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BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
     The disclosure relates generally to systems and methods for selective control of fluid flow into a production string in a wellbore. 
     2. Description of the Related Art 
     Hydrocarbons such as oil and gas are recovered from a subterranean formation using a wellbore drilled into the formation. Such wells are typically completed by placing a casing along the wellbore length and perforating the casing adjacent each such production zone to extract the formation fluids (such as hydrocarbons) into the wellbore. These production zones are sometimes separated from each other by installing a packer between the production zones. Fluid from each production zone entering the wellbore is drawn into a tubing that runs to the surface. It is desirable to have substantially even drainage along the production zone. Uneven drainage may result in undesirable conditions such as an invasive gas cone or water cone. In the instance of an oil-producing well, for example, a gas cone may cause an inflow of gas into the wellbore that could significantly reduce oil production. In like fashion, a water cone may cause an inflow of water into the oil production flow that reduces the amount and quality of the produced oil. Accordingly, it is desired to provide even drainage across a production zone and/or the ability to selectively close off or reduce inflow within production zones experiencing an undesirable influx of water and/or gas. 
     The present disclosure addresses these and other needs of the prior art. 
     SUMMARY OF THE DISCLOSURE 
     In aspects, the present disclosure provides an apparatus for controlling a flow of fluid between a wellbore tubular and a wellbore annulus. In one embodiment, the apparatus includes a flow control device that controls fluid flow in response to signals from a generator that generates electrical energy in response to a flow of an electrically conductive fluid. Because hydrocarbons fluids are not electrically conductive, no electrical energy is generated by the flow of hydrocarbons. In contrast, fluids such as brine or water are electrically conductive and do cause the generator to generate electrical energy. Thus, the flow control device may be actuated between an open position and a closed position in response to an electrical property of a flowing fluid. 
     In one embodiment, the flow control device may include an actuator receiving electrical energy from the generator, and a valve operably coupled to the actuator. The actuator may be a solenoid, a pyrotechnic element, a heat-meltable element, a magnetorheological element, and/or an electrorheological element. In certain embodiments, the actuator operates after a preset value for induced voltage is generated by the generator. In other embodiments, the flow control device may include circuitry configured to detect the electrical energy from the generator, and actuate a valve in response to the detection of a predetermined voltage value. In some arrangements, the actuator may include an energy storage element that stores electrical energy received from the generator and/or a power source configured to supply power to the actuator. 
     In aspects, the generator may use a pair of electrodes positioned along a flow path of the electrically conductive fluid to generate electrical energy. In one arrangement, one or more elements positioned proximate to the pair of electrodes generate a magnetic field along the flow path of the electrically conductive fluid that causes the electrodes to generate a voltage. In another arrangement, the pair of electrodes creates an electrochemical potential in response to contact with the electrically conductive fluid. In such embodiments, the pair of electrodes may include dissimilar metals. 
     In aspects, the present disclosure provides a method for controlling a flow of fluid between a wellbore tubular and a wellbore annulus. The method may include controlling the flow of fluid between the wellbore tubular and the wellbore annulus using a flow control device, and activating the flow control device using electrical energy generated by a flow of an electrically conductive fluid. In aspects, the method may also include generating the electrical energy using a generator and storing the electrical energy in a power storage element. In aspects, the method may include generating electrical energy using a generator; detecting electrical energy from the generator; and activating the flow control device upon detecting a predetermined voltage value. 
     In certain embodiments, the method may include generating electrical energy by positioning a pair of electrodes positioned along a flow path of the electrically conductive fluid; and positioning at least one element proximate to the pair of electrodes to generate a magnetic field along a flow path of the electrically conductive fluid. In other embodiments, electrical energy may be generated by positioning a pair of electrodes along a flow path of the electrically conductive fluid. The pair of electrodes may be electrically coupled to the flow control device and create an electrochemical potential in response to contact with the electrically conductive fluid. 
     In aspects, the present disclosure provides a method for control fluid flow in a well having a wellbore tubular. The method may include positioning a flow control device along the wellbore tubular; positioning a pair of electrodes along a flow of an electrically conductive fluid; generating an electrical signal using the pair of electrodes; and actuating the flow control device using the generated electrical signal. 
     It should be understood that examples of the more important features of the disclosure have been summarized rather broadly in order that detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the disclosure that will be described hereinafter and which will form the subject of the claims appended hereto. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages and further aspects of the disclosure will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawing and wherein: 
         FIG. 1  is a schematic elevation view of an exemplary multi-zonal wellbore and production assembly which incorporates an inflow control system in accordance with one embodiment of the present disclosure; 
         FIG. 2  is a schematic elevation view of an exemplary open hole production assembly which incorporates an inflow control system in accordance with one embodiment of the present disclosure; 
         FIG. 3  is a schematic cross-sectional view of an exemplary production control device made in accordance with one embodiment of the present disclosure; 
         FIG. 4  is an isometric view of an illustrative power generator made in accordance with one embodiment of the present disclosure; 
         FIG. 5  is a schematic of an in-flow control device made in accordance with one embodiment of the present disclosure; 
         FIG. 6  is a schematic of an illustrative electrical circuit used in connection with one embodiment of an in-flow control device made in accordance with the present disclosure; 
         FIG. 7  is a schematic of an illustrative valve made in accordance with the present disclosure; and 
         FIG. 8  is a schematic of an illustrative signal generator used in connection with one embodiment of an in-flow control device made in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present disclosure relates to devices and methods for controlling production of a hydrocarbon producing well. The present disclosure is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present disclosure with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure and is not intended to limit the disclosure to that illustrated and described herein. Further, while embodiments may be described as having one or more features or a combination of two or more features, such a feature or a combination of features should not be construed as essential unless expressly stated as essential. 
     Referring initially to  FIG. 1 , there is shown an exemplary wellbore  10  that has been drilled through the earth  12  and into a pair of formations  14 , 16  from which it is desired to produce hydrocarbons. The wellbore  10  is cased by metal casing, as is known in the art, and a number of perforations  18  penetrate and extend into the formations  14 , 16  so that production fluids may flow from the formations  14 , 16  into the wellbore  10 . The wellbore  10  has a deviated or substantially horizontal leg  19 . The wellbore  10  has a late-stage production assembly, generally indicated at  20 , disposed therein by a tubing string  22  that extends downwardly from a wellhead  24  at the surface  26  of the wellbore  10 . The production assembly  20  defines an internal axial flowbore  28  along its length. An annulus  30  is defined between the production assembly  20  and the wellbore casing. The production assembly  20  has a deviated, generally horizontal portion  32  that extends along the deviated leg  19  of the wellbore  10 . Production devices  34  are positioned at selected points along the production assembly  20 . Optionally, each production device  34  is isolated within the wellbore  10  by a pair of packer devices  36 . Although only two production devices  34  are shown in  FIG. 1 , there may, in fact, be a large number of such devices arranged in serial fashion along the horizontal portion  32 . 
     Each production device  34  features a production control device  38  that is used to govern one or more aspects of a flow of one or more fluids into the production assembly  20 . As used herein, the term “fluid” or “fluids” includes liquids, gases, hydrocarbons, multi-phase fluids, mixtures of two of more fluids, water, brine, engineered fluids such as drilling mud, fluids injected from the surface such as water, and naturally occurring fluids such as oil and gas. Additionally, references to water should be construed to also include water-based fluids; e.g., brine or salt water. In accordance with embodiments of the present disclosure, the production control device  38  may have a number of alternative constructions that ensure selective operation and controlled fluid flow therethrough. 
       FIG. 2  illustrates an exemplary open hole wellbore arrangement  11  wherein the production devices of the present disclosure may be used. Construction and operation of the open hole wellbore  11  is similar in most respects to the wellbore  10  described previously. However, the wellbore arrangement  11  has an uncased borehole that is directly open to the formations  14 ,  16 . Production fluids, therefore, flow directly from the formations  14 ,  16 , and into the annulus  30  that is defined between the production assembly  21  and the wall of the wellbore  11 . There are no perforations, and open hole packers  36  may be used to isolate the production control devices  38 . The nature of the production control device is such that the fluid flow is directed from the formation  16  directly to the nearest production device  34 , hence resulting in a balanced flow. In some instances, packers maybe omitted from the open hole completion. 
     Referring now to  FIG. 3 , there is shown one embodiment of a production control device  100  for controlling the flow of fluids from a reservoir into a flow bore  102  of a wellbore tubular (e.g., tubing string  22  of  FIG. 1 ). This flow control may be a function of water content. Furthermore, the control devices  100  can be distributed along a section of a production well to provide fluid control at multiple locations. This can be advantageous, for example, to equalize production flow of oil in situations wherein a greater flow rate is expected at a “heel” of a horizontal well than at the “toe” of the horizontal well. By appropriately configuring the production control devices  100 , such as by pressure equalization or by restricting inflow of gas or water, a well owner can increase the likelihood that an oil bearing reservoir will drain efficiently. Exemplary devices for controlling one or more aspects of production are discussed herein below. 
     In one embodiment, the production control device  100  includes a particulate control device  110  for reducing the amount and size of particulates entrained in the fluids, an in-flow control device  120  that controls overall drainage rate from the formation, and an in-flow fluid control device  130  that controls in-flow area based upon a water content of the fluid in the production control device. The particulate control device  110  can include known devices such as sand screens and associated gravel packs. 
     Referring now to  FIG. 4 , there is shown a downhole generator  140  that utilizes Faraday&#39;s Law to induce a voltage that may be used to energize or activate one or more flow control devices  130  ( FIG. 3 ). Faraday&#39;s Law states that when a conductor is moved through a magnetic field, it will produce a voltage proportional to the relative velocity of the conductor through the magnetic field, i.e., E∝V*B*d; where E=Induced Voltage; V=Average Liquid Velocity; B=Magnetic Field; and d=distance between electrodes, which is representative of the cross-sectional flow area. In embodiments, the downhole generator  140  includes one or more sets of two electrodes  142  and includes a coil  144  or other element configured to generate a magnetic field. Exemplary magnetic field generating elements may include, but are not limited to, permanent magnets, DC magnets, bars, magnetic elements, etc. The electrodes  142  and magnetic coils  144  are positioned along an inflow fluid flow path  101 . Since hydrocarbons are substantially not electrically conductive, the flow of oil will generate only a nominal induce voltage. As the percentage of water in the flowing fluid increases, there will be a corresponding increase in fluid conductivity due to the electrical conductivity of water. Consequently, the induced voltage will increase as the percentage of water in the flowing fluid increases. 
     The downhole generator  140  may be used in connection with an in-flow control device in a variety of configurations. In some embodiments, the downhole generator  140  may generate sufficient electrical energy to energize a flow control device. That is, the downhole generator  140  operates as a primary power source for an in-flow control device. In other embodiments, the downhole generator  140  may generate electrical power sufficient to activate a main power source that energizes a flow control device. In still other embodiments, the downhole generator  140  may be used to generate a signal indicative of water in-flow. The signal may be used by a separate device to close a flow control device. Illustrative embodiments are discussed below. 
     Referring now to  FIG. 5 , there is shown one embodiment of an inflow control device  160  that utilizes the above-described generator. The electrodes (not shown) and magnetic coils  144  of the generator  140  may be positioned along a fluid path  104  prior to entering the wellbore production flow and/or in a fluid path  106  along the flow bore  102 . The power generator  140  energizes an actuator  162  that is configured to a device such as a valve  164 . In one embodiment, the valve  164  is formed as a sliding element  166  that blocks or reduces flow from an annulus  108  of the wellbore into the flow bore  102 . Other valve arrangements will be described in greater detail below. 
     In other embodiments, the downhole generator may generate a signal using an electrochemical potential of an electrically conductive fluid. For example, in one embodiment, the downhole generator may include two electrodes (not shown) of dissimilar metals such that an electrochemical potential is created when the electrodes come in contact with an electrically conductive fluid such as brine produced by the formation. Examples of electrode pairs may be, but not limited to, magnesium and platinum, magnesium and gold, magnesium and silver and magnesium and titanium. Manganese, zinc chromium, cadmium, aluminum, among other metals, may be used to produce an electrochemical potential when exposed to electrically conductive fluid. It should be understood that the listed materials have been mentioned by way of example, and are not exhaustive of the materials that may be used to generate an electrochemical potential. 
     Referring now to  FIG. 6 , in one embodiment, the actuator  162  may include an energy storage device  170  such as a capacitor and a solenoid element  172 . A diode  174  may be used to control current flow. For example, the diode  174  may require a preset voltage to be induced before current can start to flow to the capacitor. Once the current starts to flow due to increasing water cut, the capacitor  170  charges to store energy. In one arrangement, the capacitor  170  may be charged until a preset voltage is obtained. A switching element  176  may be used to control the discharge of the capacitor  170 . Once this voltage is obtained, the energy is released to energize the solenoid element  172 , which then closes a valve  178  to shut off fluid flow. 
     Referring now to  FIG. 7 , there is shown one embodiment of a valve  180  that may be actuated using power generated by the previously described downhole power generators. The valve  180  may be positioned to control fluid flow from or to an annulus  108  ( FIG. 5 ) and a production flow bore  102  ( FIG. 5 ). The valve  180  may be configured as a piston  182  that translates within a cavity having a first chamber  184  and a second chamber  186 . A flow control element  188  selectively admits a fluid from a high pressure fluid source  190  to the second chamber  186 . The piston  182  includes a passage  192  that in a first position aligns with passages  194  to permit fluid flow through the valve  180 . When the passage  192  and passages  194  are misaligned, fluid flow through the valve  180  is blocked. In one arrangement, the passages  192  and  194  are aligned when the chambers  184  and  186  have fluid at substantially the same pressure, e.g., atmospheric pressure. When activated by a downhole power generator (e.g., the generator  140  of  FIG. 4 ), the flow control element  188  admits high pressure fluid from the high-pressure fluid source  190  into the second chamber  186 . A pressure differential between the two chambers  184  and  186  translates the piston  182  and causes a misalignment between the passages  192  and  194 , which effectively blocks flow across the valve  180 . The high pressure fluid source  190  may be a high-pressure gas in a canister or a fluid in the wellbore. 
     It should be understood that numerous arrangements may function as the flow control element  188 . In some embodiments, the electrical power generated is used to energize a solenoid. In other arrangements, the electric power may be used in connection with a pyrotechnic device to detonate an explosive charge. For example, the high-pressure gas may be used to translate the piston  182 . In other embodiments, the electrical power may be use to activate a “smart material” such as magnetostrictive material, an electrorheological fluid that is responsive to electrical current, a magnetorheological fluid that is responsive to a magnetic field, or piezoelectric materials that responsive to an electrical current. In one arrangement, the smart material may deployed such that a change in shape or viscosity can cause fluid to flow into the second chamber  186 . Alternatively, the change in shape or viscosity can be used to activate the sleeve itself. For example, when using a piezoelectric material, the current can cause the material to expand, which shifts the piston and closes the ports. 
     Referring now to  FIG. 8 , there is shown a downhole generator  200  may be used as a self-energized sensor for detecting a concentration of water in a fluid (water cut). The downhole generator  200  may transmit a signal  202  indicative of a water cut of a fluid entering an in-flow control device  204 . The in-flow control device  204  may include electronics  206  having circuitry for actuating a flow control device  208  and circuitry for varying power states. The electronics  206  may be programmed to periodically “wake up” to detect whether the downhole generator  200  is outputting a signal at a sufficient voltage value to energize the flow control device  208 . As described above, the voltage varies directly with the concentration of water in the flowing fluid. Such an arrangement may include a downhole power source  210  such as a battery for energizing the electronics and the valve. Once a sufficiently high level of water concentration is detected, the electronics  206  may actuate the flow control device  208  to restrict or stop the flow of fluid. While the periodic “wake ups” consume electrical power, it should be appreciated that no battery power is required to detect the water concentration of the flowing fluid. Thus, the life of a battery may be prolonged. 
     It should be understood that  FIGS. 1 and 2  are intended to be merely illustrative of the production systems in which the teachings of the present disclosure may be applied. For example, in certain production systems, the wellbores  10 , 11  may utilize only a casing or liner to convey production fluids to the surface. The teachings of the present disclosure may be applied to control the flow into those and other wellbore tubulars. 
     For the sake of clarity and brevity, descriptions of most threaded connections between tubular elements, elastomeric seals, such as o-rings, and other well-understood techniques are omitted in the above description. Further, terms such as “valve” are used in their broadest meaning and are not limited to any particular type or configuration. The foregoing description is directed to particular embodiments of the present disclosure for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope of the disclosure.

Summary:
An apparatus for controlling a flow of fluid in a well includes a flow control device and a generator that generates electrical energy in response to a flow of an electrically conductive fluid. The flow control device may include an actuator receiving electrical energy from the generator, and a valve operably coupled to the actuator. The actuator may be configured to operate after a preset value for induced voltage is generated by the generator. The generator may use a pair of electrodes positioned along a flow path of the electrically conductive fluid to generate electrical energy. In one arrangement, one or more elements positioned proximate to the electrodes generate a magnetic field along the flow path of the electrically conductive fluid that causes the electrodes to generate a voltage. In another arrangement, the electrodes create an electrochemical potential in response to contact with the electrically conductive fluid.