Reservoir characteristics and main controlling factors of the fourth member of Ordovician Majiagou Formation in the central and eastern Ordos Basin

Recent exploration practice shows that the leopard porphyry dolomite reservoir in the fourth member of Ordovician Majiagou Formation in the central and eastern Ordos Basin has good exploration and development potential. Therefore, based on drilling cores, rock slices and analysis and laboratory data, the reservoir characteristics and main controlling factors of this section were analyzed. The results show that: (1) The reservoir rocks of the fourth member of Majiagou Formation mainly include leopard porphyry dolomitic limestone, leopard porphyry limy dolomite, crystalline dolomite and clotted dolomite, and the reservoir space types mainly consist of intergranular (dissolution) pores, with a small amount of lattice pores and microcracks. (2) The reservoir in the study area is generally characte-rized by low porosity and medium-low permeability pore type reservoir, in which leopard porphyry limestone dolomite and crystalline dolomite are the best reservoir rocks with wide distribution range. However, leopard po