地质科技通报 (Nov 2023)
Seismic sedimentology of submarine fan system in the 1st Member of the Huangliu Formation, Dongfang area, Yinggehai Basin, China
Abstract
Objective The Yinggehai Basin's Dongfang area is a significant area for oil and gas exploration, characterized by the presence of large-scale submarine fan complexes. As exploration advances, the focus has shifted from structural traps to lithological-stratigraphic traps. The 1st Member of the Huangliu Formation exhibits the development of multistage submarine fan complexes with complex sand-body stacking patterns. Therefore, understanding the stages, distribution, and evolution of submarine fans, as well as sand body patterns, is crucial for further oil and gas exploration. Methods In this study, we conducted a comprehensive investigation of the seismic sedimentology of the 1st Member of the Huangliu Formation in the eastern Yinggehai Basin using core, logging, and 3D seismic data. We identified the T30 and T31 horizons as the top and bottom interfaces of the 1st Member of the Huangliu Formation, respectively, with the T301 boundary representing the first flooding surface. The submarine fan complex is bounded by the T31 and T301 interfaces, representing the lowstand system tract of the 1st Member of the Huangliu Formation. Results Seismic-lithological calibration and proportional slice mapping revealed a four-phase evolution of submarine fan complex development. The earlier two phases exhibited channelized lobe geometry on the seismic geomorphology plane, characterized by weak-amplitude mound-like cluttered reflections and sporadic strong-amplitude reflections. V- or U-shaped channels overlapped with each other, with the lithology primarily consisting of thin-bedded siltstone interbedded with mudstone. In contrast, the third phase displayed a highly typical channelized configuration, with the lithology predominantly composed of fine-grained sandstone, creating favorable reservoir and accumulation conditions. During the fourth phase, the submarine fan complex significantly contracted due to insufficient supply, resulting in a lobe-like geometry. Conclusion Based on the seismic sedimentology results, we established a two-stage deposition model for the submarine fan complex of the 1st Member of the Huangliu Formation, providing technical support for reservoir prediction, as well as oil and gas exploration and development in the Yinggehai Basin, China.
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