Whipstock retrieving overshot

Abstract

The present invention discloses a whipstock retrieval assembly for use in a wellbore to retrieve a downhole tool such as a whipstock from a borehole. In one aspect, the retriever includes a threaded barrel which is received over the tray end of the whipstock, and a securing member, preferably a conical member, pinches the whipstock tray portion received in the retriever against the barrel to prevent loss of the whipstock from the retriever as it is pulled from the borehole. In a second aspect, the retriever assembly includes a hook which is placed in a pre-supplied slot in the whipstock, and a shroud is deployed over the extending end of the whipstock to provide a smooth surface to pull the retriever and whipstock from the borehole.

1 . A downhole tool retrieving assembly for use in retrieving downhole tools from a bore comprising: 
 a tool engagement member positionable into the bore and retrievable therefrom; and    a tool security member disposed to engage with the downhole tool to ensure retention thereof with said tool engagement member.    
     
     
         2 . The downhole tool retrieving assembly of  claim 1 , wherein the security member is selectively disengageable from the downhole tool.  
     
     
         3 . The downhole tool retrieving assembly of  claim 1 , wherein the security member is selectively disengageable from the downhole tool by providing a fluid to the downhole tool.  
     
     
         4 . The downhole tool retrieving assembly of  claim 1 , wherein the security member is selectively disengageable from the downhole tool by providing a hydraulic fluid to the downhole tool.  
     
     
         5 . The downhole tool retrieving assembly of  claim 1 , wherein: 
 said engagement member includes a hook; and    the downhole tool includes a receiving member for receipt of said hook therein.    
     
     
         6 . The downhole tool retrieving assembly of  claim 5 , wherein the receiving member is a slot extending inwardly of the downhole tool.  
     
     
         7 . The downhole tool retrieving assembly of  claim 5 , wherein said security member further includes a shroud positionable in conjunction with said hook to receive at least a portion of the downhole tool therein.  
     
     
         8 . The downhole tool retrieving assembly of  claim 7 , wherein: 
 the downhole tool is a whipstock having a tray; and    a portion of said tray is received in said shroud upon engagement of said hook with the slot.    
     
     
         9 . The downhole tool retrieving assembly of  claim 8 , further comprising a shroud positioning apparatus to position said shroud relative to said hook as the retrieval assembly is received on the whipstock.  
     
     
         10 . The downhole tool retrieving apparatus of  claim 9 , wherein said positioning assembly includes: 
 a hook base having said hook extending therefrom;    a biasing member connected at one end thereof to said hook base and positioned intermediate said hook base and said shroud;    said shroud hingedly connected to, and arcuately actuable about, said hook base; and    said biasing member positioned to assist said shroud to arcuately actuate about said hook base.    
     
     
         11 . The downhole tool retriever assembly of  claim 10 , wherein the biasing member is a lever.  
     
     
         12 . The downhole tool retriever assembly of  claim 1 , wherein said tool engagement member includes a cup receivable over the downhole tool and engageable therewith.  
     
     
         13 . The downhole tool retriever assembly of  claim 12 , wherein said tool security member includes a pinch member to engage the downhole tool when the downhole tool is engaged by said cup.  
     
     
         14 . The downhole tool retriever assembly of  claim 13 , wherein the cup has profiles on an inside surface thereof for engaging the downhole tool.  
     
     
         15 . The downhole tool retriever assembly of  claim 13 , wherein the cup has threads on an inside surface thereof for engaging the downhole tool.  
     
     
         16 . The downhole tool retriever assembly of  claim 13 , wherein said cup is generally cylindrical with a longitudinal axis and said pinch member includes a conical element positioned substantially collinear with an axis of said cup.  
     
     
         17 . The downhole tool retrieval assembly of  claim 16 , further comprising a biasing member to relatively bias said conical member and cup to pinch the downhole tool therebetween.  
     
     
         18 . The downhole tool retrieval assembly of  claim 17 , wherein said biasing member is disposed and engaged between said cup and said conical member.  
     
     
         19 . The downhole tool retrieval assembly of  claim 18 , wherein the downhole tool is a whipstock.  
     
     
         20 . A method of retrieving a downhole tool from a borehole, comprising: 
 providing a tool engagement member in position adjacent to the tool;    providing a tool security member;    engaging the tool with the engagment member; and    securing the tool, at least with respect to the engagement member, with the securing member.    
     
     
         21 . The method of  claim 20 , further comprising retrieving the tool from the borehole.  
     
     
         22 . The method of  claim 20 , wherein: 
 the engagement member includes a hook; and    the downhole tool includes a receiving member for receipt of said hook therein.    
     
     
         23 . The method of  claim 22 , wherein the receiving member is a slot in the downhole tool.  
     
     
         24 . The method of  claim 22 , wherein the security member includes a shroud arcuately positionable with respect to the hook.  
     
     
         25 . The method of  claim 24 , further comprising: 
 positioning the hook adjacent the receiving member in the downhole tool;    positioning a portion of the downhole tool adjacent to the shroud; and    extending the hook into the receiving member and positioning the portion of the downhole tool into a protected position with the shroud.    
     
     
         26 . The method of  claim 20 , wherein the engagement member includes a cup.  
     
     
         27 . The method of  claim 26 , wherein the security member includes a pinch element.  
     
     
         28 . The method of  claim 27 , further comprising: 
 engaging the downhole tool with the cup; and    pinching the downhole tool between the cup and the pinch element.    
     
     
         29 . The method of  claim 28 , wherein engaging the downhole tool with the cup engages profiles on an inside surface thereof with the downhole tool.  
     
     
         30 . The method of  claim 28 , wherein engaging the downhole tool with the cup engages threads on an inside surface thereof with the downhole tool.  
     
     
         31 . The method of  claim 28 , further comprising: 
 retrieving the downhole tool from the borehole; and    disengaging the downhole tool from the engagement member.