METHOD FOR PREPARATION FOR CEMENTING OF WELLS DRILLED ON DRILLING MUD ON HYDROCARBON BASIS Russian patent published in 2025 - IPC C09K8/467 C09K8/40 C09K8/50 E21B33/138 

FIELD: construction.

SUBSTANCE: invention relates to construction of wells, in particular to methods of preparing wells for cementing, drilled with oil-based drilling mud. Method of preparing wells drilled on a hydrocarbon-based drilling fluid for cementing includes lowering casing pipes into the well, flushing them with drilling fluid, sequential pumping of spacer fluids into the well, their squeezing into the annulus with grouting solution and displacement fluid with their complete displacement from the well and installation of grouting solution in the annular space in the required interval. After running in of the casing string and flushing with oil-based drilling fluid, three spacer fluids are injected into the well: dissolving, displacing and washing fluids.

EFFECT: increase in the volume of dense contact of the cement stone with the enclosing surfaces: casing string – cement stone, cement stone – rock in wells drilled on hydrocarbon-based drilling fluids, due to complete displacement of hydrocarbon-based drilling fluids and achieving maximum adhesion of cement stone with rock and casing from the well.

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