Method and cement-drilling fluid cement composition for cementing a wellbore

A method for cementing a wellbore space occupied by a drilling fluid to sealingly fill the space, the method comprising, displacing the drilling fluid with a cement slurry composition comprising:

• a. a cementitious material;
• b. a drilling fluid;
• and
• c) a dispersant selected from the group consisting of water soluble polymers comprising allyloxybenzene sulfonate or allyloxybenzene phosphonate polymerized with at least one of acrylic acid, acrylamides, alkyl acrylamides, maleic anhydride, itaconic acid, sulfonated or phosphonated styrene sulfonated or phosphonated vinyl toluene, sulfonated or phosphonated isobutylene, acrylamidopropane sulfonate, acrylamidopropanephosphonate, vinyl alcohol, sulfonated or phosphonated propene and alkali, alkaline earth and ammonium salts thereof.

A method for cementing a wellbore space by filling the wellbore space with a cement slurry composition comprising:

• a) a cementitious material;
• b) a drilling fluid;
• and
• c) a dispersant selected from the group consisting of water soluble polymers comprising allyloxybenzene sulfonate or allyloxybenzene phosphonate polymerized with at least one of acrylic acid, acrylamides, alkyl acrylamides, maleic anhydride, itaconic acid, sulfonated or phosphonated styrene sulfonated or phosphonated vinyl toluene, sulfonated or phosphonated isobutylene, acrylamidopropane sulfonate, acrylamidopropanephosphonate, vinyl alcohol, sulfonated or phosphonated propene and alkali, alkaline earth and ammonium salts thereof.