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以沉积相和界面识别为依据,将川东北地区下三叠统飞仙关组划分为2个三级层序和6个体系域,在此基础上对飞仙关组层序地层学特征进行了分析,编制了各沉积体系域的层序—岩相古地理图和对鲕滩发育规律进行预测。结果表明:SQ1层序发育期,飞仙关组受持续海侵影响,形成以深水台盆为中心的台盆—台地边缘—开阔—局限—蒸发台地的相带展布格局,以海侵体系域的台地边缘和台内鲕滩最为发育,该体系域也是飞仙关组鲕滩相储层最发育的层位;SQ2层序发育期,受海平面大幅度下降和水循环受限及干旱炎热气候影响,区域沉积格局由开阔台地转化为局限台地,鲕滩逐渐消失,最终进入频繁暴露的蒸发台地环境,以沉积膏云岩为主,为飞仙关组天然气藏极其重要的第一套区域性致密盖层发育层位。
Based on the sedimentary facies and the interface recognition, the Feixianguan Formation of the Lower Triassic in the northeastern Sichuan is divided into two third-level sequences and six systematic intervals. Based on this, the sequence stratigraphic features of the Feixianguan Formation are studied Analyzed and compiled the sequence of each sedimentary system tract - lithofacies palaeogeography map and prediction of oolitic beach development law. The results show that during the SQ1 sequence, the Feixianguan formation was influenced by the continuous transgression to form a facies belt distribution pattern along the basin-platform edge-open-confined-evaporating platform centering on the deep water basin. The platform margin and platform oolitic beach are the most developed, which is also the most developed horizon for the oolitic beach facies in the Feixianguan Formation. During the SQ2 sequence, the sea level was greatly decreased and the water cycle was limited and the hot arid The climate change and the regional sedimentary pattern are transformed from the open platform into a restricted platform. The oolitic beach gradually disappears and finally enters the evaporating platform environment which is frequently exposed. Sedimentary palygorskite is the main deposit, and the first set of extremely important areas for the Feixianguan Group natural gas reservoir Sexual tight caprock developmental horizon.