FIELD: gas and oil industries. SUBSTANCE: the invention presents a cement slurry for the insulating shield and a method to make the insulating shield, which contains mixture of water, the natural or modified clay, a special blast-furnace slag and an activating agent. The invention also presents a method of usage of the cement slurry, that is dealt with usage of a special blast-furnace slag for preparation of this cement slurry. Technical result: increased strength of the cement slurry at the same ratio of water / cement, increased penetrating power at the same content of the dry materials, more sluggish hardening, that in the higher degree is suitable for direct boring with a cement slurry, obtaining of a system with poor reactivity allowing completely to get rid of moderating materials application. In the cement slurry for the insulating shield, that contains clay, blast-furnace slag and an activating agent, clay is presented by bentonitic slimes, and blast-furnace slag has a maximum size of grains from 50 u
