扒楼沟剖面二叠系辫状河砂体构型与非均质性特征

Braided river sand body architecture and heterogeneity of Permian in Palougou outcrop

通过露头实测、精细解剖与岩相分析等方法,结合岩石薄片与物性资料,对山西保德扒楼沟剖面二叠系山西组辫状河砂体的构型与非均质性特征进行系统研究。结果表明:辫状河主要发育河道和心滩2种成因砂体,河道砂体的垂向岩相组合为Ge-St,心滩砂体的垂向岩相组合为Ge-Sm-M-Sm-Sp-M-Sp或Ge-Sm-St-Sm-St-Sp-M-Sp;辫状河砂体可划分为5级构型单元,由小到大分别是层系、层系组、心滩/河道增生单元、心滩/辫状河道、单期河道,河道砂体由多个增生单元在垂向上加积构成,心滩砂体由多个增生单元与串沟砂体在垂向上加积构成,内部发育泥质夹层;心滩砂体物性优于河道砂体,非均质性相对较弱,整体可以作为优质储层,而河道砂体仅在靠近河心的部位物性较好,可作为优质储层;心滩砂体内规模较大的泥质夹层附近和河道砂体的边部及中上部可聚集剩余油,且心滩砂体内剩余油储量相对河道砂体较大。

Through field measurement, sand body anatomy, lithofacies analysis, and with the aid of thin sections and physical data, the architecture and heterogeneity characteristics of the braided river sand bodies of Shanxi Formation of Permian in the Palougou profile in Baode county, Shanxi province, were systematically studied. The results show that two kinds of genetic sand bodies, channel and channel bar are mainly developed in braided rivers. The vertical lithofacies combinations in channel sand body and channel bar sand body are Ge-St and Ge-Sm-M-Sm-Sp-M-Sp or Ge-Sm-St-Sm-St-Sp-M-Sp, respectively;Braided river sand bodies can be further divided into five levels of architectural elements, which are bed, bed set, channel bar/channel accretion, channel bar/braided channel, and braided river from small to large. Channel sand body is usually composed of several accretions superimposed vertically, while channel bar sand body is composed of several accretions and chute sand bodies superimposed vertically, with mud layers in it. Channel bar sand body has better physical properties and weaker heterogeneity than channel sand body, and therefore, the whole channel bar can be high quality reservoir. On the other hand, channel sand body only has good physical properties near the river center which may become potential reservoir Remaining oil mainly accumulates near large scales of mud layers in the channel bar, and in the side and upper part of the channel sand body, but with large deposition potentials in the channel bar.