Abstract:
An apparatus that is usable with a well includes a tool and a shroud. The tool is to be disposed in a wellbore and includes an opening to inject fluid into the well. The shroud at least partially surrounds the tool to eccentrically dispose the tool with respect to a longitudinal axis of the wellbore.

Description:
BACKGROUND  
       [0001]     The invention generally relates to an eccentrically-disposed choke injector.  
         [0002]     A choke injector is a well tool, which typically is used for purposes of injecting a fluid, such as sea water, into the annulus of the well. As its name implies, the choke injector typically has a controllable flow rate. However, a challenge with using the choke injector is that the fluid that exits its radially-directed openings may erode a casing of the well.  
         [0003]     Thus, there is a continuing need for a choke injector that is less harmful to a well casing.  
       SUMMARY  
       [0004]     In an embodiment of the invention, an apparatus that is usable with a well includes a tool and a shroud. The tool is to be disposed in a wellbore and includes a opening to inject fluid into the well. The shroud at least partially surrounds the tool to eccentrically dispose the tool with respect to a longitudinal axis of the wellbore.  
         [0005]     In another embodiment of the invention, a technique that is usable with a well includes providing a tool in a wellbore to inject fluid into the well via an opening of the tool. The technique includes eccentrically disposing the tool with respect to a longitudinal axis of the wellbore to reduce a velocity of fluid that impacts a casing of the well.  
         [0006]     In yet another embodiment of the invention, a system that is usable with a well includes a shroud and a string that includes a choke injector. The string and choke injector are to be disposed in a wellbore, and the choke injector includes openings to inject fluid into the well. The shroud at least partially surrounds the choke injector to eccentrically dispose the choke injector with respect to a longitudinal axis of the wellbore.  
         [0007]     Advantages and other features of the invention will become apparent from the following drawing, description and claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0008]      FIG. 1  is a schematic diagram of a well according to an embodiment of the invention.  
         [0009]      FIGS. 2 and 5  are schematic diagrams of different sections of a choke injector assembly of  FIG. 1  according to an embodiment of the invention.  
         [0010]      FIG. 3  is a cross-sectional view taken along line  3 - 3  of  FIG. 2  according to an embodiment of the invention.  
         [0011]      FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 2  according to an embodiment of the invention.  
         [0012]      FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 5  according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]     Referring to  FIG. 1 , in accordance with an embodiment of the invention, a well (a subterranean or subsea well) includes a tubular string  16 , which contains a choke injector (part of a choke injector assembly  20  of the string  16 ), a tool that may be used to radially inject fluid (sea water, for example) into the well. Unlike conventional choke injectors, the choke injector is eccentrically-disposed with respect to a longitudinal axis of the wellbore. As described below, due to the eccentric positioning of the choke injector, the openings of the choke injector are positioned far enough from a casing  14  to minimize damage to the casing  14  due to the injection of fluid from the openings.  
         [0014]     In accordance with some embodiments of the invention, the eccentric positioning of the choke injector is accomplished via outer shrouds  28  (shrouds  28   a  and  28   b  being depicted in  FIG. 1  as examples) of the choke injector assembly  20 , which generally radially extend outwardly from the string  16 . Each shroud  28  has a non-uniform radial thickness in that each shroud  28  is radially thicker over a certain continuous range of angles about the longitudinal axis of the assembly  20  than the radial thickness around the remainder of the shroud  28 .  
         [0015]     As noted above, the eccentricity of the choke injector maximizes the distance that fluid travels (after exiting its openings) before reaching the casing  14 , as compared to a conventional choke injector that is concentric with respect to the longitudinal axis of the wellbore. Due to this additional distance that the exiting fluid travels, the velocity of the fluid is reduced, thereby reducing, if not preventing, erosion of the casing  14  due to contact of the fluid with the casing  14 .  
         [0016]     As depicted in  FIG. 1 , the casing  14  generally lines a wellbore  12 , which receives the string  1   6  and the choke injector assembly  20 . The choke injector is formed from at least an inner choke sleeve (not depicted in  FIG. 1  and depicted as reference numeral “ 50  ”in  FIGS. 2-6 ) and an outer tubular choke housing  22 . The inner choke sleeve is designed to longitudinally travel inside the outer choke housing  22  to regulate the outward fluid flow from the choke injector. The inner choke sleeve includes radial ports, or openings, that when exposed through one or more windows  24  (one window  24  being depicted in  FIG. 1  and multiple windows  24  being depicted in  FIG. 4 ) of the outer choke housing  22 , inject fluid into the well. The number of openings that are exposed through the window(s)  24  are a function of the choke design and position of the internal choke sleeve.  
         [0017]     The longitudinal position of the internal choke sleeve (relative to the outer choke housing  22 ) may be mechanically manipulated from the surface of the well in accordance with some embodiments of the invention. However, in accordance with other embodiments of the invention, the choke assembly  20  includes an actuator  26 , which may be remotely controlled from the surface of the well for purposes of longitudinally moving the internal choke sleeve up and down inside the choke housing  22  to control the fluid flow from the choke injector.  
         [0018]     The actuator  26  may be controlled by a hydraulic control line, in some embodiments of the invention. Alternatively, in other embodiments of the invention, the actuator  26  may be controlled via other mechanisms, such as through, for example, a wired connection (an electrical or optical cable, for example) between the actuator  26  and the surface of the well. In other embodiments of the invention, the actuator  26  may be controlled through wireless stimuli that are communicated to the actuator  26  from the surface of the well. As examples, the wireless stimuli may include fluid pressure pulses, acoustic waves, electromagnetic waves, etc., depending on the particular embodiment of the invention.  
         [0019]      FIGS. 2 and 5  depict exemplary lower  20 A and upper  20 B sections, respectively, of the choke injector assembly  20  according to some embodiments of the invention. The depiction of the sections  20 A and  20 B are for purposes of example and are not intended to limit the scope of the appended claims. For example, in other embodiments of the invention, the choke injector assembly  20  may include sections in addition those depicted in the figures, which include additional sets of openings and choking sections that are part of the same internal choke sleeve. Thus, many variations are possible and are within the scope of the appended claims.  
         [0020]     Referring to  FIGS. 2 and 5 , in accordance with some embodiments of the invention, the choke injector assembly  20  includes a choke injector and one or more shrouds  28 . The choke injector, which may be viewed as being formed from an inner choke sleeve  50  and the outer choke housing  22 , is concentric about a longitudinal axis  100  (see also  FIG. 6 ); and the choke injector assembly  20  is concentric about a longitudinal axis  180  (see also  FIG. 6 ).  
         [0021]     The inner choke sleeve  50  is designed to move up and down longitudinally with respect to the outer choke housing  22  for purposes of regulating the flow that exits the choke injector. As depicted in  FIG. 2 , the inner choke sleeve  50  includes a central passageway  40  for purposes of communicating fluid from the surface of the well, and some of this fluid, depending on the state of the choke injector, may be communicated radially into the well.  
         [0022]     The internal choke sleeve  50  includes radial ports, or openings  54  and  56 . As shown in  FIG. 2 , the openings  54  may have generally larger cross-sectional flow areas than the openings  56 . Thus, in accordance with some embodiments of the invention, the actuator  26  moves the inner choke sleeve  50  to expose (at the window(s)  24  (see  FIG. 1 ) of the outer choke housing  22 ) the openings  54  to establish a larger radial flow from the choke injector and moves the internal choke sleeve  50  to expose the smaller openings  56  in the window(s)  24  for a reduced flow from the choke injector. For purposes of placing the choke injector in its closed state, the actuator  26  positions the internal choke sleeve  50  so that no radial opening is exposed at the window  24 .  
         [0023]     As depicted in  FIG. 2 , one or more seal assemblies  60  may be formed between the inner surface of the outer choke housing  22  and the outer surface of the inner choke sleeve  50  for purposes of forming fluid seals between the choke sleeve  50  and the outer choke housing  22 .  
         [0024]     The openings  54  and  56  are radially directed away from the inner choke sleeve  50  at angles that coincide with the eccentric portions of the shrouds  28 . Thus, the openings  54  and  56  are oriented at angles within a continuous range of angles that spans across the eccentric portions of the shrouds  28 . Therefore, as depicted in  FIG. 2 , the openings  54  to  56  are oriented to take advantage of the eccentric positioning of the choke injector  20 . Referring also to  FIG. 4  (which depicts a cross-section of the choke injector taken along line  4 - 4  of  FIG. 2 ), for purposes of orienting the openings  54  and openings  56  at the proper angle, in accordance with some embodiments of the invention, the choke injector includes a radially-extending guide  66  that resides in a longitudinal slot  64 , a slot that is exposed in the inner surface of the outer choke housing  22 . Thus, the slot  64  and guide  66  angularly orient the openings  54  and  56  to coincide with the eccentric portions of the shrouds  28 .  
         [0025]      FIG. 3  is a cross-sectional view depicting the angular orientations of the openings  56 . The inner choke sleeve  50  and the outer choke housing  22  are generally concentric about the longitudinal axis  1   00 , and the openings  56  (by virtue of the slot  64  and guide  66  arrangement ( FIG. 2 ) radially extend from the longitudinal axis  100  and are oriented at angles that coincide with the eccentric portions of the shrouds  28 , as further discussed below.  
         [0026]     Referring to  FIG. 2  in conjunction with  FIGS. 3 and 4 , openings  56   a  and  56   b  ( FIG. 3 ) of the choke injector are, by virtue of the slot  64  and guide  66  arrangement, angularly aligned to longitudinally slide (when so positioned by the actuator  26 ) into a window  24 a ( FIG. 4 ) in the outer choke housing  22 ; and openings  56   c  and  56   d  ( FIG. 3 ) are likewise angularly aligned to longitudinally slide (when so positioned by the actuator  26 ) into a window  24   b  ( FIG. 4 ) in the outer choke housing  22 .  
         [0027]      FIG. 6  depicts a cross-section of the choke assembly  20 , taken along line  6 - 6  of  FIG. 5 . As illustrated in  FIG. 6 , with the eccentrically-disposed shrouds  28 , the longitudinal axis  180  of the choke injector assembly  20  is offset from a longitudinal axis  100  of the choke injector (formed from the inner choke sleeve  50  and the outer choke housing  22 ). If the outer diameter of the choke injector  22  is close to the inner diameter of the casing string  14  then the casing  14  (not shown in  FIG. 6 ) is also generally symmetric about the longitudinal axis  180 . Because the longitudinal axis  100  of the choke injector is offset from the longitudinal axis  180 , the choke injector is eccentric with respect to the well casing  14 .  
         [0028]     Referring to  FIG. 6 , among the other features of the choke injector assembly  20 , in accordance with some embodiments of the invention, the shroud  28  includes one or more longitudinal passageways  150  and  160  for purposes of routing cables and control lines downhole. In this regard, the shroud  28  may include, for example, an internal longitudinal passageway  160 , as well as include channels  150  that are exposed on the outer surface of the shroud  28 . As also depicted in  FIG. 6 , one or more indexer pins  161  may radially extend between shroud  28  and the outer choke housing  22 .  
         [0029]     Although terms of direction and orientation, such as “up,” “down,” “vertical,” etc. have been used in the following description to describe certain embodiments of the invention, it is understood that these directions and orientations are not needed to practice the invention. For example, in other embodiments of the invention, the choke assembly  20  may be used in a vertical or lateral wellbore. As another example, in other embodiments of the invention, the choke injector may move in an upward direction to progressively open radial fluid communication and conversely, operate in a downwardly direction to progressively close off the radial fluid communication. Thus, many variations are possible and are within the scope of the appended claims.  
         [0030]     While the present invention has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.