Abstract: This invention relates to a wellbore treatment fluid and a method of enhancing wellbore treatment fluids to increase efficiency and productivity of wells. More specifically this invention provides methods for enhancing the thermal stability of wellbore treatment fluids such as drill-in, completion, workover, packer, well treating, testing, spacer or hole abandonment fluids. The methods include providing a wellbore treatment fluid that comprises polyol, polysaccharide, weighting agent, and water, wherein the fluid is solids free.

Abstract: A fluidized cellulosic polymer suspension of a cellulosic polymer in an alkali formate containing solution is particularly efficacious in the thickening of brines, particularly high density brines, in the recovery of oil and/or gas from a subterranean formation. The alkali formate containing solution preferably contains potassium formate, cesium formate or a mixture thereof. A fluid loss pill containing the cellulosic polymer suspension may further contain a crosslinking agent and glycol.

Abstract: A fluidized cellulosic polymer suspension of a cellulosic polymer in an alkali formate containing solution is particularly efficacious in the thickening of brines, particularly high density brines, in the recovery of oil and/or gas from a subterranean formation. The alkali formate containing solution preferably has between from about 40 to about 75 weight percent of alkali formate. Preferred as alkali formate are potassium formate, cesium formate and a mixture thereof. The true crystallization temperature (TCT) of the alkali formate solution is preferably less than or equal to 20°, more preferably less than or equal to 18° F., most preferably less than or equal to 10° F., ideally less than or equal to 0° F. The alkali formate solution serves as the carrier fluid, allowing the cellulose to be easily metered into the brine, thereby allowing hydration without the formation of fisheyes.