中、上扬子地区晚奥陶世—早志留世古地理演化及页岩沉积模式  

Paleogeographic evolution of the Late Ordovician-Early Silurian in Upper and Middle Yangtze regions and depositional model of shale

作　　者：孙莎莎[1,2] 芮昀[3] 董大忠 施振生[2] 拜文华[2] 马超[2] 张磊夫[2] 武瑾 昌燕[2] Sun Shasha;Rui Yun;Dong Dazhong;Shi Zhensheng;Bai Wenhua;Ma Chao;Zhang Leifu;Wu Jin;Chang Yan(Shandong University,Jinan,Shandong 250061,China;Research Institute of Petroleum Exploration and Development,PetroChina, Langfang,Hebei 065007,China;Zhejiang Oilfield Branch Company Ltd.,PetroChina,Hangzhou,Zhejiang 310023,China)

机构地区：[1]山东大学,山东济南250061 [2]中国石油勘探开发研究院,河北廊坊065007 [3]中国石油浙江油田分公司,浙江杭州310023

出　　处：《石油与天然气地质》2018年第6期1087-1106,共20页Oil & Gas Geology

基　　金：国家油气重大专项(2017ZX05035)

摘　　要：为明确南方海相页岩沉积与古地理演化关系,以中、上扬子地区晚奥陶世—兰多维列世沉积的页岩为研究对象,以24口页岩气井笔石地层划带资料为重点,配合GBDB数据库中的露头剖面信息,综合前人资料,按照相-亚相-微相划分,结合沉积物、沉积环境、地化参数及测井特征,总结出陆棚、潮坪及三角洲3种沉积相、8种亚相以及相应的多种微相的划分方案。明确中、上扬子地区总体处于隆起围限的局限低能陆表浅海环境,其中页岩储层沉积有利相带为局限深水陆棚相。以年代地层"阶"为单位,"优势相"为方法和覆盖全区的沉积相剖面/钻井为控制点,有效推测各时期隆起边界变化情况,重建中、上扬子地区凯迪期、赫南特期、鲁丹期和埃隆期4个连续断代岩相古地理格局;以"阶"为标尺卡准各时期笔石页岩段厚度,明确各期沉积体系时空展布及页岩分布规律。黑色页岩发育受控于全球海平面上升、区域构造运动和古地理格局3种因素。页岩厚度明显受控于隆-坳相间格局,沉积模式为"两隆夹一凹"型:页岩气富集区被"两隆"所夹持,位于"一凹"之中。靠近隆起区,笔石带发生不同程度缺失,不利于页岩气的开发,页岩气作业应尽量避开远离笔石页岩发育先天不足的隆起区。We studied the shale deposited during the Late Ordovician-Early Silurian in Upper and Middle Yangtze regions to investigate the link between paleogeographic evolution and marine shale deposition in southern China.The graptolite-bearing shales from 24 shale gas wells that can be used to stratigraphic division are the focus of the study.Combined with the outcrop data from the GBDB database and previous data,we proposed the classification scheme in the facies-sub-fa-cies-micro-facies sequence,that is three sedimentary facies(continental shelf,tidal-flat and delta),including eight sub-facies and several micro-facies,according to the characteristics of sediments,sedimentary setting,geo-chemical parameters and logging data.It’s made certain that during the Late Ordovician-Early Silurian,the Upper and Middle Yangtze regions were in a restricted low-energy epicontinental shallow sea environment surrounded by paleo-uplifts,and the favorable se-dimentary facies zones for shale reservoirs therein were the restricted deep shelf facies.The lithofacies paleogeographic framework of the Katian,Hirnantian,Rhuddanian,Aeronian stages in a row for the study area was reconstructed by taking the sedimentary facies profile/wells covering the whole region as controlling points,employing the“favorable facies”approach and taking chronostratigraphic“stage”as the research unit,and thus the boundaries of paleo-uplifts during va-rious stages can be predicted effectively.The thicknesses of graptolite-bearing shale intervals were accurately measured by taking the“stage”as the ruler,and the temporal-spatial distribution of sedimentary systems and shale distribution pattern in each stage were summarized.The results suggest that the distribution of black shales is controlled by global sea-level rise,regional tectonic movement and plaeogeographic framework,while the thickness of black shales is apparently controlled by the pattern of alternating uplifts and depressions.The depositional model is a type of“one depression entrapped by

关 键 词：笔石 隆-坳相间 岩相古地理演化 页岩沉积模式 页岩气 晚奥陶世-早志留世 中、上扬子地区 

分 类 号：TE121.3[石油与天然气工程—油气勘探]