Abstract: In order to reveal the characteristics of micro pore structure and distribution of remaining oil in water drive low permeability carbonate reservoir, by taking a certain porous carbonate reservoir in the Middle East as an example, based on the reservoir physical property test, constant velocity mercury injection pore throat parameter statistics, CT scanning pore parameter analysis, and the micro distribution of water drive fluid, etc., the development of the micro pore and throat in porous carbonate reservoirs was studied. On this basis, the research results of the porous carbonate and sandstone reservoirs were compared, and the differences of the pore structure and remaining oil distribution between these two types of reservoirs were further clarified. The results show that compared with the low permeability sandstone reservoir, the low permeability carbonate reservoir presents the characteristics of "large pores but small quantities" and "large number and all types of throats". The characteristic model of pore throat development of porous carbonate reservoirs is established. In view of the particularity of the micro pore structures, the remaining oil in the large pores of the low permeability carbonate reservoir is worthy of further study, as well as the way to tap the remaining oil potential.

Key words: Middle East, pore type, carbonate rock, reservoir, remaining oil