Ufa State Petroleum Technological University, Ufa, Russia

V. A. Bogdan, Research Engineer, mhen839@yandex.ru
Sh. Kh. Sultanov, Doctor of Engineering Sciences, Professor
Yu. A. Kotenev, Head of Department, Doctor of Engineering Sciences, Professor
D. Yu. Chudinova, Head of Laboratory, Candidate of Geological and Mineralogical Sciences, Associate Professor

The article discusses causes of the porosity coefficient overestimation in neutron well logging using steady-state source in comparison with laboratory analyzes of cores from the boron-bearing Lower Permian deposits. The results of mathematical modeling of the measured porosity coefficients from neutron well logging using steady-state sources in limestones and dolomites with different porosity and boron content are presented. Based on the mathematical modeling, the charts of the effect exerted by the boron concentration on the measured values of the porosity coefficient are plotted. A procedure is proposed for quantifying the boron concentration in carbonate rocks based on different effect of boron on the porosity coefficient measured by individual probes of the two-probe neutronneutron method for thermal neutrons and their ratio, as well as by the neural gamma-ray logging method. The values of the porosity coefficient measured by the long-range twoprobe neutron–neutron logging were used as a reference. The results are presented as the scatter plots of the porosity coefficients relative to their reference values. Application of the procedure at the Lower Permian deposits shows that the initial concentration of boron in dolomites is higher than in limestones, which conforms with the facies model of sedimentation. The presence of boron in the Middle Carboniferous deposits is most likely associated with the processes of dissolution of the boron-bearing Lower Permian minerals by hydrocarbonate waters, and with their subsequent migration.
This work was supported by the Ministry of Science and Higher Education of the Russian Federation under Agreement No. 075-15-2022-297 within the framework of creation and development of the World-Class Research Center for Liquid Hydrocarbons.

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