Abstract：Based on formation rock samples selected and collected from Northeast Sichuan area and buried-hill structure in Jiyang Depression and corresponding downhole acoustic logging data of the samples，the rock drillability and acoustic characteristics of the roller cone bit and the PDC bit are tested. Correlation of the compressive wave velocity and shear wave velocity of rock surface with drillability of roller cone bit and drillability of PDC bit respectively，and correlation between the compressive wave velocity of rock surface and the downhole-logged compressive wave velocity of the same formation rock samples are studied by means of mathematical statistics. A mathematical model is established for predicting drillability of carbonate formation profile by using acoustic logging data with coincidence rate F＞0.75. By substituting in-site acoustic logging data into the prediction model for calculations，the prediction accuracy is up to 91.7%，reaching and exceeding the expected technical target.
