CHARACTERISTICS OF CARBONATE RESERVOIR IN THE QUM TROOP OF TERTIARY FROM KASHAN AREA, THE IRAN BASIN

The Tertiary stratum of Iran basin has thickly and broadly deposited great carbonate sediments.A study of carbonate reservoir of the Qum troop in Kashan area indicates that,reservoir distribution has a characteristic of thicker sediments in the south and east.The important reservoir mainly consists of micrite-sparite biological clastic limestone.In addition,primary and secondary pores are both developed in re-servoir space.Primary pore includes biological antrum pore,residual intergranular pore and intercrystalline pore,and secondary pore includes mould pore,intergranular solution pore and intercrystalline solution pore.Porosity is high with predominant penetrability.Lithogenesis is dominantly controlled by cementation and dissolution,and at the same time,tectonic fractures are apparent.Under microscope,oil and gas migration can be checked out easily,which proves that,the Qum troop carbonate rock of Tertiary in Ka-shan area is predominant natural reservoir.