A Method of Plugging and Abandoning a Well

Abstract

A method of plugging and abandoning a well includes: lowering a perforation tool into a pipe string onto a longitudinal section; forming perforations along the longitudinal section; with a flushing tool attached to a work string and lowered onto the longitudinal section, pumping flushing fluid through the work string, out through at least one flushing outlet in the flushing tool, into the pipe string and into said annulus via the perforations, wherein an outlet axis of said flushing outlet is non-perpendicular to a longitudinal axis of the flushing tool; pumping a fluidized plugging material through the work string and into the pipe string at the longitudinal section; placing the fluidized plugging material in the pipe string along the longitudinal section, thereby also placing the fluidized plugging material in said annulus via the perforations; pulling the work string out of the well; and abandoning the well.

1 - 30 . (canceled) 
     
     
         31 . A method of plugging and abandoning a well, the method involving perforation, cleaning and plugging of a longitudinal section of the well, said longitudinal section comprising a wellbore, a pipe string placed within the wellbore, and an annulus located between the wellbore and the pipe string, wherein the method comprises the following steps:
 A) lowering a perforation tool into the pipe string onto said longitudinal section of the well;   (B) with the perforation tool, forming perforations in the pipe string along said longitudinal section;   (C) with a flushing tool attached to a lower end portion of a tubular work string, which is lowered into the pipe string onto said longitudinal section, pumping a flushing fluid down through the tubular work string, out through at least one flushing outlet in the flushing tool, into the pipe string and further out into said annulus via the perforations in the pipe string, thereby cleaning both the pipe string and the annulus along said longitudinal section,
 wherein an outlet axis (b) of at least one of said at least one flushing outlet in the flushing tool is non-perpendicular to a longitudinal axis (a) of the flushing tool, whereby a corresponding flushing jet from the flushing tool also is non-perpendicular to the longitudinal axis (a) of the flushing tool; 
   (D) pumping a fluidized plugging material down through the tubular work string and into the pipe string at said longitudinal section;   (E) placing the fluidized plugging material in the pipe string along at least said longitudinal section, thereby also placing the fluidized plugging material in said annulus via the perforations in the pipe string, whereupon the fluidized plugging material forms a plug covering substantially a complete cross section of the well along at least said longitudinal section of the well;   (F) pulling the tubular work string out of the well; and   (G) abandoning the well;   wherein the method, in steps (D) and (E), comprises pumping the fluidized plugging material into the pipe string via at least one spraying outlet in the flushing tool so as to discharge as a corresponding spraying jet from the flushing tool.   
     
     
         32 . The method according to  claim 31 , wherein flushing with the flushing fluid and spraying with the fluidized plugging material are performed in one and the same trip into the well. 
     
     
         33 . The method according to  claim 31 , wherein the flushing tool is formed with a plurality of flushing outlets having respective outlet axes (b) angled within ±80° of a plane (c) being perpendicular to the longitudinal axis (a) of the flushing tool, whereby corresponding flushing jets from the flushing tool also are angled within ±80° of said perpendicular plane (c). 
     
     
         34 . The method according to  claim 31 , wherein each of the at least one flushing outlet is provided with a releasable nozzle insert. 
     
     
         35 . The method according to  claim 31 , wherein the method, between steps (B) and (C), also comprises the following steps:
 pulling the perforation tool out of the well; and   attaching the flushing tool to said lower end portion of the tubular work string for subsequent performance of step (C);   whereby perforation and flushing are performed in separate trips into the well.   
     
     
         36 . The method according to any one of  claim 31 , wherein the method, before step (A), also comprises the following steps:
 connecting the perforation tool and the flushing tool into an assembly thereof; and   connecting the assembly to said lower portion of the tubular work string;   whereby perforation and flushing are performed in one and the same trip into the well.   
     
     
         37 . The method according to  claim 36 , wherein the method also comprises the following steps:
 releasably connecting, before step (A), the perforation tool to a lower end portion of the flushing tool; and   disconnecting, between steps (B) and (C), the perforation tool from the flushing tool;   whereby the perforation tool is dropped further down into the pipe string and is left behind in the well.   
     
     
         38 . The method according to  claim 31 , wherein step (E) comprises moving the tubular work string within the pipe string whilst placing the fluidized plugging material therein. 
     
     
         39 . The method according to  claim 31 , wherein the method, before step (C), comprises adding an abrasive agent to the flushing fluid. 
     
     
         40 . The method according to  claim 31 , comprising discharging the flushing fluid from said at least one flushing outlet in the flushing tool at a discharge velocity of at least 15 metres per second. 
     
     
         41 . The method according to  claim 40 , comprising discharging the flushing fluid from the at least one flushing outlet at a discharge velocity of at least 50 metres per second. 
     
     
         42 . The method according to  claim 31 , wherein the method, before step (D), also comprises disposing and anchoring a plug base in the pipe string, and below the longitudinal section (L 1 ) of the well. 
     
     
         43 . The method according to  claim 42 , wherein the plug base comprises at least one cup-shaped element. 
     
     
         44 . The method according to  claim 31 , wherein the flushing tool comprises a first section for discharging, in step (C), the flushing fluid via said at least one flushing outlet, and a second section for spraying, in steps (D) and (E), the fluidized plugging material via said at least one spraying outlet in the flushing tool. 
     
     
         45 . The method according to  claim 44 , wherein the diameter of said spraying jet of fluidized plugging material discharging from said second section of the flushing tool is larger than the diameter of said flushing jet of flushing fluid discharging from said first section of the flushing tool. 
     
     
         46 . The method according to  claim 45 , comprising discharging said spraying jet of fluidized plugging material at a discharge velocity in the order of 15-25 metres per second. 
     
     
         47 . The method according to  claim 46 , comprising discharging said spraying jet of fluidized plugging material at a discharge velocity in the order of 18-22 metres per second. 
     
     
         48 . The method according to  claim 31 , wherein said at least one flushing outlet and said at least one spraying outlet in the flushing tool are one and the same, whereby both the flushing fluid and the fluidized plugging material will discharge through said at least one outlet in the flushing tool; and
 wherein the method comprises discharging said flushing jet of flushing fluid at a higher discharge velocity than that of said subsequent spraying jet of fluidized plugging material.   
     
     
         49 . The method according to  claim 48 , comprising discharging the flushing fluid at a discharge velocity of at least 50 metres per second, and then discharging the subsequent fluidized plugging material at a discharge velocity in the order of 15-25 metres per second. 
     
     
         50 . The method according to  claim 31 , wherein the method also comprises the following steps:
 connecting, before step (D), a displacement body to the tubular work string, and in vicinity of the flushing tool; and   using, in step (E), the displacement body to further displace and distribute the fluidized plugging material in the pipe string and further out into said annulus via said perforations in the pipe string along the longitudinal section of the well;   thereby facilitating the displacement and distribution of fluidized plugging material within said longitudinal section.