Patent ID: 8921284

Claim:
A spacer fluid for separating a drilling fluid and cement composition in a well bore comprising: cement kiln dust in an amount of about 1% to about 65% by weight of the spacer fluid, fly ash in an amount of about 1% to about 60% by weight of the spacer fluid, a free water control additive in an amount of about 0.1% to about 16% by weight of the spacer fluid, and water in an amount of about 15% to about 95% by weight of the spacer fluid, wherein the spacer fluid has a higher yield point at 130° F. than at 80° F., and wherein the spacer fluid is disposed in the well bore between the drilling fluid and the cement composition, wherein the free water control additive comprises at least one additive from the group consisting of bentonite, amorphous silica, hydroxyethyl cellulose and any combination thereof.