Influences of Feldspars on the Storage and Permeability Conditions in Tight Oil Reservoirs: A Case Study of Chang-6 Oil Layer Group, Ordos Basin
详细信息
- 责任者：Xu Lei (School of Earth and Space Sciences ; Peking University ; Beijing 100871 ; China) ; Shi Yongmin
- 刊名：Petroleum Exploration and Development
- 出版年：2013
- 卷期：40(4)
- 关键词：储集层 ; reservoirs ; 鄂尔多斯盆地 ; Ordos Basin
- 页码：p.448-454
- 图表：illus., 2 tables, 14 refs.
- 分类号：1003
- issnNo：ISSN1000-0747
- isbnNo：CN11-2360/TE
摘要
Based on rock thin slice observation,casting thin slice identification,high-pressure mercury injection,constant velocity mercury injection,and X-ray diffraction,influences of feldspar minerals on the storage and permeability conditions in Chang-6 oil layer group in the Yanchang Formation of the Ordos Basin were studied from crystallography and mineralogy perspective through high resolution field emission CMOS scanning election microscope observation and analysis.Due to the differences of crystal structure and chemical composition,the brittleness and solubility of feldspar minerals varied greatly.The results indicate that basic plagioclase such as anorthite tends to split along the cleavage to form the new flow channel in the formation conditions.Alkaline feldspar rich in potassium such as K-feldspar tend to corrode along the cleavage to form secondary porosity.The brittleness and solubility of acid plagioclase,such as albite,are between anorthite and K-feldspar.The main pore type in Chang-6 oil layer group of Ordos Basin is residual inter-granular pore,the secondary pores generated by corrosion and fracture of feldspar have little contribution to porosity.In the area with higher content of anorthite,the micro-crack resulted from breaking in cleavage effectively improve the permeability.The contribution of feldspar minerals to permeability is ranked from great to small as anorthite,orthoclase and albite.