塔河油田缝洞型油藏水驱后气驱提高采收率可视化实验

Visualized Gas Drive EOR Experiments in Fractured-Vuggy Reservoirs after Waterflooding in Tahe Oilfield

塔河油田缝洞型油藏注水开发后,开展单井注气提高采收率实验,注气效果显著,但油藏开发中后期逐渐出现注水、单井注气效果变差,大量水驱后剩余油未能动用。为了提高此类油藏的注气开发效果,需要针对性地开展多井单元注气提高采收率机理研究。通过设计、制作物理可视化模型进行气驱模拟实验,探讨缝洞型油藏气驱后剩余油的分布情况及其影响因素。实验结果表明,水驱后氮气驱,能有效提高驱油效率,注气方式、注入位置和模型充填等因素对气驱效果有影响,采用连续稳定注气方式,在构造高部位注气,低部位采油,可有效提高气驱效果,为类似油藏单元水驱后剩余油的开采提供借鉴。

Tahe oilfield and good results have been gained. But the effects of waterflooding and gas injection in single wells are becoming worse at themiddle-late development stage, causing large amounts of remaining oil can＇t be produced after waterflooding. To improve the developmenteffects of gas injection in this kind of reservoirs, the study on the mechanism of gas injection EOR in multiple wells needs to be carried out.Through gas drive simulation experiments on the basis of visualized models, the paper discusses the remaining oil distribution and its influ-encing factors after gas drive in fractured-vuggy reservoirs. The experiment results show that N2 flooding after waterflooding can effectivelyimprove oil displace efficiency, and gas injection mode, injection point and model filling can influence the gas drive effects; gas drive ef-fects can be improved by using continuous and stable gas injection, and gas injection at high positions of structures and producing oil at lowpositions of structures, which can provide basis for remaining oil production in similar reservoirs after waterflooding.