Diagnostic tool for well abandonment tool

Abstract

A tool is provided for diagnosing the downhole source of a surface casing vent flow for remediation of an abandoned well. The tool is run into the bore, the tool having a stack of pleated rings slidably mounted on a tubular mandrel. The tool is actuated. One end of the stack is set to engage with the casing and the stack is compressed axially to expand the pleated rings expand the casing for diminishing casing/cement micro-cracks. If surface casing vent flow is reduced, the downhole source is identified for remediation and, if not reduced, the tool is released, traversed uphole and actuated again.

We claim: 
     
         1 . A downhole tool conveyed into a casing of a well on a string of tubulars extending downhole into the cased well from surface, comprising:
 a tubular mandrel releasably connected to the string of tubulars;   a stack of pleated rings slidably mounted on the mandrel;   a first compression plate slidably mounted on the mandrel at one end of the stack and having a slip cone;   a second compression plate mounted on the mandrel at another end of the stack with the stack of pleated rings sandwiched therebetween; and   a releasable slip assembly comprising a housing slidable over the mandrel for alternately releasing and compressing the stack of rings,
 a drag block and slips supported by the housing, and 
 a pin and slot assembly between the housing and the mandrel, the slot having a profile having at least a run-in-hole (RIH) for spacing the slips from the slip cone, a pull-out-of-hole (POOH) for spacing the slips from the slip cone, and a slip set (SET) position for engaging slips with the slip cone for axially compressing the pleated rings between the first and second compression rings for radially expanding the pleated rings. 
   
     
     
         2 . The tool of  claim 1 , wherein the mandrel has a stop formed thereon for spacing of the slips from the slip cone in the RIH and POOH positions. 
     
     
         3 . The tool of  claim 1 , wherein in the released position, the stack of pleated rings have a first diameter less than that of the casing and when in the compressed position, the stack of pleated rings has a second diameter adapted to engage the casing. 
     
     
         4 . The tool of  claim 3 , wherein the second diameter of the stack of pleated rings is radially expanded to close the bore of the casing at a sealing location in the well. 
     
     
         5 . The tool of  claim 3 , wherein the first compression plate is uphole of the second compression plate; an uphole movement of the tubular with the releaseable slip assembly in the SET position axially compressing the pleated rings. 
     
     
         6 . The tool of  claim 1 , wherein the stack of pleated rings further comprises:
 a plurality of the pleated rings; and   a plurality of flat washers, also slidably mounted on the mandrel, each flat washer axially separating a pair of adjacent pleated rings.   
     
     
         7 . The tool of  claim 1  further comprising two or more elongate leaves, secured at a first end at the first compression plate and extending axially along the stack of pleated rings to a second end adjacent the second compression plate, each leaf being arcuate and extending circumferentially about a portion of the circumference of the stack of pleated rings. 
     
     
         8 . The tool of  claim 7 , wherein each leaf further comprises:
 a guide extending axially from the second end; and   a bracket at the second compression plate through which the guide extends slidably and restraining the guide radially to the second compression plate.   
     
     
         9 . The tool of  claim 1  further comprising a plurality of compressible spacers, each spacer sized to fit radially within a pleat of a pleated ring, wherein
 the spacers are fit to one or more pleats of a plurality of pleated rings in a population distribution that varies from a sparse concentration adjacent to the first compression plate, for providing a first resistance to compression, to a dense concentration adjacent to the second compression plate, for providing a second resistance to compression, the first resistance being less than the second resistance for providing an generally equal compression of the pleated rings along the axial extent of the stack. 
 
     
     
         10 . The tool  claim 1  wherein:
 the pleated rings are formed of steel; and 
 the diameter of the uncompressed pleated rings are dimensioned so as to be insertable in the bore of the well casing and are expandable upon compression in the stack to engage the casing wall. 
 
     
     
         11 . A method for identifying a source of surface casing vent flow from an abandoned well completed with casing and having a cemented annulus about at least a portion thereof, the method comprising:
 conveying a tool to traverse the well downhole to a specified location along the cemented portion of the casing;   expanding the casing at the specified location for diminishing micro-leaks in the cemented annulus; and then   determining a change in the surface casing vent flow.   
     
     
         12 . The method of  claim 11 , wherein the conveying the tool to the specified location and expanding the casing comprises:
 adjusting the tool from a traversing the well mode to a setting the tool mode for releasable locking the tool to the casing; and   actuating the tool to expand into the casing for diminishing the micro-leaks.   
     
     
         13 . The method of  claim 12 , wherein determining a change in the surface casing vent flow comprises:
 prior to actuating the tool, determining a first baseline surface casing vent flow;   after actuating the tool, determining a second surface casing vent flow; and   comparing the difference in the first and second surface casing vent flows.   
     
     
         14 . The method of  claim 12 , wherein actuating the tool to expand into the casing comprises:
 setting a first compression plate at a first end of an axial stack of pleated rings on the tool to lock to the casing; and   axially manipulating a second compression plate relative to the casing to axially compress and expand the stack of pleated rings to expand the casing.   
     
     
         15 . The method of  claim 11 , further comprising:
 conveying the tool on a string of tubing;   traversing the well to the specified location;   shifting the tool from a run-in-hole (RIH) position to a set (SET) position;   actuating the tool in the SET position to lock a first end of a stack of pleated rings to the casing at the specified location;   pulling the string of tubing to compress the stack of pleated rings against the first end of the stack, expanding the pleated rings for expanding the casing; and then   measuring the surface casing vent flow.   
     
     
         16 . The method of  claim 15 , wherein if the measured surface casing vent flow does not represent a change, then further comprising:
 shifting the tool from the SET position to a pull-out-of-hole (POOH) position to release the stack of pleated rings;   traversing the well to an subsequent specified location uphole from the specified location; and   repeating the shifting of the tool to the SET position, actuating the tool to lock the first end of the stack of pleated rings to the casing at the subsequent specified location, pulling the string of tubing to compress the stack of pleated rings for expanding the casing; and then measuring the surface casing vent flow.   
     
     
         17 . The method of  claim 16 , wherein if the measured surface casing vent flow does change, then further comprising:
 identifying the downhole source of the surface casing vent flow being downhole of the specified location; and   shifting the tool from the SET position to a POOH position to release the stack of pleated rings and convey the tool out of the well.   
     
     
         18 . A downhole tool conveyed into a casing of a well on a string of tubulars extending downhole into the cased well from surface, comprising:
 a tubular mandrel releasably connected to the string of tubulars;   a stack of pleated rings slidably mounted on the mandrel;   a first compression plate slidably mounted on the mandrel at one end of the stack and slip assembly for releasable engagement with the casing;   a second compression plate mounted on the mandrel at another end of the stack with the stack of pleated rings sandwiched therebetween; and   one or more elongate leaves, secured at a first end at the first compression plate and extending axially along the stack of pleated rings to a second end adjacent the second compression plate, each leaf being arcuate and extending circumferentially about a portion of the circumference of the stack of pleated rings.   
     
     
         19 . The tool of  claim 18 , wherein each leaf further comprises:
 a guide extending axially from the second end; and   a bracket at the second compression plate through which the guide extends slidably and restraining the guide radially to the second compression plate.