断陷湖盆滩坝沉积特征及其控藏作用——以塔南凹陷白垩系铜钵庙组为例

根据岩心观察、测井分析和地震解释资料对塔南凹陷白垩系铜钵庙组滩坝砂的沉积特征、分布规律和成藏模式进行了研究。研究结果表明：①依据岩性和沉积构造特征可将塔南凹陷白垩系铜钵庙组滩坝微相划分为滩砂和坝砂，且发育滩坝共生、有滩无坝和有坝无滩等3种沉积组合样式。凹陷西部缓坡带发育滩坝共生组合；东部陡坡带和湖岸线凹岸发育有滩无坝组合；水下古隆起和湖岸线凸岸发育有坝无滩组合。②研究区滩坝发育特征及展布规律主要受控于古地貌、古水深和古风向。凹陷斜坡带和水下中央隆起带古地貌控制着滩坝的沉积范围；滩坝在平面上沿湖岸线呈北东向展布，主要受控于北东向的古风场；东、西部次凹的古水深差异控制了滩坝的沉积厚度及物性。③研究区滩坝成藏主要有“源储共生”内部成藏和“源储对接”侧向成藏2种类型，其中“源储共生”内部成藏主要形成岩性油藏，主要发育在东部次凹的近源洼槽带，潜力区在近源洼槽；“源储对接”侧向成藏形成构造岩性油藏，主要发育在西部斜坡带，潜力区在反向断阶带。

Sedimentary characteristics and reservoir control of beach bar in faulted lake basin:A case study of Cretaceous Tongbomiao Formation in Tanan Sag

Based on core observation,well logging analysis and seismic interpretation data,the sedimentary characteristics,distribution law and reservoir accumulation model of beach bar sand bodies of Cretaceous Tongbomiao Formation in Tanan Sag were studied. The results show that:(1)the beach bar microfacies of Cretaceous Tongbomiao Formation in Tanan Sag can be divided into beach sand and bar sand according to lithology and sedimentary structural characteristics,and there are three sedimentary assemblages,including beach bar symbiosis, beach without bar and bar without beach. Beach bar symbiotic assemblage is developed in the western gentle slope zone of Tanan Sag,beach without bar assemblage is developed in the eastern steep slope zone and the concave bank of lake shoreline,and bar without beach assemblage is developed in underwater paleouplift and convex bank of lake shoreline.(2)The development characteristics and distribution law of beach bar are mainly controlled by ancient landform,ancient water depth and ancient wind direction. The paleogeomorphology of the slope zone and underwater central uplift zone in the sag controls the sedimentary range of beach bar. The NE trending ancient wind field controls the beach bar to be distributed in the NE direction along the lake shoreline on the plane. The difference of ancient water depth between the eastern and western sub depressions controls the sedimentary properties and thickness of beach bar.(3)Beach bar reservoir formation in Tanan Sag mainly includes internal accumulation of "source reservoir symbiosis" and lateral accumulation of "source reservoir connection". The internal accumulation of "source reservoir symbiosis" mainly forms lithologic reservoirs,which are mainly developed in the near source sag belt of the eastern sub-depression,and the potential area is near source sag. The lateral accumulation of "source reservoir connection" mainly forms structural lithologic reservoirs,which are mainly developed in the western slope zone,and the potential area is in the reverse fault step zone.