【摘要】 四川盆地元坝地区上三叠统须家河组二段广泛发育的石英滩坝砂体具有良好的油气显示,已有多口钻井在该套石英砂岩中测获工业气流。研究表明,滩坝石英砂岩具有分选好、磨圆好、岩屑及杂基含量低的高成熟度特征;形成于具双向水流特征的高能滨岸环境,是湖泛早期的产物,在测井上反映为"低伽马、低密度";地震反射属性以强振幅、高频率、高连续为主。滩坝砂体近东西向展布,厚度10~20 m,发育多个厚度较大的井区,明显受米仓山—大巴山前渊带的控制。滩坝石英砂岩储层总体属低孔低渗储层,储集空间类型有原生粒间孔、粒间溶孔以及粒内溶孔;原生颗粒缝与构造缝共同构成缝网系统,扩大了储集空间。物源、古地形、湖平面升降、溶蚀作用以及裂缝是滩坝储层形成的控制因素。更多还原

【Abstract】 Better oil and gas show can be gained from the quartzose-bar sandbody, widely developed at the Upper Triassic Xujiahe 2 Member, Yuanba area, Sichuan Basin. Moreover, commercial gas has been obtained from the quartzose sandstones. After our study, it is illustrated that(1)the sandstones have some features of high maturity, such as better sorting and rounding, and low content of both debris and matrix;(2)it formed in a high-energy onshore environment with characteristics of two-way flow, which was a product of early lacustrine flooding;(3)from well-logging curves, it appears low gamma and density whereas from seismic-reflection attribute, it mainly presents strong amplitude, and high frequency and continuity; and(4) it is prone to E-W trend and is 10 to 20 m in thickness, which is obviously affected by the Micangshan-Dabashan foredeep belt. In addition, for the quartzose reservoir with low permeability and porosity, its space includes primary intergranular pore, dissolution pore, and intragranular dissolution pore. A fracture network formed from both primary grain fracture and structural fracture may enlarge the space. Such factors as source, paleo topography, lake-level fluctuation, dissolution, and fracture are the influencing ones to form this quartzose-bar reservoir.更多还原