| 摘要 |
<p>An improved non dispersing set retarder additive for foamed cements, cement compositions containing the additive, and methods of cementing in a subterranean zone penetrated by a well bore are provided. The set retarder additive includes a blend of a sulfonated lignin, preferably a lignosulfonate, with an alkali lignin, preferably a kraft lignin, having an organic sulfur content of 0 3.5 % by weight in a ratio of about 6:4 to 8:2. The methods are basically comprised of the steps of preparing a foamed cement composition comprised of hydraulic cement, a non dispersing set retarder, sufficient water to form a slurry, sufficient gas to foam the slurry and a foaming and foam stabilizing surfactant present in an amount sufficient to facilitate the formation of the foam and stabilize the foamed cement composition.</p> |
