TECTONIC EVOLUTION AND PETROLEUM PROSPECTION IN THE YIN’GEN-EJINA BASIN

The basement formed by plates and sutural zones apparently controls the evolution of Yin'gen-Ejina Basins.The tectonic evolution has undergone 5 stages: heat-upheaval and tension-crack stage of the Early Triassic,rudiment rift basin stage of the Early-Middle Jurassic,stretch faulting stage of the Early Cretaceous,relaxation depression stage of the Late Cretaceous and inland convergence stage of Tertiary.Different tectonic stages result in different trap styles.Hydrocarbon source rocks of the Lower-Middle Jurassic and the Lower Cretaceous form source and reservoir.The exploration realms of half graben-like basin are fault noses and fault block traps in the central fracture and ridgy zones,and litho-(logic) traps and stratigraphic unconformity traps in the gentle slope zones.The exploration realm of downfaulted basin is roll anticline in the fracture zones controlling basin.A new notion of source nearby exploration around sub-depression in little lacustrine basins are proposed.