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

Key words:  Palougou profile  braided river  channel  channel bar  sand body architecture  heterogeneity  remaining oil distribution

Abstract:

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.