fluids linear not cross linked polymer systems can be used in another embodiment but generally require more polymer for the same level of viscosification all crosslinked polymer systems may be used including for example delayed optimized for high temperature optimized for use with sea water buffered at various ph 39 s and optimized for low temperature any crosslinker may be used for example boron titanium and zirconium suitable boron crosslinked polymers systems include by non limiting example guar and substituted guars crosslinked with boric acid sodium tetraborate and encapsulated borates borate crosslinkers may be used with buffers and ph control agents such as sodium hydroxide magnesium oxide sodium sesquicarbonate and sodium carbonate amines such as hydroxyalkyl amines anilines pyridines pyrimidines quinolines and pyrrolidines and carboxylates such as acetates and oxalates and with delay agents such as sorbitol aldehydes and sodium gluconate suitable zirconium crosslinked polymer systems include by non limiting example those crosslinked by zirconium lactates for example sodium zirconium lactate triethanolamines 2 2 u2032 iminodiethanol and with mixtures of these ligands including when adjusted with bicarbonate suitable titanates include by non limiting example lactates and triethanolamines and mixtures for example delayed with hydroxyacetic acid any other chemical additives can be used or included provided that they are tested for compatibility with the fibers and.