Downhole debris removal tool and methods of using same

Abstract

A downhole tool for removing debris from a wellbore comprises a screen member, an incoming fluid accelerator, and a cavity for capturing debris. The incoming fluid accelerator is disposed above the screen and accelerates the flow of an incoming fluid through the accelerator and into a screen bore. The incoming fluid then exits the bottom of the tool, mixes with wellbore fluid containing debris to form a combination fluid that is transported upward within the wellbore annulus. A pressure differential between the incoming fluid flowing within the screen bore and the wellbore annulus pulls the combination fluid containing the debris into the cavity where the debris is captured. Fluid and/or debris not blocked by the screen flows through the screen into the screen bore to be circulated downward and out of the tool where it can pick up additional debris for capture.

What is claimed is: 
     
         1 . A downhole tool for capturing debris within a wellbore, the downhole tool comprising:
 a screen member having a screen upper end, a screen lower end, a screen outer wall surface, a screen inner wall surface defining a screen bore, and at least one screen aperture in fluid communication with the screen inner wall surface and the screen outer wall surface;   an incoming fluid flow accelerator disposed above the screen member, the incoming fluid flow accelerator comprising an incoming fluid flow accelerator bore through which an incoming fluid flows toward the screen bore, the incoming fluid flow accelerator bore being in fluid communication with the screen bore such that an incoming fluid flowing out of the incoming fluid flow accelerator bore and into the screen bore creates a pressure differential across at least one of the at least one apertures; and   a shroud disposed around a portion of the screen member, the shroud having an opening disposed toward an upper end of the shroud and a closed lower end to define a cavity.   
     
     
         2 . The downhole tool of  claim 1 , wherein the incoming fluid flow accelerator further comprises at least one port disposed in fluid communication with the incoming fluid flow accelerator bore and oriented to direct a portion of the incoming fluid flowing through the incoming fluid flow accelerator bore toward the opened upper end of the shroud. 
     
     
         3 . The downhole tool of  claim 1 , wherein the upper end of the shroud comprises a plurality of openings. 
     
     
         4 . The downhole tool of  claim 1 , wherein screen outer wall surface is concentric with an inner wall surface of the shroud. 
     
     
         5 . The downhole tool of  claim 1 , wherein the screen outer wall surface defines a screen outer diameter and a shroud inner wall surface defines a shroud inner diameter, the shroud inner diameter being greater than the screen outer diameter to partially define the cavity. 
     
     
         6 . The downhole tool of  claim 1 , wherein the incoming fluid flow accelerator bore comprises a shape to increase a velocity of an incoming fluid flowing through the incoming fluid flow accelerator bore. 
     
     
         7 . A downhole tool for capturing debris within a wellbore, the downhole tool comprising:
 a screen member having a screen upper end, a screen lower end, a screen outer wall surface, a screen inner wall surface defining a screen bore, and at least one screen aperture in fluid communication with the screen inner wall surface and the screen outer wall surface;   a nozzle assembly disposed above the screen member, the nozzle assembly comprising a nozzle bore shaped to increase a velocity of an incoming fluid flowing through the nozzle bore toward the screen bore, the nozzle bore being in fluid communication with the screen bore; and   a shroud disposed around a portion of the screen member, the shroud comprising a shroud upper end, a shroud lower end, a shroud outer wall surface, and a shroud inner wall surface, the shroud upper end having an opening, the shroud lower end being closed, and the shroud inner wall surface, the shroud lower end, and the screen outer wall surface define a cavity within the shroud.   
     
     
         8 . The downhole tool of  claim 7 , wherein the nozzle bore comprises a variable inner diameter that decreases from an upper end of the nozzle assembly toward a lower end of the nozzle assembly. 
     
     
         9 . The downhole tool of  claim 7 , wherein the screen member comprises a screen upper end inner diameter that is smaller than a screen lower end inner diameter. 
     
     
         10 . The downhole tool of  claim 7 , wherein shroud upper end includes a plurality of openings. 
     
     
         11 . The downhole tool of  claim 7 , wherein the nozzle assembly further comprises at least one secondary nozzle jet in fluid communication with the nozzle bore and oriented to direct the incoming fluid flowing through the nozzle bore toward the opening disposed in the shroud upper end. 
     
     
         12 . The downhole tool of  claim 11 , wherein at least one of the at least one secondary nozzle jets is directly aligned with at least one of the one or more openings disposed in the shroud upper end. 
     
     
         13 . The downhole tool of  claim 7 , wherein a lower end of the nozzle assembly is connected to the screen member upper end. 
     
     
         14 . A work string for capturing debris within a wellbore, the downhole tool comprising:
 a first downhole tool, the first downhole tool comprising   a first screen member having a first screen upper end, a first screen lower end, a first screen outer wall surface, a first screen inner wall surface defining a first screen bore, and at least one first screen aperture in fluid communication with the first screen inner wall surface and the first screen outer wall surface;   a first incoming fluid flow accelerator disposed above the first screen member, the first incoming fluid flow accelerator comprising a first incoming fluid flow accelerator bore, the first incoming fluid flow accelerator bore being in fluid communication with the first screen bore; and   a first shroud disposed around a portion of the first screen member, the first shroud having a first opening disposed toward an upper end of the first shroud and a first closed end to define a first cavity.   
     
     
         15 . The work string of  claim 14 , further comprising:
 a second downhole tool, the second downhole tool comprising   a second screen member having a second screen upper end, a second screen lower end, a second screen outer wall surface, a second screen inner wall surface defining a second screen bore, and at least one second screen aperture in fluid communication with the second screen inner wall surface and the second screen outer wall surface;   a second incoming fluid flow accelerator disposed above the second screen member, the second incoming fluid flow accelerator comprising a second incoming fluid flow accelerator bore, the second incoming fluid flow accelerator bore being in fluid communication with the second screen bore; and   a second shroud disposed around a portion of the second screen member, the second shroud having a second opening disposed toward an upper end of the second shroud and a second closed end to define a second cavity,   wherein the second incoming fluid flow accelerator bore is in fluid communication with the first screen bore.   
     
     
         16 . The work string of  claim 15 , wherein the first downhole tool is disposed adjacent the second downhole tool. 
     
     
         17 . A method of removing debris from a wellbore fluid, the method comprising the steps of:
 (a) flowing an incoming fluid through a screen bore of a screen member and out of a lower end of the screen member into a wellbore environment;   (b) after step (a), combining the incoming fluid with a wellbore fluid disposed in the wellbore environment to form a combination fluid, the wellbore fluid comprising a piece of debris;   (c) flowing the combination fluid upward within a wellbore annulus;   (d) creating a first pressure differential between the screen bore and the wellbore annulus outside the screen member, the first pressure differential causing the combination fluid to be drawn toward the screen member;   (e) passing the combination fluid through the screen member causing the piece of debris within the combination fluid to be prevented from passing through the screen, thereby causing the piece of debris to be captured within a cavity formed by a shroud disposed around an outer wall surface of the screen member.   
     
     
         18 . The method of  claim 17 , wherein the first pressure differential is created by the incoming fluid flowing through a bore of a fluid flow accelerator before entering the screen bore of the screen member, the fluid flow accelerator increasing a first velocity of flow of the incoming fluid to a second velocity of flow. 
     
     
         19 . The method of  claim 18 , wherein a second pressure differential is created within the wellbore annulus between the upper end of the shroud and an outer wall surface of the shroud, the second pressure differential causing the combination fluid to be drawn toward the screen member. 
     
     
         20 . The method of  claim 17 , wherein prior to step (d) the combination fluid flows upward within the wellbore annulus and enters an opening at an upper end of the shroud and a portion of the incoming fluid exits the bore of the incoming fluid flow accelerator toward the opening at the upper end of the shroud before entering the screen bore.