摘要 |
A low density, antimigratory cement composition includes cement, water and between about 0.5 to about 2.5 gallons per sack of cement of an additive wherein the additive is a copolymer of an impermeability agent and a gelling agent wherein said impermeability agent is a vinyl acetate-containing material and wherein said gelling agent is a vinyl ester which is compatible with said impermeability agent, whereby said cement composition in slurry form is thixotropic and resistant to gas migration.
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