On the problem of geophysical characteristic of Bazhenov rock series

Neutron logging data were used for differentiating, in a profile of the Bazhenovo formation, intervals of presumably fractured zones from which discharges of oil and gas could be obtained under favourable structural conditions. In older cased wells the most effective means of investigating the Bazhenovo band are neutron methods, including repeated gamma-gamma measurements and acoustic logging. For quantitative interpretation of these measurements, it is recommended that geophysical methods be used to check: (a) the composition of the liquid filling the well; (b) the reciprocal influence of device, string and well bore position; (c) the composition and salinization of the hardened cement behind the string. In holes drilled for the purpose of separating out fractured zones in bituminiferous argillates, the most effective set of geophysical studies is a combination of lateral, microlateral and sonic (acoustic) logging and neutron-gamma logging. To determine the effectiveness of the two-profile method it is advantageous to carry out these investigations in two or three holes. To obtain complete information about the bituminiferous argillates, it is recommended that in some holes coring be carried out along the entire bedding interval of the formation, with a detailed description of the core and with lithological, mineralogical and petrographic analyses of the rock as well as determinations of its physical and reservoir properties. (author)