Abstract: Carbonate buried?hill reservoir is the most important reservoir type in the Nanpu sag with controlling effect of karstification on it. In order to further understand the pattern of karst development in Nanpu sag, based on formation microlog imaging (FMI) logging data integrated with geological data such as conventional logging data, log data and thin section analysis of rocks, this paper summarizes the characteristics of FMI logging response controlled by karst development, and establishes 5 logging facies such as high?resistance fracture facies,high?conductivity fracture facies, enlarged dissolution fracture facies, dissolved pore facies and cave collapse facies. A relationship between karst development characteristics and FMI logging facies is established on the basis of data statistics. The result shows that epigenetic karst belt is developed in the upper part of Nanpu sag and the buried karst belt in the lower part, and high?conductivity fracture facies,dissolved pore facies and cave collapsse facies are mainly found in the epigenetic karst belt, and the cave collapse facies is a unique feature for this belt; while high?resistivity fracture facies, enlarged dissolution fracture facies and dissolved pore facies are mainly found in the burial karst belt. Lithology and fault are the dominant controlling factors for karst development