关键词: 准噶尔盆地, 吉南凹陷, 二叠系, 沉积体系, 萨探1, 成藏模式

Abstract: Recently, Well Satan 1, a risk exploration well of PetroChina, obtained high yield oil flow of the Permian Jingjingzigou Formation during the well test, achieving a major breakthrough in the exploration of lithologic reservoir in Jinan Sag in the footwall of Fukang fault zone, Junggar Basin. Based on the drilling results of Well Satan 1, hydrocarbon accumulation conditions in the east segment of Fukang fault zone are systematically studied and summarized, exploration prospects evaluated, and exploration targets put forward in Jinan Sag. The study shows that Jinan Sag is separated from Jimsar Sag by a bulge, and it is an independent hydrocarbon rich sag with great exploration prospect. The thick mature source rocks are deposited, laying the material basis for large-scale hydrocarbon accumulation. Controlled by ancient landform, two sets of largescale reservoirs of Middle and Upper Permian are developed in the slope and sag area, with similar distribution pattern and large thickness,possessing the reservoir conditions for forming large-scale lithologic-stratigraphic oil and gas reservoirs. The comprehensive analysis indicates that there are mainly two types of oil reservoirs in Jinan Sag: One is shale oil and gas reservoir of self-generation and self-storage type of Lucogou Formation. Among them, shale oil is mainly accumulated in relatively stable area, and distributed extensively and continuously in the foot wall of Fukang fault zone; The shale gas is mainly accumulated in the upper wall of Fukang fault zone, where was deeply buried in the early stage and uplifted strongly in the late stage. It is characterized by structural gas reservoir at present due to the high-maturity source rocks and affected by the damage and adjustment in the late stage. The other type is conventional sandstone oil reservoir of lower-generation upperstorage or upper-generation lower-storage types configurated by source rock of Lucaogou Formation and reservoirs of the Jurassic Badaowan Formation, Triassic Jiucaiyuan Formation, and Permian Wutonggou and Jingjingzigou Formations. The Yanshanian faults play a decisive role on the accumulation of oil reservoir, with the pattern of “fault communication, lateral adjustment, lithologic reservoir dominant and fault cutting”. Well Satan 1 opens the prelude of stereoscopic exploration in the east segment of Fukang fault zone, and replacement field of multilayer system with hundred-million-ton-level, which is a major breakthrough for benefit exploration and large-scale reserve increase in the eastern Junggar Basin.