鄂尔多斯盆地天环凹陷北段奥陶系桌子山组白云岩形成机理

发布时间：2018-05-11 15:30

本文选题：鄂尔多斯盆地 + 桌子山组　；参考：《成都理工大学》2017年硕士论文

【摘要】：白云岩是研究区石油和天然气优质储层之一,因此,白云岩及其成因研究在碳酸盐岩储层研究中占有重要的地位。鄂尔多斯盆地西北部桌子山组白云岩是油气勘探有利的热点,本文以沉积学、储层地质学、地球化学理论为指导,结合区域地质资料、岩芯、薄片等资料,研究了桌子山组沉积相特征和地球化学特征,探讨其形成机理,取得了以下几点认识:1)对桌子山组白云岩进行显微鉴定并根据成因-结构分类:主要有粉-微晶白云岩、残余砂屑细晶云岩和细-中晶白云岩,白云石主要为平直晶面自形晶-他形晶,阴极发光总体偏暗。2)通过常、微量元素、稀土元素、C-O同位素、Sr同位素地球化学资料及包裹体均一温度分析鄂尔多斯天环凹陷白云岩形成温度不高,白云岩化流体是海水或具有源流体特色。3)根据样品分析测试数据表明桌子山组粉晶白云岩在准同生时期是受大气淡水的影响,经过上覆地层的埋藏压实提供海源Mg2+和西部逆冲带的压力使在地层海源Mg2+横向运移,成岩后期与外界隔绝,主要是受地层海源流体的侵染改造,白云岩成因主要是混合水白云岩化作用和埋藏白云岩化作用。
[Abstract]:Dolomite is one of the high quality oil and gas reservoirs in the study area, so the study of dolomite and its genesis plays an important role in the study of carbonate reservoir. The dolomite of Changshan formation in northwestern Ordos Basin is a favorable hot spot for oil and gas exploration. This paper is guided by the theory of sedimentology, reservoir geology and geochemistry, combined with regional geological data, core, thin slice and so on. The sedimentary facies and geochemical characteristics of the Taijiaoshan formation are studied, and the formation mechanism is discussed. The microscopical identification of the dolomite of the Taoshan formation is obtained as follows: there are mainly powder-microcrystalline dolomite. The residual sand microcrystalline dolomite and fine-mesocrystalline dolomite, dolomite are mainly orthomorphic, cathodoluminescence (cathodoluminescence) passing through normal, trace elements, Geochemical data and inclusion homogenization temperature analysis of rare earth elements in C-O isotope and Sr isotopes; the formation temperature of dolomite is not high in Tianhuan sag, Ordos. The dolomitization fluid is seawater or has the characteristics of the source fluid. 3) according to the sample analysis and test data, it is shown that the dolomite of the Taijiaoshan formation was influenced by atmospheric fresh water during the quasi-syntectic period. The buried compaction of the overlying strata provides the pressure of the sea source Mg2 and the western thrust zone for the lateral migration of the Mg2 in the stratigraphic sea source, and the late diagenesis is isolated from the outside world, which is mainly caused by the invasion and transformation of the sea source fluids. The origin of dolomite is mainly mixed water dolomitization and buried dolomitization.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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