摘要
针对下志留统龙马溪组底部界线划分问题,在前人研究的基础上,通过对四川盆地及周缘地区的野外剖面和钻井岩芯的宏观与微观观察以及对录井、测井、分析化验等资料的分析,发现龙马溪组底部界线上下地层具有以下特征上的差异:五峰组顶部灰质含量较高,腕足类化石丰富,测井曲线上表现为低伽马高电阻率,TOC值较低,矿物组分中方解石含量较高;而龙马溪组底部不含灰质,不含腕足类化石,笔石化石丰富,测井曲线上呈高伽马低电阻率,高黏土和石英含量,TOC出现峰值。研究认为检测灰质含量和对比电测曲线是现场划分龙马溪组底界最快捷和准确的方法,能为四川盆地龙马溪组页岩气勘探提供一定的理论基础。
In order to solve the partitioning problem on the bottom boundary of lower Silurian Longmaxi Formation, based on previous researches, with the macroscopic and microscopic observation of outcrops and drilling cores and the analysis of well logging, mineralogical and geochemical data in Sichuan Basin and its peripheral areas, the differences between Longmaxi and Wufeng Formation show that there are higher limy content, many brachiopods, low GR and high RT logging values, high calcite content and lower TOC values in the top of Wufeng Formation, while the bottom of Longmaxi Formation have none limy content, none brachiopods and abundant graptolites, high GR and low RT logging values, high clay and quartz content, highest TOC values. The study suggested that the detection of limy content and comparison of log are the fast and accurate methods of demarcating Longmaxi Formation bottom boundary in practical operation, and it can provide some theoretical basis for furthermore shale gas exploration in Longmaxi Formation of Sichuan Basin.
出处
《西南石油大学学报（自然科学版）》
CAS
CSCD
北大核心
2014年第1期45-50,共6页
Journal of Southwest Petroleum University(Science & Technology Edition)
关键词
四川盆地
龙马溪组
底界
五峰组
下志留统
Sichuan Basin
Longmaxi Formation
bottom boundary
Wufeng Formation
lower Silurian
