METHOD FOR CEMENTING WELLS DRILLED ON HYDROCARBON-BASED DRILLING FLUID Russian patent published in 2025 - IPC E21B33/138 C09K8/467 

FIELD: construction of wells.

SUBSTANCE: method for cementing wells drilled on a hydrocarbon-based drilling fluid includes lowering a casing string into the well, flushing them with a hydrocarbon-based drilling fluid, then pumping a spacer fluid – diesel fuel, then pumping of self-healing grouting composition, its flushing and placement in annular space with displacement fluid in required interval. Self-repairing grouting composition used is a composition consisting of portland cement without additives with increased sulphate resistance, self-repairing additive based on thermoplastic butadiene-styrene branched structure, filtration reducer Floss 500, plasticizer DPC, setting time accelerator – calcium chloride and industrial water in weight ratio 8:(0.96-1.2):(0.016-0.024):(0.032-0.04):(0.24-0.32):(3.94-4.05), respectively.

EFFECT: increased tightness of annular space of wells drilled on oil-based drilling fluids, due to reduction of time for overlapping channels of unsubstituted drilling fluid and self-recovery of hardened grouting composition at its contact with hydrocarbon component in drilling fluid.

1 cl, 4 tbl