阿姆河盆地卡洛夫-牛津阶碳酸盐岩储层地球化学特征和成岩流体分析  

Geochemical characteristics and diagenetic fluid of the Callovian-Oxfordian carbonate reservoirs in Amu Darya basin

作　　者：郑荣才[1] 刘合年 吴蕾 陈仁金 史建南[1] 李凤杰[1] 

机构地区：[1]油气藏地质及开发工程国家重点实验室 成都理工大学,成都610059 [2]中国石油(土库曼斯坦)阿姆河天然气公司,巴格德雷

出　　处：《岩石学报》2012年第3期961-970,共10页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41172120);国家重大专项(2008ZX05030-003)联合资助

摘　　要：卡洛夫-牛津阶碳酸盐岩为土库曼斯坦阿姆河盆地主力天然气产层,以储层岩石学分析为基础,结合Fe、Sr、Mn微量元素和C、O、Sr同位素及流体包裹体地球化学特征,分析了储层成因和成岩流体性质,得出以下几点认识:(1)由厚壳蛤壳体测定的87Sr/86Sr比值在全球锶同位素地层曲线上可标定的年龄为157.2Ma,储层发育层位属于卡洛夫-牛津阶;(2)卡洛夫-牛津阶为一持续海侵-海退旋回,持续海侵期是礁、滩相储层形成期,而持续海退期为致密盖层发育期;(3)较高的Fe和Sr及较低的Mn含量,以及伴随成岩强度加大δ13C变化不大而δ18O向负值方向偏移的演化趋势,证明成岩作用发生在缺乏大陆淡水影响和以温度为主控因素的还原性封闭系统中;(4)综合同位素地球化学与流体包裹体和镜质体反射率特征,可确定洛夫-牛津阶碳酸盐岩仍处在中成岩阶段;(5)礁、滩相灰岩的溶蚀、埋藏白云化和充填缝、洞的方解石是不同成岩阶段的水-岩反应产物,成岩流体主要来自于深部富Sr的地层热卤水。The Callovian-Oxfordian carbonate rocks are the most important gas reservoirs in Amu Darya basin,Turkmenistan.Based on the reservoir petrology,the geochemical characteristics such as trace elements of Fe,Mn and Sr,isotopes of C,O and Sr and fluid inclusions,the genesis and diagenetic fluids of different carbonate reservoirs were analyzed.We got the following conclusions：（1） The rudists were calibrated at the age of 157.2Ma according to the global strontium isotope stratigraphy curve,and the reservoirs were at the age of Callovian-Oxfordian.（2） The Callovian-Oxfordian carbonates were a sustained transgressive-regressive cycle.The reef-bank facies well developed in the sustained transgression,while the regional dense caprocks developed in the sustained regression.（3） High concerntration of Fe and Sr,low concerntration of Mn,little changed δ13C and negative deviated δ18O with increased diagenesis implied that the diagenesis occurred in a closed and euxinic system which was devoid of meteoric water and were mainly controlled by temperature.（4） Combined with geochemical characteristicsof stable isotopes,fluid inclusions and the vitrinite reflectance,it was believed that the Callovian-Oxfordian carbonates are still at the stage of the middle diagenesis.（5） The dissolution of reef-bank limestones,burial dolomitization and calcites filling in fractures and vugs were all products from the interaction between the fluid and the rocks in different diagenetic phases.The diagenetic fluid was 87Sr-rich hot brine from the deep strata.

关 键 词：碳酸盐岩储层 微量元素 稳定同位素 地球化学 成岩流体 卡洛夫-牛津阶 阿姆河盆地 

分 类 号：P588.245[天文地球—岩石学]