长石族矿物对致密油储渗条件的影响——以鄂尔多斯盆地长_6油层组为例  

Influences of feldspars on the storage and permeability conditions in tight oil reservoirs:A case study of Chang-6 oil layer group,Ordos Basin

作　　者：徐蕾[1] 师永民[1] 徐常胜[2] 杨悦 李宏[2] 柴智[1] 

机构地区：[1]北京大学地球与空间科学学院 [2]中国石油新疆油田公司采油一厂 [3]陕西延安石油天然气有限公司

出　　处：《石油勘探与开发》2013年第4期448-454,共7页Petroleum Exploration and Development

基　　金：国家重点基础研究发展计划(973)项目(2009CB219302)

摘　　要：在岩石薄片观察、铸体薄片鉴定、高压压汞、恒速压汞及X射线衍射实验等多种测试分析基础上,通过高分辨率场发射万倍扫描电镜观察和分析,从结晶学和矿物学角度研究长石族矿物对鄂尔多斯盆地延长组长6油层组致密油储集层储渗条件的影响。由于晶体结构和化学组成差异,不同长石族矿物脆性和溶蚀的难易程度差别明显,地层条件下,钙长石等偏基性斜长石更易沿解理破裂形成新的渗流通道;钾长石等富钾的碱性长石更易沿解理溶蚀形成次生孔隙;钠长石等偏酸性斜长石的脆性和溶解性介于钙长石和钾长石之间。鄂尔多斯盆地长6油层组主要孔隙类型为残余粒间孔,长石溶蚀和破裂形成的次生孔缝对孔隙度贡献不大;研究区钙长石含量相对较高,其沿解理破碎形成的微裂缝有效改善了储集层渗流条件,长石族矿物对渗透率的贡献从大到小依次为:钙长石、钾长石等、钠长石。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.

关 键 词：鄂尔多斯盆地 长6油层组 致密油 长石 

分 类 号：TE122.2[石油与天然气工程—油气勘探]