致密砂岩储层微观孔隙结构对可动流体赋存特征的影响

Influence of Micro-Pore Structure on the Movable Fluid Occurrence in Tight Sandstone Reservoir

鄂尔多斯盆地安塞油田杏河地区长6储层微观孔隙结构复杂,渗流规律研究相对薄弱。针对该问题利用常规镜下测试、恒速压汞、高压压汞、核磁共振实验、真实砂岩模型等资料,对安塞油田杏河地区长6低渗透储层微观孔隙结构与可动流体赋存特征之间的关系进行讨论。研究结果表明:喉道的大小、分布、非均质性与可动流体赋存空间关系密切,影响储层的渗流能力,而物性、面孔率参数并不能精确解释可动流体饱和度的高低。通过真实砂岩微观水驱油模型对样品进行模拟分析,可将储层分为Ⅰ、Ⅱ、Ⅲ类,其驱油效率随渗透率下降而下降,驱替类型由均匀网状转变为尖峰指状。通过室内实验与矿场数据相结合进行分析,可以更好地认知储层孔隙空间特征,以指导油田高效开发。

The seepage mechanism in the Xinghe Chang6 reservoir of Ansai Oilfield in Ordos Basin needs further understanding due to its complex micro-pre structure. The conventional microscopic test,constant-rate mercury penetration,high-pressure mercury intrusion,nuclear magnetic resonance test and real sandstone model were used to discuss the relationship between the Xinghe Chang6 reservoir micro-pore structure and the movable fluid properties in Ansai Oilfield. Research indicates that the throat size,distribution and heterogeneity are closely related to the spatial distribution of movable fluid and the reservoir seepage capacity. The surface porosity and reservoir properties are incapable of characterizing the movable fluid saturation. According to the microscopic waterflooding experiment with real sandstone samples,the reservoir can be classified into Category-Ⅰ,Category-Ⅱ and Category-Ⅲ. The oil displacement efficiency decreases with the decrease of permeability,and the displacement changes from a uniform network pattern to a peak finger pattern. The combination between laboratory experiment and field production data could further understanding the reservoir spatial pore properties and provide certain guidance to efficient development.