摘要
鄂尔多斯盆地东部地区太原组储层为典型的致密砂岩储层,其黏土矿物含量高,对储层评价和天然气勘探均具有重要影响。在岩相学和地球化学分析的基础上,对研究区储层黏土矿物特征及成因进行了研究。结果表明:研究区太原组储层黏土矿物主要为伊利石和高岭石,二者均表现出蚀变成因特征;伊利石具有高Al_2O_3和K_2O含量及低FeO和MgO含量的特征,高岭石的Al_2O_3含量明显高于典型高岭石的Al_2O_3含量;伊利石和高岭石Sr/Ba值均小于1,都表现为LREE富集、HREE亏损,REE配分模式表现为"右倾型",具有一定的δEu和δCe异常特征。岩相学产状及其地球化学成分研究表明,伊利石和高岭石均为热水蚀变形成的自生黏土矿物。结合上古生界构造埋藏史和自生成岩矿物序列分析认为,热水蚀变成岩作用源于早白垩世鄂尔多斯盆地发生的热异常事件;煤系烃源岩热演化所形成的含烃流体进入太原组储层砂岩,引发热水蚀变作用,形成大量伊利石和高岭石等自生矿物。
Taiyuan Formation in eastern Ordos Basin is typical tight sandstone reservoir, with high content of clay minerals, so it has great influence on reservoir evaluation and natural gas exploration. Based on the analysis of petrography and geochemistry, the characteristics and origin of clay minerals of sandstone reservoir of Taiyuan Formation in eastern Ordos Basin were studied. The result shows that the reservoir sandstone of Taiyuan Formation is with high content of clay minerals, which is mainly of illite and kaolinite. The illite is characterized by high content of Al2O3 and K2 O and low content of FeO and MgO, and the Al2O3 content of kaolinite is more than that of typical kaolinite. Sr/Ba ratio of illite and kaolinite is less than 1. Meanwhile, illte and kaolinte are enriched in LREE, depleted in HREE, characterized by downwards sloping and some extent of 8 Eu and δ Ce anomaly. Petrographical and geochemical characteristics show that illites and kaolinites are all related with hydrothermal fluid. Combined with tectonic-burial history and authigenic diagenetic minerals sequences, it is revealed that hydrothermal diagenesis began with the early Cretaceous thermal anomaly in Ordos Basin. Hydrocarbon fluid formed by thermal evolution of coal-bearing source rocks came into resmwoir sandstone of Taiyuan Formation, which leads to the hydrothermal alteration to form large quantity of ilhes, kaolinites and other authigenic minerals.
出处
《岩性油气藏》
CSCD
北大核心
2016年第1期49-57,共9页
Lithologic Reservoirs
基金
国家自然科学基金项目"单个流体包裹体CO2碳同位素显微激光拉曼光谱分析研究"(编号:41173055)资助
