【摘要】 四川盆地上三叠统须家河组已进入大面积岩性气藏勘探的新阶段,为了给该区勘探部署以及储量评价提供地质依据,开展了砂体分布、储层展布及成因和成藏机理研究工作。具体工作和认识包括:①以层序地层学原理为指导,四位一体(测井、野外露头、岩心资料和地震资料分析),"井震"结合,建立了全盆地须家河组层序地层格架,认为6大物源体系形成6大三角洲砂体;②在格架范围内以体系域为单元研究地层、砂体的展布特征,预测有利储集砂体的分布,并分析不同类型砂体、相同砂体不同部位的储层特征及其发育的主控因素;③分析储层非均质性特征和优质储层的形成机理,划分储层类型,对研究区内储层进行综合评价,对优质储层发育的有利区带进行预测——加积式砂组中的高能河道为最高效的储层;④通过对广安、合川等典型气藏的解剖,针对须家河组低渗透砂岩气藏气水关系复杂、成藏机理复杂的特点,设计相应的地质模型和实验装置,开展了气水置换的成藏模拟试验,认为致密砂岩圈闭的充注为脉冲式充注,充注完成后在致密砂体和高孔渗砂体之间,存在多个含水滞留区带,而储层物性的相对差异是能否聚气的关键。该成果对于扩大四川盆地天然气勘探领域、寻找新的勘探接替区具有重大意义。更多还原

【Abstract】 Gas exploration in the Upper Triassic Xujiahe Formation of the Sichuan Basin has come into a new stage with targets for lithological gas reservoirs in a wide area.In order to provide robust geological basis for exploration deployment and reserves increasing,we conduct the studies on the sandbody distribution,reservoir origins and distribution,and pooling mechanism in this zone,from which the following conclusions are thus concluded.a.Followed by the principle of sequence stratigraphy,a sequence stratigraphic framework is built for the Xujiahe Formation of this whole basin,in combination with well-log and seismic data(that is,four-in-one data analysis of well logging,outcrop,core,and seismic information),and from this framework 6 delta sandstones are found to result from 6 source systems.b.The system tract within the range of this framework taken as a unit,the distribution features of formations and sandbodies are discussed,the distribution of favorable reservoir sandbodies is predicted,and reservoir characteristics of various types of sandbodies and different locations of the same sandbody are analyzed,as well as the main controlling factors of the developed sandbodies.c.Both reservoir heterogeneity and the pooling mechanism of high-quality reservoirs are analyzed,the reservoir types are classified,an overall assessment is made on the reservoirs in the study area,and favorable zones for the developed high-quality reservoirs are predicted.d.Typical gas reservoirs in Guang’an and Hechuan are thoroughly analyzed,the corresponding geological models and experimental apparatus are designed in accordance with the features of complex pooling mechanism and a complicated gas/water relationship of low-permeability sand gas reservoirs in the Xujiahe Formation.Moreover,a simulation modeling is made on the gas pooling process by the gas-water displacement,by which pulse hydrocarbon charging is thought to occur in the tight sand gas traps,after that multiple water-cut zones are found to be between the tight sandstone and high-porosity and high-permeability sandstone,thus the comparative difference of petrophysical characters between the two sandbodies becomes the key to a gas pool.All those study results above are of significance to widen the exploratory area and search for new alternative exploration zones for more gas discovery in the Sichuan Basin.更多还原