摘要
This paper deals with mudstone sampled from the first member of the Cretaceous Qingshankou Formation in the Songliao Basin.We qualitatively and quantitatively investigated characteristics of its micropores using scanning electron microscope(SEM),field-emission SEM(FE-SEM),gas adsorption and high-pressure mercury-injection methods.The results indicate that there are mainly five pore types in the mudstone,including matrix intercrystal,organic,dissolution,intergranular and intracrystal pores as well as micron to nano microfissures.Pores in the mudstone are mainly composed of micropores and meso-pores with pore volume generally ranging from 0.001 8 to 0.030 0 mL/mg,specific surface area from 0.91m2/g to 31.02m2/g and porosity from 1.2% to 3.9%.It is believed that compositions and concentrations of various minerals in the mudstone determine,to a certain extent,development of micropores.For instance,the mudstone porosity increases with increasing content of organic matter(OM),illite or pyrite but decreases with increasing content of chlorite,quartz,calcite or anorthose.Moreover,the mudstone porosity has a poor correlation with content of kaolinite,indicating that abundance of kaolinite may not affects variations of mudstone porosity.