摘要
鄂尔多斯盆地非常规油气资源丰富,盆地东部石炭系本溪组具有良好的非常规天然气勘探潜力。沉积环境是控制天然气资源分布的重要因素,因此以鄂尔多斯盆地东部石炭系本溪组重点全井段连续岩心为基础,通过对泥页岩地层矿物组成及元素地球化学特征的研究,揭示研究区本溪组泥页岩地层古沉积水体环境特征,探讨沉积相类型对泥页岩发育的控制作用。结果表明:本溪组古沉积水体盐度自下而上先减小后增大,为咸水—半咸水沉积环境;本溪组氧化—还原敏感参数自下而上呈现先增加后降低的趋势,整体反映出本溪组为缺氧—还原环境;古水深(Rb/Zr)研究表明,本溪组古水深自下而上由较小变大再逐渐变小,呈周期性变化;CaO/(Al_(2)O_(3)+MgO)、CIA等古气候指标反映了本溪组自下而上温度逐渐降低,风化程度逐渐减小,其中湖田段、畔沟段、晋祠段均为炎热潮湿气候。通过对比鄂尔多斯盆地东部本溪组泥页岩矿物组成、岩性组合、地球化学特征,认为本溪组泥页岩主要沉积类型为潮间带—潟湖沉积,且泥坪—潟湖混合沉积为本溪组富有机质泥页岩发育的有利沉积环境,并在此基础上对本溪组全段地层沉积模式进行综合分析,认为湖田段为风化淤化体系下的沼泽沉积,而畔沟段、晋祠段均为障壁海岸沉积体系,沉积环境分别为潮坪—潟湖—障壁岛混合沉积与潮坪—潟湖—障壁岛—沼泽混合沉积。
Benxi Formation of Carboniferous in the Ordos Basin has unconventional energy sources,and its sedimentary environment is complex and interactive.Therefore,through the analysis and testing of core samples of typical wells in eastern Ordos Basin,based on the observation of core samples,this study reveals the paleoclimate and the palaleobathymetry environment of shale in Benxi Formation,and discusses the control of sedimentary facies characteristics on the shale development.The results show that the salinity of the palaeobathymetry of Benxi Formation gradually decreases from smaller to bigger,and the salinity of the coal seam water at the top of Hutian Member to Jinci Member gradually changes from saline water to saline water reclamation;redox sensitive parameters(Th/U)of Benxi Formation decrease first and then increase from lower to upper.Hutian Member,Pangou Member and Jinci Member are anoxic environment,oxygen poor anoxic environment and weak redox environment,respectively.The study of ancient water depth(Rb/Zr)shows that the ancient water depth of Benxi Formation changes periodically from lower to upper,and then gradually back to lower again;CaO/(Al_(2)O_(3)+MgO),CIA and other paleoclimate indicators reflect that Benxi Formation has a hot and humid climate.We compared the mineral composition and lithologic combination characteristics of the mud shale under different sedimentary backgrounds of Benxi Formation in eastern Ordos Basin,and further divided the facies into swamp deposit,lagoon-tidal-flat-barrier island mixed sediments,and lagoon-tidal-flat-barrier island-swamp mixed sediments were developed in Hutian Member,Pangou Member and Jinci Member respectively.
作者
张力文
吴陈君
黄道军
文志刚
赵伟波
席颖洋
张辉
孙璐
宋换新
ZHANG Liwen;WU Chenjun;HUANG Daojun;WEN Zhigang;ZHAO Weibo;XI Yingyang;ZHANG Hui;SUN Lu;SONG Huanxin(Hubei Key Laboratory of Petroleum Geochemistry and Environment(Yangtze University),Wuhan 430100,China;China Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China)
出处
《天然气地球科学》
CAS
CSCD
北大核心
2022年第9期1485-1498,共14页
Natural Gas Geoscience
基金
中国石油长庆油田分公司科研项目“鄂尔多斯盆地中东部本溪组泥页岩地质特征及有利目标评价”(编号:技2020-151)资助
