| abstract |
Polymers derived by copolymerizing a hydrophilic vinyl monomer, such as acrylic acid, with at least one hydrophobic vinyl monomer, such as an acrylic acid ester, a methacrylic acid ester, a vinyl ester of a saturated monocarboxylic acid having from 1 to 3 carbon atoms, and the like, prepared in a suitable inert, low chain transfer, organic liquid medium, such as n-hexane, cyclohexane, and chlorofluorocarbons such as 1,1,2-trichloro-1,2,2-trifluoroethane, and neutralized by a suitable base while still slurried in the inert low chain transfer organic liquid medium, perform effectively as water loss additives for drilling fluids under high temperature conditions. Such water loss control additives are especially effective when employed in drilling fluids having high solids content. Also disclosed are drilling fluids employing such water loss control additives as well as a method of drilling a bore hole in the earth using drilling fluids employing such water loss control additives. |