Tubulars and methods for delivery of chemical in a well

Abstract

An apparatus for wellbore treatment includes a tubular with one or more solid, erodible blocks on its outer surface. The blocks carry a chemical for wellbore treatment that is released in the wellbore by erosion of the blocks against the wellbore wall. A method for wellbore treatment employs the tubular to release the chemical in the well by erosion of the blocks.

We claim: 
     
         1 . A tubular for use with a down hole assembly, the tubular comprising: a tubular wall, a block carried on the tubular wall, the block including a wellbore treatment chemical capable of being released by erosion of the block. 
     
     
         2 . The tubular of  claim 1 , wherein the wellbore treatment chemical comprises a plugging material, lubricity additive, or well bore formation inhibitor. 
     
     
         3 . The tubular of  claim 2 , wherein the chemical comprises a lubricity additive. 
     
     
         4 . The tubular of  claim 3 , wherein the lubricity additive comprises graphite or molybdenum disulfide. 
     
     
         5 . The tubular of  claim 2 , wherein the chemical comprises a well bore formation inhibitor. 
     
     
         6 . The tubular of  claim 5 , wherein the inhibitor comprises epoxy. 
     
     
         7 . The tubular of  claim 1 , wherein the block is a solid including a carrier comprising polymer, polyethylene, fluoropolymers, PTFE, resin, epoxy resin, HDPE, LDPE, wax, polyethylene wax, paraffin wax, microcrystalline wax, or combination thereof. 
     
     
         8 . The tubular of  claim 7 , wherein the block further includes a reinforcement comprising foam or fibers. 
     
     
         9 . The tubular of  claim 8 , wherein the carrier is polyethylene wax, the reinforcement is an open cell foam and the chemical is a lubricity additive. 
     
     
         10 . The tubular of  claim 1 , wherein the block is secured in a recess on the outer surface of the tubular wall. 
     
     
         11 . The tubular of  claim 1 , wherein the block is detachably secured on the outer surface of the tubular wall. 
     
     
         12 . The tubular of  claim 1 , further comprising a mounting structure for securing the block to the tubular wall. 
     
     
         13 . The tubular of  claim 1 , further comprising a sacrificial outer coating over the block. 
     
     
         14 . The tubular of  claim 1 , further comprising a second block on the tubular and herein the second block includes a second chemical that is different than the chemical. 
     
     
         15 . The tubular of  claim 1 , wherein the tubular is configured for attachment about the outside of a wellbore string. 
     
     
         16 . The tubular of  claim 1 , having threads at one or both ends to engage corresponding threads in a drill pipe. 
     
     
         17 . The tubular of  claim 1 , further comprising a cavity extending into the tubular wall from an opening on an outer surface of the tubular wall, the block installed in and protruding from the cavity and a mounting structure engaging the block and securing the block to the tubular wall. 
     
     
         18 . The tubular of  claim 17 , further comprising a shock absorbing material between the block and the cavity. 
     
     
         19 . The tubular of  claim 17  wherein the block comprises a carrier including wax and a reinforcement in the carrier including foam or fibers and the chemical is a lubricity additive blended into the carrier. 
     
     
         20 . A method of running a string into a well, wherein the string carries one or more tubulars of  claim 1 . 
     
     
         21 . A method of chemically treating a well having a wellbore wall, the method comprising:
 running into the well with a tubular having a tubular wall with an outer surface and a block on the outer surface, the block being a solid and including a chemical for wellbore treatment; and   treating the well with the chemical by contacting the wellbore wall with the block to release the chemical in the well.   
     
     
         22 . The method of  claim 22 , wherein treating includes applying a lubricant to the wellbore wall. 
     
     
         23 . The method of  claim 22 , wherein treating stabilizing an underground formation from hydrating or sloughing. 
     
     
         24 . The method of  claim 22 , wherein treating includes applying a well bore formation inhibitor to the wellbore wall. 
     
     
         25 . The method of  claim 22 , wherein contacting the wellbore wall includes eroding the block against the wellbore wall to apply the chemical to the wellbore wall. 
     
     
         26 . The method of  claim 22 , wherein running into the well includes supporting the tubular on the block, forming an annular area between the outer surface and the wellbore wall.