Seismic sedimentology of lacustrine delta-fed turbidite systems: Implications for paleoenvironment reconstruction and reservoir prediction

Abstract

Abstract The deltaic-turbidite systems are common features in continental lacustrine rift basins. In the Bohai Bay rift Basin, Eastern China, the turbidite sandstones are the critical targets for hydrocarbon production and development. However, their intricate sedimentary patterns and the small size of the reservoirs introduces more challenge for their understanding and prediction. Through seismic sedimentology workflow, 90°-phase adjustment, strata slicing, spectral decomposition, RGB color blending technique, and geobody extraction, 3D seismic data and wireline log information data are integrated to understand the historical evolution of delta-turbidite systems and predicting the spatial and temporal distribution of sandbodies of the Es3m sub-member in the Shahejie Formation, dongying depression. The study identifies two system tracts in the study area, transgressive and highstand system tracts, from seismic and wireline logs interpretation. We identified six fourth-order sequences within the highstand system tracts, each of which corresponds to a different period of deltas progradation. Stratal slicing mapping on multiple deposition surfaces reveals the high-resolution historical evolution of the delta-turbidite systems and the distribution of their associated sandbodies. Interpretation of slices shows six stages of deltas development, which led to widespread delta-fed turbidite reservoirs. Three multi-delta-turbidite systems: the northern fan-turbidite systems and the southeast-turbidite systems are documented, which evolved throughout all stages of delta development. Rapid progradation of multi-deltas systems played an essential role in the evolution and development of thin-bedded reservoirs in the HST. Faults and local topographic lows controlled the spatial distribution of sandbodies in the area. The individual sandbodies range from 4.48 km2 to 16.49 km2 in size, and they vertically superimposed from bottom to top. The classification scheme presented in this work shows a successful application in terms of paleoenvironmental reconstruction and reservoir prediction of the delta-fed turbidite systems, which can be applied to similar systems worldwide.