A method for analyzing a wellbore drilling operation includes acquiring sonic log data, gamma ray log data, and rate of penetration (ROP) data. The sonic log data, the gamma ray log data, and the ROP data are associated with depth intervals of a wellbore. The method further includes determining unconfined compressive strength (UCS) of a rock formation associated with the wellbore using well log data and drilling data. The well log data is limited to the sonic log data and the gamma ray log data, and the drilling data is limited to the ROP data.