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 .- 16 . (canceled) 
   
   
       17 . A drilling fluid comprising a polymer, said polymer containing at least 65% by weight of hydroxylated structural units which comprise —OH groups. 
   
   
       18 . The drilling fluid as defined by  claim 17 , said polymer comprising from 0.1% to 10% by weight thereof. 
   
   
       19 . The drilling fluid as defined by  claim 17 , said hydroxylated structural units having the following 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. 
 
   
   
       20 . The drilling fluid as defined by  claim 17 , said hydroxylated structural units being selected from the units having the following formulae: 
     
       
         
         
             
             
         
       
     
   
   
       21 . The drilling fluid as defined by  claim 17 , said hydroxylated structural units having the following formula:
   —CH 2 —CHOH—   
   
   
       22 . The drilling fluid as defined by  claim 17 , said polymer comprising a homopolymer devoid of units other than the hydroxylated structural units. 
   
   
       23 . The drilling fluid as defined by  claim 17 , 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. 
   
   
       24 . The drilling fluid as defined by  claim 17 , useful for the drilling of a well for the recovery of oil and/or gas. 
   
   
       25 . The drilling fluid as defined by  claim 17 , comprising an aqueous silicate-based fluid. 
   
   
       26 . A clay-swelling inhibitor and/or accretion-inhibiting agent and/or fluid-rheology-controlling agent and/or filtrate-reducing agent and/or lubricating agent, comprising the drilling fluid as defined by  claim 17 . 
   
   
       27 . A fluid for the drilling of a well for the recovery of oil and/or gas, comprising the drilling fluid as defined by  claim 17 . 
   
   
       28 . A clay-swelling inhibitor/well bore consolidation agent, comprising the drilling fluid as defined by  claim 17 . 
   
   
       29 . An accretion-inhibiting agent which prevents the blocking of a drilling head, comprising the drilling fluid as defined by  claim 17 . 
   
   
       30 . An aqueous silicate-based fluid comprising the drilling fluid as defined by  claim 17 . 
   
   
       31 . The drilling fluid as defined by  claim 17 , said polymer containing at least 90% by weight of said hydroxylated structural units. 
   
   
       32 . The drilling fluid as defined by  claim 18 , comprising from 0.1% to 5% by weight of said polymer. 
   
   
       33 . The drilling fluid as defined by  claim 18 , comprising from 1% to 3% by weight of said polymer. 
   
   
       34 . The drilling fluid as defined by  claim 23 , said polymer having a weight-average molecular weight of from 2,000 g/mol to 20,000 g/mol.