Abstract: Lithology discrimination of volcanics is the basis and key to volcanic reservoir evaluation. Taking the volcanics in Santanghu Basin as example, the volcanics lithology in Carboniferous Kalagang Formation is complicated; lava, volcanoclastic rock, and transition rock developed in the Formation. Aimed at the difficulties in lithology discrimination, on the basis of delinating the rock mass range of volcanics based on regional gravity and magnetic data, physical quantity including gama, resistivity, compensated density, and interval transit time sensitive to lithology is selected; detailed calibration is conducted on core and thin section data. Crossplot is used to set up the log response discrimination mask of volcanics, realizing log lithology discrimination of volcanics and then correcting geological logging lithology precisely. This provides solid basis for volcanics exploration in Santanghu Basin

Key words: Santanghu Basin, volcanics, lithology discrimination, crossplot