The Upper Triassic Braided River Thin-Bedded Tight Sandstone in the Yanchang Formation, Ordos Basin: Sedimentary Characteristics, Seismic Forecasting Method, and Implication

In the Ordos Basin, Chang 81, a Member of Yanchang Formation, features development braided river thin-bedded tight sandstones. These sandstones constitute one main production layers oil and gas in Formation within basin. This study integrates data from core samples, drilling, seismic information to identify 81 at Daijiaping, using method constrained correlation between waveform facies. approach aids determining sedimentary microfacies types reservoir characteristics We establish quantitative fitting formula for width-to-thickness ratio channel sand bodies finely characterize body stacking patterns spatial distribution channels. Braided delta plain deposits Daijiaping mainly comprise four microfacies: channels, crevasse floodplains, swamps. The thickness member is concentrated 5–25 m, with low porosity permeability, making it typical sandstone reservoir. A waveforms facies was employed Member, summarizing patterns: longitudinal incision type, separation lateral shifting single type. Furthermore, forecasting established scale, providing accurate guidance well deployment. Horizontal wells deployed body’s side towards its center yield 1.8 times higher than that horizontal opposite direction. Thin-bedded characterized by flat-top convex-bottom lenticular facies, hold practical significance guiding deployment enhancing recovery.