Well Treatment Compositions and Methods Utilizing Nano-Particles

A cement composition comprising;

• hydraulic cement consisting essentially of at least one cement selected from the group consisting of API Class A Portland cement, API Class C Portland cement, API Class G Portland cement, API Class H Portland cement, a pozzolana cement, a gypsum cement, a high-alumina-content cement, a silica cement, a slag cement, and a combination thereof,
• water;
• particulate nano-silica in an amount of about 1% to about 25% by weight of the hydraulic cement on a dry basis;
• and
• at least one additive selected from the group consisting of a strength-retrogression additive, a set accelerator, a set retarder, a weighting agent, a weight-reducing additive, a lost-circulation material, a filtration-control additive, a dispersant, a defoaming agent, a foaming agent, and a combination thereof.

A cement composition comprising:

• cement;
• water;
• and
• a contained nano-particle.