GB2499596A

GB2499596A - Downhole flow control

Info

Publication number: GB2499596A
Application number: GB1202937.7A
Authority: GB
Inventors: Giovanni Salemo; Sam Simonian; Benn Voll
Original assignee: Tendeka BV
Current assignee: Tendeka BV
Priority date: 2012-02-21
Filing date: 2012-02-21
Publication date: 2013-08-28
Also published as: GB201202937D0; WO2013124643A2; WO2013124643A3

Abstract

A downhole flow control device 22 comprises a blocking arrangement 32 mounted in proximity to the flow port 24 through the wall of a tubular member 28 to be located within a well bore. The flow control device 22 comprises a sleeve of swellable material configured to swell upon exposure to a triggering fluid, such as water, so that in an unswollen state the blocking arrangement 32 does not interfere with the flow port 24 and flow through the flow port is unrestricted, and in a swollen state the blocking arrangement encroaches axially or radially over the flow port to restrict flow therethrough. The swellable sleeve 32 may be located within an annular space 35 between the wall 28 and a concentrically mounted support sleeve 34.

Description

DOWWHOLE FLOW CONTROL DEVICE

FIELD OF THE INVENTION

The present invention relates to a downhofe flow control device.

BACKGROUND TO THE INVENTION

In the oil and gas exploration and production industry wellbores are drilled into the earth to Intercept subterranean formations or reservoirs containing hydrocarbons. The drilled bores are lined or oased with tubing to provide sealing and support and a completion assembly is located within the cased bore to facilitate production of hydrocarbons from the reservoir to the surface. The completion assembly includes a production tubing string which defines an internal flow path and extends from the reservoir production zone to surface. Produced fluids enter the production tubing string via a number of inflow ports which are typically provided axially along the length of the string.

The geological formations within which the oil reservoir is found may vary in geological type and physical characteristics, but the main characteristic of interest is the permeability of the rock. Generally, permeability determines the ease with which the oil can flow through the rock and into the well bore.

Certain rocks such as sandstone have relatively even permeability and are typically referred to as homogeneous. Oil can flow through such homogeneous rock at a relatively even rate and will be produced evenly across the drilled section of reservoir. Other reservoir rocks such as limestone and chalk can be heavily, naturally fractured and vary greatly in permeability and such rocks are typically referred to as heterogeneous. Oil from a heterogeneous reservoir will produce mainly from the areas of highest permeability such as where fractures are found.

Even though the well bore may be drilled a considerable distance through the oil reservoir, the high permeability zones may account for only 10-15% of the length of the drilled reservoir section. If allowed to produce directly into the drilled bore and production tubing string, the oil may never be produced from the remaining 85-90% of the drilled section thus reducing the efficiency of the oil well.

Located below the oil within the reservoir there is typically a layer of naturally occurring water. When a well is drilled the aim is to produce as much oil as possible and to limit the amount of natural water produced. Over time as the oil is depleted, it is replaced by the natural wafer seeping up form the rock below it. In a homogeneous

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reservoir the water may rise slowly and evenly, prolonging the time before water eventually breaks through into the wellborn. In a heterogeneous reservoir, however, the mixed permeability of the reservoir and the natural faulting may allow water to break through early in certain regions,

5 To overcome such problems it is known in the art to selectively restrict the flow from certain regions, typically regions of high permeability and natural production rates, to permit other regions to be produced In a more balanced manner. This effectively increases the oil producing area of the reservoir and extends the time before eventual localised water break-through,

10 Devices which invoke this effect are typically known in the art as inflow control devices which restrict flow by creating a pressure drop as the oil passes through them, The restriction can take the form of a series of orifices or a tortuous flow path, for example. The devices are provided in the production tubing string and are spaced out at intervals across the reservoir section. As the oil produces it will flow from the 15 reservoir rock and fill the annular space between the drilled bore and the outside of the production tubing string. Thereafter, the oil will flow towards the flow restriction devices and enter the production tubing string to be produced to surface.

However, even with such Inflow devices in place It is still typical for water to break through early in one region before another. Current remediation techniques for 20 reducing the effects of water break-through may involve blanking off the section where water break-through has occurred, setting a cement plug, setting a straddle, pulling the existing completion and running a new completion of modified design or the like. However, such methods are costly, time consuming and do not necessarily solve the problem,

25 Furthermore, monitoring equipment is normally required at intervals along the production tubing string to monitor for water ingress. This adds to the cost of the production process. Additionally, when water break-through occurs, the production process may need to be halted to permit appropriate intervention operations to be performed.

30

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a downhole flow control device, comprising:

a tubular member to be located within a well bore and defining an internal flow

35 path;

3

a flow port formed through a wall of the tubular member to provide fluid communication between the welibore and the internal flow path; and a blocking arrangement mounted in proximity to the flow port and comprising a sweilable materia! configured to swell upon exposure to a triggering fluid, wherein in an 8 unswoilen state the blocking assembly does not interfere with the flow port such that flow through the flow port is unrestricted by the blocking arrangement, and in a swollen state the blocking arrangement encroaches over the flow port to restrict flow therethrough.

In use, the sweilable material of the blocking arrangement may remain 10 unswoilen in the absence of the triggering fluid such that the blocking arrangement does not interfere with or restrict flow through the flow port. This may be particularly advantageous in circumstances where the flow port is specifically designed to provide desired fluid dynamic properties within the flowing fluid. As such, in the absence of the triggering fluid the flow port may be permitted to function as originally desired, without 15 any interference from the blocking arrangement. However, in the presence of the triggering fluid the sweilable material will swell and cause the blocking arrangement to encroach over the flow port to restrict flow therethrough,

The blocking arrangement may be configured to partially restrict flow through the flow port. In such an arrangement the blocking arrangement may function to 20 reduce the flow area through the flow port.

The blocking arrangement may be configured to completely restrict or block flow through the flow port, That is, the blocking arrangement may be configured to close the flow port when the sweilable material is in a swollen state such that flow therethrough is prevented.

25 The blocking arrangement may be configured to restrict flow, for example completely block flow, of the triggering fluid through the flow port, in such an arrangement swelling of the sweilable material in the presence of the triggering fluid may permit the blocking arrangement to passively restrict flow of the triggering fluid through the flow port. This may allow passive selective control of How through the flow 30 port while eliminating or minimising the requirement for complex sensing systems, actuators and the like.

The flow port may be configured to restrict flow therethrough. The flow port may be configured to establish a back pressure within the fluid flowing therethrough. Such an arrangement may provide a degree of flow control between the welibore and 35 the tubular member. As noted above, the blocking arrangement does not interfere with

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or restrict flow through the flow port when the sweilable material is in an unswoilen state such that in the absence of the triggering fluid the flow port may function to provide the originally desired back pressure, without any interference from the blocking arrangement

5 The device may comprise an insert located within the flow port, wherein the insert is configured to establish a desired back pressure within the fluid flowing therethrough.

In one embodiment the flow control device may be configured to permit or control th© Inflow of fluid from the well bore into the tubular member, in such an 10 arrangement the tubular member may be configured to support production of fluids, such as hydrocarbon fluids, from the welibore. The flow control device may define an inflow control device. As is known in the art conventional inflow control devices may be appropriately configured and located within a welibore to provide a degree of control over production across a region of a subterranean formation or reservoir, for example 15 to maximise recovery from the formation and delay water break-through. The flow control device according to the first aspect may be suitable for such use,

In other embodiments the flow control device may be configured to perms! or control the outflow of fluid from the tubular into the welibore, such as the flow of an injected fluid into the welibore.

20 The sweilable material may be configured to swell upon exposure to water.

This arrangement may be advantageous in embodiments where the device defines an inflow control device and is Intended to minimise or restrict flow of water from the welibore into the tubular member.

The sweilable material may be configured to swell upon exposure to a 25 hydrocarbon fluid, such as oil and/or gas.

The sweilable material may be configured to swell upon exposure to hydrocarbon. This arrangement may be advantageous in embodiments where the device defines an inflow control device and is intended to minimise or restrict flow of gas from the welibore into the tubular member.

30 The blocking arrangement may be composed entirely of sweilable material, For example, the blocking arrangement may be defined by a sweilable body configured to swell from an unswoilen state to a swollen state to encroach over the flow port.

The blocking arrangement may comprise a sealing body configured to be actuated by the swelling material to encroach over the flow port.

The blocking arrangement may be at least partially mounted externally of the tubular member, For example, the blocking arrangement may be mounted on or In relation to an external surface of the tubular member. In such an arrangement the sweilable material of the blocking arrangement may be configured to swell to increase its coverage of the external surface of the tubular member.

The blocking arrangement may be at least partially mounted internally of the tubular member, For example, the blocking arrangement may be mounted on or In relation to an internal surface of the tubular member, In such an arrangement the sweilable material of the blocking arrangement may be configured to swell to increase its coverage of the internal surface of the tubular member.

The blocking arrangement may be at least partially mounted within the wail of the tubular member. For example, the tubular member may define a pocket within a wall thereof, wherein the blocking arrangement is at least partially mounted within said pocket, In such an arrangement the sweilable material of the blocking arrangement may be configured to swell to increase the volume of the pocket occupied by the blocking arrangement, The pocket may be defined between an internal wail structure and an external wail structure. In such an arrangement the flow port may be defined In both the internal and external wail structures.

The sweilable material of the blocking arrangement may be configured to swell generally axialiy relative to the tubular member to cause the blocking arrangement to encroach over the flow port.

The sweilable material of the blocking arrangement may be configured to swell generally radially relative to the tubular member to cause the blocking arrangement to encroach over the flow port.

The blocking arrangement may be configured to define a seal relative to the flow port. The sweilable material of the blocking arrangement may be configured to define a seal relative to the flow port,

The blocking arrangement may comprise or define a generally annular structure, For example, the blocking arrangement may be provided in the form of a sleeve or sleeve structure. The blocking arrangement may be mounted coaxiaily relative to the tubular member.

The device may comprise a support structure configured to at least partially support the blocking arrangement relative to the tubular member. The support structure may be arranged to hold or support the blocking arrangement in proximity to the flow port. The support structure may be configured to permit the sweilable material

of the blocking arrangement to swell and move the blocking arrangement in a desired direction to permit encroachment over the flow port.

The support structure may be configured to support the blocking arrangement when the swelling material of said blocking arrangement is in both its unswoilen and 6 swollen states.

The support stricture may be configured to shroud or extend over the flow port in the tubular member.

The support structure may be defined at ieast partially by the tubular member. For example, the tubular member may define a pocket within a wail thereof, wherein 10 the blocking arrangement is at least partially mounted within said pocket.

The support structure may be mounted on the tubular member. The support structure may be provided by a separate component. Such an arrangement may facilitate ease of manufacture of the flow control device. Additionally, such an arrangement may facilitate retrofitting of the support structure and blocking 15 arrangement to any existing tubular member having a flow port to form a flow control device. The support structure may be removably mounted on the tubular member, for example via a threaded connection, screws or the like. The support structure may be permanently mounted on the tubular member, for example by welding or the like. The support structure may be integrally formed with the tubular member. 20 The support structure may be secured to or formed with the tubular member at one and in some embodiments both axial ends of said support structure.

The support structure may be mounted on the external surface of the tubular member. In this arrangement the blocking arrangement may also be at least partially mounted on the external surface of the tubular member.

25 In some embodiments the support structure may be mounted on the internal surface of the tubular member. In this arrangement the blocking arrangement may also be at ieast partially mounted on the internal surface of the tubular member.

The support structure may be mounted, or formed, on the tubular member to define a recess or compartment therebetween, wherein the blocking arrangement is at 30 ieast partially located within said recess. The recess may be generally annular. The recess may extend continuously around the tubular member. In other embodiments the recess may extend only partially around the tubular member,

The support structure may comprise a sleeve mounted, or formed, relative to the tubular member, for example externally of the tubular member. The support 35 structure may be mounted substantially coaxialiy relative to the tubular member.

7

The support structure may be configured to permit fluid communication between the welibore and the internal flow path of the tubular member. The support structure may he configured to permit fluid communication between the welibore and the flow port. The support structure may be configured to permit fluid communication between 5 the flow port and the interna! flow path.

The support structure may be configured to provide substantially unrestricted fluid communication between the welibore and the internal flow path of the tubular member. For example, the support structure may provide substantially unrestricted communication relative to any restriction provided by the flow port, 10 The support structure may define one or more openings providing fluid communication therethrough, An opening may be defined or provided through a wall of the support structure. An opening may be defined between the support structure and the tubular member.

The device may comprise a plurality of flow ports formed through the wall of the 15 tubular member. The device may comprise a plurality of flow ports arranged clrcumferentially around the tubular member. The device may comprise a plurality of flow ports arranged axially along the tubular member.

The device may comprise a single blocking arrangement configured to encroach over a plurality of flow ports. The device may comprise a plurality of blocking 20 arrangements each configured to swell to encroach over a least one flow port.

The device may comprise a plurality of flow ports wherein all of said flow ports are configured to be blocked or restricted by one or more blocking arrangements.

The device may comprise a plurality of flow ports wherein only some of the flow ports are configured to be blocked or restricted by one or more blocking arrangements, 25 In this embodiment following swelling of the one or more blocking arrangements some ports may be blocked or restricted while other ports may remain unrestricted, Such an arrangement may permit a reduction in flow without completely preventing flow through the flow control device. It will be understood by those of skill in the art that a reduction or blockage in only some of the flow ports will increase the pressure drop experienced 30 by the fluid such that a further restriction in flow rate will also be achieved. Further, it will also be understood by those of skill in the art that the flow rate will be reduced by a greater relative extent than the actual restriction achieved by the one or more blocking arrangements. For example, a 50% reduction in the total flow port area may result in approximately 70% to 75% reduction in flow rate as flow rate will be the square root of 35 the reduced area.

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The device may comprise a flow restrictor assembly configured to selectively restrict flow through the flow port, wherein the blocking arrangement forms part of the flow restrictor assembly. A support structure, such as defined above, may form part of the flow restrictor assembly.

5 The tubular member may form part of a production tubing string.

The tubular member may comprise or define one or more connection arrangements configured to permit said tubular member to form part of a tubing string, such as part of a production tubing string. At least one connection arrangement may comprise a threaded connection arrangement, welded connection arrangement or the 10 like.

The flow control device may be configured to form part of a completion assembly. Such a completion assembly may comprise a plurality of flow control devices. One or more of such flow control devices may be provided in accordance with the first aspect. One or more of such flow control devices may differ from that of the 15 first aspect. For example, one or more flow control devices forming part of the completion assembly may not include any blocking arrangement.

According to a second aspect of the present invention there is provided a method of controlling flow downhole, comprising:

locating a tubular member defining an internal flow path within a well bore, 20 wherein the tubular member defines a flow port through a wall thereof;

providing a blocking arrangement in proximity to the flow port and comprising a sweilable material configured to swell upon exposure to a triggering fluid;

initially configuring the blocking arrangement in an unswoilen state such that the blocking assembly does not interfere with the flow port;

25 permitting flow through the flow port between the welibore and the internal flow path, wherein the blocking arrangement does not interfere with said flow; and permitting the sweilable material of the blocking arrangement to swell upon exposure to the triggering fluid to cause the blocking arrangement to encroach over the flow port to restrict flow therethrough.

30 The method according to the second aspect may be performed using the flow control device according to the first aspect.

According to a third aspect of the present invention there is provided a flow restrictor assembly to be mounted on a tubular member, comprising;

a blocking arrangement configured to be mounted in proximity to a flow port 35 formed through a wall of the tubular member and comprising a sweilable material

9

configured to swell upon exposure to a triggering fluid, wherein In an unswoilen state the blocking assembly does not interfere with the flow port such that flow through the flow port is unrestricted by the blocking arrangement, and in a swollen state the blocking arrangement encroaches over the flow port to restrict flow therethrough, 5 The blocking arrangement defined within the third aspect may be similar to the blocking arrangement defined in accordance with the first aspect.

According to a fourth aspect of the present Invention there is provided a downhole flow device, comprising:

a tubular body defining an internal flow path;

10 a flow port for permitting flow of a fluid between an external location and the

Internal flow path; and a blocking arrangement configured to at least partially block the flow port upon exposure to a triggering fluid.

The blocking arrangement may comprise a sweilable material configured to

15 swell upon exposure to the triggering fluid.

The blocking arrangement defined within the fourth aspect may be similar to the blocking arrangement defined in accordance with the first aspect.

Other aspects of the present invention may relate to apparatus and methods for isolating water production from regions of a subterranean reservoir.

20 According to a fifth aspect of the present invention there is provided a completion assembly comprising:

a tubing string; and at least one flow control device according to the first aspect mounted within the tubing string.

25 The completion assembly may comprise a plurality of axially arranged flow control devices according to the first aspect.

The completion assembly may comprise at least one flow control device which differs from a How control device provided in accordance with the first aspect. For example, at least one flow control device may not comprise any blocking arrangement.

30 Another aspect of the present invention may relate to a flow restrictor arrangement for cooperation with a tubular member flow restrictor for use in a hydrocarbon well, the flow restrictor having at least one aperture through a wail thereof; the flow restrictor arrangement having a surface formation for retaining an expandable blocking means in the vicinity of the at least one aperture and allowing for expansion of

the blocking means when contacted by water to an expanded state servicing to substantially close the at least one aperture.

In such an aspect, as oil is produced, it must pass through the at least one aperture to gain access to the production tubing string to be produced at the surface. By altering the number of apertures having insert members therein the flow restrictor and the diameter of corresponding orifices of the insert members, each flow restrictor can be set up to create a specific pressure drop for a given flow rate. This choking effect creates a back pressure on higher quality sections of the reservoir allowing lower quality sections to contribute, thereby evening out the inflow profile from the well. This evening out of the inflow profile will result in better coning control., therefore prolonging the lifetime of the well before water break-through.

Further, where the flow restrictor arrangement is used in conjunction with at ieast two packers (where one packer is located upstream of the flow restrictor and the other downstream) in a completion arrangement, the presence of at least two packers en the tubular member compartmentalises a section of the well-bore between the two packers. The section of well-bore in a compartment between adjacent packers is effectively sealed off from the well-bore in other places, whether that be between other adjacent packers or otherwise. Thus, if wafer break-through occurs in a particular compartment, the water is prevented from reaching adjacent compartments by the packers.

Also, should water break-through occur, water may be prevented from reaching the production tubing string from a particular compartment, via at least one aperture, because the blocking means expands upon contact with water to cover the at least one aperture. This effectively provides a production tubing string with apertures which are automatically covered when water is in the region of those apertures. As will be appreciated, this may obviate the requirement for halting a production process to remove the production tubing string to insert blank pipe sections in regions of the production tubing string which correspond to regions of the well-bore where wafer break-through has occurred.

The said surface for retaining the blocking means may be spaced from a surface of said tubular member to define a space therebetween in which said blocking means is located for expansion therein.

The flow restrictor arrangement may comprise an annular member configured for arrangement in a sleeve-like manner around said tubular member adjacent said at least one aperture.

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The flow restrictor arrangement may include means for coupling at ieast one end of the arrangement to said tubular member.

The flow restrictor arrangement may include means for coupling both ends of the arrangement to said tubular member, and at feast one aperture is formed in a wall 5 of the arrangement to provide fluid communication between an exterior of said arrangement and said at least one aperture of said tubular member when said retaining means is cooperatively provided on said tubuiar member.

The arrangement may be arranged for mounting on a flow restrictor, for example, by way of an internal thread on an interior surface of said arrangement for 10 engagement with an external thread provided on an exterior of said tubuiar member, The arrangement may form part of said tubuiar member of said flow restrictor. The arrangement may be arranged to space regions of the flow restrictor from formation within the well and externa! to said flow restrictor,

According to another aspect of the present Invention, there is provided a tubuiar 15 member arranged to present at least one aperture through a wall thereof for fluid flow therethrough and to provide fluid communication between an exterior and interior of said tubuiar member; and including a flow restrictor arrangement as described above,

The flow restrictor arrangement may be mounted on said flow restrictor or may form part of said flow restrictor.

20 The fluid flow through the at least one aperture of the tubular member may be fixed upon selection of the aperture dimensions.

The at least one aperture of the tubular member may be arranged to receive an insert member arranged to control the fluid flow.

The expandable blocking means may be formed of an elastomer material such 25 as Hydrogenated Nitrite Butadiene Rubber (HNBR) or Nitrite elastomeric compounds.

The blocking means, when expanded, may be arranged to form a substantially fluid tight seal with a rim of the at least one aperture of the tubular member.

The blocking means may be arranged to expand upon contact with a fluid and absorption of it to increase in volume.

30 According to another aspect of the present invention, there is provided a flow restrictor for use in a hydrocarbon well, comprising:

a tubular member arranged to present at ieast one aperture through a wall thereof for fluid flow therethrough and to provide fluid communication between an exterior and interior of said tubular member; and

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a How restrictor arrangement, the flow restrictor arrangement comprising a collar member arranged co-axially with said tubular member and defining a space between an internal surface thereof and an external surface of said tubular member; the collar arranged to retain in said space an expandable blocking means arranged to 5 expand upon contact with water from a first, unexpanded, state where said at feast one aperture is unobstructed, to ailow for flow of fluid through said at least one aperture, to a second, expanded, state where a portion of the blocking means is arranged to substantially restrict flow of fluid through said at ieast one aperture.

According to another aspect of the present invention, there is provided a 10 completion arrangement for location in an open-hole section of a hydrocarbon well, the completion arrangement comprising:

a substantially tubular member;

at feast two packers, each having at feast one associated sealing element; and at least one flow restrictor as described above;

15 the at least two packers located around the tubular member and arranged to urge their associated sealing element into engagement with a surface of the hole section, wherein at feast part of the sealing element has a capability for expansion due to contact with fluid: wherein at least one of the at least one flow restrlotors is located in a section of the tubular member between adjacent ones of the at least two packers. 20 The sealing element may be formed of an elastomer material such as

Hydrogenated Nitrile Butadiene Rubber (HNBR) or Nitrile elastcmeric compounds and may be arranged to form a fluid fight seal around the tubuiar member. The sealing element may be arranged to form a seal between the tubular member and walls of the open-hole section following defcrmable expansion and may be further arranged to form 25 a seal between the tubular member and walls of the open-hole section upon contact with a fluid and absorption of it to increase in volume.

Features defined in relation to any one aspect may be provided in combination with any other aspect.

30 BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic illustration of an oil/gas well with a completion arrangement which incorporates multiple flow control devices according to one or more 35 embodiments of the present invention;

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Figure 2 illustrates a partial cross-sectional side view of a flow control device of the completion arrangement of Figure 1. wherein the flow control device is shown in a first state:

Figure 3 illustrates the flow control device of Figure 2 in a second state; and 5 Figure 4 is a cross-sectional view of the flow restrictor of Figure 2 taken along the tine A-A.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates an oil/gas well 10 which comprises a drilled welibore 12 10 which extends from the surface to Intercept an oil/gas bearing formation or reservoir. An open-hole section 14 has located therein a completion arrangement 18 which is hung from upper casing string 18 by means of a liner hanger 20,

The completion arrangement 18 comprises a production tubing string which Includes a number of flow control devices 22 spaced at Intervals, regular or otherwise, 15 along a length thereof, wherein the completion 18 defines an annulus 25 with the wall of the welibore 12. The flow control devices 22 are formed with at least one aperture or flow port 24 which provides fluid communication between the annulus 25 and the interior of the completion 16 to permit oil/gas from the reservoir the enter the completion arrangement 18 and be produced to surface. As such, each flow control 20 device 22 defines an inflow control device.

The completion arrangement 16 also comprises a plurality of packers 28 to provide zonal isolation within the annulus 25. The arrangement of packers 28 with respect to the flow control devices 22 is such that at ieast one flow control device 22 is located within a single zone between adjacent packers 28, However, in other 25 embodiments multiple flow control devices 22 may be located within each zone.

The packers 28 may be of conventional design and may include mechanical packers, inflatable packers, sweilable packers or the like.

Figures 2 and 3 illustrate a flow control device 22 according to one embodiment of the present invention. The device 22 comprises a tubular member or body portion 30 28 which includes a plurality of flow ports 24 (only one shown in Figures 2 and 3) formed through a wall thereof for, as noted above, establishing fluid communication between the completion 18 and annulus 25 (Figure 1). The tubular body 28 in the present embodiment includes opposing threaded connectors 28b, 28b which permit the flow control device 22 to be secured within the completion 18 and in effect define part 35 of the production tubing string.

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In one arrangement, one or more of the flow ports 24 may themselves form the means by which fluid communication is permitted. However, in the present Illustrated embodiment the flow ports 24 each receive a corresponding insert member 30. The insert members 30 may engage with the flow ports 24 by any suitable means, for 5 example via a threaded connection. Each insert member 30 has an Internal orifice 38 of given diameter to create a specific pressure drop for a specific flow rate of fluid. By altering the number of insert members 30 installed in each flow control device 22 and/or the size of the orifice 38 selected, an operator can pre-set the desired pressure drop for a given flow rate.

10 in order to resist erosion from the produced fluid over time, the insert members

30 may be manufactured from a very hard, wear-resistant material such as tungsten carbide,

The flow control devices 22 are provided in the production tubing string across an oil/gas reservoir zone. Produced oil/gas can only enter the production tubing string 15 through the insert members 30 mounted in the devices 22, The insert members 30 restrict the flow of oil into the production tubing string creating a pressure drop for any given flow rate which can be varied by altering the number of insert members 30 and the diameter of the orifice 38 in each insert member 30, The pressure drop created allows oil to be produced from areas of the reservoir which would otherwise remain 20 unproductive as the oil would take the path of feast resistance and flow only from the most permeable regions.

The flow control device 22 includes a blocking arrangement 32 held in proximity to the flow ports 24 by a support structure 34. The support structure 34 is provided in the form of a sleeve and is mounted externally and ooaxsally with the tubuiar body 28 to 25 shroud the flow ports 24, The upper end of the support structure 34 is secured to the tubular body 28 and an annular space 35 is defined between the tubular body 28 and the support structure 24, wherein the blocking arrangement 32 is located within said annular space 35. One or more ports 36 are provided through the wall of the support structure 34 to maintain fluid communication with the flow ports 24, Further, in the 30 present embodiment the lower end of the support sleeve 34 defines an annular opening 37 with the tubular body 28 to also maintain fluid communication with the flow ports 24. However, in other embodiments the lower end of the support sleeve 34 may also be secured to the tubular body 28 such that flow is only permitted through ports 38.

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The blocking arrangement 32 is formed by a sleeve of sweilable material which Is configured to swell upon exposure to a triggering fluid. In the present embodiment the sweilable materia! is configured to swell upon contact with water. When the sweilable material Is in an unswoilen state, as illustrated in Figure 2, the flow ports 24 5 are unobstructed by the blocking arrangement 32 such that fluid may flow into the tubular body 28. Accordingly, the desired restriction effect of the Inserts 30 is not Interfered with or altered by the presence of the blocking arrangement 32.

The configuration in Figure 2 will remain until such time as water becomes present within the producing fluids, at which point the sweilable material will be caused 10 to expand causing the blocking arrangement 32 to extend generally axially by the channelling effect of the support structure 34, In this way the blocking arrangement 32 will encroach over the flow ports 24 to block flow therethrough, as shown in Figure 3. As such, the blocking arrangement 32 may passively shut-off the flow control device 24 at the early stages of water production. This provides significant advantages over prior 15 art systems which may rely on sensing components, complex intervention procedures and the like.

The features illustrated in Figure 4 which correspond to features already described above are denoted by like reference numerals and will not be discussed further. As stated above, Figure 4 illustrates a cross-sectional view of the flow 20 restrictor 22 of Figure 2 taken along the line A ~~ A. in the illustrated arrangement, the tubular body portion 28 is provided with eight equally spaced flow ports 24 about its periphery, with each port 24 having located therein an insert member 30.

Also, in the arrangement of Figure 4, the ports 24 are located at positions around the periphery of the tubular body portion 28 such that pairs of the apertures are 25 diametrically opposite. However, this need not be the case.

It should be understood that the embodiments described above are merely exemplary and that various modifications may be made thereto without departing from the scope of the present invention. For example, in one or more embodiments the flow control device may be configured as a coupling between adjacent tubular members of 30 a production tubing string. Further, the flow control device may form part of a tubular member of the production tubing string. Also, the completion arrangement may comprise some flow control devices which do not include any blocking arrangement. This may permit some flow to be maintained. Further, in the embodiment described above the blocking arrangement is configured to block every flow port within the flow 35 control device. However, in other embodiments not all flow ports may be blocked such

16

that some may remain substantially unrestricted, This may facilitate a reduction in flow rate through the flow port, without complete shut-off.

17

Claims

CLAIMS:

1, A downhole flow control device, comprising:

a tubular member to be located within a well bore and defining an internal flow

5 path;

a flow port formed through a wall of the tubular member to provide fluid communication between the welibore and the internal flew path; and a blocking arrangement mounted in proximity to the flow port and comprising a sweilable material configured to swell upon exposure to a triggering fluid, wherein in an 10 unswoilen state the blocking arrangement does not interfere with the flow port such that flow through the flow port is unrestricted by the blocking arrangement, and in a swollen state the blocking arrangement encroaches over the flow port to restrict flow therethrough,

15 2, The device according to claim 1, wherein swelling of the sweilable material in the presence of the triggering fluid permits the blocking arrangement to passively restrict flow of at least the triggering fluid through the flow port.

3. The devise according to claim 1 or 2, wherein the flow port is configured to 20 establish a pressure drop within the fluid flowing therethrough,

4. The device according to claim 1, 2 or 3, wherein the device comprises an insert located within the flow port, wherein the insert is configured to establish a pressure drop within the fluid flowing therethrough.

25

5. The device according to any preceding claim, configured to permit or control the inflow of fluid from the well bore into the tubuiar member.

8. The device according to any preceding claim, wherein the sweilable material is 30 configured to swell upon exposure to wafer to minimise or restrict flow of water from the welibore into the tubular member.

7. The device according to any preceding claim, wherein the sweilable material is configured to swell upon exposure to oil and/or gas.

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8. The device according to any preceding claim, wherein the blocking arrangement is composed entirely of sweilable materia! and is defined by a sweilable body configured to swell from an unswoilen state to a swollen state to encroach over the flow port,

9, The device according to any preceding claim, wherein the blocking arrangement is at least partially mounted externally of the tubular member.

10, The device according to any preceding claim, wherein the sweilable material of the blocking arrangement is configured to swell generally axially relative to the tubular member to cause the blocking arrangement to encroach over the flow port.

11. The device according to any preceding claim, wherein the sweilable material of the blocking arrangement is configured to swell generally radially relative to the tubular member to cause the blocking arrangement to encroach over the flow port.

12, The device according to any preceding claim, wherein the blocking arrangement is configured to define a seal relative to the flow port.

13. The device according to any preceding claim, wherein the blocking arrangement is generally annular.

14, The device according to any preceding claim, wherein the blocking arrangement is mounted coaxially relative to the tubular member,

15. The device according to any preceding claim, comprising a support structure configured to at least partially support the blocking arrangement relative to the tubular member.

18. The device according to claim 15, wherein the support structure is arranged to bold or support the blocking arrangement in proximity to the flow port and permit the sweilable material of the blocking arrangement to swell and move the blocking arrangement in a desired direction to permit encroachment over the flow port.

17. The device according to claim 15 or 18, wherein the support structure is configured to support the blocking arrangement when the swelling material of said blocking arrangement is in both its unswoilen and swollen states.

18. The device according to claim 15, 18 or 17, wherein the support structure is configured to shroud or extend over the flow port in the tubular member.

19. The device according to any one of claims 15 to 18, wherein the support structure is defined by a separate component which is mounted on the tubular member.

20. The device according to any one of claims 15 to 18, wherein the support structure is at least partially integrally formed with the tubular member.

21. The device according to any one of claims 15 to 20, wherein the support structure is located on the tubular member to define a recess therebetween, wherein the blocking arrangement is at least partially located within said recess. The recess may be generally annular.

22. The device according to any one of claims 15 to 21, wherein the support structure comprises a sleeve located on the tubular member.

23. The device according to any one of claims 15 to 22, wherein the support structure is located substantially coaxially relative to the tubular member.

24. The device according to any one of claims 15 to 23, wherein the support structure is configured to permit fluid communication between the welibore and the internal How path of the tubular member.

25. The device according to claim 24, wherein the support structure defines one or more openings providing fluid communication therethrough.

26. The device according to any preceding claim, comprising a plurality of flow ports formed through the wail of the tubular member.

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27. The device according to claim 28, comprising a single blocking arrangement configured to encroach over a plurality of flow ports.

28. The device according to claim 28, wherein the device comprises a plurality of 5 blocking arrangements each configured to swell to encroach over a least one flow port.

29. The device according to any preceding claim, comprising a plurality of flow ports wherein all of said flow ports are configured to be blocked or restricted by one or more blocking arrangements,

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30. The device according to any one of claims 1 to 28, comprising a plurality of flow ports wherein only some of the flow ports are configured to be blocked or restricted by one or more blocking arrangements.

15 31. The device according to any preceding claim, wherein the tubular member is configured to form part of a production tubing string.

32. The device according to any preceding claim, wherein the tubular member comprises or defines one or more connection arrangements configured to permit said

20 tubular member to form part of a tubing string,

33. A method for controlling How downhole, comprising:

locating a tubular member defining an internal flow path within a well bore, wherein the tubular member defines a flow port through a wall thereof; 25 providing a blocking arrangement in proximity to the flow port and comprising a sweilable material configured to swell upon exposure to a triggering fluid;

initially configuring the blocking arrangement in an unswoilen state such that the blocking arrangement does not interfere with the flow port;

permitting flow through the flow port between the welibore and the internal flow 30 path, wherein the blocking arrangement does not interfere with said flow; and permitting the swellabie material of the blocking arrangement to swell upon exposure to the triggering fluid to cause the biocking arrangement to encroach over the fiow port to restrict flow therethrough.

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34. A flow restrictor assembly to be mounted on a tubular member, comprising:

a blocking arrangement configured to be mounted in proximity to a flow port formed through a wall of the tubular member and comprising a sweilable material configured to swell upon exposure to a triggering fluid, wherein in an unswoilen state 5 the blocking assembly does not interfere with the flow port such that flow through the flow port is unrestricted by the blocking arrangement, and in a swollen state the blocking arrangement encroaches over the flow port to restrict flow therethrough.

35. A downhole flow device, comprising:

a tubuiar body defining an internal fiow path;

a flow port for permitting How of a fluid between an external location and the internal flow path; and a blocking arrangement configured to at least partially block the flow port upon exposure to a triggering fluid.

36. A completion assembly comprising:

a tubing string; and at least one flow control device according to any one of claims 1 to 32.

20 37, The assembly according to claim 38, comprising a plurality of axialiy arranged flow control devices.

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