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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。
The sedimentary characteristics and sedimentary models of glutenite bodies in the Upper Member of Shahejie Formation, Block 76, Shengtuo area, were studied by means of core observation, slice identification, grain size analysis and log data interpretation. The results show that the lithofacies types in the study area include conglomerate facies, sandstone facies, mudstone facies and mixed facies. The cumulative probability distribution curve of granulometry is dominated by gentle and uplifted arc and low oblique two-stage. The sedimentary structures are mainly composed of parallel bedding , Sequence stratification, rhythmic bedding and other stratigraphic structures, scouring surface and truncated tectonic stratigraphic structure, heavy load mode, slump deformation and mudstone tear debris and other deformation structures. During the deposition of the Upper Member of the Fourth Member of the Shahejie Formation, controlled by the fault-shaped palaeogeomorphology formed by the Chennan fault and the Shengbei fault, the 76 blocks of conglomerate from Tujia uplift in the north are deposited on the descending plate of the Shengbei fault and are immediately adjacent to the fault distribution The bottom of the lake fan. The sublacustrine fan can be divided into three subfacies of inner fan, middle fan and outer fan. The study area mainly drills the middle fan and the outer fan. The middle fan is the main body of the sublacustrine fan and can be further divided into braided channels, Waterfront frontal microfacies, of which the braided channel deposition as the main oil and gas reservoir sand body.