BASE OF DENSIFIED GROUTING MORTAR MAINLY USED IN FRACTURED CARBONATE RESERVOIRS Russian patent published in 2005 - IPC

FIELD: well construction, particularly for sealing or packing boreholes or wells.

SUBSTANCE: base includes basic mixture of oil-well Portland cement with weighting additive and processing characteristics moderators, as well as mudding additive. Fractional composition of mudding additive is selected in accordance with Abrams criterion for zone with abnormal formation pressure. Weighting additive is barite or hematite or magnetite or ilmenite or iron-ore concentrate or mixture thereof. All above components are taken in the following amounts: basic mixture including 35-70% by weight of oil-well Portland cement and 30-65% by weight of weighting additive; mudding additive is 1.0-20.0% by basic mixture weight. The basic mixture may comprise chrysotile asbestos, vermiculite or fiber glass used as the mudding additive and water-retaining additive taken in amount of 0.1-1.0% by basic mixture weight or plasticizing agent in amount of 0.1-1.0% by basic mixture weight or antifoaming additive in amount of 0.1-0.2% by basic mixture weight or setting accelerator in amount of 0.1-5.0% by basic mixture weight or setting retarder in amount of 10-20% by basic mixture weight or expanding agent taken in amount of 0.1-18% by basic mixture weight, which are used as the processing characteristics moderator.

EFFECT: increased grouting mortar quality and stone formed of the grouting mortar due to providing fluid loss thereof comparable with that of drilling mud, due to prevention of suffusion processes, due to provision of high drilling mud floatability during ejection thereof into the well and possibility of quick obtaining structure-rheological properties at rest during putting grouting mortar in cementation zone and due to reduced time between grouting mortar hanging-up and setting-up processes, increased resistance to impact load application and to fracturing.

8 cl, 4 tbl