羌塘盆地西北部中侏罗统布曲组地层沉积特征  

Lithofacies paleogeographic characteristics of the Middle Jurassic Buqu Formation in the northwest Qiangtang Basin

作　　者：刘中戎 陈孔全[2] 范志伟 韩京 吴浩 何志勇 张斗中 庞一桢 马帅 LIU Zhongrong;CHEN Kongquan;FAN Zhiwei;HAN Jing;WU Hao;HE Zhiyong;ZHANGDouzhong;PANG Yizhen;MA Shuai(Petroleum Exploration and Development Branch,SINOPEC,Chengdu 610041,China;Cooperative Innovation Center of Unconventional Oil and Gas,Yangtze University,Wuhan 430100,China;School of Geosciences,Yangtze University,Wuhan 430100,China)

机构地区：[1]中国石油化工股份有限公司勘探分公司,四川成都610041 [2]长江大学非常规油气湖北省协同创新中心,湖北武汉430100 [3]长江大学地球科学学院,湖北武汉430100

出　　处：《沉积与特提斯地质》2025年第1期1-13,共13页Sedimentary Geology and Tethyan Geology

基　　金：中国石油化工股份有限公司科技部项目“羌塘盆地油气资源潜力分析与勘探关键技术”课题2“羌塘盆地油气成藏条件研究与目标评价”(P22197);中国石油化工股份有限公司勘探分公司项目“羌塘盆地中生界沉积储层特征与区带优选”。

摘　　要：中侏罗统布曲组是羌塘盆地油气勘探的重要层位,在野外地质调查期间,发现羌塘盆地西北部发育了一套优质白云岩储层。由于前期区内勘探工作较少,地层沉积特征分析仍是实现羌塘盆地西北部中侏罗统布曲组油气勘探突破的重要因素。本文基于野外剖面岩性观察和岩石薄片鉴定,总结出了区内发育的七种典型岩相组合类型,继而分析区内布曲组发育的沉积相类型及其展布特征。结果表明:(1)羌塘盆地西北部中侏罗统布曲组从南往北依次发育开阔台地亚相、台地边缘亚相、斜坡亚相、浅水陆棚亚相四种沉积亚相,可进一步细分为七种次相。(2)基于中侏罗统布曲组沉积相平面展布特征,明确其为典型镶边碳酸盐岩台地沉积模式,并建立了“开阔台地—台地边缘—斜坡—陆棚”的沉积模式。(3)结合区内三叠系至侏罗系地层垂向叠置关系,可进一步明确区内阿堵拉组(T_(3)a)、布曲组(J_(2)b)和索瓦组(J_(3)s)暗色泥岩作为烃源岩与布曲组白云岩、生物礁灰岩储层,以及布曲组上部泥晶灰岩、夏里组泥岩和膏岩盖层之间形成良好的配置关系,为羌塘盆地西北部中侏罗统布曲组的油气突破提供理论支撑。The Buqu Formation of the Middle Jurassic is an important horizon for oil and gas exploration in the Qiangtang Basin.During the field geological survey,a set of high-quality dolomite reservoirs was discovered in the northwest Qiangtang Basin.Due to the lack of exploration work in the early stages,the analysis of sedimentary facies characteristics remains an important factor for achieving breakthroughs in oil and gas exploration in the Middle Jurassic Buqu Formation of the northwest Qiangtang Basin.Based on field section lithology observations and rock thin section identification,seven typical types of lithofacies assemblage developed in the area are summarized,and the sedimentary facies types and distribution characteristics in the Buqu Formation are analyzed.The results show that:(1)From south to north,the Middle Jurassic Buqu Formation develops four types of sedimentary subfacies,namely the open platform subfacies,the platform margin subfacies,the slope subfacies,and the shallow water shelf subfacies,which can be further subdivided into seven types of suborder facies.(2)Based on the planar distribution of sedimentary facies of the Buqu Formation in the Middle Jurassic,the sedimentary model is defined as a typical rimmed carbonate platform with a sedimentary model from"open platform"to"platform margin","slope",and"shelf".(3)Combined with the vertical superposition relationship between the Triassic and Jurassic strata in the area,it can be further determined that the combination of source-reservoir-seal form with the dark mudstone of the Adula Formation(T_(3)a),the Buqu Formation(J_(2)b),and the Suowa Formation(J_(3)s)as source rocks,the dolomite and bioreef limestone of the Buqu Formation as reservoirs,along with the micritic limestone of the upper Buqu Formation and the mudstone and gypsum of the Xiali Formation as seals.It provides theoretical support for breakthroughs in oil and gas exploration in the Middle Jurassic Buqu Formation of the northwest Qiangtang Basin.

关 键 词：羌塘盆地西北部 布曲组 白云岩 岩相组合 沉积模式 

分 类 号：P618.13[天文地球—矿床学]