Abstract: Provided herein are compositions that include an aqueous-based insulating fluid that comprises an aqueous base fluid, a water-miscible organic liquid, and a synthetic polymer. In another embodiment, provided herein is a method of forming an aqueous-based insulating fluid comprising: mixing an aqueous base fluid and a water-miscible organic liquid to form a mixture; adding at least one synthetic polymer to the mixture; allowing the polymer to hydrate; optionally adding a crosslinking agent to the mixture comprising the synthetic polymer to crosslink the synthetic polymer; placing the mixture comprising the synthetic polymer in a chosen location; allowing the mixture comprising the synthetic polymer to activate to form a gel therein.

Abstract: Provided herein are methods that include In one embodiment, the present invention provides a method comprising: providing an annulus between a first tubing and a second tubing; providing an aqueous-based insulating fluid that comprises an aqueous base fluid, a water-miscible organic liquid, and a synthetic polymer; and placing the aqueous-based insulating fluid in the annulus. Another method provided is a method comprising: providing a tubing comprising a first fluid located within a well bore such that an annulus is formed between the tubing and a surface of the well bore; providing an aqueous-based insulating fluid that comprises an aqueous base fluid, a water-miscible organic liquid, and a synthetic polymer; and placing the aqueous-based insulating fluid in the annulus.