【摘要】 柴达木盆地西部油砂山上新统底部是一个典型的陆源湖成三角洲分流河道露头砂体。砂体主要由砾状砂岩及中-细粒砂岩组成,其粒度概率累积曲线为二段式和三段式;具有大型单斜层理、槽状交错层理和低角度交错层理,底部具冲刷面;垂向层序具两个不对称的正韵律;几何形态为底凸顶平。该砂体为三角洲平原上小规模的顺直型窄浅分流河道砂体。通过密集网络取样,研究了砂体内部物性参数的空间分布规律,垂向上以砂体中部细-中砂岩和中-细砂岩的孔隙度、渗透率最高。沿河道中心砂体延伸稳定,颗粒较粗,是孔隙度、渗透率的高带,由于河道中心的摆动,高带也可偏离中心移向一侧;河道两侧颗粒细,孔隙度和渗透率低。图5表6参2更多还原

【Abstract】 A typical terrigenous lacustrine deltaic distributary channel sandbody is investigated in the outcrop of Pliocene series at Youshashan, west Chaidamu basin, Qinghai province. The sandbody is composited of pebble sandstone and middle—fine sandstone with 2 or 3 segments of straight line on the grain size cumulative probability curves. Its sedimentary structure includes large-scale inclined beddings, trough cross-beddings, low-angle cross-beddings as well as an erosional basal surface. The sandbody has 2 asymmetric normal rhythems in vertical sequence and a geometry with fiat top and convex bottom. The sandbody is so believed to be a small-scale narrow and shallower straight distributary channel. A dense sampling net work is arranged for studying the reservoir parameters. The result shows that the middle-fine and fine-middle sandstones at the central part of the channel have vertically the highest porosity and permeability, and along the axis of the channel, there is a zone withthe highest porosity and permeability and the coarsest grain-size. The best reservoir zone can deviate from the central channel because of wandering of its main current. The porosity and permeability in the areas near the banks is lower.更多还原