川西南峨眉山玄武岩中蚀变绿泥石的成分特征及其地质意义  

Composition Characteristics and Geological Significance of Altered Chlorite in Basalt of Emeishan,Southwestern Sichuan

作　　者：任杰 郗爱华[1] 郑江 武浩宇 李亚 成炼 葛玉辉[1] 姜欢 Ren Jie;Xi Aihua;Zheng Jiang;Wu Haoyu;Li Ya;Cheng Lian;Ge Yuhui;Jiang Huan(School of Geosciences and Technology,Southwest Petroleum University,Chengdu 615000,China;PetroChina Changqing Oilfield Company,Xi’an 710016,China;Exploration and Development Research Institute,Petro China Southwest Oil&Gas Field Company,Chengdu 610950,China)

机构地区：[1]西南石油大学地球科学与技术学院,成都615000 [2]中国石油天然气股份有限公司长庆油田分公司,西安710016 [3]中国石油西南油气田分公司勘探开发研究院,成都610950

出　　处：《吉林大学学报（地球科学版）》2024年第3期877-889,共13页Journal of Jilin University：Earth Science Edition

基　　金：中石油西南油气田分公司项目(XNS14JS2019-029);中国地质调查局项目(DD20190159-30)。

摘　　要：在火山岩和碎屑岩储层中普遍发育大量绿泥石,影响着物性。为查明火山岩中蚀变绿泥石的成因及其对储层物性的影响,本次工作选取川西南峨眉山典型剖面、ZG1井、ZG2井以及YT1井等系列玄武岩样品进行岩相学研究和电子探针微区成分分析。结果显示:玄武岩中绿泥石大致可分为显晶质、隐晶质和微晶3种结晶类型,总体上属于富铁种属的铁斜绿泥石(辉绿泥石)和铁镁绿泥石,形成于富铁的还原环境;隐晶质与微晶和显晶质绿泥石分别受到岩浆期后热液和来自深部的多期次构造热液叠加蚀变的控制,形成主要表现为Fe^(2+)对Mg^(2+)的成分置换,反映流体具有从碱性向弱酸性-中酸性过渡的变化规律。绿泥石的形成过程对火山岩储集空间的影响具有双重作用:岩浆期后热液的充填结晶充填减少了火山岩原生孔隙并降低储层物性,对火山岩储层起到破坏性作用;多期次构造热液的溶蚀迁移沉淀则产生了新的微孔,对火山岩储层起到建设性作用。Previous research has shown that a large number of chlorites are commonly developed in volcanic and clastic rock reservoirs,which affects the physical properties of these reservoirs.In order to study the influence of the genetic mechanism of chlorite alteration in volcanic rocks on reservoir physical properties,a series of basalt samples from the typical section of Mount Emei,wells ZG1,ZG2 and YT1 were selected for petrographic research and micro-area composition analysis.The results show that chlorite in basalt can be roughly divided into three crystal types:Crystalline,cryptocrystalline and microcrystalline,and generally belonging to ferroan clinochlore(diabantite)and brunsvigite,formed in an iron-rich reducing environment.The rare earth element characteristics show that the three chlorite types result from the multi-stage superposition and transformation of hydrothermal fluids and tectonic hydrothermal fluids after the magmatic stage.During their formation process,it is mainly represented by the replacement of Fe^(2+)with Mg^(2+),reflecting a transition in fluid from alkaline to weakly acidic,following an intermediate acid acid variation law.The formation process of chlorites has a dual effect on the storage space of volcanic rocks:The filling and crystallization of hydrothermal fluid after the magmatic stage reduce the primary pores of volcanic rocks,thereby diminishing reservoir physical properties.Whereas the dissolution-migration of tectonic hydrothermal fluids generates new micropores,enhancing reservoir physical properties.

关 键 词：绿泥石 微区成分分析 峨眉山玄武岩 火山岩储层 川西南地区 

分 类 号：P58[天文地球—岩石学]