胜坨地区坨76块沙四段上亚段砂砾岩体沉积特征及沉积模式

Sedimentary characteristics and model of sandy conglomerate bodies in upper sub- member of Es_4 of Tuo 76 block,Shengtuo area

通过岩心观察、薄片鉴定、粒度分析、测井资料解释等方法,对胜坨地区坨76块沙四段上亚段砂砾岩体沉积特征及沉积模式进行了研究。结果表明,研究区岩相类型包括砾岩相、砂岩相、泥岩相和混合岩相;粒度概率累积曲线以宽缓上拱式、低斜两段式为主;沉积构造主要发育了平行层理、粒序层理、韵律层理等层理构造,冲刷面和截切构造等层面构造,重荷模、滑塌变形和泥岩撕裂屑等变形构造。在沙四段上亚段沉积时期,受陈南断层和胜北断层形成的断阶古地貌控制,坨76块砂砾岩体为来自北部陈家庄凸起,沉积于胜北断层下降盘而紧邻断层分布的湖底扇。湖底扇可划分为内扇、中扇和外扇3个亚相,研究区主要钻遇中扇和外扇沉积,中扇是湖底扇沉积的主体,可进一步划分为辫状水道、水道间和水道前缘微相,其中辫状水道沉积为主要油气储集砂体。

By means of core observation,thin section analysis,grain size analysis,log interpretation and other methods,the sedimentary characteristics and model of the sandy conglomerate bodies in upper sub-member of Es_4 in Tuo 76 block of Shengtuo area have been studied.The type of lithofacies in upper sub-member of Es_4 in Tuo 76 block includes conglomerate,sandstone,mudstone and mixed rocks;probability cumulative grain size curves mainly include uphill arched pattern and low slope 2-segment pattern;sedimentary structures mainly include parallel bedding,graded bedding,rhythmic layering,scour surface,cutting out structure,load cast,and slump structure.During the sedimentation of the upper sub - member of Es_4,controlled by fault terrace ancient landform formed by Chennan Fault and Shengbei Fault,the sublacustrine fan from northern Chenjiazhuang salient were developed in the downthrown side of Shengbei Fault.Sublacustrine fan includes inner fan,middle fan and outer fan subfacies.Middle fan and outer fan sediment were mainly drilled,and middle fan is the major part of sublacustrine fan,which can be further divided into braided channel,inter-channel and outer channel.Braided channel sediment is the main reservoir.