Additives for oil well cement slurries and aqueous based drilling fluids comprising microsilica and a method for the production thereof

摘要

The present invention relates to additives for oil well cement slurries and aqueous based drilling fluids comprising microsilica having a particle size in the range 0.02 μm to 45 μm in an amount in the range of 1-80 weight % by the total weight of dry matter, the microsilica surface being modified with polymerizable silane and the additive further comprising at least one acrylamide derivative monomer and optionally at least one acidic unsaturated monomer, and a method for the production thereof.