Seismic Imaging of the Sedimentary System of the Upper Cretaceous Nenjiang Formation in the Northern Songliao Basin

Abstract

This paper studied seismic imaging of the sedimentary system of the Nenjiang Formation in the Northern Songliao Basin based on seismic sedimentology. An accurate and detailed depiction and explanation is provided for underground geological bodies within a relative geological period using the stratal slice technology, based on three-order sequence correlations of well logging and seismic data for the purpose of obtaining high-resolution pictures of the sedimentary system. Research results have revealed that the sedimentary system of the Upper Cretaceous Nenjiang Formation in the Northern Songliao Basin includes meandering streams, anastomosing streams, lake deltas, and sediment gravity flow channels. Based on seismic imaging analysis, the genesis and seismic geomorphology of the sedimentary system of the Nenjiang Formation are explored in order to understand the spatial distribution of typical sedimentary bodies and the evolution of streams in the Nenjiang Formation. According to the research results, the sedimentation of the Nenjiang Formation was subject to the delta system in the east and northeast of the formation. The provenance in the northeastern part played a dominant role during the deposition of the Nenjiang Formation for some time; after the earlier maximum flooding in the second and third members of the Nenjiang Formation, the northeastern system began to decline and was gradually replaced by the eastern system. Stratal slices have revealed that a well-developed gravity flow channel system was developed in the first member of the Nenjiang Formation, and massive slip blocks occurred in the second and third members of the formation. The research results indicated that the large gravity flow channel system in the first member of the Nenjiang Formation was formed by streams that emptied directly into the lake; and the slip blocks in the second and third members were the results of gravity sliding of sediments along steep slopes at the delta front.