Mineralogical and Geochemical Characteristics of Caprock Formations Used for Storage and Sequestration of Carbon Dioxide

The main objective of the present study is to characterize cap rock formation used for geological storage of carbon dioxide (CO2). The petrophysical properties of several rocks were studied before CO2 injection. This step is necessary for an understanding of CO2-brine-rock interactions. The mineralogical composition of several clay samples collected from real storage sites located in the south of Tunisia was determined by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) coupled to a probe EDS, infrared spectroscopy, thermal analysis and fluorescence spectra. The obtained experimental results reveal that illite, calcite and quartz are the dominant clay minerals. Dolomite and albite are also present. Besides, SEM analysis shows laminated structure for these samples which suggests low crystallinity. This sample contains a higher content of Fe, Cl, Ca and O. The clay cover may also be useful in storage process by immobilizing the migration of CO2 outer of the geological site and activating the process of mineral sequestration.

随钻X射线衍射分析录井技术应用研究

随着油气勘探的不断深入,勘探对象向地质条件越来越复杂的区块转移,以及钻井工艺方面PDC钻头、细齿三牙轮钻头、泡沫钻井、空气钻井等新技术的应用,岩性识别更加困难,传统的依靠肉眼通过放大镜观察识别岩性的方法已不能适应目前随钻岩性识别、实时建立地质岩性剖面的要求。针对这一现状,在详述X射线衍射分析基本原理的基础上,对比分析了YST-1型X射线衍射分析仪的技术特点;分别阐述了定性与定量分析方法;探讨了X射线衍射分析结合X射线荧光元素分析实现全井段全岩分析的途径及其各自优势与劣势。实例与综合分析表明,X射线衍射分析不但可定性分析岩屑矿物组成,而且可准确确定矿物含量,将其与X射线荧光分析结合应用,即可实现全井全岩分析,也可更准确地确定岩屑中各种矿物含量。

松辽盆地古龙页岩油储层岩性识别与流体评价技术

松辽盆地古龙页岩油储层岩性组合复杂、非均质性强、孔隙流体赋存状态多样,这些特殊性造成储层岩性精细识别及流体准确评价难度大。为了有效解决研究区岩性识别和流体评价的难题,综合应用宏观观察、元素分析、薄片鉴定等岩性识别技术,总结典型岩性各项技术响应特征,建立起页岩油岩性识别组合技术,实现页岩油储层岩性精细识别;选取能够评价轻质烃类的气测录井、轻烃分析、岩石热解分析等技术的关键参数,将评价参数分别赋予不同权重,建立页岩油储层含油性综合指数,应用综合指数对页岩油储层含油性进行准确评价,取得了较好效果。研究成果为松辽盆地古龙页岩油储层后期精细评价和“甜点”层段优选提供了重要的技术依据。

X射线衍射录井技术在渤海M构造岩性识别中的应用

渤海油田深层潜山界面存在深度预测误差大、岩性复杂以及岩屑细碎辨识难、岩性界面识别难等录井作业难题。通过X射线衍射全岩矿物分析(XRD)录井技术获取的矿物含量占比数据,归纳总结出三大岩类在矿物含量上的差异性规律,筛选出石英、长石、暗色矿物等敏感元素,通过不同矿物交会分析,建立了M构造火成岩、砂泥岩和碳酸盐岩不同岩性特征的图板。在岩性识别图板的基础上,拓展利用矿物含量纵向变化及矿物曲线组合交会法,准确判断地层及岩性界面位置,为潜山界面卡取,砂泥岩剖面划分和侵入岩等特殊岩性识别提供重要依据。新方法在该区块新钻探井的成功应用,为钻井施工安全、潜山界面卡取提供了坚实的技术保障。