Formation mechanism of extreme water consumption zone and synergistic mode of flow field regulation:A case study of uncompartmentalized oilfield of continental sandstone in the late stage of ultra-high water cut
Represented by the integrated oilfield of the continental sandstone reservoir in Shengli Oil Zone,the main unit of which has entered the late stage of ultra-high water cut(＞95％).This stage has led to significant challenges,including extreme water consumption in certain areas,a sharp increase in the water-to-oil ratio,a marked decline in the utilization rate of injected water,rising operating costs per ton of oil,and diminishing economic returns.Despite these issues,approximately 60％of the remaining geological reserves are still present in the reservoir,making the widespread drilling of new wells economically unfeasible.The primary obstacles to profitable development at this stage include the preferential flow of injected water through zones of extreme water consumption and limited dynamic sweep efficiency.Addressing the identification,description,and management of these extreme water consumption zones is crucial for achieving profitable development in maturing oilfields with ultra-high water cuts.This paper suggests a comprehensive approach to tackle these challenges.It involves understanding the formation and control mechanisms of extreme water consumption zones,characterizing reservoir heterogeneity based on configuration and lithology,quantitatively describing the distribution of these zones,and devising strategies to regulate their expansion using variable streamlines in existing wells.The goal is to develop a suite of profitable development technologies that enable precise reservoir characterization and effective management of extreme water consumption zones in the late ultra-high water cut stage.Traditionally,a reservoir with a 98％water cut is considered nearly depleted.However,by applying key technologies for flow field regulation and benefit enhancement to a demonstration unit within such a reservoir,its economic lifespan can be extended by over a decade.This approach can stabilize annual oil production,reduce water cut,lower operating costs per ton of oil,and facilitate low-cost development in maturing oilfields at the late ultra-high water cut stage,thereby addressing the economic and operational challenges inherent in this phase of development.
continental reservoirthe late stage of ultra-high water cutextreme water consumption zoneflow field regulationbenefit enhancement modekey technology
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