雷东凹陷区域探井X1井变质砂岩基底元素变化特征及其指导意义  

The element characteristic variety of metasandstone basement of regionalexploration well X1 in Leidong Sag and the guiding significance

作　　者：莫国炎 张闻苑 陈沛 谢献辉 MO Guoyan;ZHANG Wenyuan;CHEN Pei;XIE Xianhui(Zhanjiang Branch of CNOOC EnerTech-Drilling&Production Co.,Guangdong Zhanjiang 524057,China;Zhanjiang Branch of CNOOC(China)Limited,Guangdong Zhanjiang 524057,China)

机构地区：[1]中海油能源发展股份有限公司工程技术湛江分公司,广东湛江524057 [2]中海石油(中国)有限公司湛江分公司,广东湛江524057

出　　处：《非常规油气》2023年第4期22-28,共7页Unconventional Oil & Gas

摘　　要：元素录井是解决当今PDC钻头钻井条件下粉末状岩性难以辨识、地层判断复杂及层间界面卡取等问题的一种录井方法。针对雷东凹陷区域风险探井变质砂岩基底岩性与上覆碎屑砂岩相似度高以及卡山难度大的问题,钻后运用元素录井数据展开归纳分析,总结出单井纵向上敏感元素的变化特征。结果表明:1)雷东凹陷区域探井X1井进入风化层后,易迁移元素Mg和Pb具有反向的变化规律,Mg相对富集,Pb显著流失;2)弱迁移元素Ni和惰性元素Cr存在富集趋势,但绝对值变化较小;3)找出了几种单元素和元素比值交会图,现场可通过快速投点来判断基底面。这些变化特征对该区后续钻探变质砂岩基底提供一种卡山思路,也对其他区块钻探变质岩基底有一定借鉴价值。The element logging is a method to solve problem such as difficult to identify lithology,complex formation judgment and the determination of interlayer interface under the condition of PDC bit drilling.In view of the high similarity between metasandstone basement and overlying clasolite in Leidong Sag and the difficulty in identifying buried hill interface,element logging data were used to sum up and analyze,the variation characteristics of sensitive elements in single well are summarize.The results show that:1)Mg and Pb,which belong to mobile elements,have a reverse change law,with Mg relatively enriched and Pb significantly lost,when drill into the regolith of exploration well X1 in Leidong Sag;2)There is an enrichment trend of the weak migrating element Ni and inert element Cr are enriched,but the change of absolute value is small;3)Several single element and element ratio crossplots are found,which can be used to determinate basement interfaces by quick spot.These characteristics provide a kind of accurately capturing basement interfaces idea for the future exploration of metamorphic sandstone basement in this area,and also have certain reference value for drilling metamorphic rock basement in other blocks.

关 键 词：元素录井 变质砂岩基底 敏感元素 交会图 

分 类 号：TE142[石油与天然气工程—油气勘探]