Tool and Method to Plug and Abandon Well

Abstract

A tool ( 10 ) is described for the handling of wells through a formation, and which shall be taken out of operation with a device for a closing plug of a material that can be hardened, such as concrete, where there is a casing pipe in the well that is cemented against the wall in the bore hole with concrete, and it is characterised in that the tool comprises an assembled unit ( 10 ) from the following three sections; a perforating lance ( 32 ) comprising a number of explosive charges to form by detonation a row of holes in the pipe and out into the surrounding layer of concrete, a cleaning unit ( 34 ) for mechanical cleaning of the inner wall of the pipe in the perforated area and a flushing unit ( 36 ) to loosen, dissolve and flush away the hardened cement material between the outer wall of the pipe and the wall of the bore hole. Also described is a method to plug a well that shall be taken out of operation.

1 . Tool for the handling of a well through a formation, and which shall be taken out of operation by arranging a closing plug of a material that can be hardened where there is a casing pipe in the well which is cemented with concrete against the a wall in the bore hole, characterised in that the tool comprises an assembled unit from the following three sections:
 a perforating lance comprising a number of explosive charges to form by detonation a perforated area in the pipe and exposed to the surrounding layer of concrete,   a cleaning unit for mechanical cleaning an inner wall of the pipe at said perforated area, and   a flushing unit for the spraying in of a fluid to release, dissolve and flush away hardened cement material between an outer wall of the pipe and the wall in the bore hole.   
     
     
         2 . Tool according to  claim 1 , characterised in that said perforating lance is arranged as an end piece of the said assembled unit, said flushing unit is fitted to an operating line, the and said cleaning unit is inserted between said lance and said flushing unit. 
     
     
         3 . Tool according to  claim 1 , characterised in that said perforating lance is set up to be released from the rest of said assembled unit after said explosive charges have been detonated. 
     
     
         4 . Tool according to  claim 1 , characterised in that said perforating lance has a number of said explosive charges around and along the circumference thereof. 
     
     
         5 . Tool according to  claim 1 , characterised in that said explosive charges in said perforating lance are formed with different blasting strengths in different sections of said lance. 
     
     
         6 . Tool according to  claim 1 , characterised in that an upper section of said perforating lance is formed with greater explosive power in said explosive charges than the rest of said explosive charges. 
     
     
         7 . Tool according to  claim 1 , characterised in that an upper and a lower(C) section of said the perforating lance are formed with a greater explosive power in said explosive charges than those explosive charges in a middle section. 
     
     
         8 . Tool according to  claim 1 , characterised in that a said cleaning unit comprises a scrubbing unit for mechanical cleaning of the inner wall of the pipe in said perforated area. 
     
     
         9 . Tool according, to  claim 1 , characterised in that said cleaning unit scraping edges on a radially outwardly facing head surface thereof. 
     
     
         10 . Tool according to  claim 1 , characterised in that said flushing unit is set up to spray out a fluid to loosen, dissolve and flush away the hardened mass of cement between the outer wall of the pipe and the wall of the bore hole. 
     
     
         11 . Tool according to  claim 1 , characterised in that the tool is fitted to the end of an operating line which is lowered down into the well from an installation on the surface. 
     
     
         12 . Method to close off a well including a casing pipe through a formation in that a plug of a material that can be hardened is established, whereby a section of the casing pipe through the well is perforated, and a hardenable material is led down through the pipe and is brought to flow out through the perforations and make contact with the walls in the original bore hole, characterised in that
 a three-part tool is used encompassing a lower part comprising a perforating lance gun to form said perforations, a middle cleaning part to clean the pipe internally and also an upper flushing section with a cleaning fluid to flush loose and dissolve concrete residues in the space between the pipe and the wall of the bore hole, and the following steps are carried out in sequence,   a) the tool connected to an operating line is fed down through the pipe until the perforating lance is in a position where the pipe is to be perforated,   b) the explosive charges are detonated to establish the perforations in the pipe,   c) the tool is conducted up and down in the perforated area to scrub clean the inner wall of the pipe with the help of the cleaning part,   d) the tool is positioned so that the flushing section in the pipe is placed adjoining a set of perforated holes and such that a number of perforated holes around the circumference lie above the flushing section and form a fluid connection from the annular space between the pipe and the wall of the well and into the annular space between the operating line,   e) flushing fluid is sprayed out through the perforations to loosen bits of concrete and dissolve the concrete in the space outside the pipe so that this is led back through the upper perforations and into the pipe above the flushing section, and   f) the tool is removed and a material that can be hardened is lowered down to fill a given section of the pipe and the gap between the outer side of the pipe and the wall of the bore hole, whereby the well is plugged when the material is hardened.   
     
     
         13 . (canceled) 
     
     
         14 . A tool for plugging a well comprising
 a lance having a plurality of explosive charges therein for forming a series of holes in a pipe disposed within a well bore;   a cleaning unit disposed above said lance and having scraping edges on a radially outwardly facing surface thereof for scraping of an inner wall of the pipe; and   a flushing unit disposed above said cleaning unit and having a pair of longitudinally spaced apart bellows for sealing against the pipe and defining a space therebetween and a plurality of holes for communicating with said space for spraying a flushing fluid into said space.   
     
     
         15 . A tool as set forth in  claim 14  wherein said lance is removably mounted on said tool for ejection therefrom. 
     
     
         16 . A tool as set forth in  claim 14  wherein said scraping edges of said cleaning unit are disposed circumferentially of said cleaning unit and are radially retractable.