东濮凹陷古近系沙河街组三段河口湾沉积亚相之沉积学与痕迹学识别与油气储层

沉积学结合痕迹学研究，识别出东濮凹陷古近系沙河街组三段，存在五类河口湾沉积亚相。这五类亚相都含有斜向异源碎屑层理及海相或咸水痕迹化石。现代和古代河口湾研究证明，斜向异源碎屑层理（Inclined Heterolithic Stratification），是潮汐水流进入河流式河口湾引发波动震荡机制形成的。表现为重复出现，厚在数厘米到数分米的泥/砂对偶层。东濮凹陷文留地区沙河街组三段岩芯研究显示，不同类型的泥/砂对偶层及其所含海相和咸水成因痕迹化石，记录下河口湾上游，受潮汐影响产生水下收缩裂隙和滨岸痕迹化石Diplocraterion的河流成因砂（亚相A）；河口湾中部，因与最大紊流带相关，出现变形层理和痕迹化石Palaeophycos、Planolites和Chondrites的泥质沉积（亚相B、C）；河口湾下游，则显示Terebellina、Rhizocrallium、Ophiomorpha、Diplocraterion等高分异度痕迹化石的海相成因砂（亚相D、E）。文留地区古近纪油田与北美白垩纪油田的研究和勘探开发说明，河流式河口湾油气资源丰富，识别这类古环境，对寻找油气储层，意义重大。

Sedimentological and Ichnological Recognition of Estuarine Subfacies and Its Reservoir Implications in Palaeogene Shahejie Formatiom from Subdivision Three Dongpu Depression,Henan, China

Five subfacies(A-E) which are all contained Inclined Heterolithic Stratification (IHS) and marine, brackish water traces have been found in Shahejie Formatiom Subdivission 3(Palaeogene) Dongpu depression, Henan, China. It is widely accepted that IHS invoke a tidal influence on a fluvial or estuarine system to provide the fluctuating regime required to produce the heterogeneous bedding which typically consists of repetitive sets of mud/sand couplets on a scale of centimeters to decimeter .Various mud/sand couplets with trace fossils of marine origin present in the wells located in Wenliu area of Dongpu depression clearly recorded a fluvial sourced sand containing syneresis and Diplocraterion traces in the upper estuary (subfacies A) muddy sediments with distortion of laminated material related to turbidity maximum and trace fossils of Palaeophycos, Planolites as well as Chondrites (SubfaciesB, C) and sand sourced from seaward consists of trace fossils of Terebellina, Rhizocorallium, Ophiomorpha, Terebellina in the lower estuary(subfacies D, E). They are interpreted as estuarine deposits based on sedimentologic and Ichnologic analysis. Examples both in home (Wenliu, Henan) and abroad (North America) show that sand sourced from seaward in the lower estuary are good target for hydrocarbon exploration.