Patent Publication Number: US-8985222-B2

Title: Method and apparatus for controlling fluid flow using movable flow diverter assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation application of U.S. patent application Ser. No. 12/770,568, filed Apr. 29, 2010. 
    
    
     FIELD OF INVENTION 
     The invention relates to apparatus and methods for controlling fluid flow in a subterranean well having a movable flow control mechanism which actuates in response to a change of a characteristic of the fluid flow. 
     BACKGROUND OF INVENTION 
     During the completion of a well that traverses a 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 control the flow rate of production fluids into the production tubing, it is common practice to install one or more inflow control devices within the tubing string. 
     Formations often produce multiple constituents in the production fluid, namely, natural gas, oil, and water. It is often desirable to reduce or prevent the production of one constituent in favor of another. For example, in an oil producing well, it may be desired to minimize natural gas production and to maximize oil production. While various downhole tools have been utilized for fluid separation and for control of production fluids, a need has arisen for a device for controlling the inflow of formation fluids. Further, a need has arisen for such a fluid flow control device that is responsive to changes in characteristic of the fluid flow as it changes over time during the life of the well and without requiring intervention by the operator. 
     SUMMARY 
     Apparatus and methods for controlling the flow of fluid, such as formation fluid, through an oilfield tubular positioned in a wellbore extending through a subterranean formation. Fluid flow is autonomously controlled in response to change in a fluid flow characteristic, such as density. In one embodiment, a fluid diverter is movable between an open and closed position in response to fluid density change and operable to restrict fluid flow through a valve assembly inlet. The diverter can be pivotable, rotatable or otherwise movable in response to the fluid density change. In one embodiment, the diverter is operable to control a fluid flow ratio through two valve inlets. The fluid flow ratio is used to operate a valve member to restrict fluid flow through the valve. In other embodiments, the fluid diverter moves in response to density change in the fluid to affect fluid flow patterns in a tubular, the change in flow pattern operating a valve assembly. 
    
    
     
       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 including a plurality of autonomous fluid control assemblies according to the present invention; 
         FIG. 2  is a side view in partial cross-section of one embodiment of the fluid control apparatus having pivoting diverter arms and in a higher density fluid according to one aspect of the invention; 
         FIG. 3  is a side view in partial cross-section of one embodiment of the fluid control apparatus having pivoting diverter arms and in a lower density fluid according to one aspect of the invention; 
         FIG. 4  is a detail side cross-sectional view of an exemplary fluid valve assembly according to one aspect of the invention; 
         FIG. 5  is an end view taken along line A-A of  FIG. 4 ; 
         FIG. 6  is a bottom view in cross-section of the valve assembly of  FIG. 2  with the valve member in the closed position (the apparatus in fluid of a relatively high density); 
         FIG. 7  is a bottom view in cross-section of the valve assembly of  FIG. 3  with the valve member in the open position (the apparatus in fluid of a relatively low density); 
         FIG. 8  is an orthogonal view of a fluid flow control apparatus having the diverter configuration according to  FIG. 2 ; 
         FIG. 9  is an elevational view of another embodiment of the fluid control apparatus having a rotating diverter according to one aspect of the invention; 
         FIG. 10  is an exploded view of the fluid control apparatus of  FIG. 9 ; 
         FIG. 11  is a schematic flow diagram having an end of flow control device used in conjunction with the fluid control apparatus according to one aspect of the invention; 
         FIG. 12  is a side cross-sectional view of the fluid control apparatus of  FIG. 9  with the diverter shown in the closed position with the apparatus in the fluid of lower density; 
         FIG. 13  is a side cross-sectional view of the fluid control apparatus of  FIG. 9  with the apparatus in fluid of a higher density; 
         FIG. 14  is a detail side view in cross-section of the fluid control apparatus of  FIG. 9 ; 
         FIG. 15  is a schematic illustrating the principles of buoyancy; 
         FIG. 16  is a schematic drawing illustrating the effect of buoyancy on objects of differing density and volume immersed in the fluid air; 
         FIG. 17  is a schematic drawing illustrating the effect of buoyancy on objects of differing density and volume immersed in the fluid natural gas; 
         FIG. 18  is a schematic drawing illustrating the effect of buoyancy on objects of differing density and volume immersed in the fluid oil; 
         FIG. 19  is a schematic drawing of one embodiment of the invention illustrating the relative buoyancy and positions in fluids of different relative density; 
         FIG. 20  is a schematic drawing of one embodiment of the invention illustrating the relative buoyancy and positions in fluids of different relative density; 
         FIG. 21  is an elevational view of another embodiment of the fluid control apparatus having a rotating diverter that changes the flow direction according to one aspect of the invention. 
         FIG. 22  shows the apparatus of  FIG. 21  in the position where the fluid flow is minimally restricted. 
         FIGS. 23 through 26  are side cross-sectional views of the closing mechanism in  FIG. 21 . 
         FIG. 27  is a side cross-sectional view of another embodiment of the fluid control apparatus having a rotating flow-driven resistance assembly, shown in an open position, according to one aspect of the invention; and 
         FIG. 28  is a side cross-sectional view of the embodiment seen in  FIG. 27  having a rotating flow-driven resistance assembly, shown in a closed position. 
     
    
    
     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. Where this is not the case and a term is being used to indicate a required orientation, the Specification will state or make such clear either explicitly or from context. Upstream and downstream are used to indication location or direction in relation to the surface, where upstream indicates relative position or movement towards the surface along the wellbore and downstream indicates relative position or movement further away from the surface along the wellbore. 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     While the making and using of various embodiments of the present invention are discussed in detail below, a practitioner of the art will appreciate that the present invention provides applicable inventive concepts which can be embodied in a variety of specific contexts. The specific embodiments discussed herein are illustrative of specific ways to make and use the invention and do not delimit the scope of the present invention. 
       FIG. 1  is a schematic illustration of a well system, indicated generally as 10, including a plurality of autonomous density-actuated fluid control assemblies embodying principles of the present invention. A wellbore  12  extends through 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 deviated section  18 , shown as horizontal, that extends through a hydrocarbon bearing subterranean formation  20 . 
     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  upstream to the surface. Positioned within tubing string  22  in the various production intervals adjacent to formation  20  are a plurality of fluid control assemblies  25  and a plurality of production tubular sections  24 . On either side of each production tubulars  24  is a packer  26  that provides a fluid seal between tubing string  22  and the wall of wellbore  12 . Each pair of adjacent packers  26  defines a production interval. 
     In the illustrated embodiment, each of the production tubular sections  24  provides sand control capability. The sand control screen elements or filter media associated with production tubular sections  24  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  24  is not critical to the present invention as long as it is suitably designed for the characteristics of the formation fluids and for any treatment operations to be performed. 
     The term “natural gas” as used herein means a mixture of hydrocarbons (and varying quantities of non-hydrocarbons) that exist in a gaseous phase at room temperature and pressure. The term does not indicate that the natural gas is in a gaseous phase at the downhole location of the inventive systems. Indeed, it is to be understood that the flow control system is for use in locations where the pressure and temperature are such that natural gas will be in a mostly liquefied state, though other components may be present and some components may be in a gaseous state. The inventive concept will work with liquids or gases or when both are present. 
     The formation fluid flowing into the production tubular  24  typically comprises more than one fluid component. Typical components are natural gas, oil, water, steam, or carbon dioxide. Steam, water, and carbon dioxide are commonly used as injection fluids to drive the hydrocarbon towards the production tubular, whereas natural gas, oil and water are typically found in situ in the formation. The proportion of these components in the formation fluid flowing into the production tubular will vary over time and based on conditions within the formation and wellbore. Likewise, the composition of the fluid flowing into the various production tubing sections throughout the length of the entire production string can vary significantly from section to section. The fluid control apparatus is designed to restrict production from an interval when it has a higher proportion of an undesired component based on the relative density of the fluid. 
     Accordingly, when a production interval corresponding to a particular one of the fluid control assemblies produces a greater proportion of an undesired fluid component, the fluid control apparatus in that interval will restrict production flow from that interval. Thus, the other production intervals which are producing a greater proportion of desired fluid component, for example oil, will contribute more to the production stream entering tubing string  22 . Through use of the fluid control assemblies  25  of the present invention and by providing numerous production intervals, control over the volume and composition of the produced fluids is enabled. For example, in an oil production operation if an undesired component of the production fluid, such as water, steam, carbon dioxide, or natural gas, is entering one of the production intervals at greater than a target percentage, the fluid control apparatus in that interval will autonomously restrict production of formation fluid from that interval based on the density change when those components are present in greater than the targeted amount. 
     The fluid control apparatus actuates in response to density changes of the fluid in situ. The apparatus is designed to restrict fluid flow when the fluid reaches a target density. The density can be chosen to restrict flow of the fluid when it is reaches a target percentage of an undesirable component. For example, it may be desired to allow production of formation fluid where the fluid is composed of 80 percent oil (or more) with a corresponding composition of 20 percent (or less) of natural gas. Flow is restricted if the fluid falls below the target percentage of oil. Hence, the target density is production fluid density of a composition of 80 percent oil and 20 percent natural gas. If the fluid density becomes too low, flow is restricted by the mechanisms explained herein. Equivalently, an undesired higher density fluid could be restricted while a desired lower density fluid is produced. 
     Even though  FIG. 1  depicts the fluid control assemblies of the present invention in an open hole environment, it should be understood by those skilled in the art that the invention is equally well suited for use in cased wells. Also, even though  FIG. 1  depicts one fluid control apparatus in each production interval, it should be understood that any number of apparatus of the present invention can be deployed within a production interval without departing from the principles of the present invention. 
     Further, it is envisioned that the fluid control apparatus  25  can be used in conjunction with other downhole devices including inflow control devices (ICD) and screen assemblies. Inflow control devices and screen assemblies are not described here in detail, are known in the art, and are commercially available from Halliburton Energy Services, Inc. among others. 
     In addition,  FIG. 1  depicts the fluid control apparatus of the present invention in a deviated section of the wellbore which is illustrated as a horizontal wellbore. It should be understood by those skilled in the art that the apparatus of the present invention are suited for use in deviated wellbores, including horizontal wellbores, as well as vertical wellbores. As used herein, deviated wellbores refer to wellbores which are intentionally drilled away from the vertical. 
       FIG. 2  shows one embodiment of a fluid control apparatus  25  for controlling the flow of fluids in a downhole tubular. For purposes of discussion, the exemplary apparatus will be discussed as functioning to control production of formation fluid, restricting production of formation fluid with a greater proportion of natural gas. The flow control apparatus  25  is actuated by the change in formation fluid density. The fluid control apparatus  25  can be used along the length of a wellbore in a production string to provide fluid control at a plurality of locations. This can be advantageous, for example, to equalize production flow of oil in situations where a greater flow rate is expected at the heel of a horizontal well than at the toe of the well. 
     The fluid control apparatus  25  effectively restricts inflow of an undesired fluid while allowing minimally restricted flow of a desired fluid. For example, the fluid control apparatus  25  can be configured to restrict flow of formation fluid when the fluid is composed of a preselected percentage of natural gas, or where the formation fluid density is lower than a target density. In such a case, the fluid control apparatus selects oil production over gas production, effectively restricting gas production. 
       FIG. 2  is a side view in partial cross-section of one embodiment of the fluid control apparatus  25  for use in an oilfield tubular positioned in a wellbore extending through a subterranean formation. The fluid control apparatus  25  includes two valve assemblies  200  and fluid diverter assembly  100 . The fluid diverter assembly  100  has a fluid diverter  101  with two diverter arms  102 . The diverter arms  102  are connected to one another and pivot about a pivoting joint  103 . The diverter  101  is manufactured from a substance of a density selected to actuate the diverter arms  102  when the downhole fluid reaches a preselected density. The diverter can be made of plastic, rubber, composite material, metal, other material, or a combination of these materials. 
     The fluid diverter arms  102  are used to select how fluid flow is split between lower inlet  204  and upper inlet  206  of the valve assembly  200  and hence to control fluid flow through the tubular. The fluid diverter  101  is actuated by change in the density of the fluid in which it is immersed and the corresponding change in the buoyancy of the diverter  101 . When the density of the diverter  101  is higher than the fluid, the diverter will “sink” to the position shown in  FIG. 2 , referred to as the closed position since the valve assembly  200  is closed (restricting flow) when the diverter arms  102  are in this position. In the closed position, the diverter arms  102  pivot downward positioning the ends of the arms  102  proximate to inlet  204 . If the formation fluid density increases to a density higher than that of the diverter  101 , the change will actuate the diverter  101 , causing it to “float” and moving the diverter  101  to the position shown in  FIG. 3 . The fluid control apparatus is in an open position in  FIG. 3  since the valve assembly  200  is open when the diverter arms are in the position shown. 
     The fluid diverting arms operate on the difference in the density of the downhole fluid over time. For example, the buoyancy of the diverter arms is different in a fluid composed primarily of oil versus a fluid primarily composed of natural gas. Similarly, the buoyancy changes in oil versus water, water versus gas, etc. The buoyancy principles are explained more fully herein with respect to  FIGS. 15-20 . The arms will move between the open and closed positions in response to the changing fluid density. In the embodiment seen in  FIG. 2 , the diverter  101  material is of a higher density than the typical downhole fluid and will remain in the position shown in  FIG. 2  regardless of the fluid density. In such a case, a biasing mechanism  106  can be used, here shown as a leaf spring, to offset gravitational effects such that the diverter arms  102  will move to the open position even though the diverter arms are denser than the downhole fluid, such as oil. Other biasing mechanisms as are known in the art may be employed such as, but not limited to, counterweights, other spring types, etc., and the biasing mechanisms can be positioned in other locations, such as at or near the ends of the diverter arms. Here, the biasing spring  106  is connected to the two diverter arms  102 , tending to pivot them upwards and towards the position seen in  FIG. 3 . The biasing mechanism and the force it exerts are selected such that the diverter arms  102  will move to the position seen in  FIG. 3  when the fluid reaches a preselected density. The density of the diverter arms and the force of the biasing spring are selected to result in actuation of the diverter arms when the fluid in which the apparatus is immersed reaches a preselected density. 
     The valve assembly  200  seen in  FIG. 2  is shown in detail in the cross-sectional view in  FIG. 4 . The valve assembly shown is exemplary in nature and the details and configuration of the valve can be altered without departing from the spirit of the invention. The valve assembly  200  has a valve housing  202  with a lower inlet  204 , an upper inlet  206 , and an outlet  208 . The valve chamber  210  contains a valve member  212  operable to restrict fluid flow through the outlet  208 . An example valve member  212  comprises a pressure-activated end or arm  218  and a stopper end or arm  216  for restricting flow through outlet  208 . The valve member  212  is mounted in the valve housing  202  to rotate about pivot  214 . In the closed position, the stopper end  216  of the valve member is proximate to and restricts fluid flow through the outlet  208 . The stopper end can restrict or stop flow. 
     The exemplary valve assembly  200  includes a venturi pressure converter to enhance the driving pressure of the valve assembly. Based on Bernoulli&#39;s principle, assuming other properties of the flow remain constant, the static pressure will decrease as the flow velocity increases. A fluid flow ratio is created between the two inlets  204  and  206  by using the diverter arms  102  to restrict flow through one of the fluid inlets of the valve assembly, thereby reducing volumetric fluid flow through that inlet. The inlets  204  and  206  have venturi constrictions therein to enhance the pressure change at each pressure port  224  and  226 . The venturi pressure converter allows the valve to have a small pressure differential at the inlets but a larger pressure differential can be used to open and close the valve assembly  200 . 
       FIG. 5  is an end view in cross-section taken along line A-A of  FIG. 4 . Pressure ports  224  and  226  are seen in the cross-sectional view. Upper pressure port  226  communicates fluid pressure from upper inlet  206  to one side of the valve chamber  210 . Similarly, lower pressure port  224  communicates pressure as measured at the lower inlet  204  to the opposite side of the valve chamber  210 . The difference in pressure actuates the pressure-activated arm  218  of the valve member  212 . The pressure-activated arm  218  will be pushed by the higher pressure side, or suctioned by the lower pressure side, and pivot accordingly. 
       FIGS. 6 and 7  are bottom views in cross-section of the valve assembly seen in  FIGS. 2 and 3 .  FIG. 6  shows the valve assembly in a closed position with the fluid diverter arms  102  in the corresponding closed position as seen in  FIG. 2 . The diverter arm  102  is positioned to restrict fluid flow into lower inlet  204  of the valve assembly  200 . A relatively larger flow rate is realized in the upper inlet  206 . The difference in flow rate and resultant difference in fluid pressure is used, via pressure ports  224  and  226 , to actuate pressure-activated arm  218  of valve member  212 . When the diverter arm  102  is in the closed position, it restricts the fluid flow into the lower inlet  204  and allows relatively greater flow in the upper inlet  206 . A relatively lower pressure is thereby conveyed through the upper pressure port  226  while a relatively greater pressure is conveyed through the lower pressure port  224 . The pressure-activated arm  218  is actuated by this pressure difference and pulled toward the low pressure side of the valve chamber  210  to the closed position seen in  FIG. 6 . The valve member  212  rotates about pivot  214  and the stopper end  216  of the valve member  212  is moved proximate the outlet  208 , thereby restricting fluid flow through the valve assembly  200 . In a production well, the formation fluid flowing from the formation and into the valve assembly is thereby restricted from flowing into the production string and to the surface. 
     A biasing mechanism  228 , such as a spring or a counterweight, can be employed to bias the valve member  212  towards one position. As shown, the leaf spring biases the member  212  towards the open position as seen in  FIG. 7 . Other devices may be employed in the valve assembly, such as the diaphragm  230  to control or prevent fluid flow or pressure from acting on portions of the valve assembly or to control or prevent fines from interfering with the movement of the pivot,  214 . Further, alternate embodiments will be readily apparent to those of skill in the art for the valve assembly. For example, bellows, pressure balloons, and alternate valve member designs can be employed. 
       FIG. 7  is a bottom cross-section view of the valve assembly  200  seen in an open position corresponding to  FIG. 3 . In  FIG. 7 , the diverter arm  102  is in an open position with the diverter arm  102  proximate the upper inlet  206  and restricting fluid flow into the upper inlet. A greater flow rate is realized in the lower inlet  204 . The resulting pressure difference in the inlets, as measured through pressure ports  224  and  226 , results in actuation and movement of the valve member  212  to the open position. The pressure-activated arm of the member  212  is pulled towards the pressure port  224 , pivoting the valve member  212  and moving the stopper end  216  away from the outlet  208 . Fluid flows freely through the valve assembly  200  and into the production string and to the surface. 
       FIG. 8  is an orthogonal view of a fluid control assembly  25  in a housing  120  and connected to a production tubing string  24 . In this embodiment, the housing  120  is a downhole tubular with openings  114  for allowing fluid flow into the interior opening of the housing. Formation fluid flows from the formation into the wellbore and then through the openings  114 . The density of the formation fluid determines the behavior and actuation of the fluid diverter arms  102 . Formation fluid then flows into the valve assemblies  200  on either end of the assembly  25 . Fluid flows from the fluid control apparatus to the interior passageway  27  that leads towards the interior of the production tubing, not shown. In the preferred embodiment seen in  FIGS. 2-8 , the fluid control assembly has a valve assembly  200  at each end. Formation fluid flowing through the assemblies can be routed into the production string, or formation fluid from the downstream end can be flowed elsewhere, such as back into the wellbore. 
     The dual-arm and dual valve assembly design seen in the figures can be replaced with a single arm and single valve assembly design. An alternate housing  120  is seen in  FIGS. 6 and 7  where the housing comprises a plurality of rods connecting the two valve assembly housings  202 . 
     Note that the embodiment as seen in  FIGS. 2-8  can be modified to restrict production of various fluids as the composition and density of the fluid changes. For example, the embodiment can be designed to restrict water production while allowing oil production, restrict oil production while allowing natural gas production, restrict water production while allowing natural gas production, etc. The valve assembly can be designed such that the valve is open when the diverter is in a “floating,” buoyant or upper position, as seen in  FIG. 3 , or can be designed to be open where the diverter is in a “sunk” or lower position, as seen in  FIG. 2 , depending on the application. For example, to select natural gas production over water production, the valve assembly is designed to be closed when the diverter rises due to its buoyancy in the relatively higher density of water, to the position seen in  FIG. 3 . 
     Further, the embodiment can be employed in processes other than production from a hydrocarbon well. For example, the device can be utilized during injection of fluids into a wellbore to select injection of steam over water based on the relative densities of these fluids. During the injection process, hot water and steam are often commingled and exist in varying ratios in the injection fluid. Often hot water is circulated downhole until the wellbore has reached the desired temperature and pressure conditions to provide primarily steam for injection into the formation. It is typically not desirable to inject hot water into the formation. Consequently, the flow control apparatus  25  can be utilized to select for injection of steam (or other injection fluid) over injection of hot water or other less desirable fluids. The diverter will actuate based on the relative density of the injection fluid. When the injection fluid has an undesirable proportion of water and a consequently relatively higher density, the diverter will float to the position seen in  FIG. 3 , thereby restricting injection fluid flow into the upper inlet  206  of the valve assembly  200 . The resulting pressure differential between the upper and lower inlets  204  and  206  is utilized to move the valve assembly to a closed position, thereby restricting flow of the undesired fluid through the outlet  208  and the formation. As the injection fluid changes to a higher proportion of steam, with a consequent change to a lower density, the diverter will move to the opposite position, thereby reducing the restriction on the fluid to the formation. The injection methods described above are described for steam injection. It is to be understood that carbon dioxide or other injection fluid can be utilized. 
       FIG. 9  is an elevation view of another embodiment of a fluid control apparatus  325  having a rotating diverter  301 . The fluid control assembly  325  includes a fluid diverter assembly  300  with a movable fluid diverter  301  and two valve assemblies  400  at either end of the diverter assembly. 
     The diverter  301  is mounted for rotational movement in response to changes in fluid density. The exemplary diverter  301  shown is semi-circular in cross-section along a majority of its length with circular cross-sectional portions at either end. The embodiment will be described for use in selecting production of a higher density fluid, such as oil, and restricting production of a relatively lower density fluid, such as natural gas. In such a case, the diverter is “weighted” by high density counterweight portions  306  made of material with relatively high density, such as steel or another metal. The portion  304 , shown in an exemplary embodiment as semi-circular in cross section, is made of a material of relatively lower density material, such as plastic. The diverter portion  304  is more buoyant than the counterweight portions  306  in denser fluid, causing the diverter to rotate to the upper or open position seen in  FIG. 10 . Conversely, in a fluid of relatively lower density, such as natural gas, the diverter portion  304  is less buoyant than the counterweight portions  306 , and the diverter  301  rotates to a closed position as seen in  FIG. 9 . A biasing element, such as a spring-based biasing element, can be used instead of the counterweight. 
       FIG. 10  is an exploded detail view of the fluid control assembly of  FIG. 9 . In  FIG. 10 , the fluid selector or diverter  301  is rotated into an open position, such as when the assembly is immersed in a fluid with a relatively high density, such as oil. In a higher density fluid, the lower density portion  304  of the diverter  301  is more buoyant and tends to “float.” The lower density portion  304  may be of a lower density than the fluid in such a case. However, it is not required that the lower density portion  304  be less dense than the fluid. Instead, the high density portions  306  of the diverter  301  can serve as a counterweight or biasing member. 
     The diverter  301  rotates about its longitudinal axis  309  to the open position as seen in  FIG. 10 . When in the open position, the diverter passageway  308  is aligned with the outlet  408 , best seen in  FIG. 12 , of the valve assembly  400 . In this case, the valve assembly  400  has only a single inlet  404  and outlet  408 . In the preferred embodiment shown, the assembly  325  further includes fixed support members  310  with multiple ports  312  to facilitate fluid flow through the fixed support. 
     As seen in  FIGS. 9-13 , the fluid valve assemblies  400  are located at each end of the assembly. The valve assemblies have a single passageway defined therein with inlet  404  and outlet  408 . The outlet  408  aligns with the passageway  308  in the diverter  301  when the diverter is in the open position, as seen in  FIG. 10 . Note that the diverter  301  design seen in  FIGS. 9-10  can be employed, with modifications which will be apparent to one of skill in the art, with the venturi pressure valve assembly  200  seen in  FIGS. 2-7 . Similarly, the diverter arm design seen in  FIG. 2  can, with modification, be employed with the valve assembly seen in  FIG. 9 . 
     The buoyancy of the diverter creates a torque which rotates the diverter  301  about its longitudinal rotational axis. The torque produced must overcome any frictional and inertial forces tending to hold the diverter in place. Note that physical constraints or stops can be employed to constrain rotational movement of the diverter; that is, to limit rotation to various angles of rotation within a preselected arc or range. The torque will then exceed the static frictional forces to ensure the diverter will move when desired. Further, the constraints can be placed to prevent rotation of the diverter to top or bottom center to prevent possibly getting “stuck” in such an orientation. In one embodiment, the restriction of fluid flow is directly related to the angle of rotation of the diverter within a selected range of rotation. The passageway  308  of the diverter  301  aligns with the outlet  408  of the valve assembly when the diverter is in a completely open position, as seen in  FIGS. 10 and 13 . The alignment is partial as the diverter rotates towards the open position, allowing greater flow as the diverter rotates into the fully open position. The degree of flow is directly related to the angle of rotation of the diverter when the diverter rotates between partial and complete alignment with the valve outlet. 
       FIG. 11  is a flow schematic of one embodiment of the invention. An inflow control device  350 , or ICD, is in fluid communication with the fluid control assembly  325 . Fluid flows through the inflow control device  300 , through the flow splitter  360  to either end of the fluid control apparatus  325  and then through the exit ports  330 . Alternately, the system can be run with the entrance in the center of the fluid control device and the outlets at either end. 
       FIG. 12  is a side view in cross-section of the fluid control apparatus  325  embodiment seen in  FIG. 9  with the diverter  301  in the closed position. A housing  302  has within its interior the diverter assembly  300  and valve assemblies  400 . The housing includes outlet port  330 . In  FIG. 12 , the formation fluid F flows into each valve assembly  400  by inlet  404 . Fluid is prevented or restricted from exiting by outlet  408  by the diverter  301 . 
     The diverter assembly  300  is in a closed position in  FIG. 12 . The diverter  301  is rotated to the closed position as the density of the fluid changes to a denser composition due to the relative densities and buoyancies of the diverter portions  304  and  306 . The diverter portion  304  can be denser than the fluid, even where the fluid changes to a denser composition (and whether in the open or closed position) and in the preferred embodiment is denser than the fluid at all times. In such a case, where the diverter portion  304  is denser than the fluid even when the fluid density changes to a denser composition, counterweight portions  306  are utilized. The material in the diverter portion  304  and the material in the counterweight portion  306  have different densities. When immersed in fluid, the effective density of the portions is the actual density of the portions minus the fluid density. The volume and density of the diverter portion  304  and the counterweight portions  306  are selected such that the relative densities and relative buoyancies cause the diverter portion  304  to “sink” and the counterweight portion to “sink” in the fluid when it is of a low density (such as when comprised of natural gas). Conversely, when the fluid changes to a higher density, the diverter portion  304  “rises” or “floats” in the fluid and the counterweight portions “sink” (such as in oil). As used herein, the terms “sink” and “float” are used to describe how that part of the system moves and does not necessitate that the part be of greater weight or density than the actuating fluid. 
     In the closed position, as seen in  FIGS. 9 and 12 , the passageway  308  through the diverter portion  306  does not align with the outlet  408  of the valve assembly  400 . Fluid is restricted from flowing through the system. Note that it is acceptable in many instances for some fluid to “leak” or flow in small amounts through the system and out through exit port  330 . 
       FIG. 13  is a side view in cross-section of the fluid control apparatus as in  FIG. 12 , however, the diverter  301  is rotated to the open position. In the open position, the outlet  408  of the valve assembly is in alignment with the passageway  308  of the diverter. Fluid F flows from the formation into the interior passageway of the tubular having the apparatus. Fluid enters the valve assembly  400 , flows through portal  312  in the fixed support  310 , through the passageway  308  in the diverter, and then exits the housing through port or ports  330 . The fluid is then directed into production tubing and to the surface. Where oil production is selected over natural gas production, the diverter  301  rotates to the open position when the fluid density in the wellbore reaches a preselected density, such as the expected density of formation oil. The apparatus is designed to receive fluid from both ends simultaneously to balance pressure to both sides of the apparatus and reduce frictional forces during rotation. In an alternate embodiment, the apparatus is designed to allow flow from a single end or from the center outward. 
       FIG. 15  is a schematic illustrating the principles of buoyancy. Archimedes&#39; principle states that an object wholly or partly immersed in a fluid is buoyed by a force equal to the weight of the fluid displaced by the object. Buoyancy reduces the relative weight of the immersed object. Gravity G acts on the object  404 . The object has a mass, m, and a density, ρ-object. The fluid has a density, ρ-fluid. Buoyancy, B, acts upward on the object. The relative weight of the object changes with buoyancy. Consider a plastic having a relative density (in air) of 1.1. Natural gas has a relative density of approximately 0.3, oil of approximately 0.8, and water of approximately 1.0. The same plastic has a relative density of 0.8 in natural gas, 0.3 in oil, and 0.1 in water. Steel has a relative density of 7.8 in air, 7.5 in oil and 7.0 in water. 
       FIGS. 16-18  are schematic drawings showing the effect of buoyancy on objects of differing density and volume immersed in different fluids. Continuing with the example, placing plastic and steel objects on a balance illustrates the effects of buoyancy. The steel object  406  has a relative volume of one, while the plastic object  408  has a relative volume of 13. In  FIG. 16 , the plastic object  408  has a relative weight in air  410  of 14.3 while the steel object has a relative weight of 7.8. Thus, the plastic object is relatively heavier and causes the balance to lower on the side with the plastic object. When the balance and objects are immersed in natural gas  412 , as in  FIG. 17 , the balance remains in the same position. The relative weight of the plastic object is now 10.4 while the relative weight of the steel object is 7.5 in natural gas. In  FIG. 18 , the system is immersed in oil  414 . The steel object now has a relative weight of 7.0 while the plastic object has a relative weight of 3.9 in oil. Hence, the balance now moves to the position as shown because the plastic object  408  is more buoyant than the steel object  406 . 
       FIGS. 19 and 20  are schematic drawings of the diverter  301  illustrating the relative buoyancy and positions of the diverter in fluids of different relative density. Using the same plastic and steel examples as above and applying the principals to the diverter  301 , the steel counterweight portion  306  has a length L of one unit and the plastic diverter portion  304  has a length L of 13 units. The two portions are both hemicylindrical and have the same cross-section. Hence the plastic diverter portion  304  has 13 times the volume of the counterweight portion  306 . In oil or water, the steel counterweight portion  306  has a greater actual weight and the diverter  301  rotates to the position seen in  FIG. 19 . In air or natural gas, the plastic diverter portion  304  has a greater actual weight and the diverter  301  rotates to the lower position seen in  FIG. 20 . These principles are used in designing the diverter  301  to rotate to selected positions when immersed in fluid of known relative densities. The above is merely an example and can be modified to allow the diverter to change position in fluids of any selected density. 
       FIG. 14  is a side cross-sectional view of one end of the fluid control assembly  325  as seen in  FIG. 9 . Since the operation of the assembly is dependent on the movement of the diverter  301  in response to fluid density, the valve assemblies  400  need to be oriented in the wellbore. A preferred method of orienting the assemblies is to provide a self-orienting valve assembly which is weighted to cause rotation of the assembly in the wellbore. The self-orienting valve assembly is referred to as a “gravity selector.” 
     Once properly oriented, the valve assembly  400  and fixed support  310  can be sealed into place to prevent further movement of the valve assembly and to reduce possible leak pathways. In a preferred embodiment, as seen in  FIG. 14 , a sealing agent  340  has been placed around the exterior surfaces of the fixed support  310  and valve assembly  400 . Such an agent can be a swellable elastomer, an o-ring, an adhesive or epoxy that bonds when exposed to time, temperature, or fluids for example. The sealing agent  340  may also be placed between various parts of the apparatus which do not need to move relative to one another during operation, such as between the valve assembly  400  and fixed support  310  as shown. Preventing leak paths can be important as leaks can potentially reduce the effectiveness of the apparatus greatly. The sealing agent should not be placed to interfere with rotation of the diverter  301 . 
     The fluid control apparatus described above can be configured to select oil production over water production based on the relative densities of the two fluids. In a gas well, the fluid control apparatus can be configured to select gas production over oil or water production. The invention described herein can also be used in injection methods. The fluid control assembly is reversed in orientation such that flow of injection fluid from the surface enters the assembly prior to entering the formation. In an injection operation, the control assembly operates to restrict flow of an undesired fluid, such as water, while not providing increased resistance to flow of a desired fluid, such as steam or carbon dioxide. The fluid control apparatus described herein can also be used on other well operations, such as work-overs, cementing, reverse cementing, gravel packing, hydraulic fracturing, etc. Other uses will be apparent to those skilled in the art. 
       FIGS. 21 and 22  are orthogonal views of another embodiment of a fluid flow control apparatus of the invention having a pivoting diverter arm and valve assembly. The fluid control apparatus  525  has a diverter assembly  600  and valve assembly  700  positioned in a tubular  550 . The tubular  550  has an inlet  552  and outlet  554  for allowing fluid flow through the tubular. The diverter assembly  600  includes a diverter arm  602  which rotates about pivot  603  between a closed position, seen in  FIG. 21 , and an open position, seen in  FIG. 22 . The diverter arm  602  is actuated by change in the density of the fluid in which it is immersed. Similar to the descriptions above, the diverter arm  602  has less buoyancy when the fluid flowing through the tubular  550  is of a relatively low density and moves to the closed position. As the fluid changes to a relatively higher density, the buoyancy of the diverter arm  602  increases and the arm is actuated, moving upward to the open position. The pivot end  604  of the diverter arm has a relatively narrow cross-section, allowing fluid flow on either side of the arm. The free end  606  of the diverter arm  602  is preferably of a substantially rectangular cross-section which restricts flow through a portion of the tubular. For example, the free end  606  of the diverter arm  602 , as seen in  FIG. 15 , restricts fluid flow along the bottom of the tubular, while in  FIG. 22  flow is restricted along the upper portion of the tubular. The free end of the diverter arm does not entirely block flow through the tubular. 
     The valve assembly  700  includes a rotating valve member  702  mounted pivotally in the tubular  550  and movable between a closed position, seen in  FIG. 15 , wherein fluid flow through the tubular is restricted, and an open position, seen in  FIG. 22 , wherein the fluid is allowed to flow with less restriction through the valve assembly. The valve member  702  rotates about pivot  704 . The valve assembly can be designed to partially or completely restrict fluid flow when in the closed position. A stationary flow arm  705  can be utilized to further control fluid flow patterns through the tubular. 
     Movement of the diverter arm  602  affects the fluid flow pattern through the tubular  550 . When the diverter arm  602  is in the lower or closed position, seen in  FIG. 15 , fluid flowing through the tubular is directed primarily along the upper portion of the tubular. Alternately, when the diverter arm  602  is in the upper or open position, seen in  FIG. 22 , fluid flowing through the tubular is directed primarily along the lower portion of the tubular. Thus, the fluid flow pattern is affected by the relative density of the fluid. In response to the change in fluid flow pattern, the valve assembly  700  moves between the open and closed positions. In the embodiment shown, the fluid control apparatus  525  is designed to select a fluid of a relatively higher density. That is, a more dense fluid, such as oil, will cause the diverter arm  602  to “float” to an open position, as in  FIG. 22 , thereby affecting the fluid flow pattern and opening the valve assembly  700 . As the fluid changes to a lower density, such as gas, the diverter arm  602  “sinks” to the closed position and the affected fluid flow causes the valve assembly  700  to close, restricting flow of the less dense fluid. 
     A counterweight  601  may be used to adjust the fluid density at which the diverter arm  602  “floats” or “sinks” and can also be used to allow the material of the floater arm to have a significantly higher density than the fluid where the diverter arm “floats.” As explained above in relation to the rotating diverter system, the relative buoyancy or effective density of the diverter arm in relation to the fluid density will determine the conditions under which the diverter arm will change between open and closed or upper and lower positions. 
     Of course, the embodiment seen in  FIG. 21  can be designed to select more or less dense fluids as described elsewhere herein, and can be utilized in several processes and methods, as will be understood by one of skill in the art. 
       FIGS. 23-26  show further cross-section detail views of embodiments of a flow control apparatus utilizing a diverter arm as in  FIG. 21 . In  FIG. 17 , the flow controlled valve member  702  is a pivoting wedge  710  movable about pivot  711  between a closed position (shown) wherein the wedge  710  restricts flow through an outlet  712  extending through a wall  714  of the valve assembly  700 , and an open position wherein the wedge  710  does not restrict flow through the outlet  712 . 
     Similarly,  FIG. 24  shows an embodiment having a pivoting wedge-shaped valve member  720 . The wedge-shaped valve member  720  is seen in an open position with fluid flow unrestricted through valve outlet  712  along the bottom portion of the tubular. Note that the valve outlet  712  in this case is defined in part by the interior surface of the tubular and in part by the valve wall  714 . The valve member  720  rotates about pivot  711  between and open and closed position. 
       FIG. 25  shows another valve assembly embodiment having a pivoting disk valve member  730  which rotates about pivot  711  between an open position (shown) and a closed position. A stationary flow arm  734  can further be employed. 
       FIGS. 21-25  are exemplary embodiments of flow control apparatus having a movable diverter arm which affects fluid flow patterns within a tubular and a valve assembly which moves between an open and a closed position in response to the change in fluid flow pattern. The specifics of the embodiments are for example and are not limiting. The flow diverter arm can be movable about a pivot or pivots, slidable, flexures, or otherwise movable. The diverter can be made of any suitable material or combination of materials. The tubular can be circular in cross-section, as shown, or otherwise shaped. The diverter arm cross-section is shown as tapered at one end and substantially rectangular at the other end, but other shapes may be employed. The valve assemblies can include multiple outlets, stationary vanes, and shaped walls. The valve member may take any known shape which can be moved between an open and closed position by a change in fluid flow pattern, such as disk, wedge, etc. The valve member can further be movable about a pivot or pivots, slidable, bendable, or otherwise movable. The valve member can completely or partially restrict flow through the valve assembly. These and other examples will be apparent to one of skill in the art. 
     As with the other embodiments described herein, the embodiments in  FIGS. 21-25  can be designed to select any fluid based on a target density. The diverter arm can be selected to provide differing flow patterns in response to fluid composition changes between oil, water, gas, etc., as described herein. These embodiments can also be used for various processes and methods such as production, injection, work-overs, cementing and reverse cementing. 
       FIG. 26  is a schematic view of an embodiment of a flow control apparatus in accordance with the invention having a flow diverter actuated by fluid flow along dual flow paths. Flow control apparatus  800  has a dual flow path assembly  802  with a first flow path  804  and a second flow path  806 . The two flow paths are designed to provide differing resistance to fluid flow. The resistance in at least one of the flow paths is dependent on changes in the viscosity, flow rate, density, velocity, or other fluid flow characteristic of the fluid. Exemplary flow paths and variations are described in detail in U.S. patent application Ser. No. 12/700,685, to Jason Dykstra, et al., filed Feb. 4, 2010, which application is hereby incorporated in its entirety for all purposes. Consequently, only an exemplary embodiment will be briefly described herein. 
     In the exemplary embodiment at  FIG. 26 , the first fluid flow path  804  is selected to impart a pressure loss on the fluid flowing through the path which is dependent on the properties of the fluid flow. The second flow path  806  is selected to have a different flow rate dependence on the properties of the fluid flow than the first flow path  804 . For example, the first flow path can comprise a long narrow tubular section while the second flow path is an orifice-type pressure loss device having at least one orifice  808 , as seen. The relative flow rates through the first and second flow paths define a flow ratio. As the properties of the fluid flow changes, the fluid flow ratio will change. In this example, when the fluid consists of a relatively larger proportion of oil or other viscous fluid, the flow ratio will be relatively low. As the fluid changes to a less viscous composition, such as when natural gas is present, the ratio will increase as fluid flow through the first path increases relative to flow through the second path. 
     Other flow path designs can be employed as taught in the incorporated reference, including multiple flow paths, multiple flow control devices, such as orifice plates, tortuous pathways, etc., can be employed. Further, the pathways can be designed to exhibit differing flow ratios in response to other fluid flow characteristics, such as flow rate, velocity, density, etc., as explained in the incorporated reference. 
     The valve assembly  820  has a first inlet  830  in fluid communication with the first flow path  804  and a second inlet  832  in fluid communication with the second flow path  806 . A movable valve member  822  is positioned in a valve chamber  836  and moves or actuates in response to fluid flowing into the valve inlets  830  and  832 . The movable valve member  822 , in a preferred embodiment, rotates about pivot  825 . Pivot  825  is positioned to control the pivoting of the valve member  822  and can be offset from center, as shown, to provide the desired response to flow from the inlets. Alternate movable valve members can rotate, pivot, slide, bend, flex, or otherwise move in response to fluid flow. In an example, the valve member  822  is designed to rotate about pivot  825  to an open position, seen in  FIG. 20 , when the fluid is composed of a relatively high amount of oil while moving to a closed position when the fluid changes to a relatively higher amount of natural gas. Again, the valve assembly and member can be designed to open and close when the fluid is of target amount of a fluid flow characteristic and can select oil versus natural gas, oil versus water, natural gas versus water, etc. 
     The movable valve member  822  has a flow sensor  824  with first and second flow sensor arms  838  and  840 , respectively. The flow sensor  824  moves in response to changes in flow pattern from fluid through inlets  830  and  832 . Specifically, the first sensor arm  838  is positioned in the flow path from the first inlet  830  and the second sensor arm  840  is positioned in the flow path of the second inlet  832 . Each of the sensor arms has impingement surfaces  828 . In a preferred embodiment, the impingement surfaces  828  are of a stair-step design to maximize the hydraulic force as the part rotates. The valve member  822  also has a restriction arm  826  which can restrict the valve outlet  834 . When the valve member is in the open position, as shown, the restriction arm allows fluid flow through the outlet with no or minimal restriction. As the valve member rotates to a closed position, the restriction arm  826  moves to restrict fluid flow through the valve outlet. The valve can restrict fluid flow through the outlet partially or completely. 
       FIG. 27  is a cross-sectional side view of another embodiment of a flow control apparatus  900  of the invention having a rotating flow-driven resistance assembly. Fluid flows into the tubular passageway  902  and causes rotation of the rotational flow-driven resistance assembly  904 . The fluid flow imparts rotation to the directional vanes  910  which are attached to the rotational member  906 . The rotational member is movably positioned in the tubular to rotate about a longitudinal axis of rotation. As the rotational member  906  rotates, angular force is applied to the balance members  912 . The faster the rotation, the more force imparted to the balance members and the greater their tendency to move radially outward from the axis of rotation. The balance members  912  are shown as spherical weights, but can take other alternative form. At a relatively low rate of rotation, the valve support member  916  and attached restriction member  914  remain in the open position, seen in  FIG. 27 . Each of the balance members  912  is movably attached to the rotational member  906 , in a preferred embodiment, by balance arms  913 . The balance arms  913  are attached to the valve support member  916  which is slidably mounted on the rotational member  906 . As the balance members move radially outward, the balance arms pivot radially outwardly, thereby moving the valve support member longitudinally towards a closed position. In the closed position, the valve support member is moved longitudinally in an upstream direction (to the left in  FIG. 27 ) with a corresponding movement of the restriction member  914 . Restriction member  914  cooperates with the valve wall  922  to restrict fluid flow through valve outlet  920  when in the closed position. The restriction of fluid flow through the outlet depends on the rate of rotation of the rotational flow-driven resistance assembly  904 . 
       FIG. 28  is a cross-sectional side view of the embodiment of the flow control apparatus  900  of  FIG. 27  in a closed position. Fluid flow in the tubular passageway  902  has caused rotation of the rotational flow-driven resistance assembly  904 . At a relatively high rate of rotation, the valve support member  916  and attached restriction member  914  move to the closed position seen in  FIG. 28 . The balance members  912  are moved radially outward from the longitudinal axis by centrifugal force, pivoting balance arms  913  away from the longitudinal axis. The balance arms  913  are attached to the valve support member  916  which is slidably moved on the rotational member  906 . The balance members have moved radially outward, the balance arms pivoted radially outward, thereby moving the valve support member longitudinally towards the closed position shown. In the closed position, the valve support member is moved longitudinally in an upstream direction with a corresponding movement of the restriction member  914 . Restriction member  914  cooperates with the valve wall  922  to restrict fluid flow through valve outlet  920  when in the closed position. The restriction of fluid flow through the outlet depends on the rate of rotation of the rotational flow-driven resistance assembly  904 . The restriction of flow can be partial or complete. When the fluid flow slows or stops due to movement of the restriction member  914 , the rotational speed of the assembly will slow and the valve will once again move to the open position. For this purpose, the assembly can be biased towards the open position by a biasing member, such as a bias spring or the like. It is expected that the assembly will open and close cyclically as the restriction member position changes. 
     The rotational rate of the rotation assembly depends on a selected characteristic of the fluid or fluid flow. For example, the rotational assembly shown is viscosity dependent, with greater resistance to rotational movement when the fluid is of a relatively high viscosity. As the viscosity of the fluid decreases, the rotational rate of the rotation assembly increases, thereby restricting flow through the valve outlet. Alternately, the rotational assembly can rotate at varying rates in response to other fluid characteristics such as velocity, flow rate, density, etc., as described herein. The rotational flow-driven assembly can be utilized to restricted flow of fluid of a pre-selected target characteristic. In such a manner, the assembly can be used to allow flow of the fluid when it is of a target composition, such as relatively high oil content, while restricting flow when the fluid changes to a relatively higher content of a less viscous component, such as natural gas. Similarly, the assembly can be designed to select oil over water, natural gas over water, or natural gas over oil in a production method. The assembly can also be used in other processes, such as cementing, injection, work-overs and other methods. 
     Further, alternate designs are available for the rotational flow-driven resistance assembly. The balances, balance arms, vanes, restriction member and restriction support member can all be of alternate design and can be positioned up or downstream of one another. Other design decisions will be apparent to those of skill in the art. 
     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.