward facing surface) of the injection body conduit.

Optionally, at least a portion of the conduit of the first nozzle comprises a cross sectional area that decreases in a direction from the inlet to the outlet end. Optionally, at least a

-5portion of the conduit of the second nozzle comprises a cross sectional area that decreases in a direction from the inlet to the outlet end. Optionally, at least a portion of the conduit of the first nozzle is annular to surround the conduit of the second nozzle. Optionally, the second nozzle is positioned radially inside the first nozzle over all or a majority of an axial length of the second nozzle.

Optionally, at least a portion of the conduit of the first nozzle comprises a plurality of bores having respective axial centres that are orientated to converge towards the axis in the fluid flow direction from the inlet to the outlet end of the first nozzle. Optionally, each bore may comprise a circular cross sectional profile with the axial centres of the bores being arranged around the longitudinal axis on an imaginary cone so as to converge towards the axis at their respective axially forwardmost ends. Optionally, at least one (or some) of the plurality of the bores has a cylindrical cross-sectional area size that is different from that of some or all of the remaining bores. Such an arrangement provides a desired control of flow rate and/or acceleration of the fluid though the nozzle.

Optionally, at least a portion of the first nozzle comprises a conical shape profile. Optionally, at least a portion of the second nozzle comprises a conical shape profile. Preferably, the first nozzle comprises a first conical section provided at the inlet end and a second section comprising the plurality of bores provided at or towards the outlet end of the nozzle. Preferably, the second nozzle is generally conical shaped over substantially all its axial length between the inlet and outlet ends. Preferably, the second nozzle is attached to a portion of the first nozzle at the region of an injector block within which the bores are formed.

Optionally, said conical portions of the first and second nozzles are positioned concentrically about the longitudinal axis, the second nozzle positioned radially inside the first nozzle.

Optionally, the conduit of the first nozzle at and/or towards the inlet end is annular and the conduit of the second nozzle at and/or towards the inlet end is conical and surrounded by the annular conduit of the first nozzle.

-6Optionally, the second nozzle comprises an eccentric radial wall thickness such that a lower region (in a vertical plane extending perpendicular to the longitudinal axis) is thicker than an upper region, such a relative thicker region extending along the axial length of the nozzle between its lengthwise ends. Accordingly, a radially outward facing surface of the second nozzle is eccentric relative to the longitudinal axis of device. As such, the cross sectional size of the outer nozzle conduit at the lower region is less than that at the diametrically opposite upper region.

Optionally, an axially forward end of the entrainment chamber in the fluid flow direction through the device is defined by a radially inward facing surface that in the plane extending in the longitudinal axis direction is orientated to converge towards the longitudinal axis. Such an arrangement is advantageous to guide and to funnel the LP and the HP fluids to the device throat and the mixing conduit to facilitate exchange of energy and momentum between the HP and LP fluids and specifically to minimise choking, jet loss and/or energy loss due to friction as the fluids flow towards and through the throat.

Optionally, generally all or a majority of an internal volume of the entrainment chamber is positioned axially forward of the second inlet port in the fluid flow direction of the first fluid through the device. This is beneficial to prevent primarily any rearward flow of the LP fluid within the entrainment chamber that would otherwise increase turbulence, back flow resistance and cause liquid flooding within a lower region of the vacuum chamber, thereby increasing the likelihood of choking of flow at the mix-tube throat inlet.

Preferably, the device further comprises an injector body having an annular wall defining an internal injection conduit having a first end section coupled in fluid communication with the first fluid inlet port and a second end section coupled in fluid communication with the inlet ends of the first and second nozzles.

Optionally, the injection conduit comprises a middle section having a cross sectional area that decreases in a direction from the first to the second end sections, and wherein a cross sectional area of the second end section increases in a direction from the first to the second

-Ίend sections. Optionally, the first end section comprises a cross sectional area that decreases in a direction from the first to the second end sections. Optionally, an axial length of the middle section is greater than that of the second end section that is in turn greater than that of the first end section. Optionally, a cross sectional area of an axially forwardmost end of the second end section is greater than a cross sectional area of an axially rearwardmost end of the first end section. Preferably, the injection conduit comprises a restriction at the first end section in the form of a fit-in ring of reduced diameter capable of being fitted tightly against the internal facing surface of the injection conduit. This leading section of the injection conduit (of reduced internal diameter) comprises a relatively sharp rounded edge portion at a first side (facing the flow of HP fluid) and an axially longer and more gradual tapered trailing portion (that interfaces with the injection conduit middle section).

The converging (decreasing) cross sectional area of the injector conduit middle section is advantageous to offer resistance to the flow of the HP fluid so as to entrain a greater volume of the gas-rich phase in the liquid-rich phase before flowing into the diverging second end section (of increasing cross sectional area). The diverging second end section of the injection conduit is advantageous to provide rapid expansion of the heavy and light fluid phases (liquid-rich and gas-rich phases respectively) so as to enlarge the separation boundary layer between the phases emerging from the annular flow pattern. The partially phase separated fluid streams are then capable of being projected axially forward towards the nozzle assembly having the outer and inner nozzles to facilitate creation and ejection of the respective liquid-rich and gas-rich fluid flow jets.

Optionally, an inward facing surface of the second nozzle comprises a plurality of axial sections wherein in the plane extending in the longitudinal axis direction an angle of the inward facing surface of the plurality of axial sections relative to the longitudinal axis is different. Optionally, the angle at a first section at the inlet end is greater than an angle at a second section at the outlet end and a middle section positioned axially between the first and second sections. Optionally, a cross sectional area of the fluid flow conduit of the second nozzle is generally uniform along the second section at and towards the outlet end. Preferably, the internal facing surface of the second inner nozzle comprises three axial

-8sections. Such sections may be categorised based on the angle of orientation of the inner surface relative to the longitudinal axis. Preferably, the convergence angle of the three sections decreases from the inlet end to the outlet end so as to provide a smooth transition and to accelerate the gas-rich phase towards the outlet end of the nozzle.

Optionally, an inward facing surface of the first nozzle comprises a plurality of axial sections wherein in the plane extending in the longitudinal axis direction an angle of the inward facing surface of the axial sections relative to the longitudinal axis is different. Optionally, an angle at a first section at the inlet end is greater than an angle at a second section at the outlet end and a middle section positioned axially between the first and second sections. Preferably, an axial length of the middle section is greater than that of the first and/or second sections. As with the second nozzle, the inward facing surface of the first nozzle may be divided into the axial sections according to the angular orientation of the inward facing surface relative to the longitudinal axis. The recited angular configuration of the surface at the three sections is configured to accelerate the liquid-rich phase towards the injection outlet end of the first nozzle.

Preferably, the second sections of the first and second nozzles at and towards the respective outlet ends are at least part cylindrical so as to encourage and maintain partial phase separation of the liquid- and gas-rich phases at a position between the outlet end of the nozzles and the inlet end of the mixing chamber through the throat. Such an arrangement is advantageous to minimise mixing and dispersion of the two phases of the HP fluid within the entrainment chamber upstream of the throat and to maximise entrainment of the LP fluid within the entrainment chamber.

Optionally, the second nozzle comprises at least one aperture extending radially through the second nozzle to provide a fluid flow communication passageway between the fluid flow conduits of the first and second nozzles. Such an arrangement is advantageous to inhibit choking within the respective nozzles. Preferably, the second nozzle is formed as a hollow body having a solid wall without apertures or radial communication pathways between the inner and outer nozzle conduits.

-9Optional ly, the radially inward facing surface at the axially forward end of the entrainment chamber is divided into a plurality axial sections each having a different angular orientation relative to the longitudinal axis. Optionally, the axial sections comprise: a first largest conical section positioned axially rearwardmost in the fluid flow direction and having a first angle of convergence; a second conical section positioned axially forwardmost and having a second angle of convergence; and a third conical section positioned axially between the first and second conical sections having a third angle of convergence; wherein the angle of convergence of the third section is greater than that of the first section which is in turn greater than that of the second section. Such an arrangement is advantageous to initiate the exchange of energy and momentum within the mixing conduit immediately downstream of the throat and the entrainment chamber. The recited configuration of the axially forwardmost end of the entrainment chamber is effective to channel and funnel the multiphase fluid (including the HP multiphase fluid and the LP fluid) into the mixing conduit and to maximise the static pressure recovery within the mixing conduit. The differential tapered sections minimises disintegration of the partial phase separation of the HP fluid immediately upstream of the throat.

Optionally, a portion of an inward facing surface that defines the entrainment chamber at a position diametrically opposite the second inlet port is curved to direct the flow of fluid in an axially forward direction towards the throat. Such an arrangement avoids turbulence within the entrainment chamber and facilitates entrainment of the LP fluid within the HP fluid at the region immediately upstream of the throat.

Reference within this specification to the inward facing surface of the nozzles and /or entrainment chamber having ‘axial sections’ in a plane in the longitudinal axis direction that encompass curved surface profiles (that define ogive shape profiles) and linear surface profiles (that define cones). The transitions between such sections may be defined or may be smooth and comprises curved transition sections that form a surface that curves seamlessly into the differently orientated surface sections.

Optionally, the phase separator comprises a spinner mechanism configured to induce spinning rotation of the first fluid about the longitudinal axis. Optionally, the spinner

-10mechanism may comprise any one or a combination of existing spinner devices configured to induce spinning rotation of a fluid about a longitudinal axis. Such an arrangement may comprise helical or twisted conduit sections, ribbed, channelled or grooved passageways that follow a helical pathway around the longitudinal axis as will be appreciated by those skilled in the art. Optionally, the spinner mechanism may comprise a single or combination of component parts that initiate a swirl induced flow by causing spinning of the flowing fluid along the longitudinal axis of the HP fluid conduit.

Preferably, the spinner mechanism is positioned within the injection conduit of the injection body axially between the first fluid inlet port and the inlet ends of the first and second nozzles. Accordingly and preferably the spinner mechanism is dimensioned radially and axially to be capable of positioning completely or at least partially within the injection conduit. Such a configuration is advantageous to provide an axially compact jet pump device. Optionally, the spinner mechanism may be positioned in the fluid flow direction upstream of the first fluid inlet port. Such embodiment may be advantageous to optimise the injection conduit for fluid conditioning prior to delivery to the nozzle assembly.

According to a second aspect of the present invention there is provided fluid extraction apparatus comprising: a first fluid source coupled via a first network conduit to the first fluid inlet port of the device as claimed herein, the first fluid source at a first pressure; a second fluid source coupled via a second network conduit to the second fluid inlet port of the device as claimed herein, the second fluid source at a second pressure being less than the first pressure.

Optionally, the apparatus may further comprise a secondary fluid source coupled to the first fluid inlet port via a third network conduit to increase a pressure of the first fluid delivered to the first fluid inlet. A secondary fluid source may comprise a water reservoir or tank from which water may be forced into the present device at relatively high pressure (equal to or greater than the pressure of the HP fluid).

-11Optionally, the apparatus may further comprise at least one fluid phase separator positioned at the respective first and second network conduits in the fluid flow direction between the first and second fluid sources and the respective first and second inlet ports.

Optionally, the apparatus and in particular the fluid flow network may comprise a plurality of valves, sensors, fluid flow regulators, diverters, pumps, phase separators etc., typically used within oil and gas well extraction networks.

Optionally, the apparatus comprises an upstream booster pump coupled in fluid communication with the first or/and third network conduit. Optionally, the booster pump is combined to a system with or without fluid phase separators operable to increase the motive fluid pressure of either a single-phase liquid or a multiphase (liquid and gas) HP source.

Optionally, the booster pump may be installed immediately (locally) upstream of the present jet pump device or further upstream such as at a subsea or downhole location.

Optionally, the present device is suitable and configured for installation and operation in industrial process plants. Preferably, the present device is suitable and configured for installation and operation at onshore and offshore oil and gas industrial locations including: subsea, underwater systems and remote operated platforms configured to involving to pump single or/and multiphase fluids.

According to a third aspect of the present invention there is provided a method of pumping a fluid comprising: allowing a first fluid to flow into a jet pump device via a first fluid inlet port; separating the first fluid using a phase separator connected in fluid communication with the first fluid inlet port so as to direct a portion of the first fluid radially outward relative to a longitudinal axis extending through the device and to allow a second portion of the first fluid to flow along the longitudinal axis; receiving the first fluid at a radially outward position relative to the longitudinal axis within a first nozzle of a nozzle assembly, the first nozzle having a radially inward facing surface that in a plane extending in a longitudinal axis direction is orientated to converge towards the axis in a fluid flow

-12direction from an inlet end to an outlet end; allowing a second fluid to flow into the device via a second fluid inlet port; receiving the first and second fluids within an entrainment chamber; allowing the first and second fluids to mix within a mixing conduit positioned in fluid communication to receive the first and second fluids from the entrainment chamber, a junction between the mixing conduit and the entrainment chamber defining a throat of the device; and receiving a second portion of the first fluid at or towards the longitudinal axis at a second nozzle positioned radially inward relative to the first nozzle, the second nozzle having a radially inward facing surface that in a plane extending in a longitudinal axis direction of the device converges towards the axis in the fluid flow direction from an inlet end to an outlet end of the second nozzle; wherein the outlet ends of the respective first and second nozzles are positioned within the entrainment chamber upstream of the throat such that the flow of the first fluid from the respective outlet ends of the first and second nozzles acts to entrain a flow of the second fluid into the device via the second fluid inlet.

Brief description of drawings

A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

Figure 1 is a cross sectional view through a plane extending along a longitudinal axis of a jet pump device according to a specific implementation of the present invention;

Figure 2 is a magnified cross sectional view of an injection portion of the jet pump device of figure 1;

Figure 3 is a magnified cross sectional view of the injection portion and an entrainment portion of the jet pump device of figure 2;

Figure 4 is a magnified cross sectional view of an injection portion and an entrainment portion of a jet pump device according to a further specific implementation of the present invention;

-13Figure 5 is a further cross sectional view of the jet pump device of figure 3 including a phase separation mechanism positioned within the injection portion;

Figure 6 is a further cross sectional view of the jet pump device of figure 3 including a phase separation mechanism positioned upstream of the injection portion in a fluid flow direction through the device;

Figure 7 is a schematic illustration of an installation of the jet pump device of figure 1 incorporated within a network for extraction of a liquid and/or gas resource;

Figure 8 is a schematic illustration of a performance test rig and data acquisition system incorporating the device of figure 1;

Figure 9 is a graph of an entrainment ratio LP flow/HP total mix flow versus HP fluid gas volume fraction for the jet pump device of figure 1 including a comparison with a conventional jet pump with and without a flow spinning phase separator;

Figure 10 is a graph of the amplitudes of pressure vibration at a throat inlet of the device of figure 1 for a range of high pressure fluid gas volume fractions for the three jet pump devices of figure 7;

Figure 11 is a time trace part of the amplitude vibration of the entrained low pressure flow rate through the jet pump device of figure 1;

Figure 12 is a corresponding time trace part for the low pressure entrained fluid for a conventional jet pump device.

Detailed description of preferred embodiment of the invention

Referring to figure 1, a multiphase-fluid driving jet pump device 10 is provided for the pumping and mixing of fluids and in particular for installation and use within oil and gas extraction networks and systems in which a high pressure fluid drives extraction of a

-14relatively pressure fluid via entrainment. Device 10 comprises three fundamental portions including an entrainment portion 11, an injection portion 12 and an ejection portion 13, with both portions 11, 12 positioned upstream and in fluid communication with portion 13. Entrainment portion 11 comprises a low pressure (LP) inlet port 14 formed within a housing body 28 that defines an internal entrainment chamber 18. The injection portion 12, mounted within the entrainment portion 11 comprises a hollow injection body defining an internal injection conduit 29a, 29b. Injection body 15 is centred on a longitudinal axis 23 extending through device 10 with the injection conduit divided into axial sections based on cross sectional area of the conduit and an orientation of an inward facing surface that defines the conduit. A high pressure (HP) inlet port 19 is provided at an inlet end of injection body 15. A nozzle assembly indicated generally by reference 49 is provided at an outlet end of injection body 15. Nozzle assembly 49 comprises a pair of concentrically arranged nozzles including a radially outer nozzle 16 and a radially inner nozzle 17 with both nozzles 16, 17 centred on longitudinal axis 23. An outer nozzle conduit 30 is defined axially and radially between the first and second nozzles 16, 17 and an inner nozzle conduit 31 is defined by inner nozzle 17 and is surrounded radially by outer nozzle conduit 30. Respective outlet ends of the nozzles 16,17 are positioned at an axially forward region of entrainment chamber 18 upstream of a throat 20 of the device 10. A mixing tube 21 having internal conduit 22 is coupled to the axially forwardmost region of entrainment chamber 18 with the junction between tube 21 and entrainment chamber 18 defining throat 20.

In operation, a HP fluid 33 is capable of flowing into injection body 15 via inlet port 19. Where the HP fluid is a multiphase fluid, device 10 comprises a phase separator (described referring to figures 5 and 6) to facilitate radial separation of gas-dominant and liquiddominant phases such that the liquid-dominant phase is propelled radially outward (arrow 25) whilst the gas-dominant phase is allowed to flow (arrow 79) along the longitudinal axis 23. Nozzles 16, 17 are aligned relative to longitudinal axis 23 so as to be convergent towards the axis 23 at their outlet ends so as to accelerate the flow of the gas-dominant and liquid-dominant phases through the injection portion 12. Corresponding liquid-dominant and gas-dominant jet streams 26 are created from nozzle assembly 49 towards throat 20 through the axially forward region of entrainment chamber 18 and into the downstream

-15mixing tube 21 (conduit 22) as shown by flow arrow 27. The high pressure jets 26 serve to entrain the LP fluid flowing into entrainment chamber 18 via inlet port 14. As described in detail below, the configuration of the injection portion 12, entrainment portion 11 and to some extent the ejection portion 13 are designed specifically to minimise choking at the region of throat 20, to minimise jet loss and recirculation within the device (and specifically entrainment chamber 18) and to minimise energy loss due to friction within the device 10. In particular, the present device 10 is configured to minimise and preferably inhibit choking at the region of throat 20 as the pressure of the HP fluid 33 is increased to maximise the magnitude and efficiency of extraction of the LP fluid 32.

Referring to figure 2, injection body 15 comprises multiple axial sections including an annular radially constricted section 34 positioned at or towards inlet port 19; a radially enlarged expansion section 36 positioned at or towards an outlet end 15b of injection body 15 and an axially intermediate flow conditioning section 35 positioned axially intermediate sections 34 and 35. Each of the sections 34 to 36 differ via their respective wall thicknesses of the injection body 15, a cross sectional area of the injection conduit 29a, 29b and the angular orientation of the radially inward facing surface 37 that defines the injection conduit 29a, 29b. At section 34, inward facing surface 34a at a leading side converges sharply towards axis 23 to transition via a curved radially innermost part to a diverging trailing surface portion 34b. At flow conditioning section 35, surface 37 converges gradually towards axis 23 along a majority of the length of injection body 15 from an axial portion 35a (towards an inlet end 15a of body 15) towards a radially innermost throat 35b (towards section 36). Inward facing surface 37 then diverges (extends radially outward) at expansion section 36 terminating at outlet end 15b. A radially external facing surface 37 of injection body 15 is also divergent (away from axis 23) between and in a direction from throat 35b to outlet end 15b. Surface 37 at the constriction and conditioning sections 34, 35 is generally cylindrical between throat 35b and inlet end 15a.

Referring to figure 5, device 10 comprises a swirl induction or spinner mechanism 48 mounted within injection conduit 29a, 29b. Swirl mechanism is configured to induce spinning rotation of the HP fluid 33 as it flows through the injection portion 12 towards the

-16nozzic assembly 49. Spinner mechanism 48 may comprise first and second helical twisted portions with the helical paths extending around longitudinal axis 23. An alternative configuration is illustrated in figure 6 with the spinner mechanism 48 is positioned upstream of the inlet port 19 and injection body inlet end 15a such that the HP fluid 33 entering injection body 15 is already partially phase-separated into the liquid-dominant and gas-dominant phases.

Returning to figure 2, flow condition section 35 provides a housing and a flow conduit for the multiphase HP fluid. The converging conditioning section 35 provides resistance to the flow so as to entrain a greater volume of gas in the liquid portion before exiting into the expansion section 36. The radial expansion of the conduit 29a at section 36 relative to the smaller diameter conduit section 29a, (at the throat region 35b of conditioning section 35) promotes an expansion of the gas-dominant and liquid-dominant phases as they transition into annular flow patterns into the nozzle assembly 49.

Referring to figure 3, outer nozzle 16 comprises inlet end 16a extending from outlet end 15b of injection body 15. The generally conical nozzle 16 comprises a radially inward facing surface that may be divided into a plurality of axial sections that may be differentiated by their angular orientation relative to longitudinal axis 23. However, over a majori ty of an axial length of nozzle 16, the inward facing surface is generally convergent towards axis 23 in a direction from inlet end 16a to an outlet end 16b. This is with the exception of a fourth section 41 d provided towards and at outlet end 16b. The inward lacing surface of outlet nozzle 16 at a first section 41a (positioned towards and at inlet end 16a) is steeply convergent so as to provide a sudden decrease in cross sectional area of the outer conduit 30 relative to injection conduit 29a within expansion section 36. The inward surface at second section 41 b is also convergent towards axis 23 but the angle of convergence is more gradual (i.e., is less than of first section 41a). The conduit 30 at sections 41 a, 41b is annular and generally conical to surround inner nozzle 17. Outer nozzle 16 is partially formed by an outer nozzle injection block 16c. Block 16c is formed as a solid body extending radially across conduit 30 and comprises a plurality of cylindrical bores distributed around axis 23 each having a respective longitudinal axis (and inward facing surface 41c) that are aligned to be convergent towards axis 23. Injection

-17block 16c provides a mount for inner nozzle 17 at and towards an inner nozzle outlet end 17b relative to an inlet end 17a. For example, inner nozzle 17 may be friction-fitted into a portion of injection block 16c so as to be suspended within conduit 30 to define the concentrically aligned outer and inner conduits 30, 31. According to the specific implementation, a diameter of each of the bores within injection block 16c is different whilst the longitudinal axis of each bore is convergent towards a common point-ofprojcction (located at an axially forward region of entrainment chamber 18). The cylindrical conduits within block 16c create and maintain a hollow cone-shaped jet-spray 43 of the liquid-enriched phase to surround a corresponding jet-spray 44 of the gasenriched phase flowing within inner nozzle conduit 31. Nozzle 16 comprises a jetconditioning and containment section 4Id formed by successive converging-curvedannular wall portions extending between outlet end 16b and injection block 16c. Such an arrangement facilitates the projection of the hollow-cone jet spray 43 of liquid-enriched product from the outer nozzle 16. Inward facing surface 41d at this exit end section is preferably aligned parallel to axis 23 which serves to facilitate the annular jet-stream 43 having a central cylindrical void portion that provides a containment passage for the gaseni iclicd products expelled from inner nozzle conduit 31. This in turn maximises forward travel and minimises dispersion. Additionally, nozzle inward surface at section 41d provides control of the angular orientation of the jet stream 43 (relative to axis 23) such that the liquid enriched stream 43 is of narrower diameter than the downstream mixing tube 21 but of sufficiently wide diameter to achieve uniform thrust to entrain the LP fluid 32 within the entrainment chamber 18 axially between nozzle outlet ends 16b, 17b and mixing tube 21. As illustrated in figures 3 and 4, an external facing surface 47 of outer nozzle 16 is conical between the inlet and outlet end 16a, 16b

Inner nozzle 17 comprises an inward facing surface divided into four axial sections that are differentiated by the angular orientation of the surface relative to axis 23. A first section 42d positioned at inlet end 17 converges steeply towards axis 23. A more tapered, less convergent second section 42a extends over a majority of the length of nozzle 17 and transitions into a third section 42b corresponding to the position of injection block 16c. A fourth section 42c is positioned at outlet end 17b with the surface at sections 42b, 42c being generally parallel to axis 23. Section 42d provides a smooth transition inlet to

-18provide a sharp leading edge to minimise turbulence. The gradually reducing diameter second section 42a acts to accelerate the gas-enriched phase towards the injection block 16c and towards the nozzle outlet end 17b. Section 42c being aligned generally parallel to axis 23 provides a cylindrical conduit section to promote a solid conical jet-stream 44 within the hollow cone jet-stream 43 of the surrounding liquid-enriched phase. Section 42c, reduces dispersion of the gas-enriched phase for maximised forward passage towards mixing tube 21 and to minimise disintegration and turbulence of the jet-streams 43, 44 within the axially forward region of the entrainment chamber 18.

Referring to figures 3 and 5, an inward facing surface of body 28 that defines entrainment chamber 18 is specifically configured (and orientated relative to axis 23) i) to maximise the effect and efficiency of entrainment of the LP fluid by the HP fluid, ii) to minimise choking at the throat 20 and iii) to minimise energy loss due to friction within the device 10. In particular, the inward facing surface at the axially forward region of entrainment chamber 18 defines a throat inlet (of throat 20) and has a three-part sectional profile formed by converging wall sections 38, 39 and 40 that may be differentiated by the angle of convergence of the surface relative to axis 23. In particular, an axially rearward first section 38 tappers gradually towards axis 23 (in the fluid flow direction), an axially forwardmost section 40 connected to an inlet end 21a of mixing tube 21 comprises an inward facing surface having a gradual taper radially inward. A third section 39 positioned axially intermediate rearward and forward end sections 38, 40 comprises an inward facing surface that is steeply convergent towards axis 23 by a convergence angle that is greater than that of first and second sections 38, 40. First section 38 provides a flow passage for the LP fluid to enter the entrainment chamber 18 at the nozzle discharge zone (corresponding to the region of jet-streams 43, 44). Second section 40 (being slightly tapered) provides a zone for the LP and HP fluids to initiate exchange of energy and momentum and to provide a similar geometrically shaped conduit to that of the downstream mixing tube 21. Third section 39 having a steep converging internal facing surface acts to project the LP fluid into the HP jet-streams 43, 44 according to a desired angle of attack. According to the specific implementation, the surfaces 38, 39 and 40 are orientated relative to axis 23 at respective angles 20 to 30°, 40 to 50°, and 0 to 5°. The mixed HP and LP fluids then flow into the mixing tube 21 where they undergo a transfer of

-19encrgy and momentum and a gradual increase in static pressure. A diffuser section (not shown) coupled with the exit end of the mixer tube 21 provides a zone for static pressure recovery of the mixed fluid as it exits the device 10 via a discharge port (not shown).

Referring to figure 5, entrainment chamber 18 is further configured to promote axially forward flow of the LP fluid towards the throat inlet (sections 38, 39 and 40). In particular, the body 28 that defines entrainment portion 11 comprises solid body portion 80 being generally annular to surround and contain injection body 15. That is, entrainment chamber 18 docs not extend axially rearward of the LP inlet port 14. In particular, a shape profile of the inward facing surface 24 of entrainment body 28 diametrically opposite inlet port 14 is curved so as to provide a smooth transition into the first throat inlet section 38. Accordingly, the LP fluid is prevented (by solid body 80) from flowing axially rearward and is instead directed exclusively axially forward by curved surface 24 into the jetstreams 43, 44. Curved surface 24 acts to streamline the entrained fluid flow in a direction aligned with the trajectory of the HP jets 43, 44 and to avoid back-flooding and turbulence within the entrainment chamber 18.

Referring to figure 4, a further embodiment of the present invention comprises an inner nozzle 17 having a plurality of vent holes 45 extending through the body of nozzle 17 between the radially inward facing surface 42a and outward facing surface 46 (with the latter in-part defining outer nozzle conduit 30). Vent holes 45 provide a passageway for a partial-transfer and mixing between the inner gas-dominant and outer liquid-dominant phases so as to provide momentary pressure relief that in turn minimises the risk of possible choking within the nozzle assembly 49 at and towards critical flow conditions where the inner nozzle conduit 31 may become restricted.

Referring to figures 5 and 6, the spinning mechanism 48 may comprise any form of helical-twisted pipe section configured to induce a swirling rotation of the HP fluid and its component phases within the injection conduit 29a (figure 5) or upstream of the HP fluid inlet port 19 (figure 6). In both embodiments, the liquid-enriched phase is projected towards and maintained at the inward facing injection conduit surface 37 whilst the gasenriched phase travels within the swirling liquid-enriched phase to be centred on axis 23.

-20I ligh level spinning is advantageous to enhance the partial separation of the two-phases within the HP fluid so as to deliver the partially-separated phases into the radially outer and inner nozzle conduits (30, 31). This creates more stable co-axial jet-streams 43, 44 for the advantages mentioned previously. The co-axial multiple nozzle assembly 49 when combined with mechanism 48 provides a jet pump device to create the defined concentric jet-streams 43, 44 which in combination with the throat inlet sections 38, 39 and 40 provide and contribute to the advantages mentioned previously.

Referring to figure 7, device 10 is suitable for installation within networks, apparatus and sy stems for the recovery of oil or gas within LP reservoirs (relative to a HP reservoir or driving fluid source). The example system of figure 7 comprises a first high pressure network 51 including high pressure liquid or gas wells 50; a second high pressure network 53 comprising a high pressure water pump 52; a first low pressure network 54 including a pump 60; a second low pressure network 55 containing a production separator 57, a low pressure gas line 65 coupled to a flare stack 59 and a further liquid to process facility network 58 also coupled to production separator 57. Low pressure liquid or gas wells 56 arc coupled to the respective low pressure networks 54, 55. The present jet pump device 10 is connected via network conduits 63, 64 to the respective high pressure networks 51, 53 and the low pressure networks 54, 55. A commingler 82 is coupled to a HP upstream in-line separator 61 via a network conduit 62, with the in-line separator 61 positioned downstream of the HP wells 50. HP water pump 52 is coupled to the jet pump supply conduit 63 via network conduit 66. In such an arrangement, the present device 10 is configured for extraction of fluid from the LP wells 56 via entrainment within the fluid from the HP networks 51, 53.

fix pcrimental

The present multiphase fluid driving jet pump device 10 was installed in a two-phase test rig in order to assess performance. The two-phase rig 93 included a process loop comprising a horizontal test pipe-route section. The total tests section having a total length of 25 m, was divided into two sections of: 15 m and 9 m of upstream and downstream pipe lengths with reference to the nozzle throat 20 respectively. Air and water were used as the

-21fluid mediums to comprise various two-phase flow combinations. Mixing of the two phases was set to occur at a commingle point, 15 m upstream the nozzle-throat 20. Test rig 93 included an air compressor 90, a water pump 92 and a water tank 91 with various flow, pressure and flurried sensors coupled to a control computer 94. The experiments performed included various jet-pump device setups and an extensive range of fluid compositions, characterized with different flow regimes including GVFs.

.Results

Figure 9 illustrates the degradation in performance of the LP ‘production’ gas flow as a result of an increase in HP fluid GVFs (for fixed liquid-water mass flow-rates). A comparison of performances is made between three different types of jet-pump device having injection bodies that comprise: (a) a conventional JP device with a convergent nozzle - results 68, (b) a device having a multi-orifice nozzle including a swirl inducer results 69, and (c) the present JP device 10 - results 67. The comparative conventional device (results 68) was similar to present device 10 but differed by not including a spinner mechanism 48 and comprised a single convergent nozzle only, having a cylindrical inlet conduit and mounted within an entrainment chamber that included a conventional convergent throat inlet (with a single tapered section). The comparative multi-orifice nozzle device (results 69) comprised a single nozzle but having a plurality of parallel injection bores, in which the sum of their collective cross-sectional area equalled the nozzle throat cross-section area of the comparative conventional/single-orifice device. It was configured that the inlet end of the multiple injection bores receives high-pressure fluid from one inlet-port, thus the inner-conduit-wall of the comparative multi-orifice nozzle comprised a single cylindrical curved wall, which extends all way through the device inlet high-pressure inlet port down to the injection block. The latter block, refers to a solid section that houses the said multiple injection bores. Furthermore, a spinner mechanism was placed just upstream the bore inlets, while the entrainment chamber included a throat-inlet having three consecutive tapered sections. The said throat configuration conforms to the present JP device.

-22The x-axis represents a range of HP flow compositions, expressed in terms of GVFs ranging between 0- 50 % respectively (where 0 % GVF represents 100 % liquid). The yaxis represents the entrainment ratio [Φ] (derived from the actual volumetric flow of gas entrained from the LP side, divided by the total actual volumetric mix flow of gas and liquid flowing through the HP side of the jet-pump device). Accordingly, an increase of the entrainment ratio signifies that more volumetric flow of gas is being entrained for the same mass flow of a HP single/two-phase fluid jet.

Figure 10 illustrates the magnitude of the amplitudes of pressure vibration [P_vib] at the throat-inlet (sections 38, 39, 40), for the covered range of HP fluid GVFs, for the corresponding injector bodies as included in figure 9. The results are: 72 - present device 10; 71 - conventional device with swirl flow multi-orifice nozzle; and 70 - conventional device with convergent-nozzle. The results indicate that pressure vibration is the result of intermittent jets, causing a considerable increase of vibration when the HP/motive fluid is more than 15 % GVF (in case of the standard conventional-converging design), while it remains relative stable for the present device 10.

The performance behaviour of the entrained flow under various HP fluid GVFs for the case of a conventional-convergent nozzle is illustrated by the results 72 of figure 10. The plotted profile represents the optimum results obtained from a sequence of applied modifications, mainly involving variance in the nozzle-to-throat clearance and upstream mixing of the two-phase flow.

From figure 9 a considerable increase of performance is observed compared to the conventional nozzles (results 68, 69) over the full range of GVFs. Additionally, the same magnitude of entrainment ratio, as obtained for the 100 % liquid for the standard case, is obtained with the present device 10 even when the HP fluid GVF reaches a value of 35 % GVF. T'his is noted by a dashed line of figure 9.

As described, the propagating jet streams 43, 44 are capable of being created with a wide enough (uniform) forward projected thrust, but being narrow enough and self-contained to enter the inlet-throat smoothly, thereby without having jet ligaments hitting the

-23surrounding wall surfaces 38, 39 and 40 to cause recirculation. The mechanisms of (a) inducing partial phase separation, (b) enhancing phase-separation, (c) introduction of separate nozzle flow conduits, (d) multiple-orifice injection conduits and (e) jet conditioning and containment, provide to a reduction in pressure vibration and a stabilisation of the high speed multi-jet along the nozzle-to-throat clearance. The amplitude of vibration was reduced, which as a result, entrained more gas flow the LP side. The reduction in vibration is illustrated by results 72 of figure 10.

The second method of illustrating the improvement between the standard/conventional design and the present device 10, was through the development of a series of time-trace plots; having time [sec] on the x-axis, and the LP entrained flowrate [LPM] as a performance parameter on the y-axis, for: 0, 10, 20, 30, 40 and 50 % GVFs corresponding to plots 73, 74, 75, 76, 77 and 78, respectively.

Figure 11 illustrates a set of time trace plots representing the amplitude of vibration for the entrained flowrate of the present device 10. A comparison was made between the respective time trace plots 73, 74, 75, 76, 77 and 78 at the respective GVF % of figure 11, and those of the standard conventional nozzle (time trace plots 79, 80, 81, 82, 83 and 84 of figure 12).

Two important characteristics were noted. The most observable is that the amplitude of vibration for the entrained flowrate continued to increase with the increase of the fluid GVF content. In addition, for the present device 10, the amplitude of vibration (respective time trace plots 73 to 78 of figure 11), was lower in all cases compared to corresponding time trace plots (figure 12) for the standard conventional design.

Secondly, increase of the average magnitude of entrainment flow was observed for device 10 compared to the conventional-injector designs. The results of present device 10, indicated a 117 % and 160 % increase in LP entrainment performance for cases comprising 0 % GVF and 35 % GVF respectively. Another observable feature of figure 12 is that the entrainment of LP gas flow is lower for the case of a HP fluid of 0 % GVF, than it is for the case when the HP fluid comprises 10 % GVF.

-24It was also noted that that while performing experiments, the flow regime shifted from a bubble flow for very low % GVFs, to an elongated bubble flow and slug flow regimes for mild to high % of GVFs, above 20 % and 35 % respectively. Thus the frequency of oscillation and the sinusoidal-like trend forms, are mainly dictated by the variance in HP flow regime.

Claims

1. A jet pump device comprising:

a first fluid inlet port to allow a flow of a first fluid into the device;

a phase separator connected in fluid communication with the first inlet port to direct at least a first portion of the fluid radially outward relative to a longitudinal axis extending through the device and to allow at least a second portion of the first fluid to flow along the longitudinal axis;

a nozzle assembly comprising at least one first nozzle having an inlet end and an outlet end and a radially inward facing surface that defines a fluid flow conduit, the inlet end positioned to receive the first portion of the first fluid at the radially outward position, the inward facing surface in a plane extending in a longitudinal axis direction orientated to converge towards the axis in a fluid flow direction from the inlet end to the outlet end;

a second fluid inlet port to allow a flow of a second fluid into the device;

an entrainment chamber provided in fluid communication to receive the first and second fluids;

a mixing conduit positioned in fluid communication to receive the first and second fluids from the entrainment chamber, a junction between the mixing conduit and the entrainment chamber defining a throat of the device;

wherein the nozzle assembly further comprises at least one second nozzle having an inlet end, an outlet end and a radially inward facing surface that defines a fluid flow conduit, the inlet end of the second nozzle positioned radially inward relative to the inlet end of the first nozzle to receive the second portion of the first fluid at or towards the longitudinal axis, the inward facing surface in a plane extending in a longitudinal axis direction orientated to converge towards the axis in the fluid flow direction;

the outlet ends of the respective first and second nozzles positioned within the entrainment chamber upstream of the throat such that the flow of the first fluid from the respective outlet ends of the first and second nozzles acts to entrain a flow of the second fluid into the device via the second fluid inlet.

2. The device as claimed in claim 1 wherein at least a portion of the conduit of the first nozzle comprises a cross sectional area that decreases in a direction from the inlet to the outlet end.

3. The device as claimed in claims 1 or 2 wherein at least a portion of the conduit of the second nozzle comprises a cross sectional area that decreases in a direction from the inlet to the outlet end.

4. The device as claimed in any preceding claim wherein at least a portion of the conduit of the first nozzle is annular to surround the conduit of the second nozzle.

5. The device as claimed in any preceding claim wherein the second nozzle is positioned radially inside the first nozzle over all or a majority of an axial length of the second nozzle.

6. The device as claimed in any preceding wherein at least a portion of the conduit of the first nozzle comprises a plurality of bores having respective axial centres that are orientated to converge towards the axis in the fluid flow direction from the inlet to the outlet end of the first nozzle.

7. The device as claimed in any preceding claim wherein at least a portion of the first nozzle comprises a conical shape profile.

8. The device as claimed in claim 7 wherein at least a portion of the second nozzle comprises a conical shape profile.

9. The device as claimed in claim 8 wherein said portions of the first and second nozzles are positioned concentrically about the longitudinal axis, the second nozzle positioned radially inside the first nozzle.

10. The device as claimed in any preceding claim wherein the conduit of the first nozzle at and/or towards the inlet end is annular and the conduit of the second nozzle at and/or towards the inlet end is conical and surrounded by the annular conduit of the first nozzle.

11. The device as claimed in any preceding claim wherein an axially forward end of the entrainment chamber in the fluid flow direction through the device is defined by a radially inward facing surface that in the plane extending in the longitudinal axis direction is orientated to converge towards the longitudinal axis.

12. The device as claimed in any preceding claim wherein generally all or a majority of an internal volume of the entrainment chamber is positioned axially forward of the second inlet port in the fluid flow direction of the first fluid through the device.

13. The device as claimed in any preceding claim further comprising an injector body having an annular wall defining an internal injection conduit having a first end section coupled in fluid communication with the first fluid inlet port and a second end section coupled in fluid communication with the inlet ends of the first and second nozzles.

14. The device as claimed in claim 13 wherein the injection conduit comprises a middle section having a cross sectional area that decreases in a direction from the first to the second end sections, and wherein a cross sectional area of the second end section increases in a direction from the first to the second end sections.

15. The device as claimed in claim 14 wherein the first end section comprises a cross sectional area that increases in a direction from the first to the second end sections.

16. The device as claimed in claim 15 wherein an axial length of the middle section is greater than that of the second end section that is in turn greater than that of the first end section.

17. The device as claimed in claim 16 wherein a cross sectional area of an axially forwardmost end of the second end section is greater than a cross sectional area of an axially rearwardmost end of the first end section.

18. The device as claimed in any preceding claim wherein an inward facing surface of the second nozzle comprises a plurality of axial sections wherein in the plane extending in the longitudinal axis direction an angle of the inward facing surface of the plurality of axial sections relative to the longitudinal axis is different.

19. The device as claimed in claim 18 wherein the angle at a first section at the inlet end is greater than an angle at a second section at the outlet end and a middle section positioned axially between the first and second sections.

20. The device as claimed in claim 19 wherein a cross sectional area of the fluid flow conduit of the second nozzle is generally uniform along the second section at and towards the outlet end.

21. The device as claimed in any preceding claim wherein an inward facing surface of the first nozzle comprises a plurality of axial sections wherein in the plane extending in the longitudinal axis direction an angle of the inward facing surface of the axial sections relative to the longitudinal axis is different.

22. The device as claimed in claim 21 wherein an angle at a first section at the inlet end is greater than an angle at a second section at the outlet end and a middle section positioned axially between the first and second sections, wherein an axial length of the middle section is greater than that of the first and second sections.

23. The device as claimed in any preceding claim wherein the second nozzle comprises at least one aperture extending radially through the second nozzle to provide a fluid flow communication passageway between the fluid flow conduits of the first and second nozzles.

24. The device as claimed in any preceding claim when dependent on claim 11 wherein the radially inward facing surface at the axially forward end of the entrainment chamber is divided into a plurality axial sections each having a different angular orientation relative to the longitudinal axis.

25. The device as claimed in claim 24 wherein the axial sections comprise:

a first largest conical section positioned axially rearwardmost in the fluid flow direction and having a first angle of convergence;

a second conical section positioned axially forwardmost and having a second angle of convergence; and a third conical section positioned axially between the first and second conical sections having a third angle of convergence;

wherein the angle of convergence of the third section is greater than that of the first section which is in turn greater than that of the second section.

26. The device as claimed in any preceding claim wherein a portion of an inward facing surface that defines the entrainment chamber at a position diametrically opposite the second inlet port is curved to direct the flow of fluid in an axially forward direction towards the throat.

27. The device as claimed in any preceding claim wherein the phase separator comprises a spinner mechanism configured to induce spinning rotation of the first fluid about the longitudinal axis.

28. The device as claimed in claim 27 when dependent on claim 13 wherein the spinner mechanism is positioned within the injection conduit of the injection body axially between the first fluid inlet port and the inlet ends of the first and second nozzles.

29. The device as claimed in claim 27 when dependent on claim 13 wherein the spinner mechanism is positioned in the fluid flow direction upstream of the first fluid inlet port.

30.

Fluid extraction apparatus comprising:

-30a first fluid source coupled via a first network conduit to the first fluid inlet port of the device as claimed in any preceding claim, the first fluid source at a first pressure;

a second fluid source coupled via a second network conduit to the second fluid inlet port of the device as claimed in any preceding claim, the second fluid source at a second pressure being less than the first pressure.

31. The apparatus as claimed in claim 30 comprising a secondary fluid source coupled to the first fluid inlet port via a third network conduit to increase the pressure of the first fluid delivered to the first fluid inlet.

32. The apparatus as claimed in claims 30 or 31 comprising at least one fluid phase separator positioned at the respective first and second network conduits in the fluid flow direction between the first and second fluid sources and the respective first and second inlet ports.

33. The apparatus as claimed in claims 31 or 32 comprising a booster pump coupled in fluid communication with the first or/and the third network conduit.

34. The apparatus as claimed in claim 33, wherein the booster pump is installed upstream of the device.

35. A method of pumping a fluid comprising:

allowing a first fluid to flow into a jet pump device via a first fluid inlet port;

separating the first fluid using a phase separator connected in fluid communication with the first fluid inlet port so as to direct a portion of the first fluid radially outward relative to a longitudinal axis extending through the device and to allow a second portion of the first fluid to flow along the longitudinal axis;

receiving the first fluid at a radially outward position relative to the longitudinal axis within a first nozzle of a nozzle assembly, the first nozzle having a radially inward facing surface that in a plane extending in a longitudinal axis direction is orientated to converge towards the axis in a fluid flow direction from an inlet end to an outlet end;

allowing a second fluid to flow into the device via a second fluid inlet port;

-31receiving the first and second fluids within an entrainment chamber;

allowing the first and second fluids to mix within a mixing conduit positioned in fluid communication to receive the first and second fluids from the entrainment chamber, a junction between the mixing conduit and the entrainment chamber defining a throat of the

5 device; and receiving a second portion of the first fluid at or towards the longitudinal axis at a second nozzle positioned radially inward relative to the first nozzle, the second nozzle having a radially inward facing surface that in a plane extending in a longitudinal axis direction of the device converges towards the axis in the fluid flow direction from an inlet

10 end to an outlet end of the second nozzle;

wherein the outlet ends of the respective first and second nozzles are positioned within the entrainment chamber upstream of the throat such that the flow of the first fluid from the respective outlet ends of the first and second nozzles acts to entrain a flow of the second fluid into the device via the second fluid inlet.