Petrophysical Support to Interpretation of Pulsed Neutron and Spectral Gamma Logs

Interpretation of nuclear logs allows determine a material composition of rocks - mineral componential composition of solid matrix and fluid-dynamic model of a pore space. Interpretation of Pulsed Neutron and Spectral Gamma Logs is based on solution of a system of petrophysical equations where the left part includes concentrations of elements and macroscopic thermal neutron absorption cross-sections, concentrations of minerals and non-mineral components (water, oil, and gas) are unknown, and petrophysical characteristics are concentrations of elements in specific minerals and components of rocks. <br> Proposed is a system of extended petrophysical study of formation rocks including the following components: determination of mineral composition, content of organic matter, porosity (total and effective), residual water saturation, content of physically and chemically bounded water, density, concentrations of rock-forming, natural radioactive elements and elements &#8211;abnormal absorbers of thermal neutrons. Thus, the core analysis gives us information about the contents and elemental composition of mineral and non-mineral components.Presented are results of testing this technique for Achimov pay deposits of Zapolyarnoye field including core analysis, building of mineral-componential model, calculating petrophysical characteristics for each specific macro-component and building a resulting petrophysical model. <br>