四川盆地东北部马路背地区上三叠统须家河组二段气藏高产机制

摘要

The tight sandstone gas reservoir of the second Member in the Upper Triassic Xujiahe Fm (Xu 2 Member for short) in the Malubei area of the northeastern (NE) Sichuan Basin is a part of the Tongnanba structural belt,presenting the development characteristics of high yields,stable production rates and high producible degrees without water.To promote the exploration of the Xujiahe Fm gas reservoir in the Tongnanba structural belt,it is necessary to discuss the high and stable yield mechanism of Xu 2 Member gas reservoir in the Malubei area from the aspects of source rock,reservoir and fault conduit system based on abundant assay data.And the following research results were obtained.First,double hydrocarbon supply of marine and continental quality source rocks is the foundation for the formation of this reservoir,and it provides the guarantee of natural gas resources.Second,the reticular effective reservoir permeability system which is the superimposition product of large-scale reticular fractures and extensive tight reservoirs is important for the formation of this gas reservoir,and it provides the space for natural gas storage.And third,the fault conduit system is the key to the formation of this gas reservoir and it efficiently communicates the deep marine hydrocarbon source with the continental reticular effective reservoir permeability system.To sum up,the Tongnanba structural belt is generally a large-scale special structure which is complicated by the cutting of faults,and it is distributed in rows and zones like the Malubei structure,so the important direction of future natural gas exploration in the Tongnanba structural belt is to search for the gas reservoirs similar to the Xu 2 Member gas reservoir in the Malubei structure in terms of source rock,reservoir and fault conduit system.%四川盆地东北部马路背地区上三叠统须家河组二段致密砂岩气藏具有“高产、稳产、不含水、可动用程度高”的开发特点.为推进其所属通南巴构造带须家河组气藏的勘探工作,基于大量的分析化验资料,从烃源岩、储集体、断裂输导体系等方面深入探讨了马路背地区须二段气藏的高产稳产机制.结果表明:①海、陆相优质烃源岩双重供烃,提供了天然气的资源保障,是该气藏形成的基础;②规模网状裂缝与大面积致密储层叠加形成网状有效储渗体,为天然气的赋存提供了场所,是该气藏形成的重要条件;③断裂输导体系有效沟通深层海相烃源与陆相网状有效储渗体,是该气藏形成的关键.结论认为:考虑到通南巴构造带总体表现为一个被断层切割复杂化的大型特殊构造,类似于马路背的构造成排成带分布,因而寻找在烃源岩、储集体、断裂输导体系等方面与马路背须二段气藏类似的气藏,是该构造带下一步天然气勘探的重要方向.