METHOD FOR STACKED OIL POOL DEVELOPMENT Russian patent published in 2008 - IPC E21B43/14 E21B21/00 

FIELD: oil production, particularly obtaining oil from a multiple-zone well.

SUBSTANCE: method involves drilling well to upper reservoir bottom; performing well survey; lowering casing pipe and cementing casing-formation annulus; continuing well drilling with the use of drilling bit having lesser diameter to lower reservoir bottom; performing well survey; developing lower reservoir; arranging cement bridge within lower reservoir interval; perforating upper reservoir interval and developing upper reservoir. Well is drilled to upper reservoir bottom with the use of mineralized water as drilling mud and at the end of drilling operation mineralized water is substituted for clay mud solution. Well drilling to lower reservoir bottom with the use of drilling bit having lesser diameter is carried out with the use of mineralized water as drilling mud. At the end of said drilling operation mineralized water is substituted for clay mud solution. After lower reservoir development reservoir pressure is reduced in lower reservoir in well zone. After that mineralized water-based clay mud solution is injected under lower reservoir roof and fresh water is injected under lower reservoir roof.

EFFECT: increased oil recovery from stacked pool.

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