英台地区粉砂岩内部毫米级泥膜的微变形构造及其对储层的影响

英台地区白垩纪均质粉砂岩储层中发育大量毫米级别的黑色泥质薄层——泥膜，其厚度在0.2～3 mm之间，成分主要为泥质，部分为破碎的碳屑粉末富集层。其剖面形态有三种:近直线形、锯齿形和不规则曲线形。泥膜的表面发育多种起伏不平的微变形构造，垂向规模通常在3 mm以内，按照平面形态特征可分为9种:直线形、C/S形、圆形、椭圆形、竹叶形、波痕形、树枝形、网状和不规则形，部分微变形构造较为严重可以使泥膜发生穿透。泥膜主要发育在三角洲前缘的席状砂和河口坝砂体中，主要由短暂沉积间断的泥质沉降或侧向冲刷形成，而泥膜表面微变形构造的原因主要是同沉积干扰、差异压实、顺层滑脱拖拽、生物扰动和成岩收缩以及地震活动的影响等多种因素。对泥膜的成因和微变形构造进行研究将对英台地区的沉积环境和储层精细空间结构的确定具有重要意义。

The Micro-Transmutation Structures and the Reservoir Significance of mm-class Mud-film in the Silt in Yingtai Area

There are many thin mud laminas of mm-class in the Cretaceous equal silt stone in Yingtai area, western Songliao Basin, which we call them mud-films, have a thickness between 0.2 and 3 mm, and the main component is shale while some are carbon dust layers. They are three kinds of conformation of mud-films on section: close-straight line, serrated denticle and irregular curve. There are many micro transmutation structures with the scale less than 3 mm on the surface of mud-films, we divide all the micro transmutation structures into 9 types: straight line, C/S, circle, ellipse, and leaf of bamboo, ripple mark, twig, mesh and irregular patterns. Some micro transmutation structures are too hard to be breakthrough and so the silt stone up and below the mud-film can connect each other. The origin of the mud films are mud subsidence or sideway mud erosion in may momentary sedimentary break. There are many causes of formations of the mud-films such as syndeposit interfere, differential compaction, bedding glide, bioturbation, diagenesis shrink and earthquake activities. The study on the cause of formations and micro transmutation structures of the mud-films will have an important significance for the research of sedimentary environment and the fine space structure of the reservoirs.