鄂尔多斯盆地苏里格气田储层微观孔隙结构特征

Characteristics of Micro-pore Structure in Sulige Gasfield in Ordos Basin

通过物性分析、扫描电镜、铸体薄片、高压压汞、恒速压汞等技术对鄂尔多斯盆地苏里格气田低渗透砂岩储层样品进行了测试分析,研究了其微观孔隙结构特征。研究表明,苏里格气田低渗透砂岩储层的孔隙类型为溶孔、粒间孔、晶间孔、微孔,其中以前3种为主要孔隙类型。孔喉组合以小孔微细喉为主,最有利的孔喉组合类型为高孔-粗喉型和中孔-中喉型,喉道类型、大小及喉道分布控制着储层的渗透性。孔隙结构非均质性强、孔隙类型多样、粒间孔百分比低是储层渗透性差的主要原因;储层非均质性强的根源在于微观孔隙结构特征的不均一性。

By means of the physical property analysis, SEM, and casting slice, high pressure Hg injection, and rate-controlled Hg penetration, the low permeability sandstone samples of Sulige Gasfield in Ordos Basin were tested in order to analyze the micro-pore structure. The research shows the pore types consist of solution opening-intergranular pores, solution opening- intercrystal pores, corroded hollows and micro-fractures , predominated by the first three types of pores. The main pore-throat type is low pore-minuteness throat. The most favorable ones is the high and medium pore-coarse throat. The types of the pore- throat, their magnitude and distribution control the reservoir＇s permeability. The heterogeneity, the various pore-throats, and low proportion intergranular pores are the main reasons for the low reservoir permeability. The intense heterogeneity results from the irregularity of the micro-pore structure.