西湖凹陷曲流河三角洲古地貌恢复及沉积特征  

Paleogeomorphic restoration and sedimentary characteristics of meandering river delta in Xihu Depression,East China Sea

作　　者：王红岩 WANG Hongyan(CNOOC China Limited,Shanghai Branch,Shanghai 200335,China)

机构地区：[1]中海石油(中国)有限公司上海分公司,上海200335

出　　处：《成都理工大学学报（自然科学版）》2020年第3期318-327,共10页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：国家科技重大专项(2016ZX05027-002)。

摘　　要：利用地层倾角校正、去压实校正、正演模拟、地震相及测井相分析等技术,探讨西湖凹陷平北斜坡带中新世早期古地貌恢复方法及曲流河三角洲沉积特征,为寻找有利储层提供依据。结果表明:本区砂岩、泥岩地表孔隙度分别为48%、62%,压实系数分别为4.1×10^-4m^-1、9.5×10^-4m^-1;微古地貌显示工区内斜列发育3个局部凸起和1个低洼地带;目的层砂岩的-90°雷克子波合成地震记录表现为强波峰反射,反映高阻砂岩特征;曲流河弯曲指数范围为1.57~5.12,主河道地震相具有透镜状、强振幅波峰反射特征,边滩具有单边叠瓦状、中强振幅波峰反射特征;三角洲平原分流河道呈现串珠状、较强振幅波峰反射,测井相为低伽马、高幅、微齿化-箱型,分流间湾多为弱振幅波谷反射;三角洲砂体距离河口越远,砂体越薄,砂地比越小,粒度越细,分选性和磨圆度越好。本区曲流河三角洲沉积体主要沿北东向低洼带展布,北部以曲流河河道砂、点坝砂等微相的储层为主,南部以分流河道、席状砂等微相的储层为主。In order to provide a basis for finding favorable reservoir in Pingbei slope zone of Xihu depression,the techniques of dip correction,decompaction correction,forward modeling,analysis of seismic facies and well logging facies are used to discuss the methods of paleogeomorphic restoration and sedimentary characteristics of meandering river delta of the early Miocene in the area.The results show that the surface porosity of sandstone and mudstone is 48% and 62%,and the compaction coefficient is 4.1×10^-4m^-1 and 9.5×10^-4m^-1 respectively.Analysis of micro paleogeomorphology reveals that there are three oblique arranged local bulges and one low-lying area in the study region.The -90° ricker wavelet synthetic seismogram of the target sandstone shows strong peak reflection,characteristic of high P-wave impedance sandstone.The curve index of meandering river ranges from 1.57 to 5.12.Seismic facies of the main channel are characteristic of lenticular and strong amplitude wave peak reflection,while the point dam has the characteristics of single side imbrication and strong amplitude wave peak reflection.The distributary channels of delta plain are in a bead-like shape,with strong amplitude peak reflection.Logging facies display low gamma,high amplitude and micro toothed box type,and distributary bay mostly displays weak amplitude trough reflection.The farther the delta sand body is from the estuary,the thinner the sand body is,the smaller the percentage of the sand is,the finer the grain size is,the better the sorting and rounding are.The sedimentary body of meander river delta in this region is mainly distributed along the northeast low-lying belt.In the north,the main reservoirs are meandering river channel sand and beach sand,while in the south,the main reservoirs are distributary channel sand and sheet sand.

关 键 词：西湖凹陷 曲流河三角洲 沉积特征 古地貌恢复 正演模拟 

分 类 号：P512.3[天文地球—地质学]