Abstract

By examining the seismic data, logging data, core description, thin sections, rare earth elements, heavy minerals, and detrital zircon U-Pb dating, we studied the sedimentary features and provenance implications of the five fan deltas (fan deltas A-E) spread along the 428 Uplift in Bohai Bay Basin during the deposition of the first and second members of the Shahejie Formation (Es12). The glutenite volumes of the fan deltas and the erosion volumes of their catchments were calculated as well as the sand-production rates. The results indicated that during the sedimentation of the first and second members of the Shahejie Formation (Es12): (1) the true lithology of the 428 Uplift, which was completely eroded, could not be represented by the residual lithology (Mesozoic igneous rocks with interlayers of clastic rocks on the western subuplift and Permian sedimentary rocks on the eastern subuplift), (2) fan deltas A and B were dominated by Mesozoic igneous rocks from the eastern low uplift, whereas the fan deltas C-E were dominated by sedimentary rocks with interlayers of igneous rocks from the western low uplift, and (3) during Es12, the volumes of the glutenites of the five fan deltas were 3.0×109  m3, 2.1×109  m3, 0.73×109  m3, 0.95×109  m3, and 0.9×109  m3, respectively, whereas the erosion volumes of the catchments are 4.17×109  m3, 3.9×109  m3, 2.1×109  m3, 3.2×109  m3, and 3.1×109  m3 respectively. (4) The sand production rates of the five fan deltas were 71.9%, 53.8%, 34.7%, 29.6%, and 29%, respectively. (5) Approximately 53.8%–71.9% of the eroded igneous rocks formed the near-source fan-delta glutenites, whereas only 29.0%–34.7% of the eroded sedimentary rocks with igneous rock interlayers formed the near-source fan-delta glutenites. The igneous parent rocks featured higher sand production rates and were responsible for the development of the most sand-rich reservoirs. Based on the research finding, it is possible to predict the development of the sandstone reservoirs at the poorly explored steep slope areas.

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