Improvements In Or Relating To Well Abandonment

Abstract

A method and apparatus for the combined cleaning and plugging of an annulus in a well across a longitudinal section of the well were the annulus is located outside a conduit in the well. The conduit is perforated over the longitudinal section. Washing fluid is passed through the longitudinal section to clear material in the annulus before the longitudinal section is plugged. Pressure variations are created in the washing fluid by use of a flow modifier device to pulse the washing fluid. Embodiments include creating pressure variations in the plugging material.

1 . A method for the combined cleaning and plugging of an annulus in a well across a longitudinal section of the well, said annulus being located outside a conduit in the well, comprising the steps:
 (a) perforating the conduit to form a plurality of holes in the conduit along the longitudinal section;   (b) passing a washing fluid through at least one of said holes at a first location on the longitudinal section and via the annulus to exit into the conduit through at least one of said holes at a second location on the longitudinal section;   (c) pumping a fluidized plugging material through at least one of said holes to fill the annulus and conduit with fluidized plugging material and thereby plug said well along at least said longitudinal section of the well;   
       wherein, the method includes the step of creating pressure variations in the washing fluid. 
     
     
         2 . The method according to  claim 1  wherein the pressure variations are pressure pulses created in the washing fluid. 
     
     
         3 . The method according to  claim 2  wherein the pressure pulses are created downhole by pumping washing fluid through a flow modifier device. 
     
     
         4 . The method according to  claim 1  wherein the washing tool is pulled out of the conduit along the longitudinal section while creating the pressure variations in the washing fluid. 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . The method according to  claim 1  wherein the step of passing the washing fluid through the annulus is by operation of a washing tool located on a fluid carrying string run into the conduit. 
     
     
         8 . (canceled) 
     
     
         9 . The method according to  claim 1  wherein the fluidized plugging material is cement. 
     
     
         10 . The method according to  claim 1  wherein the fluidized plugging material is pumped from surface through a cementing tool. 
     
     
         11 . The method according to  claim 1  wherein the washing tool and the cementing tool are combined in a jetting tool. 
     
     
         12 . The method according to  claim 1  wherein the method includes the step of setting a bridge plug in the conduit. 
     
     
         13 . The method according to  claim 1  wherein the method includes the step of creating pressure pulses in the fluidized plugging material. 
     
     
         14 . The method according to  claim 13  wherein the step of creating pressure pulses in the fluidized plugging material is by use of the flow modifier device. 
     
     
         15 . (canceled) 
     
     
         16 . The method according to  claim 8  wherein the perforating tool, the flow modifier device and the washing tool are on the same string and the steps of the method are carried out on a single trip in the wellbore. 
     
     
         17 . The method according to  claim 8  wherein the perforating tool, the flow modifier device, the washing tool and the cementing tool are on the same string and the steps of the method are carried out on a single trip in the wellbore. 
     
     
         18 . (canceled) 
     
     
         19 . (canceled) 
     
     
         20 . The method according to  claim 1  wherein the conduit is casing and the annulus is between the casing and the formation of the borehole. 
     
     
         21 . The method according to  claim 1  wherein the annulus is the B-annulus between inner casing and a surrounding casing. 
     
     
         22 . An apparatus for the combined cleaning and plugging of an annulus in a well across a longitudinal section of the well, said annulus being located outside a conduit in the well, comprising a string for running inside the conduit, the string including a perforating tool, a flow modifier device, and a washing tool. 
     
     
         23 . An apparatus according to  claim 22  wherein the flow modifier device is a pressure pulse-generator actuated by fluid being circulated through the string. 
     
     
         24 . An apparatus according to  claim 22  wherein the flow modifier device is a tubular member for mounting on the string, the member comprising a flow modifier for producing cyclic variations in the flow of fluid therethrough. 
     
     
         25 . An apparatus according  claim 22  wherein the perforation tool is a perforating gun. 
     
     
         26 . An apparatus according to  claim 22  wherein the washing tool is a fluid jetting tool, including a plurality of radial ports and one or more of the ports include nozzles. 
     
     
         27 . (canceled) 
     
     
         28 . (canceled) 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . An apparatus according to  claim 22  wherein the apparatus includes a bridge plug.