YENSHANIAN OIL/GAS GENERATION AND EVOLUTION IN WEST SICHUAN AND ITS OIL/GAS EXPLORATION PROSPECTS

Since the Yenshanian movement is a peak stage for oil/gas generation of the Triassic source rocks in west Sichuan, the tectonic evolution in this stage would be significant for oil/gas accumulation in the area. On the basis of tectonic settings and sedimentary characters, the tectonic evolution in west Sichuan can be divided into three developing stages of upliftings and depressions, compressional foldings and shrinking subsidence, among which the upliftings play a significant part in the distribution of gas pools in west Sichuan. The west Sichuan Area then can be grouped by different structural belts of the Longquanshan fault-folded belt in east, the uplifting fault-folded belt in south, the steep-slope fault-folded belt in front of the Longmenshan in west and the depressional zone in the central part based on the present-day tectonic framework and the characters of the Yenshanian tectonic evolution. The superimposed areas between the upliftings or slope and the fault-folded belts mentioned above developed in the Yenshanian Period are most promising prospects for oil/gas exploration.