Abstract:
A downhole tool for removing debris from a wellbore comprises a body having a bore, a collection member, and a means for creating a hydraulic barrier within a wellbore annulus. The hydraulic barrier within the wellbore annulus restricts upward movement of a debris laden fluid within the wellbore annulus causing the debris laden fluid to be directed toward the collection member. Thus, the hydraulic barrier facilitates removal of debris from the wellbore.

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 downhole clean-up tools that are capable of creating a hydraulic barrier within the wellbore annulus above the collection member to facilitate capture of debris flowing within the wellbore annulus. 
     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 mandrel and a collection member for capturing debris within the wellbore. A fluid flow member for creating a hydraulic barrier above an opening of the collection member is operatively associated with the mandrel. Creation of the hydraulic barrier facilitates movement of the debris laden fluid within the wellbore into the collection member by restricting upward movement of the debris laden fluid. In one particular embodiment, the fluid flow member includes one or more ports disposed above the opening of the collection member, at least one of the ports being oriented to expel a fluid flowing down the bore of the mandrel into the wellbore annulus to create the hydraulic barrier. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a partial cross-sectional view of a specific embodiment of a downhole tool disclosed herein. 
         FIG. 2  is a partial cross-sectional view of the downhole tool shown in  FIG. 1  disposed in a tool string and disposed in a wellbore. 
     
    
    
     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. 1-2 , in one particular embodiment, downhole tool  30  comprises mandrel or body  31  having upper end  32 , lower end  33 , and bore  34  defined by inner wall surface  35 . Both upper and lower ends  32 ,  33  include threads  39  for releasably connecting downhole tool  30  within a tool or work string (not shown in  FIG. 1 ). Bore  34  runs the entire longitudinal length of body  31 . Bore  34  permits a fluid flowing down the tool string to pass through downhole tool  30  where it can ultimately be expelled from the tool string into the wellbore to facilitate a downhole operation such as milling. Upon being expelled into the wellbore, the fluid travels up the wellbore annulus carrying debris so that it can be captured by downhole tool  30 . 
     Downhole tool  30  captures the debris within collection member  40 . As shown in the embodiment of  FIGS. 1-2 , collection member  40  included upper end  41  and lower end  42 . Upper end  41  includes one or more openings  43  for receiving debris laden fluid. Lower end  42  is closed so that debris is captured within cavity  44 . One or more ports  46  are disposed around collection member  40  to permit fluid and small debris to flow out of cavity  44 . Thus, port(s)  46  facilitate circulation of debris laden fluid into and out of cavity  44  so that debris that is too large to pass through port(s)  46  is captured within cavity  44 . 
     To facilitate capturing debris within cavity  44 , downhole tool  30  includes one or more fluid flow members to create a hydraulic barrier within the wellbore annulus above opening(s)  43 . Creation of the hydraulic barrier restricts the upward movement of the debris laden fluid within the wellbore annulus. As a result, more debris laden fluid is directed into opening(s)  43  so that debris can be captured within cavity  44 . In the embodiment of  FIGS. 1-2 , the fluid flow member that creates the hydraulic barrier is one or more ports  37 . Port(s)  37  are in fluid communication with bore  34  so that a portion of the fluid flowing through bore  34  is directed out of port(s)  37  into the wellbore annulus. 
     Although each port  37  can be shaped and sized as desired or necessary to create the hydraulic barrier, in certain embodiments, one or more of ports  37  include a jet nozzle to facilitate creation of the hydraulic barrier. In addition, one or more of ports  37  can be disposed at an angle that is perpendicular to a longitudinal axis of downhole tool  30 . Alternatively, one or more ports  37  can be disposed at an acute angle, oriented in a downward direction such as shown in  FIGS. 1-2 . 
     Referring now to  FIG. 2 , in operation, downhole tool  30  is placed in tool string  14  and lowered to the desired location within casing  12  of wellbore  10 . A fluid is flowed or pumped down tool string bore  16  into mandrel bore  34 . A portion of the fluid flowing through mandrel bore  34  is directed through ports  37  into wellbore annulus portion  18  as indicated by arrows  17 . Additional fluid continues down bore  34 , and thus tool string  14  until it is ultimately expelled from tool string  14  into the wellbore. Upon being expelled into the wellbore, the fluid travels up wellbore annulus portion  19  carrying debris as indicated by arrows  21 . Upon encountering the hydraulic barrier created by fluid flowing out of ports  37  (arrows  17 ), the debris laden fluid flowing up through wellbore annulus portion  19  is restricted from flow further up wellbore annulus portion  18 , or above wellbore annulus portion  18 . As a result, the debris laden fluid is directed toward opening  43  of collection member  40  as indicated by arrow  23 . 
     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 port(s)  37  can be disposed perpendicular to an axis of the downhole tool or they can be disposed at any other angle desired or necessary to create the hydraulic barrier within the wellbore annulus. 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.