萨北油田北二西区点坝内部侧积层定量表征

Quantitative characterization of lateral accretion bedding in point bar in West Ⅱ Region of Sabei Oilfield

萨北油田北二西区萨Ⅱ1＋2b小层层内非均质性强，剩余油分散，难以挖潜。文中依据研究区的地质特征和沉积环境．总结出该区点坝内部侧积层的坝面分布为水平斜列式，分布形态呈“缓一陡”模式。基于研究区的密井网资料，在点坝内部侧积层分布模式的指导下，综合利用经验公式、岩心及密井网剖面的方法，对点坝内部侧积层进行了定量表征，分析了各种方法的局限性，通过研究得出：研究区位于点坝顶部的侧积层倾角多在5。以内，位于点坝中部的侧积层角度在4～10°，侧积层间距为40m左右．单一侧积体水平宽度在70m左右。以此参数为基础结合研究区侧积层的“缓一陡”模式，建立了能够用于油藏数值模拟的三维构型模型，分析了侧积层控制的剩余油分布模式，认为点坝内部剩余油在剖面上主要分布在中上部．注采井间侧积体内的剩余油更富集，平面上由于不同侧积层顶部的水驱油状况存在较大差异而使得剩余油呈条带状分布.按照剩余油分布模式总结出相应的挖潜措施，为厚油层剩余油挖潜提供更准确的地质依据。

The layer heterogeneity is strong in the S Ⅱ 1 ＋2b layer of West Ⅱ Region, Sabei Oilfield. The remaining oil potential tapping is difficult, with remaining oil scattered. According to the geologic characteristics and sedimentary environment in the area, this paper summarizes that the bar surface distribution of lateral accretion shale beddings in point bar is horizon and echelon pattern, and the distribution form is ＂slow-steep＂ pattern. Based on the dense well pattern data in the region and the distribution pattern of lateral accretion shale beddings in point bar, the quantitative characterization is conducted for the lateral accretion shale bedding in point bar through using the empirical formula, core and dense well pattern section data. Then the limitation of various methods is analyzed. The angle of lateral accretion bedding is usually less than 5° on the top of the point bar according to the study, while the angle of lateral accretion bedding in the middle part of the point bar is between 4-10~. The interval of lateral accretion bedding is about 40 m and the horizontal width of single lateral accretion is about 70 m. Based on the quantitative parameters and the ＂slow-steep＂ pattern of lateral accretion bedding, 3D configuration model which can be applied for reservoir simulation is established. Then the remaining oil distribution pattern of lateral accretion bedding is analyzed. It is believed that the remaining oil distribution in point bar is mainly in the upper part for profile, and the remaining oil in lateral accretion body is enriched among the injection-production wells. The water displacing oil status on the top of different lateral accretion beds indicates a great difference in plane, so the remaining oil distribution presents the banding. Based on the distribution pattern of remaining oil, relevant potential tapping measures have been proposed, which provides the accurate basis for the remaining oil potential tapping of thick reservoir.