Lmd油田二类油层孔隙结构与微观剩余油分布特征研究

Study on Pore Structure and Microscopic Remaining Oil Distribution Characteristics of Type-Ⅱ Oil Reservoirs in Lmd Oilfield

随着开发的深入,Lmd油田二类油层经历了水驱开发,逐步进入到聚驱开发阶段,并成为今后稳产的重要支撑。由于前期对二类油层储层孔隙结构认识不足,没有达到预期的开发效果,为进一步提高开发效果,有必要厘清储层微观结构特征和微观剩余油分布特征。利用天然岩心,采用恒速压汞法和扫描电镜,研究了二类油层微观孔隙结构特征;利用岩心分析数据,回归了宏观孔渗参数与微观孔喉半径之间的关系;根据渗透率、孔喉尺寸等参数,将孔喉结构划分为五种类型。研究了现阶段ⅡA聚驱后、ⅡB油层和厚油层内部不同孔隙类型储层的微观剩余油分布特征。ⅡA油层聚驱后,簇状剩余油变化幅度最大,其次依次为角隅状、膜状、喉道状。ⅡB油层聚驱后,簇状剩余油变化幅度最大,其次是膜状、角隅状、喉道状。因此,ⅡB油层聚驱开发的重点是针对簇状和膜状剩余油开展进一步挖潜工作,开展驱油试验,明确了水聚驱前后微观剩余油变化特征。

Along with the deepening of development,Type-Ⅱ oil reservoirs in Lmd Oilfield has experienced water flooding development,and entered the stage of polymer flooding,which has become the important support for the stable production in the future.The expected results have not achieved for insufficient understanding of pore structure of the Type-Ⅱ oil reservoirs at early stage.In order to improve the development effect,it is necessary to make clear reservoir microstructure characteristics and the distribution characteristics of microscopic remaining oil.The rate-contrlled mercury intrusion method and scanning electron microscope are applied to the study on the microscopic pore structure of Type-Ⅱ oil reservoirs in the natural cores.Relationship between macro-porosity and permeability parameters and micro-pore throat radius is regressed by using core analysis data.The pore-throat structure is divided into five types according to the parameters of permeability,pore-throat size and so on.Distribution characteristics of microscopic remaining oil for the reservoirs with different pore types in ⅡA after polymer flooding,ⅡB reservoir and thick reservoirs at present are studied.After the polymer flooding in Ⅱ A reservoir,cluster remaining oil has the greatest changing range,and corner,film and throat one changes less and less.After the polymer flooding in Ⅱ B reservoir,cluster remaining oil has the greatest changing range,and film,corner and throat one changes less and less.So,the key of the development by polymer flooding for IB reservoir is to tap the potential of cluster and film remaining oil,and oil displacement experiment should be carried out for knowing the microscopic remaining oil change characteristics before and after water-polymer flooding.