An hydraulic cement composition comprising an aluminous cement and an alum and method of cementing comprising admixing said composition with water and emplacing it in a geologic formation via a well penetrating the formation.
A cement slurry is provided which is useful to cement wellbores in high temperature service. A high alumina cement is used. The density of the slurry is relatively low as a result of using a low density aggregate. In a preferred embodiment, the low density aggregate is graphite. The graphite additionally imparts a significantly improved thermal and electrical conductivity to the hardened cement.
Methods and compositions for sealing subterranean zones penetrated by well bores are provided. The methods basically comprise the steps of introducing a sealing composition into the subterranean zone comprised of a hydraulic cement, sufficient water to form a slurry and a rapidly acting thixotropy providing gelling agent, and allowing the sealing composition to remain at rest in the zone whereby the sealing composition rapidly gels and then sets into a hard impermeable mass therein.
A method for cementing a wellbore wherein a slurry comprising at least five percent by weight of particles having a particle size greater than about 0.04 inches is placed in the wellbore. The slurry has a density which exceeds the hydraulic fracture gradient of the formation but the slurry is not lost to fractures because the larger particles enable the solids in the slurry to bridge and prevent excessive slurry loss. The cement slurry of the present invention is preferably placed in the wellbore by a direct placement method such as a coil tubing placement to minimize the pressure placed on the formation by any particular cement slurry.
