Patent Publication Number: US-9404349-B2

Title: Autonomous fluid control system having a fluid diode

Description:
FIELD OF INVENTION 
     The invention relates to apparatus and methods for autonomously controlling fluid flow through a system using a fluid diode. More specifically, the invention relates to using a fluid diode defined by an orifice having a high resistance side and a low resistance side. 
     BACKGROUND OF INVENTION 
     Some wellbore servicing tools provide a plurality of fluid flow paths between the interior of the wellbore servicing tool and the wellbore. However, fluid transfer through such a plurality of fluid flow paths may occur in an undesirable and/or non-homogeneous manner. The variation in fluid transfer through the plurality of fluid flow paths may be attributable to variances in the fluid conditions of an associated hydrocarbon formation and/or may be attributable to operational conditions of the wellbore servicing tool, such as a fluid flow path being unintentionally restricted by particulate matter. 
     SUMMARY OF THE INVENTION 
     The invention provides apparatus and methods for autonomously controlling fluid flow in a subterranean well, and in particular for providing a fluid diode to create a relatively high resistance to fluid flow in one direction and a relatively low resistance to fluid flowing in the opposite direction. The diode is positioned in a fluid passageway and has opposing high resistance and low resistance entries. The low resistance entry providing a relatively low resistance to fluid flowing into the diode through the low resistance entry. The high resistance entry providing a relatively high resistance to fluid flowing into the diode through the high resistance entry. In a preferred embodiment, the high resistance entry has a concave, annular surface surrounding an orifice and the low resistance entry has a substantially conical surface. The entries can have a common orifice. In one embodiment, the concave, annular surface of the high resistance entry extends longitudinally beyond the plane of the orifice. That is, a portion of a fluid flowing through the diode from the high resistance side will flow longitudinally past, but not through, the orifice, before being turned by the concave, annular surface. In a preferred embodiment, the fluid will flow in eddies adjacent the concave, annular surface. 
     The apparatus and method can be used in conjunction with other autonomous flow control systems, including those having flow control assemblies and vortex assemblies. The invention can be used in production, injection and other servicing operations of a subterranean wellbore. The invention can be positioned to provide relatively higher resistance to fluid flow as it moves towards or away from the surface. 
    
    
     
       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 flow control systems according to an embodiment of the invention; 
         FIG. 2  is a cross-sectional view of a fluid diode of a preferred embodiment of the invention; 
         FIG. 3  is a flow diagram representative of a fluid flowing into the fluid diode through the high resistance entry; 
         FIG. 4  is a flow diagram representative of a fluid flowing into the fluid diode through the low resistance entry; 
         FIGS. 5A-C  are exemplary embodiments of fluid diodes according to the invention; 
         FIG. 6  is a cross-sectional view of an alternate embodiment of a fluid diode according to an aspect of the invention; and 
         FIG. 7  is a schematic diagram of an exemplary fluid control system  59  having a fluid diode according to aspects of the invention. 
     
    
    
     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. “Uphole,” “downhole” are used to indicate location or direction in relation to the surface, where uphole indicates relative position or movement towards the surface along the wellbore and downhole indicates relative position or movement further away from the surface along the wellbore, regardless of the wellbore orientation (unless otherwise made clear). 
     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 limit the scope of the present invention. 
       FIG. 1  is a schematic illustration of a well system, indicated generally  10 , including a plurality of autonomous flow control systems 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, which extends through a hydrocarbon-bearing subterranean formation  20 . As illustrated, substantially horizontal section  18  of wellbore  12  is open hole. While shown here in an open hole, horizontal section of a wellbore, the invention will work in any orientation, and in open or cased hole. The invention will also work equally well with injection systems. 
     Positioned within wellbore  12  and extending from the surface is a tubing string  22 . Tubing string  22  provides a conduit for 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 autonomous fluid control systems  25  and a plurality of production tubing sections  24 . At either end of each production tubing section  24  is a packer  26  that provides a fluid seal between tubing string  22  and the wall of wellbore  12 . The space in-between each pair of adjacent packers  26  defines a production interval. 
     In the illustrated embodiment, each of the production tubing sections  24  includes sand control capability. Sand control screen elements or filter media associated with production tubing sections  24  are designed to allow fluids to flow therethrough but prevent particulate matter of sufficient size from flowing therethrough. 
     The fluid flowing into the production tubing section typically comprises more than one fluid component. Typical components are natural gas, oil, water, steam or carbon dioxide. Steam 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 invention provides a method and apparatus for use of a fluid diode in a passageway to provide a relatively high resistance to fluid flow through a passageway in one direction while providing a relatively low resistance to fluid flow in the opposite direction. It is envisioned that such relative restriction of fluid flow can be used in any operation where fluid flow is desired in one direction and undesired in the opposite direction. For example, during production of hydrocarbons from the wellbore, fluid typically flows from the wellbore, into the tubing string, and thence uphole towards the surface. However, if flow is reversed for some reason, a fluid diode, or series of diodes, will restrict flow in the reverse direction. The diodes can be used similarly in injection operations to restrict fluid flow uphole. Persons of skill in the art will recognize other uses where restriction of flow in one direction is preferable. 
       FIG. 2  is a cross-sectional view of a fluid diode of a preferred embodiment of the invention. The fluid diode  100  is positioned in a fluid passageway  102  defined by a passageway wall  101 . The passageway  102  can be positioned in a downhole tool, tubing string, as part of a larger autonomous fluid control system, in series with additional fluid diodes, or individually. 
     The fluid diode  100  has a low resistance entry  104  and a high resistance entry  106 . The low resistance entry  104 , in the preferred embodiment shown, has a substantially conical surface  108  narrowing from a large diameter end  110  to a small diameter end  112  and terminating at an orifice  114 . The substantially conical surface is preferably manufactured such that it is, in fact, conical; however, the surface can instead vary from truly conical, such as made of a plurality of flat surfaces arranged to provide a cone-like narrowing. The high resistance entry  106  narrows from a large diameter end  116  to a small diameter end  118  and terminates at an orifice  114 . In the preferred embodiment shown, the orifice  114  for the high and low resistance ends is coincident. In other embodiments, the orifices can be separate. The orifice  114 , high resistance entry  106  and low resistance entry  104  are preferably centered on the longitudinal axis  103  of the passageway  102 . The orifice  114  lies in a plane  115 . Preferably the plane  115  is normal to the longitudinal axis  103 . 
     The high resistance entry  106  preferably includes a concave surface  120 . The concave surface  120  is annular, extending around the orifice  114 . In a preferred embodiment, as seen in  FIG. 2 , the concave surface  120  curves along an arc through more than 90 degrees. Here, “arc” does not require that the surface be a segment of a circle; the surface seen in  FIG. 2  is not circular, for example. The concave surface can be a segment of a circle, ellipse, etc., or irregular. The concave surface extends longitudinally from one side of the plane  115  of the orifice  114  to another. For purposes of discussion, the concave surface  120  extends longitudinally from a point upstream of the plane of the orifice (when fluid is flowing into the high resistance entry  106 ) to a furthest extent downstream from the place of the orifice. That is, the concave surface extends longitudinally beyond the plane of the orifice. The furthest extent downstream of the concave surface  120  is indicated by dashed line  121 . In the embodiment shown, the longitudinal extent of the conical surface  108  overlaps with the longitudinal extent of the concave surface  120 . 
     In use, fluid F can flow either direction through the diode  100 . When fluid flows into the diode through the low resistance entry  104 , as indicated by the solid arrow in  FIG. 2 , the diode provides a lower resistance to fluid flow than when fluid flows into the diode through the high resistance entry  106 , as indicated by the dashed arrow in  FIG. 2 . In a typical use, fluid flow in the low resistance direction is preferred, such as for production of well fluid. If flow is reversed, such that it flows through the diode from the high resistance entry, flow is restricted. 
       FIG. 3  is a flow diagram representative of a fluid F flowing into the fluid diode  100  through the high resistance entry  106 .  FIG. 4  is a flow diagram representative of a fluid F flowing into the diode  100  through the low resistance entry  104 . The flow lines shown are velocity flow lines. Where fluid enters from the high resistance side, as in  FIG. 3 , a portion of the fluid flow is directed substantially radially, toward the axis  103 . The fluid flow through the orifice  114  is substantially restricted or slowed, and total fluid flow across the diode is similarly restricted. The pressure drop across the diode is correspondingly relatively higher. In a preferred embodiment, eddies  122  are created adjacent the concave surface of the high resistance entry. Where fluid enters the diode from the low resistance side, as in  FIG. 4 , fluid flows through the diode with relatively lower resistance, with a corresponding lower pressure drop across the diode. 
     The following data is exemplary in nature and generated from computer modeling of a diode similar to that in  FIG. 2-4 . The pressure drops across the diode and resistance to fluid flow is dependent on the direction of fluid flow through the diode. Water at a flow rate of 0.2 kg per second experienced a pressure drop across the diode of approximately 4200 Pa when flowing into the diode from the high resistance side. Water flowing the opposite direction, from the low resistance side, only experienced a pressure drop of approximately 2005 Pa. Similarly, air having a density of 1.3 kg per cubic meter and at the same flow rate, experienced a pressure drop of 400 psi when flowing in the restricted direction and only a 218 psi pressure drop in the unrestricted direction. Finally, gas modeled at 150 kg per cubic meter and at the same flow rate, experienced a pressure drop of 5 psi in the restricted direction and 2 psi in the unrestricted direction. These data points are exemplary only. 
       FIGS. 5A-C  are exemplary embodiments of fluid diodes according to the invention.  FIGS. 5A-C  show alternate profiles for the concave, annular surface  120  of the fluid diode  100 . In  FIG. 5A , the profile is similar to that in  FIG. 2 , wherein the concave surface  120  curves through more than 90 degrees, has a comparatively deep “pocket,” and extends to a point at  121  past the plane  115  of the orifice  114 .  FIG. 5B  is similar, however, the concave surface  120  is shallower. In  FIG. 5C  the concave surface  120  curves through 90 degrees and does not extend longitudinally past the orifice plane  115 . The design of  FIG. 5A  is presently preferred and provides the greatest pressure drop when flow is in the restricted direction. Using modeling techniques, the pressure drops across the diodes in  FIGS. 5A-C  were 4200 Pa, 3980 Pa and 3208 Pa, respectively. Additionally, the high resistance entry can take other shapes, such as curved surfaces having additional curvatures to the concave surface shown, concave surfaces which vary from the exact curvature shown, a plurality of flat surfaces which provide a substantially similar concave surface when taken in the aggregate, or even having a rectangular cross-section. Further, the passageway can have round, rectangular, or other cross-sectional shape. 
       FIG. 6  is a cross-sectional view of an alternate embodiment of a fluid diode according to an aspect of the invention.  FIG. 6  shows an alternate embodiment wherein the orifice  114   a  of the high resistance entry  106  is not coincident with the orifice  114   b  of the low resistance entry  104 . A relatively narrow conduit  124  connects the orifices. 
       FIG. 7  is a schematic diagram of an exemplary fluid control system  59  having a fluid diode according to aspects of the invention. The fluid control system  59  is explained in detail in references which are incorporated herein by reference and will not be described in detail here. The fluid control system is designed for fluid flow in the direction indicated by the double arrows, F. Fluid, such as production fluid, enters the fluid control system  59 , flows through the passageways  62  and  64  of the flow control assembly  60 , exits through outlets  68  and  70 . Fluid then flows into the vortex assembly  80  through an inlet  84  or  86 , by optional directional elements  90 , through vortex chamber  82  and out of the vortex outlet  88 . Fluid then flows downstream (which in this embodiment is uphole), such as to the surface. While flow in this direction is preferred and typical, the fluid diode of the invention can be used in conjunction with or as part of the flow control system to restrict or prevent reverse fluid flow through the system. As indicated, one or more fluid diodes  100  can be employed at locations along the system, upstream or downstream from the system. 
     In a preferred embodiment, fluid diodes  100  are arranged in series, such that the fluid flow passes through a plurality of diodes. For example, two diodes  100  are seen downstream of the vortex assembly  80  in  FIG. 7 . As discussed above, when fluid flows through the high resistance side of the diode, a greater pressure drop is realized across the diode than when flow is in the opposite direction. However, the pressure drop across a plurality of diodes will be greater still. It is preferred that a plurality of diodes in series be used to create a much greater total pressure drop across the plurality of diodes. In such a manner, the reverse flow through the system can be substantially restricted. 
     The diode explained herein can be used in conjunction with the various flow control systems, assemblies and devices described in the incorporated references as will be understood by those of skill in the art. 
     Descriptions of fluid flow control using autonomous flow control devices and their application can be found in the following U.S. Patents and Patent Applications, each of which are hereby incorporated herein in their entirety for all purposes: U.S. patent application Ser. No. 12/635,612, entitled “Fluid Flow Control Device,” to Schultz, filed Dec. 10, 2009; U.S. patent application Ser. No. 12/770,568, entitled “Method and Apparatus for Controlling Fluid Flow Using Movable Flow Diverter Assembly,” to Dykstra, filed Apr. 29, 2010; U.S. patent application Ser. No. 12/700,685, entitled “Method and Apparatus for Autonomous Downhole Fluid Selection With Pathway Dependent Resistance System,” to Dykstra, filed Feb. 4, 2010; U.S. patent application Ser. No. 12/791,993, entitled “Flow Path Control Based on Fluid Characteristics to Thereby Variably Resist Flow in a Subterranean Well,” to Dykstra, filed Jun. 2, 2010; U.S. patent application Ser. No. 12/792,095, entitled “Alternating Flow Resistance Increases and Decreases for Propagating Pressure Pulses in a Subterranean Well,” to Fripp, filed Jun. 2, 2010; U.S. patent application Ser. No. 12/792,117, entitled “Variable Flow Resistance System for Use in a Subterranean Well,” to Fripp, filed Jun. 2, 2010; U.S. patent application Ser. No. 12/792,146, entitled “Variable Flow Resistance System With Circulation Inducing Structure Therein to Variably Resist Flow in a Subterranean Well,” to Dykstra, filed Jun. 2, 2010; U.S. patent application Ser. No. 12/879,846, entitled “Series Configured Variable Flow Restrictors For Use In A Subterranean Well,” to Dykstra, filed Sep. 10, 2010; U.S. patent application Ser. No. 12/869,836, entitled “Variable Flow Restrictor For Use In A Subterranean Well,” to Holderman, filed Aug. 27, 2010; U.S. patent application Ser. No. 12/958,625, entitled “A Device For Directing The Flow Of A Fluid Using A Pressure Switch,” to Dykstra, filed Dec. 2, 2010; U.S. patent application Ser. No. 12/974,212, entitled “An Exit Assembly With a Fluid Director for Inducing and Impeding Rotational Flow of a Fluid,” to Dykstra, filed Dec. 21, 2010; U.S. patent application Ser. No. 12/983,144, entitled “Cross-Flow Fluidic Oscillators for use with a Subterranean Well,” to Schultz, filed Dec. 31, 2010; U.S. patent application Ser. No. 12/966,772, entitled “Downhole Fluid Flow Control System and Method Having Direction Dependent Flow Resistance,” to Jean-Marc Lopez, filed Dec. 13, 2010; U.S. patent application Ser. No. 12/983,153, entitled “Fluidic Oscillators For Use With A Subterranean Well (includes vortex),” to Schultz, filed Dec. 31, 2010; U.S. patent application Ser. No. 13/084,025, entitled “Active Control for the Autonomous Valve,” to Fripp, filed Apr. 11, 2011; U.S. Patent Application Ser. No. 61/473,700, entitled “Moving Fluid Selectors for the Autonomous Valve,” to Fripp, filed Apr. 8, 2011; U.S. Patent Application Ser. No. 61/473,699, entitled “Sticky Switch for the Autonomous Valve,” to Fripp, filed Apr. 8, 2011; and U.S. patent application Ser. No. 13/100,006, entitled “Centrifugal Fluid Separator,” to Fripp, filed May 3, 2011. 
     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.