WATER INFLOW ZONES CEMENTING METHOD Russian patent published in 2014 - IPC E21B33/138 C09K8/46 

FIELD: oil and gas industry.

SUBSTANCE: water inflow zones cementing method includes running in of the tubing string into the well, setting of the tubing string open end above the water inflow zone. Specific permeability is determined for the water inflow zone in two operating modes of the pumping unit. When specific permeability is more than 2 m³/(h·MPa) flush liquid and waterproofing compound are injected in sequence until specific permeability reaches 0.5-2 m³/(h·MPa). Then total volume of cement suspension is determined against specific permeability of the water inflow zone. Simultaneously cement suspension is made of suspension of oil-well Portland cement in quantity of 35% of the total cement suspension volume and suspension of microcement quantity of 65% of the total cement suspension volume. When specific permeability is 0.5-2 m³/(h·MPa) flush liquid, suspension of microcement quantity and suspension of oil-well Portland cement are injected in sequence. Then the consumption rate and injection pressure is increased up to the limit value for the production casing, and at this rate with this pressure maintained flush fluid and the whole volume of the microcement suspension is flushed. Then the consumption rate and injection pressure is decreased up to the permitted minimum value at which the well continues receipt, and oil-well Portland cement suspension is flushed to the water inflow zone until zero permeability is obtained. The flushing is stopped; the process is set to exposure, then remains of cement Portland cement suspension are washed with counterpressure flow equal to final pressure of flushing of the oil-well Portland cement suspension to the water inflow zone.

EFFECT: increased efficiency of water inflow zones cementing in wells, increased coverage of the water inflow zones by cementing.

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