莺歌海盆地DF13区黄流组沟道砂体特征研究

Study on Characteristic of the Sand Bodies of Huangliu Formation in DF13 Area,Yinggehai Basin

莺歌海盆地晚中新统黄流组浅海厚层泥岩中发育的块状厚层粉细砂岩是近期天然气勘探热点,其储集砂体纵向多期叠置、横向变迁快。构造演化及古沉积背景控制了黄流组内三级层序格架的分布及演化,但未控制沉积体系或储集砂体的分布。该沉积体系与经典海底扇相比,没有明显的扇体亚相分异、主水道和天然堤等典型沉积特征,而为规模小、迁移快、堆积厚的沟道沉积砂体组合,将其定义为"非典型"重力流,用不同类型沟道+漫流体系来表征其特点。不稳定陆坡背景通过古地貌形态和物源供给样式来控制四级层序砂体分布规律,按沟道沉积水动力特征及堆积样式进一步划分为充蚀沟道、迁移沟道和充填构造,其中充蚀沟道和充填沟道储集条件好,是有利的勘探目标。

The massive fine-grained sandstone developed from the thick mudstone lager powder of late Miocene deposits in shallow yellow stream group in Yingge Sea Basin is the recent gas exploration hotspot. The reservoir is sand vertically stacked multi-stage, and changes fast horizontally. Though tectonic evolution and ancient deposition setting control the distribution and evolution of third-order sequences framework within Huangliu Formation, they do not control the distribution of depositional systems or reservoir sand bodies. Compared with the classic submarine fan phase, typical deposition characteristics can hardly be found in this depositional system like obvious fan body sub-phase differentiation, main waterway, levee, etc. It is consid- ered as a channel sand bodies＇ combination of small-scale, fast migration, and thick accumulation. In the article, it is called non-typical Turbidity current, using different channels ＋ spring current to show this sedimentary characteristic. The studies suggest that the unstable continental slope setting controls the distribution of sand bodies in four-order sequences by means of controlling the Palaeogeomorphology and sedimentary source rechargement. According to the hydrodynamic characteristics and accumulation styles of the channel deposition, the sand bodies are further divided into the sub-erosion channel, migration channel and filling structure. Among them sub-erosion channel and filling structure have good reservoir conditions, that can be new gainful exploration targets.