宏观及微观剩余油分布及机理分析——以大庆喇嘛甸油田为例

Microscopic Morphology and Distribution of Remaining Oil in Structural Unit of Thick Oil Layer——Taking Lamadian Oilfield in Daqing as An Example

喇嘛甸油田现有微观形态和分布特征研究成果不足以支撑技术决策,给后续剩余油挖潜措施选择带来困难。为此,利用宏观物理模拟剩余油分布情况,并采用岩心冷冻薄片制作、荧光显微镜剩余油观测以及剩余油类型识别等技术,进行了喇7-检PS30225井岩心内剩余油类型微观识别和占比计算。结果表明:在水驱过程中,随注入PV数增加,渗流阻力减小,注入压力减小,含水率逐渐增大,采收率增加。随测试点距注入端距离增加,水驱后剩余油饱和度增大。水驱和聚合物驱后,剩余油主要呈薄膜状、角隅状、喉道状和簇状分布,其中薄膜状和角隅状剩余油占比超过90%。与水驱相比,聚合物驱大幅度提高注入压力,致使中小孔隙吸液压差和吸液量增加,波及程度提高,因而低簇状和角隅状残余油明显减小。水驱或聚驱难以动用薄膜状剩余油,有效动用途径是利用表面活性剂来提高洗油效率。

The existing research results on micro morphology and distribution characteristics of Lamadian oilfield are not enough to support technical decision-making, which brings difficulties to the selection of follow-up potential tapping measures for remaining oil. Therefore, macro physical simulation was used to simulate the distribution of remaining oil, and the techniques of core frozen thin section production, fluorescence microscope remaining oil observation and remaining oil type identification were used to carry out the micro identification and proportion calculation of remaining oil type in the core of L7-JPS30225 well.The results showed that,with the increase of injected PV number, the seepage resistance decreased, the injection pressure decreased, the water cut increased and the recovery increased.The remaining oil saturation increased with the increase of the distance between the test point and the injection end. After water flooding and polymer flooding, the remaining oil was mainly distributed in film, corner,throat and cluster, of which the remaining oil in film and corner accounted for more than 90%.Compared with water flooding, polymer flooding greatly increased the injection pressure, increased the liquid absorption pressure difference and liquid absorption capacity of small and medium pores, and improved the sweep degree, so the low cluster and corner residual oil were significantly reduced. Thin film residual oil was difficult to be produced by water flooding or polymer flooding. The effective way was to use surfactant to improve oil washing efficiency.