准噶尔盆地北缘山前带湿地扇沉积特征及控藏作用

综合野外露头、岩心、钻测井以及分析测试资料等,对准噶尔盆地北缘哈拉阿拉特山山前带侏罗系八道湾组开展了系统的沉积相研究。结果表明:八道湾组一段沉积时期,受构造背景、古物源、古气候的综合影响,哈山南缘山前带发育一套典型的湿地扇沉积,可识别出扇根、扇中、扇缘三种亚相,扇中可进一步分为辫状水道和泥炭沼泽两类微相;在明确了相类型及其展布特征的基础上,建立研究区湿地扇沉积相模式,其在岩性特征、沉积序列、平面规模、微相组合等方面均与洪积扇有明显区别;山前带湿地扇沉积区具有良好的勘探潜力,有利的微相、岩石相以及原始沉积组构共同控制着油藏分布,其中扇中辫状水道砂砾岩相和粗砂岩相为原油富集的有利储集相带。

Sedimentary characteristics and accumulation effect of humid fan in northern margin piedmont belt of Junggar Basin

Based on the outcrops, core, drilling and logging data, and a large number of laboratory measurements, the sedimentary facies of Jurassic Badaowan Formation in the northern margin piedmont belt of Junggar Basin were studied systematically. The results show that during the depositional period of the first member of Badaowan Formation, a typical humid fan is developed in the piedmont belt of Hala ''alt southern edge, under the comprehensive influences of tectonic setting, paleo-provenance and paleo-climate. There are three subfacies identified in the humid fan, including the root fan, middle fan and fan edge. The middle fan can be further divided into two microfacies, including the braided river channel and the peat bog. After the microfacies types and their distribution characteristics are defined, the sedimentary facies model is built, which has significant differences from arid alluvial fan regarding the lithologic features, sedimentary sequences, distribution scales and microfacies match patterns. The depositional regions of humid fan in the piedmont belt show a good exploration potential. Reservoir distribution is mainly controlled by the favorable microfacies, lithofacies and depositional fabric. Lastly, our studies suggest that the braided river channel glutenite lithofaices and grit lithofacies in the middle fan subfacies are the most favorable reservoir facies belt for hydrocarbon accumulation.