METHOD OF DETECTION OF WATER-SATURATED AND OIL-SATURATED FORMATIONS IN DRILLED-IN PRODUCTIVE RESERVOIR Russian patent published in 1997 - IPC

FIELD: geophysical investigations of productive reservoirs in oil producing industry. SUBSTANCE: the offered method includes determination of background value of natural gamma radiation of rocks of productive reservoir of wellbore by gamma logging instrument, filling of the interval of productive reservoir with indicating fluid activated by radon and possessing salinity exceeding that of drilling mud by 2-3 times, but of the same density. Pipe string is reciprocated in the medium of indicating fluid activated by radon in wellbore. Gamma logging is repeated within the interval of productive reservoir of wellbore. The latter is washed from indicating fluid with washing fluid in volume of 3 to 5 volumes of productive reservoir of wellbore. Control gamma logging and electric logging are effected by probes of various sizes. Depth of penetration of indicating fluid activated by radon into fluid-containing layers of productive reservoir is determined, and degree of variation of parameters of gamma activity in them in time determined to find presence of layers saturated with water and oil. EFFECT: higher efficiency.