沁水盆地武乡地区中二叠统下石盒子组河流相沉积储层构型特征

CHARACTERISTICS OF FLUVIAL SEDIMENTARY RESERVOIR CONFIGURATION OF MIDDLE PERMIAN SHIHEZI FORMATION IN WUXIANG AREA,QINSHUI BASIN

沁水盆地是我国石炭—二叠系的主要含煤盆地。本次研究运用沉积学、岩石学的理论,结合沉积相与储层构型分析方法,对盆地东部武乡县温庄村中二叠统下石盒子组河流相剖面的砂体构型特征进行了精细解剖,总结了砂体内部构型特征并建立储层构型模式。结果表明,沁水盆地武乡地区下石盒子组为辫状河沉积,主要发育辫状河道沉积和心滩沉积两种成因的砂体;在该剖面研究层段识别出9种岩相类型,分别为块状层理砾岩相(Gm)、槽状交错层理砂岩相(St)、板状交错层理含砾砂岩相(Gsp)、楔状交错层理砂岩相(Sl)、板状交错层理砂岩相(Sp)、泥岩相(M)、平行层理砂岩相(Sh)、槽状交错层理含砾砂岩相(Gst)、水平层理粉砂岩相(Fh);其砂体内部构型可划分为0~6级7个构型界面,分别为沉积纹层界面、简单层系界面、简单层系组界面、沙坝内部增生体界面、心滩及辫状河道充填界面、单一河道带界面、复合河道带界面;通过对河道充填沉积、心滩沉积、越岸沉积和废弃河道沉积这4种构型单元作为辫状河主要储层构型单元进行精细解译,建立了武乡地区温庄村剖面下石盒子组辫状河复合砂体三维构型模式。研究成果为盆地及其相邻地区砂岩储层精细描述提供了地质依据和参考。

Qinshui Basin is the main coal bearing basin of Carboniferous Permian in China.Based on the theory of sedimentology and petrology,this paper subtly dissectes the fluvial facies profile sand body configuration characteristics of the Lower Shihezi Formation of middle Permian in Wenzhuang Village,Wuxiang County,eastern part of the Qinshui basin.It also summarized the internal configuration characteristics of the sand body and established the reservoir configuration model with the analytical method of sedimentary facies and reservoir configuration.The results show that the Shihezi Formation in Wuxiang area belongs to braided river deposit,mainly developing the braided channel deposited sand body and river islands deposited sand body.Nine types of lithofacies have been identified in the studied formation section,including Gm,St,Gsp,Sl,Sp,M,Sh,Gst and Fh.The internal configurations of sand bodies can be divided into 7configuration boundary interfaces of 6levels,including sedimentary laminar interface,simple stratigraphic interface,simple stratigraphic group interface,internal accretion of the sandbank,river islands and braided channel,single-channel belts and composite channel belts.A three-dimensional configuration model of braided river composite sand body for Shihezi Formation at Wenzhuang Village section has been established by fine interpretation of four configuration units as the main reservoir configuration units of braided river,including channel filling deposition,river island deposition,overland deposition and abandoned channel deposition.The research results provide geological basis and reference for the fine description of sandstone reservoirs in the Qinshui basin and its adjacent areas.