CEMENT COMPOSITIONS WITH LOW-TEMPERATURE HYDRATION AND THEIR APPLICATIONS Russian patent published in 2012 - IPC E21B33/13 C09K8/467 

FIELD: oil and gas production.

SUBSTANCE: method of servicing borehole in underground formation comprises the following operations. Preparing cement composition containing water cementing material including vitrified shale and fitting said composition into borehole. Note here that said underground formation contains permafrost, gas hydrates or both. In compliance with one version, cementing material represents blast-furnace slag, vitrified shale, potassium sulphate hemihydrate or combination thereof. In compliance with another version, proposed method comprises: preparing cement composition containing water cementing material including vitrified shale and fitting said composition into borehole. Hardening retarder represents sodium citrate. Note here that said underground formation contains permafrost, gas hydrates or both. Cement composition of water cementing material including vitrified shale and blast-furnace slag and/or potassium sulphate hemihydrate and fitting said composition into borehole. Note here that said underground formation contains permafrost, gas hydrates or both. Note also that ratio between said blast-furnace slag and/or potassium sulphate hemihydrate varies from 1:4 to 4:1.

EFFECT: reduced heat hydration.

17 cl, 6 ex, 7 tbl