Abstract: A foamable drilling fluid for use in well operations such as deep water offshore drilling where risers are not employed in returning the fluid to the surface mud pit. A preferred foamable drilling fluid comprises a prehydrated clay such as bentonite, sea water, a surfactant selected from the group consisting of .alpha.-olefinsulfonates, alkylpolyglycosides, alcohol sulfates, salts of ethoxylated alcohol sulfates, and a stabilizing surfactant consisting of cocoamine betaine. The stabilized foam drilling fluid resists foam breakdown upon drilling cessation, prevents fluid loss to reduce filter cake buildup and increases the carrying capacity of cuttings and other solids. In addition, a foamable drilling fluid is provided including an hydraulic material selected from the group consisting of Portland cement, siliceous material like fumed silica, blast furnace slag and pozzolans such as fly ash.

Abstract: A foamable drilling fluid for use in well operations such as deep water offshore drilling where risers are not employed in returning the fluid to the surface mud pit. A preferred foamable drilling fluid comprises a prehydrated clay such as bentonite, sea water, a surfactant selected from the group consisting of .alpha.-olefinsulfonates, alkylpolyglycosides, alcohol sulfates, salts of ethoxylated alcohol sulfates, and a stabilizing surfactant consisting of cocoamine betaine. The stabilized foam drilling fluid resists foam breakdown upon drilling cessation, prevents fluid loss to reduce filter cake buildup and increases the carrying capacity of cuttings and other solids. In addition, a foamable drilling fluid is provided including an hydraulic material selected from the group consisting of Portland cement, siliceous material like fumed silica, blast furnace slag and pozzolans such as fly ash.

Abstract: The present invention provides well cementing methods and compositions for use in cold environments which are particularly suitable for cementing conductor strings in deep water offshore wells. The cement compositions are basically comprised of a relatively coarse particulate hydraulic cement mixed with an ultra fine particulate hydraulic cement, sufficient water to form a pumpable slurry and a fluid loss control additive.