鄂尔多斯盆地中部奥陶系马五盐下沉积环境与海平面变化

发布时间：2018-12-09 17:15

【摘要】：鄂尔多斯盆地中部奥陶系马家沟组赋存有丰富的天然气资源,前人研究多集中于顶部与风化壳相关的储集层。文中基于岩心、薄片及阴极发光分析,将鄂尔多斯盆地中部奥陶系马五盐下碳酸盐岩-蒸发岩划分为10种岩石类型。根据各岩类的宏观、微观特征以及它们在纵横向上的组合与分布特点,利用岩石类型组合的方法,将研究区划分为局限-蒸发o_湖、台内滩、滩间海、微生物丘和台坪5种沉积环境。根据各亚段岩石类型发育的差异性及统计结果发现,研究区马五盐下具有蒸发岩与碳酸盐岩间互的旋回性沉积演化与海平面升降特征,每个亚段都代表一次海侵或海退的旋回沉积。其中,马五6、马五8和马五10亚段为海退期沉积,以纹层状云质膏岩、泥晶云岩构成的局限-蒸发o_湖沉积为主,蒸发岩矿物含量高,反映沉积环境相对闭塞、能量较低且盐度较高;马五7和马五9亚段为海进期沉积,以相对高能的台内滩或微生物丘沉积为主,并与相邻的局限-蒸发o_湖和台坪沉积构成较完整的向上变浅米级沉积旋回,表明该阶段水体循环相对更好,整体沉积环境开阔且能量较高。
[Abstract]:There are abundant natural gas resources in the Ordovician Majiagou formation in the central Ordos Basin. Based on core, thin slice and cathodoluminescence analysis, the carbonate rocks and evaporites of Ordovician in the middle part of Ordos Basin are divided into 10 rock types. According to the macroscopical and microscopic characteristics of each rock group and their combination and distribution in vertical and horizontal direction, the study area is divided into limit-evaporative och, flat and interbeach by using the method of rock type combination. Five sedimentary environments of microorganism mound and platform. According to the differences of rock types and statistical results of each submember, it is found that there are cyclic sedimentary evolution and sea level rise and fall characteristics between evaporite and carbonate rock under Ma Wu salt in the study area. Each submember represents a cyclic deposit of transgression or regression. Among them, Ma Wu 6, Ma Wu 8 and Ma Wu 10 were deposited in the regressive period, mainly composed of lamellar dolomite and mud-crystal dolomite. The evaporite mineral content is high, which shows that the sedimentary environment is relatively closed. Lower energy and higher salinity; The Ma-57 and Ma-9 submember are marine sedimentary periods, which are dominated by relatively high energy deposits in the flat or microbe hills, and together with the adjacent limit-evaporative oghu and Taiping sediments form a relatively complete upward shallow meter scale sedimentary cycle. The results show that the water circulation is better, the whole sedimentary environment is open and the energy is higher.
【作者单位】：中国石油长庆油田分公司勘探事业部;油气藏地质及开发工程国家重点实验室·西南石油大学;中国石油碳酸盐岩储层重点实验室沉积—成藏研究室·西南石油大学;中国石油川庆钻探工程公司长庆固井公司;
【基金】：国家科技重大专项(编号:2016ZX05004002-001,2016ZX05004006-001-002)资助~~
【分类号】：P618.13

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