Cement set activators for set-delayed cement compositions and associated methods

A method for activating a set-delayed cement composition comprising:

• providing a set-delayed cement composition comprising pumice, hydrated lime in an amount of about 10% to about 30% by weight of the pumice, a set retarder in an amount of about 1% to about 5% by weight of the pumice, water in an amount of about 35% to about 70% by weight of the pumice, and a dipsersant;
• wherein the set retarder comprises a phosphonic acid derivative;
• wherein the dispersant comprises a polycarboxylated ether dispersant;
• storing the set-delayed cement composition for a period of at least about 1 day;
• activating the set-delayed cement composition with a cement set activator, wherein the cement set activator comprises a polyphosphate and an additive selected from the group consisting of nanosilica and a monovalent salt;
• introducing the set-delayed cement composition into an annulus between a conduit disposed in a well bore and a wall of the well bore or another conduit;
• and
• allowing the set-delayed cement composition to set in the annulus.

A cementing system comprising:

• mixing equipment for mixing a set-delayed cement composition, the set-delayed cement composition comprising water, pumice, hydrated lime, a set retarder, a dispersant, and a cement set activator;
• wherein the cement set activator comprises at least one activator selected from the group consisting of nanosilica, a polyphosphate, and combinations thereof;
• wherein the set retarder comprises a phosphonic acid derivative;
• and wherein the dispersant comprises a polycarboxylated ether dispersant;
• and
• pumping equipment for delivering the set-delayed cement composition into a well bore.