摘要
页岩储层研究已经成为页岩气研究的重点,页岩组构特征的特殊性使得页岩储层发育纳米/微米级孔隙。岩石及矿物中的纳米/微米级空隙是黔北黑色页岩的结构组分之一,传统的光学显微镜方法由于分辨率及放大倍数的限制无法对页岩储层的孔隙类型进行观察;核磁共振等仪器虽能准确测试页岩储层的孔隙度,但是无法获得孔隙的形貌及分布特征等信息。本文整合扫描电镜微区分析与X射线谱学分析的优点,运用Hitachi S-4800型场发射扫描电镜与IE250X-Max50牛津能谱仪组合,对黔北黑色页岩储层中矿物的分布、形态特征及矿物的组成元素进行分析测试。分析结果表明,利用场发射扫描电镜发现黑色页岩中发育微裂缝、纳米/微米级粒内溶孔;通过X射线能谱发现黑色页岩矿物主要有伊利石、石英、钠长石,其次为绿泥石、白云母、白云石等。黔北黑色页岩中裂隙直径为 0.1~20 μm,其中主要分布在1~5 μm,均大于甲烷分子直径(0.414 nm),因此可作为天然气的运移通道与储集空间。此外通过X射线能谱仪对黔北黑色页岩中的石英、方解石、白云石、伊利石等脆性矿物进行分析,发现石英的含量(9.1%~78%)较高,伊利石(17.6%~25.5%)等黏土矿物含量较低,所以该页岩具有很高的脆性,易产生裂缝,可为游离气提供运移通道及储集空间,提高页岩气的产能及储量,进而为黔北地区储层评价及预测等提供依据。
Shale reservoir research has become a focus in the study of shale gas, and the special structure feature of shale development at the nano/micro level pore size. Guizhou is one of the shale gas test pilot areas in our country. The northern region under the lower Cambrian Niutitang group hosts more than 100 m of black rock series. The nano/micron level pore in rocks and minerals is a typical structure for black shale in northern Guizhou. According to the limitation of resolution and magnification, the pore types in the shale reservoir cannot be observed using the traditional optical microscope. Nuclear magnetic resonance instruments can accurately study shale reservoir porosity, but cannot obtain the pore morphology and distribution of information. By combining the advantages of Scanning Electron Microscopy (SEM) and X-ray Spectrometry microanalysis, Hitachi S-4800 type of field emission SEM and Energy Spectrometer of Oxford IE250X Max50 to study mineral distribution, morphological characteristics and element composition in the black shale reservoir, a new study was conducted and is reported in this paper. Results indicate that micro fracture and nano/micro level intragranular dissolved pore were found in black shale using field emission SEM. Through the X-ray Energy Spectrum, minerals in black shale are mainly illite and quartz, albite, followed by chlorite, white mica, dolomite, to name a few. The black shale fracture diameter is 0.1-20 μm, which is mainly distributed in 1-5 μm, which is greater than the methane molecule diameter (0.414 nm). Thus, it can be used as a gas migration channel and storage space. In addition, through the X-ray Spectrometer study on the brittleness mineral analysis in quartz, calcite, dolomite and illite, the brittle mineral content of quartz contains 9.1%-78%, and the clay mineral content of illite is 17.6%-25.5%. Therefore, the black shale has high brittleness, making it prone to cracking. The study can provide the basis for reservoir evaluation and prediction of Northern Guizhou.
出处
《岩矿测试》
CAS
CSCD
北大核心
2014年第5期634-639,共6页
Rock and Mineral Analysis
基金
沉积岩岩石矿物鉴定现代检测技术方法研究(201011029-1)
关键词
黔北
牛蹄塘黑色页岩
扫描电镜
X射线能谱仪
形态特征
矿物组成
Northern Guizhou
black shale of Niutitang
Scanning Electron Microscopy
Energy Dispersive X-ray Spectrometer
speciation characteristics
mineral composition