三角洲砂体构型对水驱波及特征的影响——以南图尔盖盆地Kumkol South油田J-Ⅱ层为例

Influences of delta sandstone architecture on waterflooding sweep characteristics:A case study of layer J-Ⅱ of Kumkol South oilfield in South Turgay Basin,Kazakstan

以哈萨克斯坦南图尔盖盆地Kumkol South油田上侏罗统J-Ⅱ层为例,运用砂体精细表征、水淹层综合解释、产吸剖面统计分析和油藏数值模拟方法,研究了三角洲砂体构型特征及其非均质性,明确了砂体构型对水驱波及特征的影响。研究结果表明,三角洲砂体构型特征复杂,为泥岩隔层和泥质夹层发育的"镶嵌式"构型模式,砂体构型特征控制其水驱波及特征:三角洲各单砂体之间由于非渗透或弱渗透边界、水下分流间湾泥岩的侧向或垂向遮挡,砂体叠置结构特征复杂,注入水优先流向物性较好的水下分流河道和河口坝砂体,致使这两类砂体水淹作用强,采出程度高,水驱平面波及效果好;单砂体内部,水下分流河道和河口坝单砂体一方面由于内部发育泥质夹层,对注入水具有纵向阻挡和分流作用,砂体纵向动用程度高,水驱波及效果好,另一方面由于单砂体内渗透率级差大,水驱优势通道发育程度高,水驱波及不均匀,而侧缘席状砂为均质薄层细粒砂,物性差,水淹均匀,水驱波及效果差。

Taking layer J- Ⅱ of Upper Jurassic of Kumkol South oilfield in South Turgay Basin, Kazakstan as an example, the article studied the architecture characteristics and heterogeneity of delta sandstones, and determined the influence of sandstone architecture on waterflooding sweep characteristics using fine characterization of sandstones, comprehensive interpretation of waterflooded layers, statistical analysis of production and injection profiles, reservoir numerical simulation methods. The result shows that the delta sandstones have a complex architecture of mosaic structure with mudstone baffles and mud-interbeds, and the sandstone architecture controls the sweeping characteristics of waterflood： due to impermeable or low permeable boundaries between single sand bodies, and lateral and vertical blocking of underwater distributaries bay mudstone, sands in delta have very complicated architecture, and the injected water flows priorly into underwater distributaries channel sand and mouth bar sand with better physical properties, making these two types of sands suffer stronger warterflooding, and have higher recovery degree and better waterflooding sweep effect in plane. Inside single sand bodies, on the one hand, underwater distributaries channel sand and mouth bar sand have high vertical producing degree and good waterflooding sweep effect because mud interbeds in the sands have vertical blocking and shunt effect on injected water; on the other hand, these two types of sands have inhomogeneous waterflood sweeping because of large permeability difference and high development of dominant water channels. In contrast, made up of thin homogeneous fine sand with poor physical properties, lateral sheet sand often has even water-flooding and poor waterflooding sweep effect.