Patent Publication Number: US-9416626-B2

Title: Downhole debris removal tool and methods of using same

Description:
BACKGROUND 
     1. Field of Invention 
     The invention is directed to a downhole clean-up tool or junk basket for use in oil and gas wells, and in particular, to a downhole clean-up tool that is capable of creating a pressure differential to transport debris from within the wellbore annulus into the tool where it can be collected by the tool. 
     2. Description of Art 
     Downhole tools for clean-up of debris in a wellbore are generally known and are referred to as “junk baskets.” In general, the junk baskets have a screen or other structure that catches debris as debris-laden fluid flows through the screen of the tool. Generally, this occurs because at a point in the flow path, the speed of the fluid carrying the debris decreases such that the junk or debris falls out of the flow path and into a basket or screen. 
     SUMMARY OF INVENTION 
     Broadly, downhole tools for clean-up of debris within a well comprise a shroud having a cavity disposed around the outer wall surface of a mandrel. A fluid pumped downward through the tool travels through the bore of the mandrel, out of one or more mandrel ports, and into the cavity of the shroud. The fluid exiting each of the mandrel ports flows through one or more shroud ports disposed in the shroud. In flowing fluid out of the one or more mandrel ports, a low pressure zone is created at the upper end of the shroud causing wellbore fluid to flow from the wellbore annulus into the cavity. In certain specific embodiments, the debris carried in the wellbore fluid is trapped by a screen disposed in the cavity so that the debris is captured within the cavity. In other different specific embodiments, the debris is captured by flowing the wellbore fluid around at least one baffle disposed within the cavity that causes the debris to fall out of the flow path and, therefore, remain in the cavity. In yet other different embodiments, the wellbore fluid flows through two additional shrouds nested around the shroud in alternating orientations and through a plurality of apertures disposed at the upper end of the shroud so that the debris is captured in one of these two additional shrouds. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a specific embodiment of a downhole tool disclosed herein. 
         FIG. 2  is a partial cross-sectional view and partial perspective view of the downhole tool shown in  FIG. 1  showing the downhole tool disposed in a wellbore in an initial or run-in position. 
         FIG. 3  is a partial cross-sectional view and partial perspective view of the downhole tool shown in  FIG. 1  showing the downhole tool disposed in the wellbore in an actuated or operational position. 
         FIG. 4  is a partial cross-sectional view and partial perspective view of another specific embodiment of a downhole tool disclosed herein. 
         FIG. 5  is a partial cross-sectional view and partial perspective view of the downhole tool shown in  FIG. 4  taken along the line  5 - 5 . 
         FIG. 6  is a perspective view of an additional specific embodiment of a downhole tool disclosed herein. 
         FIG. 7  is a partial cross-sectional view and partial perspective view of the shroud of the downhole tool shown in  FIG. 6 . 
     
    
    
     While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF INVENTION 
     Referring now to  FIGS. 1-3 , in one particular embodiment, downhole tool  20  is disposed in wellbore  10  on work or tool string  11  having tool string bore  12  ( FIGS. 2-3 ). Wellbore  10  can be an open-hole well or a cased well. 
     In the embodiment of  FIGS. 1-3 , downhole tool  20  comprises mandrel  30  having upper end  31 , lower end  32 , outer wall surface  33 , and inner wall surface  34  defining mandrel bore  35 . Threads  26  are disposed at upper and lower ends  31 ,  32  for connecting downhole tool  20  within tool string  11  such as one having tool string components  25 ,  27  ( FIGS. 2-3 ). Disposed through outer wall surface  33  and inner wall surface  34  in fluid communication with mandrel bore  35  are mandrel ports  36 . Although multiple mandrel ports  36  are shown, it is to be understood that certain embodiments include only one mandrel port  36 . 
     Mandrel ports  36  can include a shape or insertable device such that fluid is accelerated as it flows from mandrel bore  35  through mandrel ports  36 . In one particular embodiment, each of mandrel ports  36  comprises a shape to form a nozzle. Alternatively, mandrel ports  36  can include a removable nozzle device (not shown). 
     As illustrated in  FIGS. 1-3 , each of mandrel ports  36  is disposed perpendicularly relative to mandrel bore  35 . It is to be understood, however, that one or more of mandrel port(s)  36  are not required to be oriented in this manner. Instead, one or more of mandrel port(s)  36  can be disposed at an angle other than perpendicular relative to mandrel bore  35 . For example, one or more mandrel port(s)  36  can be orientated in a downward or upward angle relative to mandrel bore  35 . 
     Disposed around a portion of outer wall surface  33  of mandrel  30  is basket or shroud  60 . Shroud  60  includes upper end  61 , lower end  62 , outer wall surface  63 , and inner wall surface  64  defining bore  65 . Lower end  62  is closed through its connection to outer wall surface  33  of mandrel  30  such as by connecting lower end  62  to shoulder  28  disposed on outer wall surface  33  of mandrel  33 . Upper end  61  includes opening  59  as it is not connected to outer wall surface  33  of mandrel  30 . As a result, cavity  66  is defined by outer wall surface  33 , inner wall surface  64 , and lower end  62 . 
     Disposed around the circumference of shroud  60  is one or more fluid flow ports  67  also known as shroud ports. Each fluid flow port  67  is in fluid communication with outer wall surface  63  and inner wall surface  64  and, thus, cavity  66 . Although two fluid flow ports  67  are shown in  FIGS. 1 and 2 , it is to be understood that as few as one fluid flow port  67  may be included in shroud  60 , or more than two fluid flow ports  67  may be included in shroud  60 . 
     As illustrated in  FIGS. 1-3 , fluid flow ports  67  are disposed perpendicularly relative to cavity  66 . It is to be understood, however, that one or more of fluid flow ports  67  are not required to be oriented in this manner. Instead, one or more of fluid flow ports  67  can be disposed at an angle other than perpendicular relative to cavity  66 . For example, one or more of fluid flow ports  67  may be angled upwardly or downwardly relative to cavity  66 . 
     In addition, as shown in the embodiment of  FIGS. 1-3 , each fluid flow port  67  is in alignment with a respective mandrel port  36 . It is to be understood, however, that each fluid flow port  67  is not required to be in alignment with a respective mandrel port  36 . Instead, one or more or all of the fluid flow ports  67  can be out of alignment with the mandrel ports  36 . 
     As best shown in  FIGS. 2 and 3 , screen member  70  is disposed within cavity  66  thereby dividing cavity  66  into lower cavity  68  and upper cavity  69 . Screen member  70  includes one or more apertures for permitting fluid and debris having a size smaller than the one or more apertures to flow there-through. As shown in  FIGS. 2-3 , screen member  70  is connected to outer wall surface  33  of mandrel  30  and inner wall surface  64  of shroud  60 . In addition, screen member  70  is disposed perpendicularly relative to both outer wall surface  33  of mandrel  30  and inner wall surface  64  of shroud  60 . It is to be understood, however, that screen member  70  is not required to be disposed perpendicularly relative to both outer wall surface  33  of mandrel  30  and inner wall surface  64  of shroud  60 , but instead can be disposed at another angle relative to one or both of outer wall surface  33  of mandrel  30  and inner wall surface  64  of shroud  60 . In addition, screen member  70  can have any shape desired or necessary to filter debris from fluid flowing through screen member  70 . For example, screen member  70  can be a three-dimensional filter or a relatively flat filter. 
     As also shown in  FIGS. 2-3 , screen member  70  is disposed above mandrel ports  36  and fluid flow ports  67 . 
     Operatively associated with mandrel port(s)  36  is a valve member that selectively opens mandrel port(s)  36 . As shown in  FIGS. 2-3 , the valve member comprises sleeve  40  having upper end  41 , lower end  42 , outer wall surface  43 , and inner wall surface  44  defining bore  45 . Disposed toward lower end  42  along inner wall surface  44  is seat  46 . Outer wall surface  43  is in sliding engagement with inner wall surface  34  of mandrel  30 . One or more seal members  48  are disposed around the circumference of outer wall surface  43  of sleeve  40  to isolate mandrel port(s)  36  until actuated. Shear screw  38  or other retaining member holds sleeve  40  in the initial or run-in position ( FIG. 2 ) until actuation of sleeve  40 . In the embodiment of  FIGS. 1-3 , outer wall surface  33  of mandrel  30  includes cavities  29  which facilitate insertion of shear screws  38 . 
     Actuation of sleeve  40  can be accomplished by landing a plug member such as ball  55  on seat  46  and increasing fluid pressure above ball  55 . Upon reaching a certain pressure above ball  55 , the increased pressure forces ball  55  into seat  46  which, in turn, causes sleeve  40  to slide downward along inner wall surface  34  of mandrel  30 . Sleeve  40  continues its downward movement until lower end  42  of sleeve  40  engages shoulder  39  disposed on inner wall surface  34  of mandrel  30 . Thus, sleeve  40  has an initial or run-in position ( FIG. 2 ) in which mandrel each of ports  36  are closed or blocked off to fluid flow, and a fully actuated position ( FIG. 3 ) in which each of mandrel port(s)  36  is opened to fluid flow. However, it is to be understood that sleeve can have other actuated positions (not shown) in which less than all of mandrel ports  36  are opened. In the preferred embodiment, sleeve  40  is disposed in its fully actuated position having all mandrel ports  36  opened to fluid flow. 
     In operation, downhole tool  20  is placed in tool string  11  and lowered to the desired location within wellbore  10  ( FIGS. 2-3 ). Upon reaching the desired location, plug member such as ball  55  is transported down bore  12  of tool string  11  and into mandrel bore  35  until it lands on seat  46  of sleeve  40 . Upon landing on seat  46 , fluid flow through seat  46  is blocked. Thus, additional fluid flow in the direction of arrow  13  ( FIG. 3 ) down bore  12  of tool string  11  and into mandrel bore  35  causes an increase in pressure above ball  55 . Upon reaching a certain pressure, sleeve  40  is forced downward within mandrel bore  35  from its initial or run-in position ( FIG. 2 ) to its fully actuated position ( FIG. 3 ) such that all of mandrel ports  36  are no longer blocked to fluid flow. Although  FIG. 3  shows sleeve landed on shoulder  39 , it is to be understood that sleeve  40  is not required to be landed on shoulder  39  before reaching either the fully actuated position ( FIG. 3 ) at which all of mandrel ports  36  are opened, or any other actuated position of sleeve  40 , i.e., any position at which not all of mandrel ports  36  are opened. 
     Upon mandrel ports  36  being opened, the fluid being pumped downward through mandrel bore  35  (referred to as “incoming fluid”) is directed through mandrel ports  36  in the direction of arrow  14  ( FIG. 3 ). As a result, the velocity of the incoming fluid is increased as it exits mandrel ports  36 . The now accelerated incoming fluid flowing out of mandrel ports  36  flows out of fluid flow ports  67  of shroud  60  and into wellbore  10 . In addition, fluid flowing from above and below mandrel ports  36  (arrows  15 ,  16  respectively) flows through fluid flow ports  67  of shroud  60 . 
     Upon exiting fluid flow ports  67 , the incoming fluid mixes with wellbore fluid contained within annulus  80  of wellbore  10 . The wellbore fluid includes one or more pieces of debris. The mixture of the incoming fluid exiting fluid flow ports  67  and the wellbore fluid is referred to herein as the “combination fluid.” The combination fluid is carried upward within wellbore  10  in the direction of arrow  17 . As a result, debris that is desired to be captured by tool  20  is carried upward. Upon reaching upper end  61  of shroud  60 , the pressure differential across screen member  70  created by the accelerated flow of incoming fluid exiting mandrel ports  36  causes the combination fluid to be drawn into cavity  66  and, thus, toward screen member  70  as indicated by arrow  18  ( FIG. 3 ). The combination fluid continues to be pulled downward (arrow  19 ) and ultimately through screen member  70  ( FIG. 3 ). In so doing, debris within the combination fluid is prevented from flowing through screen member  70  and is captured within upper cavity  69 . The portion of combination fluid that can pass through screen member  70  (arrow  15 ) mixes with the incoming fluid flowing out of mandrel ports  36  from mandrel bore  35  and is carried through fluid flow ports  67  into annulus  80  of wellbore  10 . 
     It is to be understood that even though some of the combination fluid mixes with the incoming fluid after the combination fluid passes through screen member  70 , and some of this combination fluid may still contain small debris within it, for simplicity, the resulting mixture of the fluid that has passed through screen member  70  and fluid that is flowing from mandrel bore  35  through mandrel ports  36  continues to be referred to herein as the “incoming fluid.” Thus, the term “incoming fluid” means any fluid flowing out of fluid flow ports  67  and “combination fluid” means the mixture of the fluid that has exited fluid flow ports  67  and combined with the wellbore fluid in annulus  80  that is available to be pulled into cavity  66  through opening  59  when the incoming fluid exits mandrel ports  36 . 
     Circulation of the combination fluid upward can be facilitated by placing tool  20  above a restriction or blockage within wellbore  10 . For example, tool  20  can be placed near a bridge plug, packer, or other isolation device. Alternatively, tool  20  can be placed toward the bottom of wellbore  10 . 
     Downhole tool  20  can remain within wellbore  10  until upper cavity  68  is filled with debris or until all debris within wellbore  10  is captured within upper cavity  68 . Thereafter, downhole tool  20  is removed from wellbore  10  and, in so doing, the debris captured within upper cavity  68  is also removed. 
     Referring now to  FIGS. 4-5 , in another specific embodiment, downhole tool  200  comprises many of the same components and structures described above with respect to the embodiments of  FIGS. 1-3  and, therefore, use like reference numerals in this embodiment. The main differences between the embodiments of  FIGS. 1-3  and the embodiments of  FIGS. 4-5  is the addition of one or more ingress apertures  210  disposed toward upper end  61  of shroud  60  and the inclusion of cap  220  and outer shroud  260 . 
     Cap  220  closes opening  59  at upper end  61  of shroud  60 . In the specific embodiment of  FIGS. 4-5 , cap  220  comprises a shroud having upper end  221 , lower end  222 , outer wall surface  223 , and inner wall surface  224  defining bore  225 . Upper end  221  is closed through its connection to outer wall surface  33  of mandrel  30  such as through welding, threads and the like. Lower end  222  includes opening  226  as it is not connected to outer wall surface  33  of mandrel  30  or to any other structure. As a result, cavity  227  is defined by upper end  221 , inner wall surface  224 , and outer wall surface  33  of mandrel  30 . 
     As upper end  61  of shroud  60  is closed off by cap  220 , upper portion  212  of shroud  60  is disposed within cavity  227  such that at least one of apertures  210  is disposed within cavity  227 . 
     In an alternative embodiment (not shown), cap  220  is not a shroud, but instead simply closes opening  59 . In this embodiment, one or more apertures such as apertures  210  are disposed through the walls of shroud  60  and, in certain embodiments, along the entire outer and inner wall surfaces  63 ,  64  of shroud  60 . 
     Outer shroud  260  is disposed around a portion of outer wall surface  63  of shroud  60  and at least a portion of outer wall surface  223  of cap  220 . 
     Outer shroud  260  includes upper end  261 , lower end  262 , outer wall surface  263 , and inner wall surface  264  defining bore  265 . Lower end  262  is closed through its connection to outer wall surface  63  of shroud  60  above fluid flow port(s)  67  such through welding, threads and the like. Upper end  261  includes opening  259  as it is not connected to outer wall surface  63  of shroud  60 , or any other surface. As a result, cavity  266  is defined by inner wall surface  264 , outer wall surface  63  of shroud  60 , and lower end  262 . 
     In the embodiments in which cap  220  is a shroud ( FIGS. 4-5 ), cap  220  is referred to as a “middle shroud” and shroud  60  is referred to as an “inner shroud.” As illustrated in  FIGS. 4-5 , inner and outer wall surfaces  223 ,  224  of cap  220  are disposed within cavity  266 . Similarly, upper portion  212  of shroud  60  is disposed within cavity  227  of cap  220 . In addition, an upper portion  268  of outer shroud  260  extends above cap  220  and, thus, upper end  61  of shroud  60 . 
     In operation, the embodiments of  FIGS. 4-5  function in a similar manner as described above with respect to the embodiments of  FIGS. 1-3 . Instead of the combination fluid entering opening  59  of upper end  61  of shroud  60  as in the embodiments of  FIGS. 1-3 , in the embodiments of  FIGS. 4-5 , the combination fluid flows through opening  259  into cavity  266  of outer shroud  260 . The combination fluid then flows into cavity  227  of cap  220  and through aperture(s)  210  disposed through inner and outer wall surfaces  63 ,  64  of shroud  60 . In so doing, debris within the combination fluid is collected in cavity  266  of outer shroud  260 . It is to be understood, however, that some debris could travel through aperture(s)  210  and into cavity  66  of shroud  60  where it could be trapped within cavity  66  by a screen member (not shown), or it may pass through the screen member and flow out of fluid flow port(s)  67 . In an alternative embodiment, a screen member, such screen member  70 , is not included. Instead, any filter or screening of the fluid is performed only by apertures  210 . 
     In an alternative embodiment of  FIGS. 4-5  (not shown), cap  220  is a shroud as shown in  FIGS. 4-5 , but apertures  210  are absent and cap  220  does not close off opening  59 . In other words, cap  220  is disposed above shroud  60  such that upper end  221  of cap  220  does not touch upper end  61  of shroud  60 . Thus, a circuitous flow path is created in which fluid enters cavity  226 , flows upward through cavity  227 , through opening  59 , and into cavity  66 . In so doing, debris falls out of the fluid flowing into cavity  266 , through cavity  227 , through opening at upper end  61  of shroud  60 , and into cavity  66 . 
     Referring now to  FIGS. 6-7 , in another specific embodiment, downhole tool  300  comprises many of the same components and structures described above with respect to the embodiments of  FIGS. 1-3  and, therefore, use like reference numerals in this embodiment. The main difference between the embodiments of  FIGS. 1-3  and the embodiments of  FIGS. 6-7  is the addition baffles  310 ,  320  to direct the combination fluid through shroud  60  and out of fluid flow port  67 . 
     As illustrated in  FIGS. 6-7 , shroud  60  includes one or more upper baffles  310  and one or more longitudinal baffles  320 . Upper baffle(s)  310  include upper portion  311  and two extensions  312  defining baffle cavity  314 . Upper portion  311  partially blocks opening  59 . 
     Longitudinal baffles  320  are disposed to the left and right of fluid flow port  67 , thereby directing fluid downward through bore  65  toward fluid flow port  67 . Upper portions  322  of longitudinal baffles  320  are disposed within cavity  314 . 
     Although not shown in  FIGS. 6-7 , a screen member such as screen member  70  can be included in the embodiment of  FIGS. 6-7 . In addition, or alternatively, apertures (not shown) can be disposed through the walls of longitudinal baffles  320  along the length of longitudinal baffles  320  to filter debris from the fluid flowing through the apertures. 
     In operation, the embodiments of  FIGS. 6-7  function in a similar manner as described above with respect to the embodiments of  FIGS. 1-3 . Like the embodiments of  FIGS. 1-3 , the combination fluid enters opening  59  of upper end  61  of shroud  60  and flows into cavity  66 . The fluid then flows around extensions  312  of upper baffles  310  and flows upward. In so doing, debris within the combination fluid falls out of the flow path and into the bottom of cavity  66  where it is captured. The combination fluid then flows around the upper ends  321  of longitudinal baffles  320  and down toward and ultimately out of fluid flow port  67 . 
     It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. For example, the mandrel ports can have any shape desired or necessary to increase the velocity of the incoming fluid as it passes through the mandrel ports. Alternatively, a nozzle or other device can be placed within mandrel ports to increase the velocity of the incoming fluid as it flows through the mandrel ports. In addition, the shroud is not required to be disposed concentrically with the mandrel. Instead, it can be disposed eccentrically so that one side has a larger opening compared to another side to facilitate capturing larger sized debris on that side. Nor is the shroud or the mandrel both required to have a circular cross-section. Instead, one or both of the shroud or the screen member can have a square or other cross-sectional shape as desired or necessary to facilitate capturing debris within the cavity of the shroud. 
     Further, it is to be understood that the term “wellbore” as used herein includes open-hole, cased, or any other type of wellbores. In addition, the use of the term “well” is to be understood to have the same meaning as “wellbore.” Moreover, in all of the embodiments discussed herein, upward, toward the surface of the well (not shown), is toward the top of Figures, and downward or downhole (the direction going away from the surface of the well) is toward the bottom of the Figures. However, it is to be understood that the tools may have their positions rotated in either direction any number of degrees. Accordingly, the tools can be used in any number of orientations easily determinable and adaptable to persons of ordinary skill in the art. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.