鄂尔多斯盆地东北缘致密砂岩孔隙特征及其分类

Pore Characteristics and Classification of Tight Sandstone in the Northeast Margin of Ordos Basin

以压汞测试为主要手段,并辅以常规孔渗以及扫描电镜等测试,对鄂尔多斯盆地东北缘盒8段致密砂岩孔隙大小及结构特征进行了研究。结果显示:(1)孔渗测试评价盒8砂岩以超低渗-低孔隙度为主,且孔隙度与渗透率正相关;(2)扫描电镜下孔隙主要以纳米孔为主,孔隙发育程度低,岩石较致密;(3)压汞结果显示目标层位孔隙以中孔及小孔为主,少量大孔,部分地区微孔含量较高;(4)研究区致密砂岩孔隙结构类型多样,主要有双峰型、宽峰型、单峰递减型、单峰递增型四种类型。

He8 tight sandstone in northeast margin of Ordos Basin was target bed in this paper,in which the pore size and structur⁃al characteristics were studied mainly by the technology of high pressure Hg injection,combined with conventional porosity and perme⁃ability test and SEM.The results show that:1.The sandstone in He8 is composed of tight sandstones with ultra-low permeability and low porosity and there is a positive correlation between the porosity and the permeability;2.Results of SEM show that the pores types are mainly nanopores,the sand rocks have the characteristics of less pores and high density;3.The pores of He8 tight sandstone are mainly consisted of mesopores and small pores,with few large pores,but more micropores in some areas;4.The pores structure types are various,mainly including bimodal type,broad peak type,single-peak-decreasing type and single-peak-increasing type.