Seismic interpretation of tectonic and paleogeomorphologic controls on sediment dispersal patterns in a continental rift basin: A case study from the Bohai Bay Basin, China

Tectono-paleogeomorphologic frameworks exert a major control on sediment dispersal patterns and types of depositional systems, both of which influence reservoir geometry and quality. In this study, we analyze the framework of the Ed(3) Member of the Dongying Formation in QHD29-2 Block, Bohai Bay Basin, China. The framework is constructed through (1) conventional sedimentologic study of single-well facies, cumulative frequency curves, and thin section analysis, (2) seismic stratigraphic interpretation of sectional seismic facies, and (3) seismic sedimentologic mapping through stratal slicing and seismic multiattribute analysis. The structural system is marked by a master boundary fault in the Shijiutuo Uplift that has greater displacement at its center than at the propagating fault tips. The resulting paleogeomorphologic architecture is characterized by a steep slope in the central part of the boundary fault and two gentle slopes at fault tips. Sediment dispersal patterns indicate that fan-shaped and lobate proximal fan deltas were rapidly deposited in the central steep slope and belt-shaped distal river deltas were deposited in the gentle slopes after long-distance transport. Proposed sediment dispersal patterns for the central fault segment and the propagating fault tips should serve as a useful reference for the stratal geometry, depositional patterns, distribution of depositional facies and of potential reservoir and source rocks, and evaluation of hydrocarbon reservoirs in extensional rift basins in eastern China and similar basins around the world.