摘要
异重流作为一种向深水输送沉积物的重要方式,正逐渐成为国际沉积学的研究热点。结合岩心、微观薄片和测井等资料,首次在东海盆地西湖凹陷中部花港组发现了异重流沉积。岩心上主要表现为一系列反粒序-正粒序的层序组合,反映了洪水期水体能量增强—减弱的变化过程;发育水平层理、爬升沙纹层理、波状层理、软沉积物变形等沉积构造;上、下2个粒序层之间有时可见侵蚀面,反映洪峰时期对下伏地层的侵蚀作用。薄片中可见砂岩层中石英含量较高,泥质含量变化与粒序变化一致。薄片中可见与岩心相似的粒序变化特征,中部粒度最粗,最大粒径将近0.3 mm。储层物性参数垂向变化显示出与岩心粒序变化相似特征,反映出异重流沉积的粒序层对储层层内非均质性具有明显影响。花港组异重流发育主要受强烈的构造运动和亚热带季风气候所造成的季节性集中降水综合影响。花港组发育3种异重流沉积模式,表现出不同的粒度、沉积厚度、沉积构造差异,反映了不同的水动力背景及沉积速率。花港组异重流沉积的发现对深化西湖凹陷花港组沉积体系认识,明确花港组沉积时期古环境背景,提供新的油气勘探方向具有重要意义。
As an important way to transport deposits to deep water,hyperpycnal flow has been a world-wide hotspot for the sedimentology research.Based on data about rock core,microscopic thin sections and logging,hyperpycnal flow deposits have been found in the Huagang Formation of the Xihu sag in the East China Sea basin for the first time.As suggested by the rock core analysis,a series of intervals following alternately upwards-coarsening and upwards-fining patterns,which is the main feature of rock cores,reflects the rise and decline of waterbody energy;depositional structures like horizontal bedding,climbing ripple bedding,wavy bedding,deformation of soft sediments,etc.,have been found;erosional surfaces occasionally occur between graded bed sequences,reflecting erosion of underlying formations during the floodpeak age.The thin section observation indicates that sandstone layers have high content of quartz and the variation of argillaceous content following grain size changes;and the grain size changes in the observation are similar to that reflected by the rock core analysis,with grains in largest diameter nearly of 0.3 mm in the middle.Besides,the vertical variation of physical properties of reservoirs matching that of grain sizes in rock cores indicates the evident effects of graded bed sequences on the in-layer heterogeneity of reservoirs.In the Huagang Formation,the development of hyperpycnal flow was mainly affected by both seasonal centralized precipitation caused by the sub-tropical monsoon climate as well as intense tectonic movements.And three sedimentary models have been developed with variations in grain size,sedimentary thickness and tectonics,reflecting different hydrodynamic settings and depositional rate.The discovery of hyperpycnal flow deposits in the Huagang Formation can deepen the understanding of the depositional system of the Huagang Formation in the Xihu sag,be significant to the determination of the palaeoenvironment while the Huagang Formation depositing,and provide a new orientation towards oi
作者
刘江艳
张昌民
侯国伟
何苗
黄苓渝
朱锐
胡威
LIU Jiangyan1, ZHANG Changmin1,HOU Ouowei2 ,HE Miao2, HUANG Lingyu3 ,ZHU Rui,HU Wei(1. College of Geosciences, Yangtze University, Wuhan , Hubei 430100, China ; 2. CNOOC China Limited, Shanghai Branch, Shanghai 200050, China; 3. CNOOC Research Institute Co., Ltd., Beijing 100028, Chin)
出处
《中国海上油气》
CAS
CSCD
北大核心
2018年第2期17-24,共8页
China Offshore Oil and Gas
基金
"十三五"国家科技重大专项项目"深层优势储层沉积成因机制及地质预测技术(编号:2016ZX05027)"
国家自然科学基金面上项目"中国西部主要盆地周缘及邻区分支河流体系分布与沉积模式(编号:41772094)"部分研究成果
关键词
西湖凹陷
花港组
异重流
正粒序
逆粒序
沉积特征
沉积模式
Xihu sag
Huagang Formation
hyperpycnal
1ow
normal grading
inverse grading
depositional characteristics
depositional model
