dodecanediol cycloaliphatic diols for example 1 4 cyclohexanediol 1 4 cyclohexanedimethanol and isosorbide and polyhydroxy compounds for example glycerol trimethylolpropane and pentaerythritol a preferred group of comonomer diols is selected from the group consisting of ethylene glycol 2 methyl 1 3 propanediol 2 2 dimethyl 1 3 propanediol 2 2 diethyl 1 3 propanediol 2 ethyl 2 hydroxymethyl 1 3 propanediol c 6 c 10 diols such as 1 6 hexanediol 1 8 octanediol and 1 10 decanediol and isosorbide and mixtures thereof a particularly preferred diol other than 1 3 propanediol is ethylene glycol and c 6 c 10 diols can be particularly useful as well one preferred po3g that contains comonomer is poly trimethylene ethylene ether glycol such as described in us20040030095a1 preferred poly trimethylene ethylene ether glycols are prepared by acid catalyzed polycondensation of from 50 to about 99 mole preferably from about 60 to about 98 mole and more preferably from about 70 to about 98 mole 1 3 propanediol and up to 50 to about 1 mole preferably from about 40 to about 2 mole and more preferably from about 30 to about 2 mole ethylene glycol the poly trimethylene ether glycol esters that can be used in the wellbore fluid comprise one or more compounds of the formula i wherein q represents the residue of a poly trimethylene ether glycol after abstraction of the hydroxyl groups r.