FLOW CONTROL APPARATUS FOR USE IN A SUBTERRANEAN WELL

Abstract: The downhole flow control assembly has a first variable flow choke (150) and a second flow choke (200). The first and the second variable flow choke each define an inner bore such that a fluid path is defined by each of the inner bores when the chokes are coupled in tandem. The first variable flow choke can place its respective inner bore can in fluid communication with a production zone of the well for regulating a fluid flow from that production zone. The second variable flow choke can place its respective inner bore in fluid communication a second production zone of the well for regulating a fluid flow from that production zone.

Description: FLOW CONTROL APPARATUS FOR USE IN A SUBTERRANEAN WELL Technical Field The present invention relates generally to downhole fluid flow control devices for a subterranean well, and in particular to control and selective regulation of fluid flow through a tubing string disposed within a well having multiple production zones. Background of the Invention An item of well completion equipment, particularly for subsea well completions, is a flow control device. These flow control devices have been manually adjusted, typically at the surface, to allow fluid flow into a production tubing string. These flow control devices have been used where a well has multiple production zones, and individual on or off regulation of the fluid flow from each zone into the tubing string is desired. Control of the flow from each of the zones in a well controls the producing characteristics of the well, such as formation pressure. If the pressure cannot be regulated, then the producing lifespan of a well could be unnecessarily, and undesirably, shortened. For example, the flow from one production zone may provide more desirable petroleum products than another production zone. Accordingly, it would be desirable to allow a greater flow from the desirable formation and less from the less attractive formation to optimize the overall production capacity. Flow control is also desirable because regulatory authorities have required reports for each production flow rate from each production zone, requiring devices or measurement devices to determine or control the production rate of each zone. Safety concerns could also dictate controlling the rate of production from each zone. Flow control has been typically provided by full-open/full-close devices such as downhole sliding valves, ball valves, or choke assemblies to provide either no-flow or full-flow conditions from a production zone. Thus, downhole valves have not been able to variably, or incrementally, regulate fluid flow. Furthermore, such downhole valves do not allow ready access past the valve for well maintenance operations. An example of such a conventional downhole valve is provided by PCT Application WO 99/31352, published 24 June 1999, to applicant Schlumberger Technology Corporation, which recites an isolation system for two producing formations . The device provides isolation for flow and control capacity for a well having two production zones. That is, the device is a fully-closed or fully-opened control for dual production zones to isolate the respective flow of one production zone from the other for eliminating intermingling of production fluids from the different zones. Variable flow control has been typically provided by devices configured at the surface. Once installed, these variable flow controls could not be adjusted to compensate for changes in the production flow as well as formation pressures. Such downhole chokes simply limit flow from a certain formation or wellbore. Unfortunately, conventional downhole valves and chokes are limited in their usefulness because intervention, and production down-time, is required to adjust the fixed orifice or to otherwise open or close the downhole valve. Furthermore, the deployment and installation of multiple flow chokes becomes a time and labor involved process to allow adjustment of each individual choke. Furthermore, present devices have not allowed ready flow control downhole for wells having multiple production zones, either in the fashion of a multilateral well, or in a single bore well penetrating several production zones. Accordingly, a need exits for a variable flow control device that is rugged, reliable, and long-lived, so that it may be utilized in completions without requiring frequent servicing. A need also exists for the ability to provide variable flow control for multiple production zones within a downhole environment, either in the context of adjacent flow control, distal flow control, or a combinations thereof for deployment in the well. Summary of the Invention Provided is a downhole flow control assembly for controlling a fluid production flow for a well. The downhole flow control assembly has a first variable flow choke and a second flow choke. The first and the second variable flow choke each define an inner bore such that a fluid path is defined by each of the inner bores when the chokes are coupled in tandem. The first variable flow choke can place its respective inner bore can in fluid communication with a production zone of the well for regulating a fluid flow from that production zone. The second variable flow choke can place its respective inner bore in fluid communication a second production zone of the well for regulating a fluid flow from that production zone. In yet another aspect of the invention, a selective aspect component is provided which is also responsive to a remote command. In response to a remote command, the valve allows access through the flow member by a well tool to regions below the flow chokes. Brief Description of the Drawings The accompanying drawings are incorporated into and form a part of the specification to illustrate examples of the present invention. The drawings together with the description serve to explain the principles of the invention. The drawings are only included for purposes of illustrating preferred and alternative examples of how the inventions can be made and used and are not to be construed as limiting the inventions to only the illustrated and described examples. Various advantages and features of the present inventions will be apparent from a consideration of the drawings in which: FIGURE 1 is a plan view of a remotely-controlled, multi-zone variable flow choke of the present invention deployed in a multilateral well; FIGURES 2A - 2H are quarter-sectional views of successive axial portions of an in-line variable flow choke of the present invention, the choke shown in a closed position such that flow from a distal producing formation is not conveyed through a choke structure; and FIGURES 3A - 3H are quarter-sectional views of successive axial portions of the choke of FIGS.2 A - 2H, the choke being shown in a configuration in which the trim set of the choke is in a full-open position. Detailed Description The principles of the present invention and their advantages are best understood by referring to the illustrated embodiment depicted in the FIGURES, in which like reference numbers describe like parts. In the drawing and the accompanying description arrow "C" is used to indicate the upward or uphole direction. The reverse of arrow "C" refers to the downward or downhole direction. The upward and downward directions used herein are for reference purposes only, and it is appreciated that not all wells extend vertically, and that the present inventions have utility in nonvertical well configurations. The choke and associated structures are shown in the accompanying drawings as successive axial sections, and it is to be understood that the sections form a continuous assembly. Additionally, it is to be understood that the various embodiments of the present invention described herein maybe utilized in various orientations, such as inclined, inverted, horizontal, vertical, and the like, without departing from the principles of the present invention. FIGURE 1 is a plan view of a remotely-controlled, multi-zone variable flow choke assembly 100 of the present invention deployed in a multilateral well 10. The multilateral well 10 has a main wellbore 11 and at least one lateral wellbore 12. Although the variable flow choke assembly 100 is shown deployed in a multilateral well, it is to be expressly understood that the flow choke assembly 100 may be used in other well structures and production methods without departing from the principles of the present invention. For example, it is contemplated that the flow choke assembly 100 can be implemented in a single-bore well having multiple production zones, and as well as multilateral wells as shown in FIGURE 1. The main wellbore 11 and the lateral wellbore 12 have been drilled into the earth 14, which is generally referred to as "material surrounding the wellbores." A main casing 16 is set into the main wellbore 11 with cement 18, using methods known to those skilled in the art. The lateral wellbore 12 is formed using methods known in the art, such as that disclosed in U.S. Patent No. 5,735,350 issued April 7, 1998, to Longbottom et al., which is incorporated herein by reference for all purposes. The lateral wellbore has a lateral lining 18 set into the lateral wellbore 12 with lateral liner cement 21. The flow choke assembly 100 has a variable radial-flow choke 150 coupled in tandem to an in-line flow choke 200. As set forth in detail below, the variable radial-flow choke 150 defines an inner bore that is in fluid communication with a first production zone 40 of the well 10 for regulating a fluid flow from the first production zone 40 into the inner bore of the radial-flow choke 150. The combination of a radial-flow choke 150 and the in-line flow choke 200 provides greater flow control of producing formations. Each flow choke 150 and 200 are individually-controllable to provide a mixed production fluid to the surface 24. That is, a desired fluid ratio can be obtained for a desirable fluid composition that can serve to prolong the useful production life span of a well. For example, different production zones may be optimally produced at different depletion rates. Conventional on/off flow mechanisms can only provide one flow rate as defined by the openings of the device. Accordingly, retrieval of an optimum flow of production fluid is a function of time with respect to the period that full flow is permitted by an on/off flow mechanism. During this period, downhole formation pressures may be depleted, or less desirable production fluid constituents may become predominate, requiring the conventional on/off flow mechanism be placed in an off position to avoid these conditions. In this regard, it is desirable to allow continuous flow over time through a choke mechanism that can be gradually adjusted to maintain pressure within the formations while flowing a desirable production yield to the surface 24. For the flow choke assembly 100, a preferable radial-flow choke 150 is provided in United States Patent Application 08/898,567, filed July 22, 1997, to Brett Wayne Bouldin et al., for a "Variable Choke for Use in Subterranean Well," which is incorporated herein by reference. The in-line flow choke 200 provides in-line flow control capabilities to production zones accessed by bores narrower than the main wellbore 11. The term "in-line" as used herein is understood to refer to the flow vector of the fluid being choked by the flow choke device. For example, the production fluid 40' from the first production zone 40 is choked along a flow vector relative to a longitudinal axis of the in-line flow choke 200. The term "radial" as used herein is understood to refer to the flow vector of the fluid being choked by the device, which is generally orthogonal to the longitudinal axis of the radial flow choke 150. Accordingly, the production fluid 60' from the second production zone 60, although conveyed by the lateral wellbore 12, is provided a flow vector that is radially choked through the radial-flow choke 150. The combination of these variable chokes accommodates the varying well structure diameters of the well 10. The in-line flow choke 200 defines an inner bore, which is in fluid communication with a production zone of the well 10. The in-line flow choke 200 regulates a fluid flow 40' from the first production zone 40 into the inner bore. It should be noted that the in-line flow choke 200 provides simplified installation of the choke over conventional flow control devices in that well bore isolation techniques typically required for production devices are not needed. Referring to FIGURE 1 , and as discussed later in further detail, the inner bores of the radial flow choke 150 and the in-line flow choke 200 are in tandem, or cooperate, to provide a unitary flow path. The in-line flow choke 200 and the radial flow-choke 150 control fluid from the first and second production zones 40 and 60, respectively, to a unitary fluid path defined by these inner bores. The in-line variable choke assembly 200 allows incremental regulation of a fluid flow between the flow passages 132 and an internal axial fluid passage 134 (see FIGURES 2A through 2H) extending through the choke 200. It should be noted that multiple chokes may be installed in the tubing string 22 (see FIGURE 1), with each of the chokes corresponding to one of multiple zones intersected by the well, and with the zones being isolated from each other external to the tubing string 22. Thus, the choke 200 provides incremental regulation of a fluid flow rate from each of the multiple zones within a well, with the fluids being commingled in the tubing string 22. It is to be understood that, although the tubing string 22 is illustrated with the fluid 40' from the first production zone 40 entering the choke 200 and flowing upwardly through a fluid passage defined by the choke and the tubing string, the lower connector may be closed off or otherwise isolated from such fluid flow in a conventional manner, such as by attaching a ball plug thereto . Production fluids may also be flowed downwardly through the fluid passages; for example, to inject the fluid into a formation intersected by the well, without departing from the principles of the present invention. The radial flow choke 150 and the in-line variable flow choke 200 may be hydraulically, electrically, mechanically, magnetically or otherwise controlled without departing from the principles of the present invention. As described in detail below, the chokes 150 and 200 are remotely-controlled from the surface 24 by a microcontroller-based control system 26. The control system 26 is coupled with an electro-hydraulic downhole completion system that can be manipulated to modify the flow profile of the multilateral well 10 through the chokes 150 and 200. A downhole communication and power cable 28 couples the microcontroller-based system 26 to the chokes 150 and 200. The chokes 150 and 200 are responsive to commands transmitted from the control system 26. The communication and power cable 28 is a dual-redundant umbilical line, each line having at least a return and an input hydraulic line, and a one-wire conductor. It should be noted, however, that other communication and power systems may be used to service and control the chokes 150 and 200. For example, electromagnetic transmission techniques or acoustic transmission techniques, which are known to those skilled in the art, can be used to control the choke in combination with an uphole or downhole power supplies. The hydraulic lines provide a conduit for applying pressure from the surface 24 to either the radial flow choke 150 or the in-line flow choke 200 to selectively exert a hydraulically-generated pressure-differential force for manipulation of the chokes. The one wire conductor can be used to carry commands from the control system 26 and command signals to the chokes 150 and 200. For example, a high-frequency command and a comparatively low-frequency power signal is transmitted through the conductor wire, through a downhole microprocessor, which directs the hydraulic circuits in the chokes 150 and 200 to effect a change in the flow state of the chokes. An example of a downhole control system is discussed in further detail in U.S. Patent No. 5,547,029, issued August 20, 1996 to Rubbo et al., which is incorporated herein by reference. FIGURES 2A - 2H are quarter-sectional views of successive axial portions of the in-line variable flow choke 200 of the present invention, the choke shown in a closed position such that flow from a distal producing formation is not conveyed through a choke structure. The remotely-controlled, in-line variable flow choke 200 is coupled to the radial flow choke 150 (see FIGURE 1). The choke 200 is threadingly and sealingly attached to an actuator 202, which is used to operate the choke 200. Referring to FIGURES 2A and 2B, the actuator 202 has an inner mandrel 204 with an upper mandrel 204a coupled to a lower mandrel 204b. The inner mandrel is longitudinally-displaceable about an axis A relative to the choke 200 through hydraulic pressure applied to the actuator 202. For clarify, the FIGURES provided are simplified to demonstrate by example the use of such hydraulic manipulation techniques. One such example is the application of hydraulic pressure to the actuator 202 through a hydraulic port 206 defined in the outer housing 210. Hydraulic pressure acts on a piston chamber 212, defined between the seals 212a and 212b, to urge the choke 200 to a closed position. As can be readily appreciated by those skilled in the art, a complementary hydraulic-piston chamber 214, defined between the seals 214a and 214b (see FIGURE 2C) with the outer housing 210, serves to urge the choke 200 in an open position. A separate hydraulic port is in fluid communication with the reciprocal piston chamber 214 so that the actuator 202 may be remotely controlled. The choke 200 may be placed in numerous open positions that are variable in nature. In this manner, fluid flow through the choke 200 can be variably regulated to allow management of the petroleum formation, as well as the relative proportion of fluid from other producing formations that may be within the well. As illustrated in FIGURES 2A - 2H, a formation fluid may flow through the choke 200 and actuator 202 to the surface 24 through the tubing string 22 (see FIGURE 1). With a fluid flow from, for example, a production zone of the well below the choke 200, an additional portion of the tubing string 22 including a packer (not shown) may be attached in a conventional manner to a lower adapter 30 of the choke 200 (see FIGURE 2H), and set in the well to isolate the production zone below the choke from other zones of the well, such as a zone in fluid communication with a passage 132 surrounding the choke 200. The mandrel 204a and 204b is slidingly and sealingly received in the upper connector 205 of the outer housing 210. To operate the choke 200, the mandrel 204a and 204b is longitudinally displaced relative to the upper connector 205 to correspondingly displace an inner cage member 216 relative to an outer housing 210 of the choke 200. The mandrel 204a and 204b is sealingly interconnected with the cage member 208 through a cage coupling 218. In FIGURE 2B, a releasable mandrel lock assembly 300 is provided to releasably secure the mandrel 204a and 204b in a fixed relation with the outer housing 210. Such mandrel locks are known to those skilled in the art, and a discussion relating to the general operation of the lock assembly 300 is provided. It should be noted that the mandrel lock assembly 300 is utilized when the sealing relationship between the outer housing 210 and the mandrel/cage member has a tendency to creep from the closed position towards an open position due to formation pressure build-up. Accordingly, a lock assembly 300 limits creeping, and maintains the choke 200 in a closed position. The releasable lock assembly 300 has a latch 302 that engages a shoulder 220 defined on an inner surface 222 of the outer housing 210. The latch 302 is urged into engagement with the shoulder 220 through a latch member 304 having a head 306. Longitudinal travel of the mandrel 204a and 204b is limited through a lock stop 224, which is threadingly secured to the mandrel 204b. The latch member 304 is biased by a spring 308 such that the latch head 306 is urged beneath the latch 302. As shown, upward travel, and accordingly creeping, of the mandrel 204a and 204b, and the cage member 216, is limited, maintaining the closed position of the choke 200. The lock assembly 300 is released through compression of the spring 308 by a downward movement of the mandrel components 204a and 204b. The spring compression allows the latch member 304 to travel upward, which disengages the head 306 from beneath the latch 302. The latch 302 is no longer urged radially-outward, and may pass the shoulder 220. Defined in the outer housing 210 is a longitudinally-extending slot 226, which provides a channel for conveying hydraulic and/or electrical lines carried downhole with the choke 200. The slot 226 can also be used to provide a position sensor device for indicating the position of the mandrel 204 and the coupled cage member 216 (see FIGURE 2D) with respect to the outer housing 210. The position of the mandrel 204, and accordingly, the cage member 216, with respect to the outer housing 210 is sensed by a choke position sensor, such as inductance-shift sensor, or a magnetic position sensor. A magnetic-position sensor operates on the principal of shifts in magnetic fields, generally brought on by a magnetic field source reference. Such sensing techniques are known to those skilled in the art. Further detail concerning position sensors is available in U.S. Patent No.5,231 ,352, issued July 27, 1993 to Huber, which is incorporated herein by reference. It should be noted that other position sensing techniques of the cage member 216 with respect to the outer housing 210 can be deployed, such as that shown in U.S. Patent No. 5,532,585, issued July 2, 1996, to Oudet et al., which is incorporated herein by reference. It is also noted that a choke position sensor can be provided with the radial-flow choke 150. The sensor allows position sensing of the choke and provides for facilitating remote control of the flow choke assembly 100 (see FIGURE 1 ). Other positioning techniques can be used, such as calculating the longitudinal choke displacement with respect to the control pressure exerted; however, these techniques may provide less control accuracy than use of the choke position sensors. The outer housing 210 is threadingly and sealingly coupled to a shroud 400. Referring to FIGURES 2B and 2C, an outer surface 402 flares outward in a generally-conical manner extending to a radially-increased portion 404. Extending from the radially- increased portion 404 is a shroud coupling 406 that is threadingly coupled to a casing coupler 408. An inner housing 500 is theadingly-coupled to a radially-reduced portion 412, which extends substantially-coaxially with respect to the shroud coupling 406. Adjustment bolts 502 extend through the inner housing 500 and engage longitudinally-alignment grooves 414 defined in the radially-reduced portion 412. The adjustment bolts 502 serve to maintain a radial-alignment of the inner housing 500 with respect to the shroud 400 and the outer housing 210, respectively. As shown in FIGURE 2C, the radially-reduced portion 412 has an outer radial dimension less than the outer radial dimension of the shroud coupling 406. The difference between these radial dimensions define the annular passage 132, which is sufficiently sized for a formation production flow to selectively enter the internal axial flow passage 134. Threadingly coupled to an opposing end of the casing coupler 408 is a casing string 410. The casing string 410 is of a metal tubing that is installable with the choke 200 downhole. An example of a suitable metal is one that is exhibits corrosion resistant properties such as stainless steel. It is understood that other completion structures can be provided about the choke 200 when installed downhole, such as a concrete outer casing, or other downhole stabilization structures. Referring to FIGURE 2D, the inner housing 500 defines therethrough a series of spaced apart alignment slots 504, which are also circumferentially distributed about the inner housing 500. The alignment slots 504 receive alignment pins 230. The alignment pins 230 extend from the cage coupling 218, which is fixed with respect to the mandrel 204. The alignment slots 504 and the alignment pins 230 serve to limit the radial freedom of the cage member 216 with respect to the inner housing 500. The inner housing 500 also defines therethrough a first flow-choke opening 506a and a second flow-choke opening 506b (shown in phantom lines), which are also circumferentially distributed about the housing 500. The openings 506a and 506b provide fluid communication between the passage 132 external to the inner housing 500 and the interior of the housing 500. The cage member 216 extends downwardly from the cage coupling 218 through a seal member 219. Opposingly-mounted with respect to the seal member 219 is a substantially-stationary seal member 250, which is fixed with respect to the inner housing 500 through an enlarged-radial inner surface 508 defining a shoulder 510. The shoulder 510 engages a corresponding seal shoulder 252. Referring briefly to FIGURE 2E, a lower end 254 of the seal member 250 engages a spring cradle 256 having heavy-gauge compression springs 258. Accordingly, the seal member 219 is substantially-stationary in that its longitudinal movement about the axis A is limited by the engagement with the shoulder 510 and the cradle 256. The spring cradle 256 serves to urge the seal member 219 and the substantially-stationary seal member 250 into a compression seal that may adjust the mating of the members as wear through repeated use occurs, and to also encourage a sealing relation in the closed position, which is illustrated in FIGURES 2 A - 2H. That is, a compressive pre-load is provided by each of the springs 258 to sealingly engage the seal members 219 and 250, accordingly. The seal member 219 has a lip portion 221 that sealingly engages a corresponding lip portion 251 in the closed position. The cage member 216 defines flow apertures 216a and 216b. The mating lip portions 221 and 251, with the flow apertures 216a and 216b provide a flow trim set. The term "trim set" is understood to describe an element or combination of elements that perform a function of regulating fluid flow. The lips 221 and 251 act to limit erosion of the seal surfaces 260. The seal surfaces 260 are cooperatively shaped to sealingly engage seal surfaces formed on the mating lip portions 221 and 251. Preferably, the seal surfaces are formed of hardened metal or carbide for erosion resistance, although other materials, such as elastomers, resilient materials, etc., may be utilized without departing from the principles of the present invention; however, it is to be understood that it is not necessary for the choke 200 to include the seal surfaces in keeping with the principles of the present invention. The cage member 216 has two axially spaced-apart sets of flow apertures 216a, and two axially spaced-apart sets of comparatively larger flow apertures 216b, formed radially therethrough. Each of the sets of apertures 216a and 216b include two circumferentially spaced-apart and oppositely disposed apertures, although only one of each is visible in FIGURE 2D. It should be noted that other numbers of ports may be utilized in the flow aperture sets 216a and 216b without departing from the principles of the present invention. Preferably, the flow apertures 216a and 216b are positioned radially and orthogonal (one pair to the other) so as to minimize erosive linking of the apertures and to provide greater flow control. That is, fluid jets from each aperture impinge upon each other within the cage member bore to absorb energy from the fluid flow into the choke. Accordingly, wear of the choke 200 is minimized. As illustrated in the accompanying drawings, the flow aperture sets 216a are relatively small, to provide an initial relatively highly restricted fluid flow therethrough as the seal member 219 is displaced longitudinally with respect to the substantially-stationary seal member 250. Additionally, the flow aperture sets 216a are shown similarly-dimensioned and positioned (albeit axially spaced apart); however, it is to be understood that the flow aperture sets 216a may be otherwise dimensioned, otherwise positioned, otherwise dimensioned with respect to each other, and otherwise positioned with respect to each other, without departing from the principles of the present invention. For example, the upper flow aperture set 216a may be larger or smaller apertures, may have larger or smaller ports than the lower flow aperture set 216a, may be positioned differently on the cage 216, may be positioned differently with respect to the lower flow aperture set 216b, and the like. Similar changes maybe made to the flow aperture sets 216b. It should also be noted that the cage member 216 may have a unitary set of configured flow apertures that are similar in radial dimension. The flow apertures illustrated in FIGURE 2D maybe modified to provide dissimilar flow characteristics. For example, the upper flow aperture sets 216a may be comparatively larger or smaller than the lower flow aperture sets 216b to provide for a wider range of flow characteristics. The compression springs 258 are biased against the substantially-stationary seal member 250 and, in the closed position, biasing against the seal member 219, which is secured to the cage member 216, accordingly biasing the cage member 216 relative to the housing inner housing 500. Furthermore, the configuration of these elements, as shown in the accompanying drawings and described above, tends to bias the elements so that the sealing member 219 sealingly engages the lip portion 221 and the substantially-stationary sealing member 250 sealingly engages the corresponding lip portion 251 , with no external forces applied. It should be noted, however, that the springs 258 serve to increase the sealing contact of the sealing members 219 and 250, and accordingly, it is to be understood that it is not necessarily in keeping with the principles of the present invention for the springs 258 to be included in the choke 200, for the sealing members 219 and 250 to sealingly engage in the closed configuration for the choke, nor for the cage member 216 to be biased toward the neutral position. The cage member 216 maybe axially displaced relative to the inner housing 500 by, for example, axial displacement of the actuator mandrel 204, to disengage the sealing members 219 and 250, accordingly. With the springs 258 biasing both the sealing members 219 and 250 into sealing contact with their respective lip portions 221 and 251, the choke 200 is in a closed configuration as shown in FIGURES 2A - 2H, and fluid flow is prevented through the flow port apertures 216a and 216b. In the event that the remote mechanisms for actuation of the choke 200 are inoperable, the choke 200 may contain a latch profile 240 (see FIGURE 2A) so that manual operation from the surface can be conducted with respect to the actuator 202. For example, if a problem is experienced with the actuator 204 or its associated control lines, such that the mandrel 204 cannot be axially displaced in a normal fashion by the actuator 202, a slickline or wireline having a conventional shifting tool attached thereto may be conveyed into the tubing string 22, engaged with a latch profile formed internally on the extension, and utilized to axially displace the cage 216 relative to the housing inner housing 500 to select a trim setting for the choke 200. For installation into a downhole position, the choke 200 may be maintained in an install configuration using frangible components such as shear members. Such techniques are known to those skilled in the art, and accordingly, are described herein generally. A shear member may be used to maintain the actuator 202 and the cage member 216 in a closed position with respect to the outer housing 210. Once placed in a desired downhole position, the shear member may be sheared to release the actuator 202 from the outer housing 210. The shear member may be sheared by exerting a longitudinal force through the actuator 202 through the hydraulic actuator, mechanisms, or through with a shifting tool engaged with a shifting profile defined in the mandrel 204. FIGURES 2F - 2H is an illustration of a flow diversion 600 that selectively obstructs the internal axial fluid passage 134 to divert production flow to the spaced-apart flow choke openings 506 (see FIGURE 2D) of the in-line flow choke 200. The flow diversion 600 is preferably provided by a valve assembly 602 that selectively allows access below the choke 200 to allow, for example, well maintenance operations. It should be noted, however, that the flow diversion 600 may be provided by other relatively less complex components such as a set-plug, which may be drilled through for access to lower portions of a well, or another form of removable plug. Examples of suitable valve assemblies 602 are ball valve assemblies, such as that in U.S. Patent No. 5,050,839, issued September 24, 1991, to Dickson et al., and in U.S. Patent No. 5,338,001, issued August 16, 1994 to Godfrey et al., both of which are incorporated herein by reference, or flapper valve assemblies, such as that in U.S. Patent No. 4,846,281, issued July 11, 1989, to Clary et al., which is incorporated herein by reference. The advantage of the selective access component provided by the valve assembly 602 is that access past the flow choke assembly 100 is provided. Such access provides the ability, for example, to service the well without the need from removal of the flow choke assembly 100. The control line 604 for the valve assembly 602 are provided through the inner housing 500, which is in a fixed relation with respect to the outer housing 210, and accordingly, the shroud 400 and casing string 410. It should be noted that the control lines 604 may be provided as discrete pressure lines, or as ports defined within the housing structures of the choke 200 to provide pressure control to the pressure-responsive systems described herein. The valve assembly 602 is controllable through the downhole control system described in detail above, in which control signals, in the form of electrical or pressure signals, may be applied from the surface 24 (see FIGURE 1) to the valve assembly 602 to exert a hydraulically-generated pressure-differential force to mechanically operate the valve 602. Referring to FIGURES 2F and 2G, the diversion housing is provided by an upper sub 608, a connector 610 depending therefrom, a spring housing 612, a valve housing 614 and a lower sub 612. The internal axial fluid passage 134 extends through the housing and is controlled by the valve seat 618 having the valve 620 cooperable therewith to open and close the fluid passage 134. Reciprocation of the valve seat 618 and the valve 620 is accomplished by reciprocation of the actuator tube 622, which is attached to the valve seat 618. The actuator tube 622 is in turn reciprocated by the piston 624 in a chamber 626 in response to pressure differential across the piston. Control fluid pressure is applied from the surface through control line 604 and port 606 to the chamber 626 and the upper side of the piston 624. Thus in normal operation, increase in pressure against the upper side of piston 624 results in downward movement of the piston to open the valve such that the valve aperture 628 is substantially aligned with the flow passage 134, and a reduction in this pressure results in upward movement of the piston 624 to the valve closed position of FIGURE 2G. As shown in FIGURE 2H, the casing string 410 has a progressively-reduced portion 416 that extend to a lower adapter 130, which may be coupled to a subsequent tubing string portion. As shown in FIGURES 2A - 2H, the present invention provides a flow control device for an in-line production flow. The passage 132 of the choke 200 is in fluid communication with a production flow conveyed through the casing string 410 and a subsequent tubing string coupled to the casing string 410 through the adapter 130. When the valve 602 is closed, production flow is diverted to the passage 132 defined by the shroud 400, the casing string 410, and the inner housing 500. As can be readily appreciated by those skilled in the art, the production flow coupled to the choke 200 can be regulated by adjustment of the in-line flow choke mechanism provided by the flow choke apertures 216a and 216b of the cage member 216 with respect to the spaced-apart flow choke openings 506 defined in the inner housing 500. FIGURES 3A - 3E illustrate the choke 200 in a full-open configuration in which the upper flow aperture set 216a and 216b are exposed to direct fluid flow between the passage 132 and the internal axial fluid passage 134. Referring to FIGURES 3A - 3H, the choke 200 is illustrated in a fully-open configuration in which the flow apertures 216a and 216b. The production fluid is, thus, permitted to flow unobstructed inwardly through the flow apertures 216a and 216b and into the internal fluid passage 134. FIGURE 3B illustrates the cage member 216 positioned so that the flow apertures 216a and 216b are substantially-aligned with corresponding spaced-apart flow choke openings 506, through the alignment pins 230 engaging the spaced-apart alignment slots 504. It will be readily apparent to one of ordinary skill in the art that the flow proportions of the fluids conveyed through the tubing string 22 may be conveniently regulated by selectively permitting greater or smaller fluid flow rates through the flow apertures 216a and 216b of the cage member 216. Thus has been described the choke 200 and methods of controlling fluid flow within the well using the choke, which provide redundancy, reliability, ruggedness, longevity, and do not require complex mechanisms. Of course, modifications, substitutions, additions, deletions, etc., may be made to the exemplary embodiment described herein, which changes would be obvious to one of ordinary skill in the art, and such changes are contemplated by the principles of the present invention. For example, the actuator mandrel 204 may be releasably attached to the upper coupling, so that, if the actuator 202 becomes inoperative, the cage 216 may be displaced independently from the mandrel 204. As another example, the cage 216 may be displaced circumferentially, rather than axially, in order to selectively open multiple trim sets, such as trim sets positioned radially about the cage, rather than axially, in order to selectively open multiple trim sets, such as trim sets positioned radially about the cage rather than being positioned axially relative to the cage. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims.

Claims: What is Claimed is: 1. A downhole flow control assembly for controlling a fluid production flow for a well, the downhole flow control assembly comprising: a first variable flow choke defining an inner bore in fluid communication with a production zone of the well for regulating a fluid flow from said production zone into said inner bore of said first variable flow choke; and a second variable flow choke defining an inner bore in fluid communication with a second production zone of the well for regulating a fluid flow from said second production zone into said inner bore of said second variable flow choke, said second variable flow choke coupled to said first variable flow choke such that a fluid path is defined by each of said inner bores are in tandem. 2. The downhole flow control assembly of Claim 1 wherein said second variable flow choke further comprises: a selective access component received in said inner bore of said second variable flow choke for allowing selective access therethrough. 3. The downhole flow control assembly of Claim 2 wherein said selective access component is a ball valve. 4. The downhole flow control assembly of Claim 1 wherein said first variable flow choke is a radial flow choke. 5. The downhole flow control assembly of Claim 4 wherein said second flow choke is an in-line flow choke. 6. A method for regulating a well production flow downhole, the method comprising the steps of: positioning a first variable flow choke in fluid communication with a first production zone of a well for regulating a fluid flow from the first production zone into an inner bore of the first flow choke; positioning a second variable flow choke in fluid communication with a second production zone of the well for regulating a fluid flow from the second production zone into an inner bore of the second variable flow choke; and manipulating the first and the second variable flow choke such that a desired production flow ratio is provided through the first variable flow choke and the second variable flow choke. 7. The method for regulating downhole a well production flow of Claim 6 further comprising the step of: selectively accessing a well bore portion beyond the first and the second variable flow choke. 8. A downhole production device for regulating a production flow originating from multiple production zones, the flow choke comprising: a radial flow variable choke having a choke position sensor for regulating a fluid from an adjacent production zone; and an in-line flow variable choke having a second choke position sensor, said in-line flow choke coupled in tandem with said radial flow choke such that a production flow bore is defined, said in-line flow choke for regulating a fluid from a distal production zone. 9. The downhole production device of Claim 8 further comprising: a selective access port received in said production flow bore for allowing selective access past said radial flow choke and said in-line flow choke through said production flow bore. 10. The downhole production device of Claim 9 wherein said selective access port is a flapper valve. 11. The downhole production device of Claim 10 wherein said selective access port is a ball valve. 12. A downhole flow control assembly for controlling a fluid production flow for a well, the downhole flow control assembly comprising: a first variable flow choke defining an inner bore in fluid communication with an adj acent production zone of the well for regulating a fluid flow from said adjacent production zone into said inner bore of said first variable flow choke; and a second variable flow choke defining an inner bore in fluid communication with a distal production zone of the well for regulating a fluid flow from said distal production zone into said inner bore of said second variable flow choke, said second variable flow choke coupled to said first variable flow choke such that each of said inner bores are in tandem. 13. The downhole flow control assembly of Claim 12 wherein said second variable flow choke further comprises: a selective access component received in said inner bore of said second flow choke for allowing selective access therethrough. 14. The downhole flow control assembly of Claim 13 wherein said selective access component is a ball valve. 15. The downhole flow control assembly of Claim 12 wherein said first variable flow choke is a radial flow choke. 16. The downhole flow control assembly of Claim 15 wherein said second variable flow choke is an in-line flow choke. 17. The downhole flow control assembly of Claim 12 wherein each of said first and said second variable flow choke has a choke position sensor providing a choke position data. 18. A method for regulating downhole a well production flow with at least two production zones, the method comprising the steps of: providing a first variable flow choke coupled in tandem with a second variable flow choke; positioning the first flow choke in fluid communication with an adjacent production zone of a well for regulating a fluid flow from the adjacent production zone into an inner bore of the first flow choke; positioning the second flow choke in fluid communication with a distal production zone of the well for regulating a fluid flow from the distal production zone into an inner bore of the second flow choke; and manipulating the first and the second flow choke such that a desired production flow ratio flows from the first flow choke and the second flow choke. 19. The method for regulating downhole a well production flow of Claim 18 further comprising the step of: selectively positioning each of the inner bores to allow passage therethrough; and servicing the well past the first and the second flow choke.

Inventors: FREEMAN TOMMIE AUSTIN, GODFREY CRAIG WILLIAM, FREEMAN, TOMMIE, AUSTIN, GODFREY, CRAIG, WILLIAM
Applicants: HALLIBURTON ENERGY SERV INC, HALLIBURTON ENERGY SERVICES
Application year: 2000
Main classification: E21B43
IPC codes: E21B34, E21B41, E21B43