FIELD: geology, geophysics, petroleum and gas industry, in particular, geophysics investigations of holes. SUBSTANCE: method involves emission of fast neutron flux to medium during continuous synchronous movement of neutron source and gamma-quantum detector with respect to investigated rock with speed of 300-700 m/s. Induced gamma radiation from chlorine nuclei is detected. Short-period isotope C1-38m is used as indicator. Induced radiation is measured in pauses between neutron pulses which are emitted with delay of 2-5 mcs. Induced radiation is measured simultaneously using three energy ranges 0.57-0.77 MeV, 0.77-1.5 MeV and more than 2.5-3.0 MeV using detector which is spaced by 10-40 cm from pulse neutron source. Intensity of induced gamma radiation of short-lived chlorine constituent provides data for position and quality of chlorine intervals taking into account natural radiation and oxygen induced gamma radiation. EFFECT: increased precision. 2 cl, 2 dwg, 1 tbl
