FIELD: nuclear geophysics, gas and oil geology. SUBSTANCE: invention refers to family of geophysical methods meant for determination of character of saturation of collectors under conditions of salted stratal waters by neutron characteristics of natural surroundings. Procedure consists in irradiation of rocks with flux of fast neutrons from ampoule source and in recording of density of flux of thermal neutrons at two or more distances from radiation source. Spatial-time distribution of density of flux of thermal neutrons in 10-15 strata with known composition of skeleton and stratal fluid P is measured in advance and used to compute two-dimensional reference nomogram N= f(R, P), where P=Ko.g.+Kw, Ko.g. is coefficient of oil and gas saturation; Kw is coefficient of water saturation, N and R are relations of scattering and absorbing parameters of media for recorded spatial-time distribution of density of flux of thermal neutrons expressed in terms of absorption macrocross-section (Σa) and scattering macrocross-section (Σs) of thermal neutrons, slow-down time (ts) and life t of neutrons, length (Ls) of slow-down and diffusion (Ld). Regions of predominantly water, hydrocarbon and water-hydrocarbon saturation of strata are highlighted in nomogram. Relation of scattering and absorbing properties of examined media are determined by measured distributions of density of fluxes of thermal neutrons in unknown strata in the form of same analytical parameters N and R as for reference strata and are fixed by output unit as logging diagrams. While comparing diagrams certain strata are allocated for quantitative processing after preliminary evaluation of character of their saturation. Average values of analytical parameters N and R for selected intervals are utilized to construct nomogram N=f(R,P) and then obtained nomogram is compared with reference one to determine character of saturation of unknown collectors. EFFECT: increased accuracy of identification of gas and oil/gas saturated collectors, decreased financial expenses. 5 dwg, 2 tbl
