东海陆架盆地西湖凹陷油气成藏主控因素及成藏模式

以现代石油地质理论和油气复式成藏理论为指导，总结西湖凹陷已发现油气分布规律，认为西湖凹陷具有油气规模“深大浅小”、油气类型“上油下气”、油气富集“近源近断”的特征。分析了油气成藏主控因素，从而建立了特色的西湖凹陷“塔”式成藏模式。研究表明，中浅层花港组由于泥岩盖层条件相对较差以及晚期近EW向断裂对早期油气藏的破坏和改造作用，油气成藏条件不是非常有利；而深层-超深层具有形成大型油气田的有利地质条件：烃源岩持续生烃提供了充足的油气源，深层-超深层砂岩储集性能依然保持较好，异常高压改善了储层物性并提供油气运移的动力，“千层饼”式储盖组合和早期烃源断裂控制了油气纵向展布。因此，西湖凹陷深层-超深层砂岩气资源潜力较大，具有良好的勘探前景。

Main controlling factors and reservoir forming model for hydrocarbon accumulation in the Xihu Sag,the East China Sea Shelf Basin

Under the guidance of modern petroleum geological and hydrocarbon accumulation theory, we summarized the distribution law of discovered oil and gas in Xihu Sag, and holds that the sag is characteristic of "large in deep and small in shallow" on scale, "upper oil and lower gas" in type, and oil and gas enrichment "near source and near fault". The main controlling factors of oil and gas accumulation were analyzed, and the characteristic "tower-shaped" reservoir forming model of the Xihu Sag was established. Result shows that the conditions of oil and gas accumulation in the middle and shallow Huagang Formation are not very favorable due to the relatively poor mudstone capping and the transformation and destruction of early oil and gas reservoirs by later near-EW trending faults. The deep to ultra-deep layer have favorable geological conditions for the formation of large oil and gas fields. Continuous hydrocarbon generation from source rocks provides sufficient oil and gas sources. The reservoir performance of deep to ultra-deep sandstone remains good. The abnormal high pressure improved the reservoir physical properties and provides a driving force for oil and gas migration; and the lasagna-like intercalation of reservoir and cap and early faulting across the source area controlled the vertical distribution of oil and gas. Therefore, the deep and ultra-deep sandstone gas resources in the Xihu Sag have great potential and good exploration prospects.