Drilling fluids comprising hydroxylated polymers

Abstract

Drilling fluids comprising polymers containing hydroxylated structural units are useful as accretion inhibiting agents, and/or as fluid rheology controlling agents, and/or as filtrate reducing agents, and/or as lubricating agents.

1 . A drilling fluid comprising a polymer containing at least 65% by weight of hydroxylated structural units. 
     
     
         2 . The drilling fluid of  claim 1 , wherein said polymer contains at least 65% by weight of hydroxylated structural units. 
     
     
         3 . The drilling fluid of  claim 1 , wherein said polymer contains at least 90% by weight of hydroxylated structural units. 
     
     
         4 . The drilling fluid of  claim 1 , wherein said drilling fluid comprises from 0.1% to 10% by weight of said polymer. 
     
     
         5 . The drilling fluid of  claim 1 , wherein said drilling fluid comprises from 0.1% to 5% by weight of said polymer. 
     
     
         6 . The drilling fluid of  claim 1 , wherein said drilling fluid comprises from 1% to 3% by weight of said polymer. 
     
     
         7 . The drilling fluid of  claim 1 , wherein said hydroxylated structural units have the formula:
   —CH 2 —CHR 6 [—X 2 —R 8 ]—
   in which:
 R 6  is a hydrogen atom or a methyl radical, 
 X 2  is a group of formula —CO—O—, —CO—NH— or —C 6 H 4 —CH 2 —, 
 R 8  is a hydrocarbon group of at least two carbon atoms comprising at least two —OH groups, optionally on two consecutive carbon atoms. 
   
     
     
         8 . The drilling fluid of  claim 1 , wherein said hydroxylated structural units are selected from units having the formula: 
       
         
           
           
               
               
           
         
       
     
     
         9 . The drilling fluid of  claim 1 , said hydroxylated structural units being units of the formula: —CH 2 —CHOH—. 
     
     
         10 . The drilling fluid of  claim 1 , said polymer comprising a homopolymer devoid of units other than the hydroxylated structural units. 
     
     
         11 . The drilling fluid of  claim 1 , said polymer having a weight-average molecular weight of from 1,000 g/mol to 400,000 g/mol, measured by GPC calibrated with poly(ethylene oxide) standards. 
     
     
         12 . The drilling fluid of  claim 1 , said polymer having a weight-average molecular weight of from 2,000 g/mol to 20,000 g/mol, measured by GPC calibrated with poly(ethylene oxide) standards. 
     
     
         13 . The drilling fluid of  claim 1 , further comprising a liquid vehicle. 
     
     
         14 . The drilling fluid of  claim 13 , wherein said liquid vehicle comprises an aqueous silicate-based fluid. 
     
     
         15 . The drilling fluid of  claim 13 , wherein said liquid vehicle comprises an aqueous silicate-free fluid.