南堡凹陷西斜坡中深层高精度层序地层及沉积体系研究

Study on high-resolution sequence stratigraphy and sedimentary system of middle-deepbeds on western slope, Nanpu sag

应用高精度层序地层学理论和方法,通过对地震资料新一轮处理和精细解释,结合岩—电响应特征,共识别出南堡凹陷西斜坡中深层4个三级层序界面,划分了3个三级层序(SQ7、SQ8、SQ9)。以三级层序内部相对稳定的水进面和岩性突变面为界进行高精度层序地层划分,进一步划分出12个四级层序或体系域的地层单元。在对研究区物源研究的基础上,开展系统的岩心相、测井相精细研究,共识别出扇三角洲和湖泊两种沉积体系。并在高精度层序地层格架内研究了各沉积体系平面展布特征,其中扇三角洲平原分布范围相对较小,主要集中在研究区北部靠近物源口附近;而扇三角洲前缘分布范围较广,主要发育于研究区的中心部位。

Four third-order sequence boundaries are identified and three third-order sequences（SQ7, SQS, SQ9） are divided by high-resolution sequence stratigraphy theory and method, new seismic data processing and interpretation combined with lithological-electrical response characteristics. Stratigraphic units of twelve fourth-order sequences or systems tracts are divided by therelatively stable transgressive surfaces and abrupt changes of lithology in the third-order sequences as the boundaries. Core facies and electrofacies are systematically analyzed and two sedimentary systems （fan delta and lacustrine） are identified based on provenance research in this study area. Moreover, the planar distribution law of each sedimentary system in high-resolution sequence stratigraphy framework is studied. Hereinto,the fan delta plain range is smaller near northern provenance entrance of the study area, but the fan delta front subfacies range is wider in the central part of the study area.