METHOD OF DEVELOPMENT OF OIL POOL WITH ARGILLIFEROUS RESERVOIR Russian patent published in 2015 - IPC E21B43/20 

FIELD: oil-and-gas industry.

SUBSTANCE: method comprises cyclic decrease and increase of pressure in a formation by pumping of water through injection wells and oil withdrawal through production wells. Into the formation through injection wells the mineralised water is pumped periodically in the volume of 0.1-5 of pore volume of the formation and fresh water in the volume of 0.1-5 of pore volume of the formation. The transition to fresh water pumping after mineralised water pumping is performed without gradual decrease in mineralisation. The structure and concentration of salts of the pumped mineralised water are remained at the level of the formation one. The cycle of pumping of waters with different mineralisation is repeated many times. Fresh water is pumped until the moment when decrease of intake capacity of the injection well exceeds the allowable production level - critical drop of reservoir pressure in target impact areas. The mineralised water is pumped until the moment when the injection well sets to initial or close to initial operating mode which depends from the flow rate of the injected liquid and well head pressure.

EFFECT: increase of oil recovery of formations due to increase of their coverage.

2 dwg