华北黄骅坳陷层序地层学研究——以白水头—唐家河地区Es_1—Nm为例

STUDY ON SEQUENCE STRATIGRAPHY OF HUANGHUA DEPRESSION IN NORTH CHINA:TAKING Es_1-Nm STRATA IN BAISHUITOU-TANGJIAHE AREA AS EXAMPLES

根据层序地层学理论,对地质、钻井、测井及地震等资料进行综合分析,将华北黄骅坳陷白水头—唐家河地区的沙河街组一段(Es1)—明化镇组(Nm)地层划分为2个一级层序,4个二级层序,从下向上依次为:层序Ⅰ(对应于沙河街组一段)、层序Ⅱ(对应于东营组)、层序Ⅲ(对应于馆陶组)、层序Ⅳ(对应于明化镇组)。其中层序Ⅰ和Ⅱ为湖泊相层序,分为低位(LST)、湖扩展(EST)和高位(HST)等3个沉积体系域;层序Ⅲ和Ⅳ为河流相层序,分为基准面上升和基准面下降等2个沉积体系域。在此基础上,分析了湖泊相和河流相层序的沉积特征,总结了本区层序地层的发育模式。最后指出,层序Ⅰ的HST,层序Ⅱ的LST,层序Ⅲ的基准面上升体系域为本区最有利的油气勘探目标层段;层序Ⅳ主要发育岩性圈闭。

Based on the theory of sequence stratigraphy and through comprehensive analyses of geologic, drilling, logging, and seismic data, the first member of Shahejie Formation (Es1)-the Minghuazhen Formation (Nm) in Baishuitou-Tangjiahe area in Huanghua depression are divided into 2 first-order and 4 second-order sequences. They are successively, from the bottom to the top, the sequence Ⅰwhich corresponds to the first member of Shahejie Formation, the sequence Ⅱ which corresponds to the Dongying Formation, the sequence Ⅲ which corresponds to the Guantao Formation, and sequence Ⅳ which corresponds to the Minghuazhen Formation. Of these second-order sequences, the sequence Ⅰ and Ⅱ are of lacustrine facies, and can be divided into 3 depositional system tracts, including lowstand system tract (LST), lake expanding system tract (EST) and highstand system tract (HST). While the sequence Ⅲ and Ⅳ are of fluvial facies and can be divided into a base level ascending and a base level descending system tracts. Based on sequence division and stratigraphic correlation, sedimentary features of lacustrine facies sequence and fluvial facies sequence are analyzed, and a sequence stratigraphic model is built in the study area. It is believed that the HST of sequence Ⅰ, LST of sequence Ⅱ and base-level ascending system tract of sequence Ⅲ are the most favorable exploration targets in the study area. The HST of sequence Ⅰ is dominated by stratigraphic unconformity traps, the base-level ascending system tract of sequence Ⅲ is dominated by structural-lithologic traps, and the sequence Ⅳ is dominated by lithologic traps.