黔北地区茅口组古岩溶储层稀土元素地球化学特征  

Geochemical characteristics of rare earth elements in karst reservoirs in Maokou Formation,northern Guizhou Province

作　　者：王帅 王甘露[1] 秦政 高泽远 罗腾 Wang Shuai;Wang Gan-lu;Qin Zheng;Gao Ze-yuan;Luo Teng(College of Resources and Environmental Engzneering ,Guizhou University ,Guizhou 550025 ,China;Southwest Ezploration Company BGP ,CNPC ,Chengdu 610213,China)

机构地区：[1]贵州大学资源与环境工程学院,贵州贵阳550025 [2]中国石油东方地球物理公司西南物探研究院,四川成都610213

出　　处：《天然气地球科学》2019年第1期143-150,共8页Natural Gas Geoscience

基　　金：贵州省地勘基金项目"页岩气开发建设对区域水资源的需求及其影响评估"(编号:[2014]23)资助

摘　　要：黔北地区茅口组表生期及埋藏期岩溶缝洞体系发育良好。为研究古岩溶储层REE分布特征及意义,对黔北地区34个岩溶岩及胶结物样品进行稀土元素地球化学特征分析,研究表明:黔北地区样品∑REE值为(4.08～23.04)×10^(-6),平均为9.21×10^(-6),总体上呈LREE富集、HREE亏损的右倾型配分模式,表明在沉积、成岩过程中存在着富集LREE的相;样品δCe值为0.71～0.98,平均为0.85,指示其岩溶环境主要为渗流—潜流带的氧化性水流环境;δCe—∑REE图解表明,δCe与∑REE存在一定的线性正相关性,且随着岩溶作用的进行,∑REE逐渐减小,δCe值也随着减小,LREE分异作用越来越明显;δEu值为0.55～0.93,平均值为0.69,这与低温还原性质的古水文环境和晚二叠世早期黔北地区被岩浆多次侵蚀有关;(La/Yb)_N—∑REE图解表明,弱溶蚀段至强溶蚀段沉积速率不断增大;溶蚀强烈段沉积速率降低,随着岩溶作用的进行,指示研究区经历了海平面先降低再升高的古海洋环境。The experiment and analysis of REE were carried out on the rock samples of the Maokou Formation in northern Guizhou Province.The study showed that the REE value of the ancient karst rock samples in the northern Guizhou Province was(4.08-23.04)×10^-6,with an average of 9.21×10^-6,showing slightly right-diagonal REE pattern.The parameters of(La/Yb)N-∑REE show that with the progress of karstification,the enrichment of rare earth elements will decrease.The karst rocks of various genetic types have the feature that the migration rate of light rare earth elements is higher than that of heavy rare earth elements,and the differentiation of light and heavy rare earth elements will become more apparent;theδCe value of rock samples is 0.71-0.98,with an average of 0.85.The value ofδEu is 0.55-0.93 and the average value is0.69.The anomaly of Ce is much worse than that of Eu,indicating that the paleo-karst reservoirs in the northern part of Guizhou were mainly formed in the oxidative flow environment of the seepage-active subduction zone.

关 键 词：古岩溶 黔北 茅口组 稀土元素 储层 

分 类 号：TE122.113[石油与天然气工程—油气勘探]