Quantitative Seismic Sedimentology of the Neogene Shawan Formation in the Chepaizi Uplift, Junggar Basin, China

Abstract

The main objective of this article is to demonstrate the utility of stratal slice images for exploring the sequence stratigraphy and sedimentology of complex depositional systems. A quantitative seismic sedimentological study was performed to map sediment dispersal characteristics of the Neogene Shawan Formation in the Chepaizi Uplift of the Junggar Basin, China. The Chepaizi Uplift is a successive fault-related uplift developed on the Carboniferous igneous rock basement that lies at the western boundary of the Junggar Basin. The data sources primarily include well-recording, well-logging and seismic data. In the main target strata, the Neogene Shawan Formation can be divided into three fourth-order sequences (SQN1s1, SQN1s2, and SQN1s3), and the sequence SQN1s1 is subdivided into three fifth-order sequences (SQN1s11, SQN1s12, and SQN1s13). Based on the established fine-sequence stratigraphic framework, the sedimentary facies types have been identified according to well-recording and well-logging data combined with regional tectonic-depositional settings, they are shallow braided-river deltas, fan deltas, shore-shallow lakes, meandering rivers, and terminal fans. Then, strata slices have been used to clearly depict the boundaries of sedimentary microfacies. Accurate results have been obtained that characterize meandering river channels, point bars, terminal fans, shore-shallow lake beach bars, and subaqueous distributary channels in the braided-river delta front. Additionally, this seismic sedimentology study reflects variations in sedimentary provenance and vertical evolution characteristics of sedimentary facies. Finally, the important sandbodies were showed in the 3D volume and carried out the quantitative seismic sedimentology study, results showed the relationship among the area, length and width of the braided-river delta, and depicted channel widths, channel length, meander-belt widths (MBWs), and meander-arc height (MAH) in the subaqueous distributary channels of braided-river delta.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015