A swellable packer device upon exposure to brine in a well. The device may be swellable to a substantially constant profile in spite of significant fluctuations in brine concentrations. Thus, the likelihood of packer failure due to under-swelling or over-swelling is reduced. Indeed, the packer may be employed for long-term operations or isolations ranging from a couple of weeks to twenty years or more without undue concern over packer failure from under or over swelling.