Major breakthrough of Well Gaotan 1 and exploration prospects of lower assemblage in southern margin of Junggar Basin, NW China

Well Gaotan 1 was tested a high yield oil and gas flow of more than 1 000 m3 a day in the Cretaceous Qingshuihe Formation, marking a major breakthrough in the lower assemblage of the southern margin of Junggar Basin. The lower assemblage in the southern margin of the Junggar Basin has favorable geological conditions for forming large Petroleum fields, including: (1) Multiple sets of source rocks, of which the Jurassic and Permian are the main source rocks, with a large source kitchen. (2) Multiple sets of effective reservoirs, namely Cretaceous Qingshuihe Formation, Jurassic Toutunhe Formation and the Khalza Formation etc. (3) Regional thick mudstone caprock of Cretaceous Tugulu Group, generally with abnormally high pressure and good sealing ability. (4) Giant structural traps and litho-stratigraphic traps are developed. The northern slope also has the conditions for large-scale litho-stratigraphic traps. (5) Static elements such as source rocks, reservoirs and caprocks are well matched, and the dynamic evolution is suitable for large oil and gas accumulation. The lower assemblage of the southern margin of the Junggar Basin has three favorable exploration directions, the Sikeshu Sag in the west part, the large structures in the middle and eastern part, and the northern slope.