Lower Triassic Feixianguan Formation is 400~550 m thick in Jiannan area. It can be divided into four members, among which the 3rd member (T1f3) is the main gas pay bed. TheT1f3 reservoir is porous or porous-fractured locally but is the one with very low porosity and low permeability. The sedimentation environment of it commonly is the open platform and platform marginal shoal and slope facies. It is commonly composed of micritic limestone, calcarenite and oolite. The reservoir loggings shows low resistivity values of LLd and LLs corresponding to the background of high resistivity value, low values of GR, high values of AC, low values of DEN, and high value of CNL. Based on the analysis of reservoir logging response characteristics and seismic response characteristics, it is indicated that a set of low-impedance layers exists at the bottom of the 4th member (T1f4), which will be the key to solve the prediction of beach-facies oolite reservoir distributed in the south and north parts of this area.