Identification Method of Gas Migration Channels for CO2 Drive in Tight Oil Reservoirs
Jilin Oilfield is systematically conducting study on the integrated CO2 capture,displacement,and storage(CCUS)technology.Injecting CO2 into the downhole formation for oil recovery in block H of x oilfield,while achieving effective CO2 sequestration.However,due to complex factors such as strong heterogeneity of the formation,large differences in permeability among different zones,natural fractures in individual locations,and rapid changes in sand body thickness,CO2 tends to preferentially flow along dominant channels,leading to cross-zone gas migration and gas breakthrough within the same zone.This results in suboptimal planar sweep efficiency and subsequently impacts the oil displacement effect.At present,identifying gas migration channels is a top priority.In view of the gas migration phenomenon and the unclear direction of gas migration in the CCUS project of Jilin oilfield,it is urgently needed to conduct research on identifying gas migration channels.This study utilizes dynamic and static well logging data,along with core assay analysis,to establish reservoir classification standards and analyze water and gas absorption patterns.It reveals that single-zone water(or gas)absorption is directly proportional to reservoir properties and effective thickness.Utilizing reservoir physical properties and effective thickness,a classification method is developed to characterize inter-well connectivity between injection and production wells,identifying dominant gas migration channels.By comparing with the CCUS tracer monitoring results of block H,a high degree of consistency is observed.This method can identify the dominant channels for CO2 drive,guide construction operations such as plugging and profile control,and enhance oil recovery.It is valuable for application in tight oil reservoirs with low and ultra-low permeability.
CO2 drivegas migration channelreservoir classificationwater absorption(gas absorption)lawidentification method
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