中国南海珠江口盆地西江油田运聚再生油藏模式创新认识与挖潜效果

针对开发中后期海上老油田剩余油零星散落分布和运移-富集规律难预测等问题，将“势控论”与“构型级次界面”结合，以储层内部单砂体为基本单元，研究不同类型油藏剩余油运移方向和运聚时间，由此构建“运聚再生油藏模式”。研究表明：①主力油藏砂体以叠置接触为主，夹层较少发育，储层主要为高孔、高渗特征，易形成优势渗流通道，高度分散状态的剩余油经过1年左右运移，在井控低且势能低部位小规模聚集成藏，挖潜潜力有限，生产井表现出高产短命的生产效果；②非主力油藏砂体横向接触主要以侧叠和孤立类型为主，3级和4级构型界面较为发育，剩余油动态运聚时间、方向与储层韵律性、夹层级次和流体性质等因素有关，一般非主力油藏关停约3年以上时间，4级界面控制的剩余油通过侧向绕流，逐渐向低势闭合区富集成藏，3级界面控制的剩余油通过垂向渗透，向低势闭合区聚集，剩余油运移富集规模较大，生产井表现出高产、高效、长命的生产效果。研究成果为海上中-高含水期老油田深度、立体挖潜提供技术支持，将为公司年度生产目标实现或超产保驾护航。

New understanding and tapping effect of remaining oil reservoirs in Xijiang oilfield,PRBM,South China Sea

To tackle problems in understanding the distribution and mechanisms of remaining oil reservoirs in mature offshore oilfields of middle or later stages of development,this study focuses on the migration direction and migration-accumulation time of remaining oil in various types of reservoirs in Xijiang oilfield,PRBM,South China Sea,while combining“potential control theory”with“reservoir architecture interface”and taking single sand body in the reservoirs as research unit.It concludes that the remaining oil mainly concentrates in low-potential trapped areas,and thereby constructs a“migration-accumulation regenerated reservoir model”.The results show that:(1)Sand bodies in major pay reservoirs are mainly superimposed with rare interbeds;the reservoirs are mostly high-porosity and high-permeability and conducive to generate preferential seepage channels.After shutting wells down for about one year,the remaining oil migrates and accumulates in small amounts to high parts of structures of low potential energy and beyond well area.These wells tend to yield high but only for a short time after the 1 year shut-in.(2)Sand bodies in non-major pay reservoirs are usually laterally overlapping or completely isolated with the well developed third-and fourth-order architectural interfaces in the reservoirs.The dynamic migration and accumulation time and direction of remaining oil are related to reservoir rhythm,interlayer order and fluid property.After shutting wells down for more than 3 years,the remaining oil in these reservoirs that once were controlled by the fourth-order interfaces gradually flows around and accumulates into low-potential closed areas;those once controlled by the third-order interfaces would accumulate in large scale in low-potential closed areas by vertical permeation.These wells perform good after 3-year shut-in with high production for a long time.The research results are of technically supportive value to the rejuvenation of mature offshore oil fields in medium-high water cut stage and to the realization of the company’s annual production target.