EXPANDING PLUGGING COMPOSITION FOR LOW-TEMPERATURE WELLS Russian patent published in 2000 - IPC

FIELD: production of light-weight expanding plugging compositions applicable in well cementing under climatic conditions of Extreme North, consolidation of permafrost and fissured rocks, prevention of formation hydraulic fracturing, gas showing and permafrost thaw, improvement of well seal. SUBSTANCE: mixing of plugging portland cement for cold wells with peat suspensions in solutions of aluminum sulfate in proposed plugging composition is carried out with the following ratio of ingredients, wt.%: plugging portland cement for cold wells, 35.3-56.5; aluminum sulfate, 2.0-5.0; peat, 2.0-10.3; water, the balance. Mixing of specified components results in obtaining on the base of single-component binder in the form of plugging cement of light-weight plugging composition with high degree of expansion, proper process terms of setting at low temperatures, low heat conduction and efficient adhesion to metal casing string. EFFECT: higher efficiency. 2 tbl