锶同位素在塔河古岩溶期次划分中的应用

THE APPLICATION OF STRONTIUM ISOTOPES IN DIVISION OF PALEOKARST STAGES IN TAHE OIL FIELD

张涛 云露 邬兴威 叶德胜

Zhang Tao Yun Lu Wu Xingwei Ye Desheng

中国石化石油勘探开发研究院, 北京, 100083 2. 西北石油局规划院, 乌鲁木齐, 830011 3. 中国地质大学, 北京, 100083

Research Institute of Exploration & Production, SINOPEC, Beijing 100083, China 2. Design and Planning Institute of Northwest Petroleum Bureau, SINOPEC, Urumqi, Xinjiang 830011, China 3. China University of Geoscience, Beijing 100083, China

塔河油田主要是与不整合面有关的奥陶系碳酸盐岩岩溶缝洞型油藏,储层经历多期岩溶作用的叠加改造,因此岩溶期次的划分识别与不同期次岩溶分布范围的确定对塔河油田下一步勘探至关重要.通过近几年的探索,认为锶同位素比值是区分加里东中期和海西早期岩溶的一种有效方法,其应用原理是,地质历史中的任何时间全球范围内海水的锶同位素组成都是均一的,海水87Sr/86Sr比值随时间变化.结合塔河地区加里东期与海西早期岩溶地层水中87Sr/86Sr比值存在差异的地质背景和实验分析数据,可以对塔河古岩溶期次进行识别预测,探讨其分布模式,为塔河油田外扩提供地质依据.

Tahe oilfield is an Ordovician carbonate rock fissure vug oil pool which is mainly related to unconformity.Its reservoir rock is reformed by superimposition of multistages karstification,so it is very important to identify paleo-karstification stages and confirm distribution of different stage of karstfication reservoir for further exploration.Through recent years exploration,it is thought that the ratio of 87Sr/86Sr is an effective indicator distingishing middle Caledonian stage of karstification reservoir from early Hercynian stage of karstification reservoir.Its theory is that strontium isotope composition in the global ocean water at any one time in geologic history is homogeneous,that is,87Sr/86Sr value in ocean water changes timely.Combined with the geological setting that 87Sr/86Sr value in Caledonian stage of karstification reservoir is different from 87Sr/86Sr value in Hercynian stage of karstification reservoir and the experimental data,Pa-leokarstification reservoir stages is identified and predicted,and distribution pattern in Tahe oilfield is discussed in the paper,which provides geological evidence for further petroleum exploration in Tahe oilfield.

“十五”国家科技攻关项目(2003BA613A-03-01).

https://doi.org/10.11781/sysydz200503299