Reservoir characteristics of Ma 5_(1+2) sub-member of the Ordovician Majiagou Formation in Gaoqiao area,Ordos Basin

Based on cores,cast thin sections,scanning electron microscope,mercury injection data,this paper studied the reservoir characteristics of Ma 51+2 sub-member of the Ordovician Majiagou Formation in Gaoqiao area.The result shows that the types of reservoir rock are mainly of dissolved dolomite,mud powder crystal dolomite,followed by grain(sand clastic) dolomite and brecciated dolomite.The main reservoir pore types are mainly dissolved pores,intercrystal pores,intercrystal dissolved pores,followed by gypsum mould pores and fractures.The properties of reservoir rocks are poor,the average porosity is 3.26%,and the average permeability is 1.2 mD.With strong heterogeneity,it is totally a low permeability and low porosity reservoir.The study of reservoir characteristics can provide geologic basis for the further exploration and development in this area.