Petroleum geological conditions and exploration direction in north piedmont zone of Tuha Basin

The north piedmont zone of Tuha Basin is adjacent to three large oil-gas generating depressions (Shengbei, Qiudong and Xiaocaohu), and developed several reservoir-cap assemblages. Experienced multiple tectonic movements such as Yanshanian tectonic movement and Himalayan tectonic movement, it developed thrust belt, anticlinal belt and slope nose-shaped uplift belt from north to south, and the reservoirs formed by multi-stage hydrocarbon migration and accumulation. At present, five oilfields have been found such as Shanle, Qialekan, Kekeya, Yuguo and Qiquanhu, and six layer series obtained commercial oil and gas flow. The reservoir forming and distribution are controlled by Yanshanian palaeostructure, the existing structural high, faults, reservoirs and caps. It is proposed that the prospecting for Shuixigou Group reservoir and the middle-eastern shallow reservoir should be strengthened while expanding the dominated reservoir ofJ2s.