Sedimentary evolution and reservoir distribution of northern Upper Yangtze plate in Sinian-Early Paleozoic

The sedimentary evolution of the northern Upper Yangtze plate is affected by South Qinling structure on the north, Longmenshan structure on the west, and also long-term inherited uplift of Hannan paleocontinent on the north. In Sinian-Early Paleozoic with Qinling Sea on the north, Bayan Har Sea on the west, its sedimentary filling evolution is different from NE edge of Yangtze plate. On top of volcanic-sedimentary rock of Tiechuanshan Formation-Xixiang Formation and tillite of Nanhua System, mainly underwent carbonate platform in Sinian, shelf in Early-Middle Cambrian, carbonate platform and pericratonic uplift in Late Cambrian-Early Ordovician, platforms drowning in Middle Ordovician, and shelf deposition in Late Ordovician-Early Silurian. Some sets of regional source rock and favorable reservoir are formed in the sedimentary evolution. The reservoir mainly include algal reef-dolomite reservoir of Denigying Formation, oolitic limestone reservoir of Xiannvdong Formation, sand reservoir of Canglangpu Formation, and dolomite reservoir of Shilongdong Formation. The reservoir distributes widely. Although dominated by low porosity and low permeability overall, carbonatite reservoir in some areas develops corrosion and the permeability is favorable. The Dingying Formation and Shilongdong Formation are the main reservoir and potential exploration target in northern Yangtze plate, in which oil and gas exploration potential is considerable.