METHOD OF OIL POOL DEVELOPMENT AT LATE STAGE Russian patent published in 2002 - IPC

FIELD: oil producing industry, particularly, development of oil pool at late stages with presence of water-oil contact in formation; applicable in production of residual difficult-to-recover oil from formation roof low-permeability part. SUBSTANCE: method includes development of oil pool by well row systems, geophysical research for control of motion of water-oil contact. First, casing string is perforated below water-oil contact. Forced pumping out of water is carried out with maximum pressure differential acting on formation to form oil-water-saturated zone. Then perforated interval in casing string is isolated against formation water-saturated part. Oil saturated part of formation is perforated above water-oil contact. Products are withdrawn with minimum pressure differential acted on formation. Water is injected through injection wells. Front of water injection is transferred from on row of wells to another one. Artificially formed oil-water-saturated zone prevents formation of water cone and rapid water cutting of oil production. Effect of water shutoff is attained due to low permeability of water in formed zone. EFFECT: higher oil recovery factor of oil pool due to possibility of oil recovery from low permeability part of formation. 1 ex