JIN, Q., and C.WANG, University of Petroleum, Dongying, Shandong, China
Abstract: Prediction of Turbidite Reservoirs in Steep and Gentle Slope Depositional Systems in Eocene Lacustrine Basin - A Case Study of the Huagou Sag in the Bohai Bay Basin, China
In lacustrine basins, sandy turbidites are significant hydrocarbon reservoirs, and often deposited in steep and gentle slope depositional systems. The Huagou sag is a typical case in the Bohai Bay basin, Eastern China. The steep slope, on one flank of the sag, is based on extensional discordant faults; the gentle slope, on another flank of the sag, is over the uplift adjacent to the basin. Sequence stratigraphy and seismic facies studies revealed that fluvial subaqueous fan-turbidite depositional system and delta fan-turbidite depositional system were developed on the steep slope and on the gentle slope of the Huagou sag, respectively.
Six basic facies building blocks comprise the steep slope system: channel fills, channel and lobe complexes, fluidized apron, slump debris-flow lobes and tongues, muddy turbidite fills and sheets, and muddy lacustrine drapes and fills. The authors identified turbidite sands mainly in facies of the fluidized apron, slump debris-flow lobes and tongues, and occasionally in facies of the muddy turbidite fills and sheets by analyzing of 3D seismic and well logging data.
In the gentle slope system, reservoir architecture consists of beach sand bodies, branch channel fills, and sandy turbidite sheets.These turbidite sands were recognized as long distant turbidites with small thickness and good petrophysical properties.
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