张家垛油田阜三段Ⅲ砂组沉积微相特征与沉积模式

Microfacies characteristics and sedimentary models of the third member of Funing Formation in Zhangjiaduo oilfield

苏北盆地张家垛油田阜宁组三段发育4种岩相:黑色泥岩相,生物扰动粉砂岩相、泥质纹层+生物钻孔粉-细砂岩相及平行层理细砂岩相。剖面结构主要为向上变粗的反韵律,其次是向上变粗复变细的复合韵律,几乎不见正韵律。根据岩石相、剖面结构、测井相及粒度累计曲线,认为阜宁组三段为浅湖滩坝沉积。根据沉积特征和砂体展布规律,将储层进一步划分为坝砂和滩砂,并提出该地区的滩坝沉积模式。坝砂由于泥质含量低、储层物性好,油气充满度高;而滩砂泥质纹层理发育,非均质性弱。由于主要充填在平行层理细砂岩相和泥质纹层+生物钻孔粉砂岩相中,充注程度差别大。

Four types of lithofacies are identified in the 3rd member of Funing Formation in Zhangjiaduo oilfield, the Su- bei Basin, including dark mudstone, bioturbated siltstone, siltstone-fine sandstone lithofacies with argillaceous laminates and burrow as well as fine sandstone with parallel bedding. Upward-coarsening reverse rhythm is the main section struc- ture, followed by first upward-coarsening and then upward-thinning composite rhythm All the features of lithofacies, section structure,logging facies and cumulative grading , while positive rhythm is very rare. curve show that the 3rd member of Funing Fm is typical shallow lake beach-bar facies. According to the sedimentary characteristics and spatial distributions, the reservoirs are further divided into sandstone of bar rnicrofacies and sandstone of beach microfacies. A beach-bar sedi- mentary model is proposed. The sandstone reservoirs of bar microfacies are high in hydrocarbon fullness, due to its low shale content and high porosity. In contrast, the sandstone reservoirs of beach microfacies show great variance in hydrocar- bon fullness as argillaceous laminations are well developed, heterogeneity is week, and hydrocarbons mainly fill in the fine sandstone lithofacies with parallel bedding and argillaceous laminates ＋ burrow fine sandstone lithofacies.