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徐家围子断陷为“西断东超”的箕状断陷,伸展断裂和走滑断裂这2种性质断裂对天然气成藏具有明显的控制作用。伸展断裂系统在控盆同时控制有效烃灶分布,近SN向张扭断裂即徐西断裂与NNE向断裂共同控制了沙河子组煤层分布,形成有效烃源灶。走滑断层为火山喷发的通道,徐中断裂和徐东断裂控制营一段和营三段火山分布,与之相交的北北东向断裂有诱导火山喷发作用,交点位置火山规模最大。徐中断裂在泉头组沉积晚期到青山口组沉积早期再次强烈活动,右旋走滑变形使火山岩产生大量裂缝,特别是在断层交点处最发育,形成优质储层。徐东断裂此时无明显活动,优质储层不受裂缝控制。与此同时断裂强烈活动配合沙河子组气源岩大量生排气,成为气源断层,徐中断裂是最主要的气源断裂,由于岩性对接封闭作用,天然气主要分布在气源断裂下盘,因此,天然气围绕倾向变化的徐中断裂两盘呈“正弦曲线”状分布。反转断层和盖层控制天然气富集层位,火山岩顶面的“混岩”盖层品质好,在反转断层不发育区使天然气富集在火山岩储层中。反转断层发育区,易将火山岩中天然气调整到青山口组区域性盖层下的扶杨油层中聚集,调整期为明水组沉积末期。走滑断裂是天然气成藏的主控因素,明水末期没发生强烈反转是保存的关键。
The Xujiaweizi fault depression is the half-graben fault, extensional fault and strike-slip fault, which have obvious control over the accumulation of natural gas. The extensional fracture system controlled the distribution of effective hydrocarbon stoves in the control basin at the same time. The near SN trending torsional fracture, that is, the Xuhe fault and the NNE fracture, jointly controlled the distribution of coal seams in Shahezi Formation and formed an effective hydrocarbon source stove. The strike-slip faults are volcanic eruption channels, volcanic eruptions, Xuzhong fault and Xu Dong fault control camp volcanic distribution of the first and third batches, with the intersection of the NE-trending northeastern fault induced volcanic eruptions, the largest intersection volcano sites. The Xuzhong fault once again moved intensively in the Early Qingshankou Formation to the Early Qingshankou Formation during the sedimentary period of the Quantou Formation. The dextral strike-slip deformation caused a large number of fractures in the volcanic rocks, especially the most developed faults at the intersections, forming high-quality reservoirs. Xu Dong fault at this time no significant activity, high-quality reservoir is not crack control. In the meantime, the fracture is strongly associated with a large amount of gas from the gas source rocks of the Shahezi Formation and becomes a gas source fault. The Xuzhong fault is the most important gas source fault. Due to the close docking of lithology, natural gas is mainly distributed in the gas source fracture plate Therefore, the Xuzhong fault, whose natural gas changes around the propensity, is distributed in a “sinusoidal” shape. Inverted faults and caprocks control natural gas-rich reservoirs, and the quality of the “rock” cover on the top of volcanic rocks is good. The gas is enriched in the volcanic reservoirs in the reverse faultless zone. Reverse the fault zone, it is easy to adjust the natural gas in volcanic rocks to accumulate in the Fuyang reservoir under the regional caprock of the Qingshankou Formation, and the adjustment period is the late sedimentation of the Mingshui Formation. Strike-slip faults are the main controlling factors of natural gas accumulation. The key point of conservation is that there is no strong reversal at the end of bright water.