Applying wellbore lining

Abstract

Application of a photocurable lining to a downhole fixed surface surrounding the axis of a wellbore is carried out by skimming an applicator over the downhole surface while delivering a porous tape impregnated with a photocurable liquid composition between the applicator and the downhole surface so that the tape lies on the downhole surface and directing light of wavelength in a range from 100 nm to 1500 nm onto the curable composition impregnating the tape so as to initiate curing of the composition and thereby attach the tape to the downhole surface.

1 . A method of applying a photocurable lining to a downhole fixed surface surrounding the axis of a wellbore containing a wellbore fluid, the method comprising
 skimming at least one applicator over the downhole surface while delivering a porous tape between the applicator and the downhole surface so that the tape lies on the downhole surface;   providing a photocurable liquid composition impregnating at least part of the tape; and   directing light of wavelength in a range from 100 nm to 1500 nm onto the curable composition impregnating the tape so as to initiate curing of the composition and thereby attach the tape to the downhole surface.   
     
     
         2 . A method according to  claim 1  wherein the tape is preimpregnated with the photocurable liquid composition before it is delivered between the applicator and the downhole surface. 
     
     
         3 . A method according to  claim 1  comprising supplying a photocurable liquid composition between the applicator and the downhole surface to impregnate at least part of the tape. 
     
     
         4 . A method according to  claim 1  wherein the applicator comprises a light transmitting barrier between a light output and tape which is at least partially impregnated with the photocurable liquid composition, the light-transmitting barrier facing and being adjacent the impregnated tape on the downhole surface and the light output being configured to directing light of wavelength in the range from 100 nm to 1500 nm through the light-transmitting barrier onto the tape so as to initiate curing of the impregnating composition. 
     
     
         5 . A method according to  claim 4  wherein the tape plus photocurable composition impregnating the tape extend more than three quarters the distance between the barrier and the downhole surface. 
     
     
         6 . A method according to  claim 5  wherein the light-transmitting barrier is in direct contact with photocurable composition impregnating the tape. 
     
     
         7 . A method according to  claim 6  wherein the light-transmitting barrier has a fluorocarbon at its surface in contact with the curable layer. 
     
     
         8 . A method according to  claim 1  wherein the applicator comprises a laminar web of light-transmitting material and support means for positioning a portion of the web facing the downhole surface and in contact with impregnated tape between the portion of the web and the downhole surface
 wherein any movement of the said portion of the web relative to the tape and downhole surface is slower than the movement of other parts of the applicator assembly relative to the tape and downhole surface as the applicator is skimmed over the downhole surface; and 
 wherein the light is directed through the said portion of the web onto the tape impregnated with curable composition so as to initiate curing of the composition between the said portion of the web and the downhole surface. 
 
     
     
         9 . A method according to  claim 8  wherein the support means comprises a pair of rotary elements spaced one from another and the laminar web is a belt running in a continuous loop over these rotary elements. 
     
     
         10 . A method according to  claim 9  wherein the assembly comprises a light output positioned between the rotary elements and within the loop of the belt so that it can direct light through the said portion of the belt. 
     
     
         11 . A wellbore tool for applying a photocurable coating to a fixed downhole surface surrounding the axis of a wellbore wherein the tool comprises
 at least one applicator to face a downhole surface surrounding the wellbore tool;   means to skim the applicator over the downhole surface;   means to deliver a porous tape and photocurable liquid composition between the applicator and the downhole surface, and   at least one light output configured to direct light of wavelength in a range from 100 nm to 1500 nm onto the photocurable composition.   
     
     
         12 . A wellbore tool according to  claim 11  further comprising a container with a supply of the tape therein, configured for delivery of tape from the supply to between the applicator and the downhole surface. 
     
     
         13 . A wellbore tool according to  claim 11  wherein the applicator further comprises a light transmitting barrier between the light output and the impregnated tape, with the barrier facing and adjacent the at least partly impregnated tape on the downhole surface and the light output configured to direct light through the barrier onto the impregnated tape. 
     
     
         14 . A wellbore tool according to  claim 11  wherein the applicator comprises a pair of rotary elements spaced one from another and a light transmitting belt running in a continuous loop over these rotary elements with a portion of the belt facing the downhole surface and at least one light output configured to direct light through the said portion of the light-transmitting belt towards the downhole surface. 
     
     
         15 . A wellbore tool according to  claim 14  wherein the light output is positioned between the rotary elements and within the loop of the belt so that it can direct light through the said stationary portion of the belt. 
     
     
         16 . A wellbore tool according to  claim 11  wherein the at least one applicator includes one or more light emitting diodes to provide the light output. 
     
     
         17 . A wellbore tool according to  claim 11  wherein the tool comprises a light source and a fibre optic cable to carry light to the at least one applicator. 
     
     
         18 . A wellbore tool according to  claim 11  comprising means to move the at least one applicator outwardly towards and inwardly from said fixed downhole surface.