ISOLATION METHOD OF PRODUCTIVE FORMATION FROM BOTTOM WATER INFLOW Russian patent published in 2012 - IPC E21B33/13 

FIELD: oil and gas industry.

SUBSTANCE: isolation method of productive formation from bottom water inflow involves well drilling with opening of productive formation and arrangement of the working face below the level of oil-water contact (OWC), installation of casing pipes above OWC level with further cementing, cleaning of the well below casing pipes, pumping of waterproofing sealant to the cleaned well zone with isolation of bottom water and perforation of casing pipes. Well is drilled in two stages, the first one of which is performed with the main shaft to the roof of productive formation, and the second one - with pilot shaft of smaller diameter. Formation properties are investigated, and the main shaft is deepened to the level located above OWC level before casing pipes are installed. Shaft cleaning below casing pipes is performed after cementing by drilling the pilot shaft with the bit of larger diameter below OWC, and OWC zone is perforated.

EFFECT: method provides the creation of a reliable screen in OWC zone owing to avoiding the operation used for creation of sand-clay plug and cleaning of the well shaft in OWC zone after it is drilled and reinforced with casing pipes, creation of reliable waterproofing screen due to OWC zone perforation, reduction of costs for waterproofing sealant, which is due to the fact that it is pumped directly to OWC zone after perforation.

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