松辽盆地徐家围子断陷天然气聚集规律与下步勘探方向

Natural gas accumulation rule of Xujiaweizi Depression in Songliao Basin and future exploration target

徐家围子断陷内部充填了火石岭组、沙河子组和营城组的三层火山岩和四层碎屑岩地层 ,构成了复杂的生储盖层组合。烃源岩以沙河子组湖相泥岩和煤层为主 ,天然气类型以煤型气和混合气为主 ,并有油型气和无机气存在。已发现的气藏主要分布在断陷西部的控陷断裂带和升平—兴城构造带上 ,断陷东部的榆西断展构造带、宋站低隆起和丰乐低隆起区以及安达次坳也具有优越的成藏条件 ,是可能取得战略突破的新领域。

Xujiaweizi depression is a faulted depression,controlled by Xuxi,Songxi boundary fractures, which internal filled with three layer volcanics of Huoshiling Formation,Shahezi Formation and Yingcheng Formation and four layer clastic formations,which constituting a complicated oil source,reservoir and cap rock assemblage.Lacustrine shale of the Shahezi Formation and coal bed dominated over the oil source rock of Xujiaweizi depression and the type of natural gas is mainly coal type gas and mixed gas,and there exists oil-type gas and in organic gas.Under the effective sealing of Deng 2 member, Quan 1,Quan 2 and Qing 1 members three regional cap rocks,three volcanics,multi sets of sand,conglomerate reservoir and effective reservoir of the basement form multi trap types and gas type.Centred on gas source sag,Xujiaweizi depression,outer edge and internal uplift and structural high are the favourable areas of the natural gas accumulation. The discovered gas reservoirs mainly distributed in palaeo central uplift, Xuxi expanding fractural belt, Shengping-Xingcheng structural belt and Songxi fracture and Yuxi fracture expanding structural belt,Songzhan low uplift and Fengle low uplift and Anda sub-depression,having favourable reservoir forming conditions, are probably the new areas of achieving strategy breakthrough.