| abstract |
There is provided a wellbore fluid having a continuous aqueous phase, and comprising at least one polymer which:—has a molecular weight in the range of from 2,000 to less than 100,000; contains hydrophilic units such that the polymer is at least 2% soluble in water at 20° C., and such that less than 50% by weight of said hydrophilic units comprise —CH 2 —CH 2 O— units; and contains pendant alkyl groups having at least 10 carbon atoms, the combined molecular weight of said pendant alkyl groups being in the range of from 15 to 70% by weight based on the weight of the polymer. Such aqueous based wellbore fluids exhibit significantly improved fluid loss properties when used in wellbore operations, such as drilling, completion or workover. |