塔里木盆地下寒武统肖尔布拉克组储层成因  

Origin of Reservoirs in the Lower Cambrian Xiaoerbulak Formation,Tarim Basin

作　　者：魏天媛 蔡春芳[1,2,3] 扈永杰 刘大卫 蒋子文 WEI TianYuan;CAI ChunFang;HU YongJie;LIU DaWei;JIANG ZiWen(Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Institutions of Earth Science,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;SINOPEC International Exploration and Production Corporation,Beijing 100029,China;Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 102206,China)

机构地区：[1]中国科学院地质与地球物理研究所,中国科学院新生代地质与环境重点实验室,北京100029 [2]中国科学院地球科学研究院,北京100029 [3]中国科学院大学地球与行星科学学院,北京100049 [4]中国石化集团国际石油勘探开发有限公司,北京100029 [5]中国石化石油勘探开发研究院,北京102206

出　　处：《沉积学报》2023年第2期527-544,共18页Acta Sedimentologica Sinica

基　　金：国家科技重大专项(2017ZX0508-003-040)。

摘　　要：在深层—超深层碳酸盐储层仍有大量油气出现,但优质储层成因尚不明确。通过对塔里木盆地寒武系肖尔布拉克组典型井和露头样品进行岩石学观察,总结出主要发育四类岩石类型:微生物岩、颗粒云岩、晶粒云岩和泥晶灰岩。根据阴极发光、流体包裹体测试、碳酸盐矿物碳氧同位素测试,认为上述白云岩基质形成于弱氧化海水;近地表—浅埋藏环境下则主要形成细晶白云石胶结物;深埋藏条件发育中粗晶白云石胶结物和鞍形白云石。随着埋深增大,白云石δ18O呈现降低的趋势,反映形成温度升高,但都具有较正的δ13C。方解石由于烃类并入,具有负偏的δ13C(-4.07‰±0.92‰),为热化学硫酸盐还原(TSR)成因。原位微量稀土测试显示成岩流体从早期到晚期:从具有海水特征的配分曲线逐步演化为中稀土富集,最终变为轻稀土富集的模式,反映了从海水为主的孔隙水演化为热流体为主的孔隙水的过程。定量统计表明热液溶蚀可提高储层3%的面孔率,最大孔隙度达10%。根据沉积—成岩改造类型,划分出三类优质储层:热液/大气水改造的凝块石储层、热液/TSR改造的浅滩相颗粒云岩储层、TSR改造的膏盐相关白云岩储层。该研究为塔里木盆地寒武系碳酸盐岩油气勘探提供了有利的指导,有助于理解深层—超深层优质白云岩储层成因。Well-developed deep-time and deep-burial dolostone reservoirs are currently sedimentlogical research top⁃ics in petroleum exploration,for example in the Sichuan and Tarim Basins in China,and the South Oman Salt Basin.Due to the influence of sedimentary environments and constructive diageneses,ancient deep and ultra-deep dolostone(>4500 m)have demonstrated high-quality reservoir properties in some case studies.The porosity of some intervals is up to 10%⁃20%,producing oil and gas of industrial standard,and are of great importance in hydrocarbon explora⁃tion.However,our understanding of the genesis of the pore structures of deeply buried dolostone reservoirs is still lim⁃ited:are they generated from later diagenesis,or are they preserved sediments retaining early diagenetic pores?Dis⁃tinguishing between these two types of pores and explaining their formation mechanisms is a controversial and muchdebated topic in sedimentology.The Cambrian Xiaoerbulak Formation underwent long periods of deep burial settings,to a maximum burial depth of 6000 m.This formation is characterized by the complexity of the diagenesis of dolos⁃tone and the heterogeneity of the reservoirs.In addition,they are associated with many different microbialite types.Overall,this suggested that the Xiaoerbulak Formation is a suitable case for solving the debated issue of late microbi⁃alitic dissolution.For this reason,the Cambrian Xiaoerbulak Formation in the Tarim Basin was selected as the re⁃search object,and the rocks from typical wells and field profiles were carefully selected and used in a variety of ad⁃vanced experiments,comprising multi-scale geological and geochemical methods included microscopic observation of rocks and minerals,stableδ13C andδ18O isotope analysis,and in-situ trace element and rare earth element analyses.Combined with basic data from previous sedimentological studies,this paper attaches importance to the analysis of fluid⁃rock interactions and solves deep and ultra-deep issues such as the evolution of di

关 键 词：塔里木盆地 肖尔布拉克组 白云岩储层 成岩流体 热液 TSR 

分 类 号：P618.13[天文地球—矿床学]