Depositional system and sand body distribution in the third member of the Yanchang Formation in the Yijun area in the southern Ordos Basin

The southern Ordos Basin is an important oil-producing area in China and the third member of the Upper Triassic Yanchang Formation in the Yijun area in the southern Ordos Basin is a major hydrocarbon exploration target.Based on well logs and 3D seismic data, the provenance of the study area was studied using cathode luminescence, seismic progradation tendency and angle conversion methods.The Yijun area was influenced by the Weibei uplift in the south during the Late Triassic.The deposition system in the study area developed when the third member of the Yanchang Formation was deposited, and this provenance controlled the distribution of sand bodies.Braided river delta-front sediments were widespread in the study area, and subsea river channels and mouth bar sand bodies were favorable reservoirs for hydrocarbons.The distribution of sand bodies and features of the sedimentary facies from the third section to the first section of the third member of the Yanchang Formation were studied to determine its potential for hydrocarbon reservoirs.