Abstract:
A well conduit that has an aperture for communicating with a target reservoir and a one-way valve in the aperture may be used in injection and production wells. Other devices, systems, methods, and associated uses are also included in the present invention. For example, the conduit housing the valves may be used as a base pipe for a sand screen. It is emphasized that this abstract is provided to comply with the rules requiring an abstract, which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims

Description:
BACKGROUND OF INVENTION  
       [0001]     The present invention relates to the field of flow control in a well. More specifically, the invention relates to a device and method for controlling flow in a well using valves mounted within apertures in a well conduit as well as related systems, methods, and devices.  
       SUMMARY OF INVENTION  
       [0002]     One aspect of the present invention is a well flow control device comprising a conduit having an aperture for communicating with a target reservoir and a one-way valve in the aperture. Other devices, systems, methods, and associated uses are also included in the present invention. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0003]     The manner in which these objectives and other desirable characteristics can be obtained is explained in the following description and attached drawings in which:  
         [0004]      FIG. 1  illustrates an embodiment of the present invention in an injection well in which the conduit has a plurality of one-way valves mounted thereto.  
         [0005]      FIG. 2  illustrates a conduit section having valves mounted in the wall thereof.  
         [0006]      FIGS. 3-5  illustrates different types of one way valves mounted in the wall of a well conduit.  
         [0007]      FIG. 6  illustrates a sand screen having one-way valves mounted in its base pipe.  
         [0008]      FIG. 7  shows the screen of  FIG. 6  in a multizone well.  
         [0009]      FIG. 8  illustrates a completion that has sand screen of  FIG. 6  and in-line valves.  
         [0010]      FIG. 9  shows a conduit with valves mounted in the walls of the conduit and having a varying density of valves along its length. 
     
    
       [0011]     It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.  
       DETAILED DESCRIPTION  
       [0012]     In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.  
         [0013]     The present invention relates to various apparatuses, systems and methods for controlling fluid flow in a well. One aspect of the present invention relates to a conduit having an aperture for communicating with a target reservoir and a one-way valve in the aperture. Other aspects of the present invention, which are further explained below, relate to improving injection well performance using valves, preventing cross-flow in multizone and multilateral completions, and other methods and apparatuses for controlling fluid flow in a well.  
         [0014]     As an example,  FIG. 1  illustrates a well  10  having a cased section  12  and an open hole section  14 . A conduit  16 , or liner, extends from a packer  18  positioned in the cased section  12  downward into the open hole section  14 . At least a portion of the conduit  16  is perforated to define multiple orifices or apertures  20  therein. Mounted within each of the apertures  20  is a one-way valve or check valve  22 . The check valve  22  may take a variety of forms. However, the one-way valve  22  acts to allow flow in one direction and restrict or limit flow in an opposite direction. Depending upon the application and aperture size and other factors, some of the apertures  20  may omit valves  22 , for example, if some bidirectional flow is acceptable.  
         [0015]     The arrows  23  in  FIG. 1  illustrate the direction of flow in an injection application. In an injection application, fluid is injected into a well  10 . For example, a common practice used to increase recovery of oil from a reservoir is water-flooding. Water is injected into the reservoir through an injection well  10  as a nearby producing well produces oil from the formation. The goal is to maintain reservoir pressure and to generate a sweep effect pushing the oil using the injected water. One problem often encountered in injection applications occurs when injected fluid flows back into the well  10  or when cross-flow occurs. Another problem occurs when an inline valve or a pump is shut suddenly. When this happens an over pressure wave is generated creating a water hammer. This wave, or water hammer, propagates downhole and “liquefies” the poorly consolidated sand of the formation. Each of these problems can create a sanding issue in which sand enters the well  10 , progressively plugging the well  10  and requiring expensive cleaning operations. Traditionally, this problem has been addressed with standard sand control methods, such as sand screens, gravel packs, and expandable sand screens. However, by preventing the flow of fluids back into the conduit  16 , the present invention prevents sanding and acts as a dampener in the water hammer scenario reducing the water hammer affect. Thus, one aspect of the invention is a method to dampen a wave by limiting the flow of fluid into a well  10  with valves  22  positioned in the conduit wall that respond to the flow of fluid (e.g., like a check valve  22 ).  
         [0016]     The check valve(s)  22  in the conduit  16  allows fluid to flow from an interior  24  of the conduit  16  to its exterior  26  and, thus, into the target reservoir. However, the valve(s)  22  limits or prevents flow in the opposite direction, from the conduit exterior  26  to its interior  24 .  
         [0017]      FIG. 2  illustrates a conduit  16  or tubing for use in a well  10 . The conduit  16  has substantially radial apertures  20  extending through its wall  28 . Valves  22  are mounted in each of the apertures  20  and are adapted to limit or prevent flow therethrough. For example, in the injection example described above, the valves  22  could be one-way check valves that allow flow from the conduit  16  only (or at least limit inward flow). In other applications, the valves  22  may limit flow in the opposite direction (i.e., limit flow from the tubing). The valve  22  may take a variety of forms and may be mounted to the conduit  16  in a variety of ways. For example, the valve  22  may be mounted to the tubing by threaded connection, welding, interference fit, friction, detents, snap rings, or by any other connection technique. The valves  22  shown in the figure are generally flush with the exterior  26  of the wall  28 , although they could extend from the wall  28  without departing from the scope of the present invention.  
         [0018]      FIG. 3  illustrates one type of valve  22 . The valve  22  is threaded into an opening (aperture  20 ) in the conduit wall  28  and extends from the wall  28 . The valve  22  has a housing  30 , attached to the conduit wall  28 , that defines an interior  32  and a valve seat  34 . A valve member  36 , such as a poppet, in the housing  30  is biased to a closed position by a spring  38 . When the valve  22  is exposed to sufficient opening fluid pressure, the valve member  36  moves to an open position, off-seat to allow fluid flow through the valve  22 . The valve  22  shown in  FIG. 3  provides for flow from an interior  24  of the well conduit  16  to an exterior  26  of the conduit  16 , but prevents or restricts flow in the opposite direction (as in an injection well  10 ).  
         [0019]      FIG. 4  illustrates another type of valve  22  that may be used in a well conduit wall  28  of the present invention. The valve  22  comprises a housing  30  defining a passageway therethrough and a valve seat  34 . A flapper (valve member  36 ) allows flow in one direction through the valve  22 , but prevents flow in an opposite direction. In  FIG. 4 , the valve  22  is oriented to allow flow into the conduit  16  and prevent flow from the conduit  16  (as in a production well  10 ).  
         [0020]      FIG. 5  shows a ball-type check valve  22  in a well conduit wall  28 . In the closed position, the ball (valve member  36 ) seats on the valve seat  34  defined by a valve housing  30 . The ball unseats in the open position and is supported on the ball supports  40  of the housing  30 . The supports  40  are spaced to provide for flow around the ball when the ball is in the open position. The valve  22  in  FIG. 5  is oriented to allow injection into a formation and prevent the inflow of fluids into the well conduit interior  24 .  
         [0021]     In some cases it may be advantageous to incorporate the valves  22  of the present invention into the base pipe  16  of a sand screen  42 . As used herein, the term “screen” refers to wire wrapped screens, mechanical type screens and other filtering mechanisms typically employed with sand screens. Screens generally have a perforated base pipe  16  with a filter media (e.g., wire wrapping, mesh material, pre-packs, multiple layers, woven mesh, sintered mesh, foil material, wrap-around slotted sheet, wrap-around perforated sheet, mesh filter material, or a combination of any of these media to create a composite filter media and the like) disposed thereon to provide the necessary filtering. The filter media may be made in any known manner (e.g., laser cutting, water jet cutting and many other methods). Sand screens need to have openings small enough to restrict gravel flow or flow of material to be filtered, often having gaps in the 60 120 mesh range, but other sizes may be used. The screen element can be referred to as a screen, sand screen, or a gravel pack screen. Many of the common screen types include a spacer that offsets the screen member from a perforated base tubular, or base pipe  16 , that the screen member surrounds. The spacer provides a fluid flow annulus between the screen member and the base tubular.  
         [0022]      FIG. 6  illustrates a sand screen  42  having a base pipe  16  and a filter media  44 , which is shown as a wire wrap in the figure. The base pipe  16  has numerous openings through the base pipe wall  28 . Valves  22  are mounted in the openings to control the flow into or from the screen  42 . For example, in an injection well  10 , the screen  42  with the check valves  22  in the base pipe wall  28  may be used to alleviate the sanding problems discussed above. Combining the check valves  22  with the screen  42  may enhance the desired effect of reducing sanding.  
         [0023]     Likewise, the sand screen  42  shown in  FIG. 6  may be used in a production well  10 . The screen  42  allows fluid to be produced while preventing sand to enter the production conduit  16  and, at the same time, prevents fluid from exiting the production conduit  16 .  
         [0024]      FIG. 7  illustrates one use of the sand screen  42  of  FIG. 6  having the check valves  22  therein in a production well  10 , although many other uses in production wells are possible. In this aspect of the invention, a production conduit  16  extending into the well  10  has at least one substantially radial aperture  20  and may have many apertures  20 . A valve  22 , such as a check valve or other valve described herein, is mounted within in at least a portion of the apertures  20 . The valve  22  allows flow therethrough from an exterior  26  to an interior  24  of the production conduit  16 , but limits flow therethrough from the interior  24  to the exterior  26 . Thus, fluid is allowed into the production conduit  16 , but flow out of the production conduit  16  is restricted or prevented.  
         [0025]     As one example of a use of this aspect of the present invention, some production wells, such as the one shown in the figure, have multiple zones  46 , which may include multilateral wells. One problem sometimes associated with multizone wells is cross-flow. Cross-flow may occur when the pressure in one zone  46  is different than the pressure in another zone  46 . In this case, fluid may flow from the higher-pressure zone  46  into the lower-pressure zone  46  rather than to the surface. The present invention may alleviate this problem by limiting the flow of fluid from the production conduit  16  to a target reservoir  46  with a valve  22  mounted within at least a portion of the apertures  20 . Some apertures  20  may remain open depending upon the application (e.g., if some flow into the formation is permissible). Thus, a sand screen  42  as described above in connection with  FIG. 6 , is provided in each of the zones  46  in  FIG. 7 . The production zones  46  are separated fluidically by packers  18 . The check valves  22  in the sand screens  42  prevent cross-flow between the formations. Note that the screens  42  may be replaced by a conduit  16  having the check valves  22  therein (e.g., as shown in  FIG. 2 ) in those cases where the sand control provided by the screens  42  is not necessary or desired.  
         [0026]      FIG. 8  illustrates another aspect of the current invention in which the conduit  16  having check valves  22  therein (which happen to be incorporated into sand screens  42  in  FIG. 8 ) is combined with in-line flow control valves  47 . The in-line flow control valves  47  may be used to regulate (e.g., choke) the flow to or from the various zones  46 . See U.S. Patent Application Publication No. U.S. 2001/0045290 A1, published Nov. 28, 2001, for some examples of in-line valves  47 .  
         [0027]     Another problem often associated with injection applications involves channeling. Uncontrolled injectivity can create channeling, which prevents sweep uniformity and can lead to early water production in the production well  10 . As illustrated in  FIG. 9 , the present invention provides for variation in the density and concentration of valves  22  according to the well  10 . Using data relating to the well(s) or reservoir, spacing between conduit apertures  20  is set to provide a uniform sweep of injected fluid. By varying the spacing between apertures  20  (and associated valves  22 ) in the conduit  16 , the sweep of injected fluid into the well  10  and target reservoir  46  is controlled to alleviate the risk of channeling. In  FIG. 9 , the conduit  16  has one section  48  with a relatively lower concentration of openings and associated valves  22  and another section  50  with a relatively higher concentration of openings and associated valves  22 . The relative concentration may vary depending upon the particular requirements and characteristics of the well  10 . The varying of the concentration of the valves  22  also has application in a production environment or system. For example, in production wells it is often desirable to vary the flow of fluid produced along the length of the well  10  to reduce coning. Horizontal wells tend to produce faster from the heel  52  of the well  10  relative to the toe  54  of the well  10 . Accordingly, it may be desirable to have a lower concentration of valves  22  near the heel  52  of the well  10  (as illustrated in  FIG. 9 ) to reduce the rate of production at the heel  52 .  
         [0028]     Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. For example, the valve  22  in each case described above may be designed to completely block flow when in the closed position or merely limit or restrict flow through the aperture  20 . Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words “means for” together with an associated function.