Title:
Apparatus for controlling the inflow of production fluids from a subterranean well
Kind Code:
A1


Abstract:
A flow control apparatus (100) for controlling the inflow of production fluids into an interior passage (118) of a tubular member (116) in a wellbore includes a flow restrictor (104) positioned in the flow path between an exterior of the tubular member (116) and the passage (118). The flow restrictor (104) has an active chamber (114) and a bypass chamber (112). A bypass tubing is disposed within the bypass chamber (112). The bypass tubing (122) has a constant effective flow area for allowing production fluids to enter the passage (118) from the bypass chamber (112). A plurality of flow blocking members (132) is disposed within the active chamber (114) and cooperate with outlets (128) of the tubular member (116) to autonomously vary an effective flow area for allowing production fluids to enter the passage (118) from the active chamber based upon the constituent composition of the production fluids.



Inventors:
Saetre, Geirmund (Carrollton, TX, US)
Freyer, Rune (Stavanger, NO)
Application Number:
11/807653
Publication Date:
02/21/2008
Filing Date:
05/30/2007
Primary Class:
Other Classes:
166/193
International Classes:
E21B43/12
View Patent Images:
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Primary Examiner:
NEUDER, WILLIAM P
Attorney, Agent or Firm:
LAWRENCE R. YOUST (Dallas, TX, US)
Claims:
What is claimed is:

1. A flow control apparatus for controlling the inflow of production fluids into an interior passage of a tubular member in a wellbore, the flow control apparatus comprising: a flow restrictor positioned in the flow path between an exterior of the tubular member and the passage such that fluid entering the passage from the exterior of the tubular member flows through the flow restrictor, the flow restrictor having an active chamber and a bypass chamber; a bypass tubing disposed within the bypass chamber, the bypass tubing having a constant effective flow area for allowing production fluids to enter the passage from the bypass chamber; and a plurality of flow blocking members disposed within the active chamber, the flow blocking members cooperating with outlets of the tubular member to autonomously vary an effective flow area for allowing production fluids to enter the passage from the active chamber based upon the constituent composition of the production fluids.

2. The flow control apparatus as recited in claim 1 wherein the flow blocking members autonomously reduce the effective flow area for allowing production fluids to enter the passage from the active chamber when the production fluids include an undesired fluid.

3. The flow control apparatus as recited in claim 1 wherein at least a portion of the blocking members have a density greater than that of oil.

4. The flow control apparatus as recited in claim 1 wherein at least a portion of the blocking members have a density less than that of oil.

5. The flow control apparatus as recited in claim 1 wherein a first portion of the blocking members have a density greater than that of oil and wherein a second portion of the blocking members have a density less than that of oil.

6. The flow control apparatus as recited in claim 1 wherein a first portion of the blocking members have a density that is greater than that of a second portion of the blocking members.

7. The flow control apparatus as recited in claim 1 wherein the blocking members are spherically shaped.

8. The flow control apparatus as recited in claim 1 further comprising nozzles disposed within the outlets of the tubular member.

9. The flow control apparatus as recited in claim 1 further comprising tubular flow restrictors associated with the outlets of the tubular member.

10. The flow control apparatus as recited in claim 1 wherein the bypass tubing extends at least partially circumferentially around the tubing member.

11. The flow control apparatus as recited in claim 1 wherein the bypass tubing has a plurality of opening in a sidewall portion thereof.

12. The flow control apparatus as recited in claim 1 wherein the bypass tubing further comprises at least two independent bypass tubings each having a constant effective flow area for allowing production fluids to enter the passage from the bypass chamber.

13. The flow control apparatus as recited in claim 1 wherein the effective flow areas for allowing production fluids to enter the passage from the bypass chamber is between about ten and about thirty-five percent of the initial effective flow area for allowing production fluids to enter the passage from the active chamber.

14. The flow control apparatus as recited in claim 1 wherein the effective flow area for allowing production fluids to enter the passage from the bypass chamber is between about fifteen and about twenty-five percent of the initial effective flow area for allowing production fluids to enter the passage from the active chamber.

15. The flow control apparatus as recited in claim 1 wherein the effective flow area for allowing production fluids to enter the passage from the bypass chamber is about twenty percent of the initial effective flow area for allowing production fluids to enter the passage from the active chamber.

16. A flow control apparatus for controlling the inflow of production fluids into an interior passage of a tubular member in a wellbore, the flow control apparatus comprising: a sand control screen element positioned in the flow path between an exterior of the tubular member and the passage; a flow restrictor positioned in the flow path between the sand control screen element and the passage, the flow restrictor having an active chamber and a bypass chamber; a bypass tubing disposed within the bypass chamber, the bypass tubing having a constant effective flow area for allowing production fluids to enter the passage from the bypass chamber; and a plurality of flow blocking members disposed within the active chamber, the flow blocking members cooperating with outlets of the tubular member to autonomously vary an effective flow area for allowing production fluids to enter the passage from the active chamber based upon the constituent composition of the production fluids.

17. The flow control apparatus as recited in claim 16 wherein the flow blocking members autonomously reduce the effective flow area for allowing production fluids to enter the passage from the active chamber when the production fluids include an undesired fluid.

18. The flow control apparatus as recited in claim 16 wherein the bypass tubing extends at least partially circumferentially around the tubing member.

19. The flow control apparatus as recited in claim 16 wherein the bypass tubing has a plurality of opening in a sidewall portion thereof.

20. The flow control apparatus as recited in claim 16 wherein the bypass tubing further comprises at least two independent bypass tubings each having a constant effective flow area for allowing production fluids to enter the passage from the bypass chamber.

21. A flow control apparatus for controlling the inflow of production fluids into an interior passage of a tubular member in a wellbore, the flow control apparatus comprising: a flow restrictor positioned in the flow path between an exterior of the tubular member and the passage, the flow restrictor having an active chamber and a bypass chamber; a bypass tubing disposed within the bypass chamber, the bypass tubing extends at least partially circumferentially around the tubing member and having a plurality of opening in a sidewall portion thereof, the bypass tubing having a constant effective flow area for allowing production fluids to enter the passage from the bypass chamber; and a plurality of flow blocking members disposed within the active chamber, the flow blocking members cooperating with outlets of the tubular member to autonomously reduce an effective flow area for allowing production fluids to enter the passage from the active chamber when the production fluid includes an undesired fluid type.

Description:

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation-in-part application of co-pending application Ser. No. 11/466,022 filed Aug. 21, 2006 entitled Autonomous Inflow Restrictors for Use in a Subterranean Well, the entire contents of which is hereby incorporated by reference.

TECHNICAL FIELD OF THE INVENTION

This invention relates, in general, to controlling the production of fluids from a well that traverses a hydrocarbon bearing subterranean formation and, in particular, to an apparatus for controlling the flow rate of production fluids from the subterranean well based upon the constituent composition of the production fluid.

BACKGROUND OF THE INVENTION

Without limiting the scope of the present invention, its background will be described with reference to producing fluid from a subterranean formation, as an example.

During the completion of a well that traverses a hydrocarbon bearing subterranean formation, production tubing and various equipment are installed in the well to enable safe and efficient production of the formation fluids. For example, to prevent the production of particulate material from an unconsolidated or loosely consolidated subterranean formation, certain completions include one or more sand control screens positioned proximate the desired production intervals. In other completions, to control the flow rate of production fluids into the production tubing, it is common practice to install one or more flow control devices within the tubing string.

Recently, attempts have been made to utilize fluid flow control devices within completions requiring sand control. For example, in one such device, after production fluids flows through the filter media of the sand control screen, the fluids are directed into a flow control labyrinth. A slidable sleeve on the labyrinth controls the fluid velocity therethrough. The slidable sleeve is moved by a remotely and electrically-operated device placed in the sand control screen. The fluid leaving the labyrinth passes to the tubing string for carrying to the surface. While certain benefits have been achieved through the use of such devices, many of these devices are complicated to operate and have suffered from poor reliability.

Accordingly, need has arisen for a fluid flow control device for controlling the inflow of formation fluids in a completion requiring sand control. A need has also arisen for such a fluid flow control device that is reliable in a variety of flow conditions.

SUMMARY OF THE INVENTION

The present invention disclosed herein comprises a flow control apparatus for controlling the inflow of formation fluids. The flow control apparatus of the present invention can be used in completions requiring sand control. In addition, the flow control apparatus of the present invention is reliable in a variety of flow conditions.

In one aspect, the present invention is directed to a flow control apparatus for controlling the inflow of production fluids into an interior passage of a tubular member in a wellbore. The flow control apparatus includes a flow restrictor positioned in the flow path between an exterior of the tubular member and the passage such that fluid entering the passage from the exterior of the tubular member flows through the flow restrictor. The flow restrictor includes an active chamber and a bypass chamber. Disposed within the bypass chamber is a bypass tubing having a constant effective flow area for allowing production fluids to enter the passage from the bypass chamber. Disposed within the active chamber is a plurality of flow blocking members that cooperate with outlets of the tubular member to autonomously vary an effective flow area for allowing production fluids to enter the passage from the active chamber based upon the constituent composition of the production fluids.

In one embodiment of the flow control apparatus, the flow blocking members autonomously reduce the effective flow area for allowing production fluids to enter the passage from the active chamber when the production fluids include an undesired fluid such as water or gas in an oil production scenario or water in a gas production scenario. In certain embodiments, at least a portion of the blocking members have a density greater than that of oil. In other embodiments, at least a portion of the blocking members have a density less than that of oil. In still other embodiments, a first portion of the blocking members have a density greater than that of oil and a second portion of the blocking members have a density less than that of oil. In yet further embodiments, a first portion of the blocking members have a density that is greater than that of a second portion of the blocking members. In any of these embodiments, the blocking members may have a spherical shape or other suitable shape. Also, in any of these embodiments, nozzles or other flow control devices such as tubular restrictor members may be associated with the outlets of the tubular member.

In one embodiment of the flow control apparatus, the bypass tubing may extend at least partially circumferentially around the tubing member. In another embodiment, the bypass tubing may have a plurality of opening in a sidewall portion thereof. In a further embodiment, the bypass tubing may include at least two independent bypass tubings each having a constant effective flow area for allowing production fluids to enter the passage from the bypass chamber.

In one embodiment of the flow control apparatus, the effective flow area for allowing production fluids to enter the passage from the bypass chamber is between about ten and about thirty-five percent of the initial effective flow area for allowing production fluids to enter the passage from the active chamber when the flow blocking members are not cooperating with the outlets. In another embodiment, the effective flow area for allowing production fluids to enter the passage from the bypass chamber is between about fifteen and about twenty-five percent of the initial effective flow area for allowing production fluids to enter the passage from the active chamber. In still another embodiment, the effective flow area for allowing production fluids to enter the passage from the bypass chamber is about twenty percent of the initial effective flow area for allowing production fluids to enter the passage from the active chamber.

In another aspect, the present invention is directed to a flow control apparatus for controlling the inflow of production fluids into an interior passage of a tubular member in a wellbore. The flow control apparatus includes a sand control screen element positioned in the flow path between an exterior of the tubular member and the passage. A flow restrictor is positioned in the flow path between the sand control screen element and the passage. The flow restrictor includes an active chamber and a bypass chamber. Disposed within the bypass chamber is a bypass tubing having a constant effective flow area for allowing production fluids to enter the passage from the bypass chamber. Disposed within the active chamber is a plurality of flow blocking members that cooperate with outlets of the tubular member to autonomously vary an effective flow area for allowing production fluids to enter the passage from the active chamber based upon the constituent composition of the production fluids.

In a further aspect, the present invention is directed to a flow control apparatus for controlling the inflow of production fluids into an interior passage of a tubular member in a wellbore. The flow control apparatus includes a flow restrictor positioned in the flow path between an exterior of the tubular member and the passage. The flow restrictor has an active chamber and a bypass chamber. A bypass tubing is disposed within the bypass chamber. The bypass tubing extends at least partially circumferentially around the tubing member and has a plurality of opening in a sidewall portion thereof. The bypass tubing has a constant effective flow area for allowing production fluids to enter the passage from the bypass chamber. A plurality of flow blocking members are disposed within the active chamber. The flow blocking members cooperating with outlets of the tubular member to autonomously reduce an effective flow area for allowing production fluids to enter the passage from the active chamber when the production fluid includes an undesired fluid type.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:

FIG. 1 is a schematic illustration of a well system operating a plurality of fluid flow control devices according to the present invention;

FIG. 2 is side view partially in cross section of a fluid flow control device according to the present invention, which may be used in the system of FIG. 1;

FIG. 3 is a side view of the fluid flow control device of FIG. 2 with an outer housing of the flow restrictor section removed;

FIG. 4A-4B are cross sectional views of a fluid flow control device according to the present invention having blocking members that have a density greater than oil;

FIG. 5A-5B are cross sectional views of a fluid flow control device according to the present invention having blocking members that have a density less than oil;

FIG. 6A-6B are cross sectional views of a fluid flow control device according to the present invention having certain blocking members that have a density greater than oil and certain blocking members that have a density less than oil;

FIG. 7 is a cross sectional view of a fluid flow control device according to the present invention having a single perforated bypass tubing;

FIG. 8 is a cross sectional view of a fluid flow control device according to the present invention having two perforated bypass tubings;

FIG. 9 is side view partially in cross section of another embodiment of a fluid flow control device according to the present invention, which may be used in the system of FIG. 1; and

FIG. 10 is a side view of the fluid flow control device of FIG. 9 with an outer housing of the flow restrictor section removed.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.

Referring initially to FIG. 1, therein is depicted a well system including a plurality of fluid flow control devices embodying principles of the present invention that is schematically illustrated and generally designated 10. In the illustrated embodiment, a wellbore 12 extends through the various earth strata. Wellbore 12 has a substantially vertical section 14, the upper portion of which has installed therein a casing string 16. Wellbore 12 also has a substantially horizontal section 18 that extends through a hydrocarbon bearing subterranean formation 20. As illustrated, substantially horizontal section 18 of wellbore 12 is open hole.

Positioned within wellbore 12 and extending from the surface is a tubing string 22. Tubing string 22 provides a conduit for formation fluids to travel from formation 20 to the surface. Positioned within tubing string 22 is a plurality of seal assemblies 24, 26, 28, 30, 32, 34 and a plurality of fluid flow control devices 36, 38, 40, 42, 44. Each of the seal assemblies 24, 26, 28, 30, 32, 34 provides a fluid seal between tubing string 22 and the wall of wellbore 12. Each pair of seal assemblies defines a production interval. As illustrated, seal assemblies 24, 26 define production interval 46, seal assemblies 26, 28 define production interval 48, seal assemblies 28, 30 define production interval 50, seal assemblies 30, 32 define production interval 52 and seal assemblies 32, 34 define production interval 54.

Through use of the fluid flow control devices 36, 38, 40, 42, 44 of the present invention and by providing numerous production intervals 46, 48, 50, 52, 54, precise control over the volume and composition of the produced fluids is enabled. For example, in an oil production operation if an undesired fluid component, such as water or gas, is entering one of the production intervals, the fluid flow control device in that interval will autonomously restrict the production of fluid from that production interval. Accordingly, when a production interval corresponding to a particular one of the fluid flow control devices produces a greater proportion of an undesired fluid, the fluid flow control device in that interval will increasingly restrict flow from that interval. Thus, the other production intervals which are producing a greater proportion of desired fluid, in this case oil, will contribute more to the production stream entering tubing string 22. In particular, there will be a greater pressure drop from formation 20 to tubing string 22, resulting in a greater production of the desired fluid, due to the increased restriction to flow from the production interval or intervals producing a greater proportion of the undesired fluid.

In the illustrated embodiment, each of the fluid flow control devices 36, 38, 40, 42, 44 provides not only fluid flow control capability but also sand control capability. The sand control screen elements or filter media associated with fluid flow control devices 36, 38, 40, 42, 44 are designed to allow fluids to flow therethrough but prevent particulate matter of sufficient size from flowing therethrough. The exact design of the screen element associated with fluid flow control devices 36, 38, 40, 42, 44 is not critical to the present invention as long as it is suitably designed for the characteristics of the formation fluids and any treatment operations to be performed. For example, the sand control screen may utilize a nonperforated base pipe having a wire wrapped around a plurality of ribs positioned circumferentially around the base pipe that provide stand off between the base pipe and the wire wrap. Alternatively, a fluid-porous, particulate restricting, metal material such as a plurality of layers of a wire mesh that are sintered together to form a fluid porous wire mesh screen could be used as the filter medium. As illustrated, a protective outer shroud having a plurality of perforations therethrough may be positioned around the exterior of the filter medium.

Even though FIG. 1 depicts the fluid flow control devices of the present invention in an open hole environment, it should be understood by those skilled in the art that the fluid flow control devices of the present invention are equally well suited for use in cased wells. Also, even though FIG. 1 depicts one fluid flow control device in each production interval, it should be understood by those skilled in the art that any number of fluid flow control devices of the present invention may be deployed within a production interval without departing from the principles of the present invention.

In addition, even though FIG. 1 depicts the fluid flow control devices of the present invention in a horizontal section of the wellbore, it should be understood by those skilled in the art that the fluid flow control devices of the present invention are equally well suited for use in deviated or vertical wellbores. Accordingly, it should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure. Further, even though FIG. 1 depicts the fluid flow control devices of the present invention as including sand control screen elements, it should be understood by those skilled in the art that the fluid flow control devices of the present invention are equally well suited for use in completions that do not require sand control.

Referring next to FIGS. 2-3, therein is depicted a fluid flow control device according to the present invention that is representatively illustrated and generally designated 100. Fluid flow control device 100 may be suitably coupled to other similar fluid flow control devices, production packers, production tubulars or other downhole tools to form a tubing string such as that described above. Fluid flow control device 100 includes a sand control screen section 102 and a flow restrictor section 104. Sand control screen section 102 includes a suitable sand control screen element or filter medium, such as a wire wrap screen, a woven wire mesh screen or the like, designed to allow fluids to flow therethrough but prevent particulate matter of sufficient size from flowing therethrough. In the illustrated embodiment, a protective outer shroud 106 having a plurality of perforations 108 is positioned around the exterior of the filter medium.

Flow restrictor section 104 is configured in series with sand control screen section 102 such that fluid must pass through sand control screen section 102 prior to entering flow restrictor section 104. Flow restrictor section 104 includes an outer housing 110 that defines an annular bypass chamber 112 and an annular active chamber 114 with base pipe 116. Base pipe 116 defines an internal flow passageway 118 that forms a portion of the interior of the tubing string. Disposed between bypass chamber 112 and active chamber 114 is an annular retainer ring 120. Disposed within bypass chamber 112 is a bypass tubing 122. Bypass tubing 122 includes a plurality of openings 124 and an outlet 126 that is in fluid communication with internal flow passageway 118 of base pipe 116. Outlet 126 has a predetermined effective flow area that determines the restriction to flow through bypass tubing 122 into internal flow passageway 118.

In the portion of base pipe 116 adjacent to active chamber 114, base pipe 116 includes a plurality of outlets 128 circumferentially spaced therearound. Outlets 128 are designed to provide a fluid passageway from active chamber 114 to internal flow passageway 118. In the illustrated embodiment, outlets 128 have nozzles 130 positioned therein. Each of the nozzles 130 has a predetermined effective flow area. Together, the effective flow areas of all the nozzles 130 define the maximum effective flow area of active chamber 114. As used herein the term effective flow area refers to the combined influence of the length of a flow restriction and the cross-sectional flow area of the flow restriction under Bernoulli's principle wherein a relationship exists between the exit velocity of the fluid from the nozzle and the inlet pressure of the fluid at the nozzle, the outlet pressure of the fluid at the nozzle, the density of the fluid and the entrance velocity of the fluid.

Disposed within active chamber 114 is a plurality of flow blocking members 132, depicted as spherical members or balls. Flow blocking members 132 are retained within active chamber 114 by retainer ring 120 and cooperate with outlets 128 to restrict the flow when an undesired fluid component is included within the production fluids that enter flow restrictor section 104. For example, when the desired fluid component of oil is produced along with an undesirable fluid component of water, the density of members 132 is such that certain of the outlets 128 are blocked by certain of the members 132 to shut off or choke the flow therethrough.

As explained in greater detail below, the density of each of the members 132 is preferably greater than that of the oil enabling each to either maintain a position within active chamber 114 distant from outlets 132 when either no water or only a very small proportion of water is present in active chamber 114, or a position shutting off or choking flow through outlets 128 when a larger proportion of water is present in active chamber 114. Thus, when the production fluid is mainly oil, members 132 will be positioned relatively distant from outlets 128, for example, at the bottom of active chamber 114. When a sufficient proportion of water is present in the production fluid, however, members 132 will restrict flow of the water by shutting off or choking flow through certain ones of the outlets 128.

Even when the production from an interval includes a high percentage of an undesired fluid, a complete closedown of production from such a production interval may not be wanted. In the illustrated embodiment, bypass tubing 122 assures that a complete shut off will not occur. Specifically, in the illustrated embodiment, bypass tubing 122 remains open to a certain amount of flow even during production of a high percentage of an undesired fluid. For example, the effective flow area of outlet 126 of bypass tubing 122 and the initial effective flow area nozzles 130, i.e., the flow area when none of the members 132 are blocking any of the outlets 128, may allow between about ten and about thirty-five percent of the entire production stream into internal flow passageway 118 through outlet 126 when the entire production stream is of a desired fluid. In certain embodiments, the effective flow area of outlet 126 and the initial effective flow area of nozzles 130 may allow between about fifteen and about twenty-five percent of the entire production stream into internal flow passageway 118 through outlet 126 when the entire production stream is of a desired fluid. In yet other embodiments, the effective flow area of outlet 126 and the initial effective flow area of nozzles 130 may allow about twenty percent of the entire production stream into internal flow passageway 118 through outlet 126 when the entire production stream is of a desired fluid.

As production of an undesired fluid takes place and members 132 begin to block some of the outlets 128, the effective flow area of nozzles 130 is reduced, thereby increasing the restriction to flow therethrough. The effective flow area of outlet 126, however, remains unchanged such that a greater percentage of the production stream passes through bypass tubing 122 and outlet 126 relative to outlets 128. The ratio of production through bypass tubing 122 and outlet 126 relative to outlets 128 continues to adjust until members 132 block all of the outlets 128. In this configuration, all or the vast majority of production passes through bypass tubing 122 and outlet 126. Also, in this configuration, the volume of production through flow control device 100 is substantially reduced, thereby preferentially reducing the production of the unwanted fluid. As such, flow restrictor section 104 is operable to restrict the flow of the production fluids through fluid flow control device 100.

Even though fluid flow control device 100 has been described as incorporating nozzles 130 within outlets 128, it should be understood by those skilled in the art that outlets 128 could operate without nozzles 130 positioned therein or other types of flow control devices could alternatively be associated with outlets 128 without departing from the principles of the present invention. For example, tubular flow restrictors having seats that receive members 132 allowing members 132 to cooperate with outlets 128 to autonomously vary the effective flow area therethrough could alternatively be used such as tubular flow restrictors 10 and seats 22 described in co-pending application Ser. No. 11/466,022 filed Aug. 21, 2006 entitled Autonomous Inflow Restrictors for Use in a Subterranean Well, the entire contents of which is hereby incorporated by reference.

Referring now to FIGS. 4A-6B, the operation of fluid flow control device 100 in various flow regimes and with various configurations of flow blocking members will now be described. FIG. 4A depicts a flow regime in which all or nearly all of the production fluid is oil. Members 132 are preferably not buoyant as long as the well is producing a sufficient proportion of oil. As can be seen, members 132 are substantially positioned in a bottom portion of active chamber 114 and generally at distance from most of the outlets 128. This result is achieved by forming members 132 to have a density that is greater than that of oil and preferably about that of the water expected to be produced or at least of a density between the density of water and the density of oil. For example, the density of members 132 may preferably be about 1030 kg/m3.

As best seen in FIG. 4B, as water is produced into fluid flow control device 100, members 132 provide the capability of increasingly restricting flow of fluid therethrough. When the density of the produced fluid increases by a sufficient amount, members 132 become neutrally buoyant and are carried by the water phase and engage outlets 128, due to the pressure drop across the outlets, thereby restricting flow of the production fluid therethrough. Neutral buoyancy of members 132 only occurs when a sufficient proportion of water is produced. As illustrated, member 132 have engaged the lowest three outlets 128. Specifically, an oil and water interface level exists within fluid flow control device 100 near the locations identified as 136, 138. Thus, when the production fluid contains an undesirable fluid such as water, restriction to flow through fluid flow control device 100 increases. A greater proportion of undesirable fluids in the produced fluid results in a greater restriction to flow through fluid flow control device 100. This results in production from those production intervals producing undesirable fluids being reduced due to the increased restriction to flow through its corresponding fluid flow control device 100, while production from other production intervals producing more desirable fluids is increased due to the overall pressure drop in the system.

FIG. 5A depicts a flow regime in which all or nearly all of the production fluid is oil. Members 132 are preferably buoyant as long as the well is producing a sufficient proportion of oil. As can be seen, members 132 are substantially positioned in a top portion of active chamber 114 and generally at distance from most of the outlets 128. This is achieved by selecting members 132 that have a density of about 600 kg/m3 to about 800 kg/m3, which is generally between the density of oil and the density of gas. By selecting an average density preferably from about 600 kg/m3 to about 800 kg/m3, and by keeping in mind that the density of oil is typically somewhat less than 900 kg/m3, these members 132 will be in a buoyant or free-floating state as long as the gas included in the fluid does not lower the overall density of the production fluid below the selected member density.

As best seen in FIG. 5B, if an influx of gas results in an overall density of the fluid approximately equal to the member density, then these members 132 will have neutral buoyancy and will be dragged to the upper outlets 128 due to the pressure drop thereacross. Also, since the density of certain members 132 is between the density of oil and the density of gas, some of these members 132 will be positioned at the interface between the oil and gas near the locations identified as 140, 142. If the interface descends in chamber 114 due to an increase in the proportion of gas in the production fluids, an increasing number of outlets 128 will be blocked by members 132. Thus, when the production fluid contains an undesirable fluid such as gas, restriction to flow through fluid flow control device 100 increases. A greater proportion of undesirable fluids in the produced fluid results in a greater restriction to flow through fluid flow control device 100. This results in production from those production intervals producing undesirable fluids being reduced due to the increased restriction to flow through its corresponding fluid flow control device 100, while production from other production intervals producing more desirable fluids is increased due to the overall pressure drop in the system.

FIG. 6A depicts a flow regime in which all or nearly all of the production fluid is oil. Certain of members 132 are preferably not buoyant as long as the well is producing a sufficient proportion of oil. As can be seen, these members 132 are substantially positioned in a bottom portion of active chamber 114 and generally at distance from most of the outlets 128. Other of members 132 are preferably buoyant as long as the well is producing a sufficient proportion of oil. As can be seen, these members 132 are substantially positioned in a top portion of active chamber 114 and generally at distance from most of the outlets 128. This embodiment of fluid flow control device is particularity use in three phase flow scenarios.

Specifically, as best seen in FIG. 6B, the production fluid is depicted as being stratified in chamber 114 into a layer of water at the bottom, a layer of oil in the middle and a layer of gas at the top. As illustrated, one of the members 132 is blocking flow through the uppermost outlet 128 and another of the members 132 is blocking flow through the lowermost outlet 128. In this embodiment, not all the members 132 have the same density. Preferably, certain of the members 132 have a density of about 600 kg/m3 to about 800 kg/m3, which is generally between the density of oil and the density of gas, while other of the members 132 have a density that is greater than that of oil and preferably about that of the water expected to be produced or at least of a density between the density of water and the density of oil. For example, the density of theses members 124 may preferably be about 1030 kg/m3. As illustrated, since the density of certain members 132 is between the density of oil and the density of gas, some of these members 132 will be positioned at the interface between the oil and gas near the locations identified as 144, 146. In addition, other of these members 132 are neutral buoyancy at an oil and water interface level within chamber 114 near the locations identified as 148, 150.

Even though members 132 have been described as having discrete densities based upon their desired service, it should be understood by those skilled in the art that all of the members intended to block an outlet due to gas production do not necessarily have the same density and all of the members intended to block an outlet due to water production do not necessarily have the same density. Instead, the members in each category could have a range of different densities so that the members are neutrally buoyant in different densities of production fluids. In this manner, a greater number of the members intended to block an outlet due to water production would be available to restrict flow of the production fluid having a greater proportion of water, and a greater number of the members intended to block an outlet due to gas production would be available to restrict flow of the production fluid having a greater proportion of gas.

Referring next to FIG. 7, therein is depicted a cross sectional view of a fluid flow control device according to the present invention at a location near a bypass tubing. As described above, disposed within bypass chamber 112 of fluid flow control device 100 is a bypass tubing 122. As illustrated, bypass tubing 122 includes a plurality of openings 124 that allow productions fluids to enter bypass tubing 122. Bypass tubing 122 includes manifold 152 that receives fluids from each of two partially circumferential tubing sections. A portion of manifold 152 extends into base pipe 116 and includes outlet 126 (see FIG. 2). As described above, outlet 126 provides a flow restriction to production fluids entering internal flow passageway 118 via bypass tubing 122, while production fluids are allowed to enter bypass tubing 122 through openings 124 with little pressure drop.

Even though bypass tubing 122 has been described as having a single outlet 126, it should be understood by those skilled in the art that other configurations of bypass tubings having other numbers of outlets are within the scope of the present invention. For example, as best seen in FIG. 8, the illustrated embodiment of fluid flow control device 100 includes two independent bypass tubings 154, 156. Bypass tubing 154 includes a plurality of openings 158 and a manifold 160 that receives fluids from each of two partially circumferential tubing sections of bypass tubing 154. Likewise, bypass tubing 156 includes a plurality of openings 162 and a manifold 164 that receives fluids from each of two partially circumferential tubing sections of bypass tubing 156. In this embodiment, each of manifolds 160, 164 includes an outlet that is in fluid communication with internal flow passageway 118. As such, the bypass tubing of the present invention may include any number of manifolds coupled to any number of tubing sections and have any number of outlets into internal flow passageway 118.

Referring next to FIGS. 9-10, therein is depicted an alternate fluid flow control device according to the present invention that is representatively illustrated and generally designated 200. Fluid flow control device 200 may be suitably coupled to other similar fluid flow control devices, production packers, production tubulars or other downhole tools to form a tubing string such as that described above. Fluid flow control device 200 includes a sand control screen section 202 and a flow restrictor section 204. Sand control screen section 202 includes a suitable sand control screen element or filter medium, such as a wire wrap screen, a woven wire mesh screen or the like, designed to allow fluids to flow therethrough but prevent particulate matter of sufficient size from flowing therethrough. In the illustrated embodiment, a protective outer shroud 206 having a plurality of perforations 208 is positioned around the exterior of the filter medium.

Flow restrictor section 204 is configured in series with sand control screen section 202 such that fluid must pass through sand control screen section 202 prior to entering flow restrictor section 204. Flow restrictor section 204 includes an outer housing 210 that defines an annular bypass chamber 212 and an annular active chamber 214 with base pipe 216. Base pipe 216 defines an internal flow passageway 218 that forms a portion of the interior of the tubing string. Disposed between bypass chamber 212 and active chamber 214 is an annular retainer ring 220. The upstream end of active chamber 214 is defined by annular retainer ring 221. Disposed within bypass chamber 212 is a bypass tubing 222. Bypass tubing 222 includes a plurality of openings 224 and an outlet 226 that is in fluid communication with internal flow passageway 218 of base pipe 216. Outlet 226 has a predetermined effective flow area that determines the restriction to flow through bypass tubing 222 into internal flow passageway 218.

In the portion of base pipe 216 adjacent to active chamber 214, base pipe 216 includes a plurality of outlets 228 circumferentially spaced therearound. Outlets 228 are designed to provide a fluid passageway from active chamber 214 to internal flow passageway 218. In the illustrated embodiment, outlets 228 have nozzles 230 positioned therein. Each of the nozzles 230 has a predetermined effective flow area. Together, the effective flow areas of all the nozzles 230 define the maximum effective flow area of active chamber 214.

Disposed within active chamber 214 is a plurality of flow blocking members 232, depicted as spherical members or balls. Flow blocking members 232 are retained within active chamber 214 by retainer rings 220, 221 and cooperate with outlets 228 to restrict the flow when an undesired fluid component is included within the production fluids that enter flow restrictor section 204. For example, when the desired fluid component of oil is produced along with an undesirable fluid component of water, the density of members 232 is such that certain of the outlets 228 are blocked by certain of the members 232 to shut off or choke the flow therethrough.

Even when the production from an interval includes a high percentage of an undesired fluid, a complete closedown of production from such a production interval may not be wanted. In the illustrated embodiment, bypass tubing 224 assures that a complete shut off will not occur. Specifically, in the illustrated embodiment, bypass tubing 222 remains open to a certain amount of flow even during production of a high percentage of an undesired fluid. Specifically, as production of an undesired fluid takes place and members 232 begin to block some of the outlets 228, the effective flow area of nozzles 230 is reduced, thereby increasing the restriction to flow therethrough. The effective flow area of outlet 226, however, remains unchanged such that a greater percentage of the production stream passes through bypass tubing 222 and outlet 226 relative to outlets 228. The ratio of production through bypass tubing 222 and outlet 226 relative to outlets 228 continues to adjust until members 232 block all of the outlets 228. In this configuration, all or the vast majority of production passes through bypass tubing 222 and outlet 226. Also, in this configuration, the volume of production through flow control device 200 is substantially reduced, thereby preferentially reducing the production of the unwanted fluid. As such, flow restrictor section 204 is operable to restrict the flow of the production fluids through fluid flow control device 200.

It may now be fully appreciated that fluid flow control devices of the present invention may have various configurations described above and are capable of achieving a variety of desirable benefits in different situations. For example, when it is desired to limit the production of water from an oil or a gas well, the configuration of FIGS. 4A-4B may be used with the members each having a density approximately equal to, or less than that of water. In this manner, the members will either have neutral buoyancy in the water, or will float on top of the water, such that the members will be carried by the water to the outlets to thereby increasingly restrict or prevent flow therethrough.

As another example, when it is desired to limit the production of gas from an oil well, the configuration of FIGS. 5A-5B may be used with the members each having a density less than that of oil. In this manner, the members will float on top of the oil, or remain at the top of the chamber and away from the outlets until a sufficient proportion of gas is produced. If such a sufficient proportion of gas is produced, the members will descend within the chamber and close off or at least increasingly restrict flow through the outlets to thereby restrict or prevent flow therethrough.

Note that the case of restricting production of gas from an oil well is quite different from the case of restricting production of water from an oil or a gas well. When restricting the production of gas from an oil well, the members are preferably not neutrally buoyant in the liquid phase, otherwise the members would be carried with the flow of the liquid to the outlets. When restricting the production of water from an oil or a gas well, the members may be neutrally buoyant in the liquid phase, since it is desired for the members to be carried with the flow of the liquid.

As yet another example, when it is desired to limit the production of gas and water from an oil well, the configurations of FIGS. 6A-6B may be used, with certain members having a density less than that of oil, and certain members having a density greater than that of oil. In this manner, certain members will float on top of the oil, or be oriented to the top of the chamber and away from the outlets until a sufficient proportion of gas is produced to allow the members to close off or at least increasingly restrict flow through the upper outlets. Also, in this manner, certain members will remain toward the bottom of the chamber and away from the outlets until a sufficient proportion of water is produced to allow the members to close off or at least increasingly restrict flow through the lower outlets.

While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.