MODERN ALGORITHMS AND SOFTWARE FOR INTERPRETATION OF RESISTIVITY LOGGING DATA

The electrodynamics of geological media investigates the interrelations of resistivity logging signals and properties of fluid-containing rocks and creates innovative well logging technologies. Its development is inextricably linked with modern techniques for mathematical modeling and quantitative interpretation of high-precision data. In order to increase the information content of galvanic and electromagnetic logging, we have developed algorithms and software for numerical simulation and inversion of field data. In our study of the Cretaceous and Jurassic deposits of West Siberia, a quantitative interpretation of high-frequency electromagnetic and lateral logging signals was carried out. To create geoelectric models, we interpreted the field resistivity logging data by an unconventional quantitative technique based on their joint numerical inversion and estimations of the vertical resistivity of permeable deposits. Another line of our research was aimed at a scientific substantiation of a new technology for mapping and spatial tracking of lateral heterogeneities and oil-promising zones in the Bazhenov Formation. The aim was achieved by using the TEM sounding data on a spatially distributed system of directional and horizontal wells

Fast solution of two-dimensional inverse problem of high-frequency electromagnetic logging in oil-gas boreholes

The paper is dedicated to development of physical-mathematical tools of interpretation of the data of electromagnetic logging in oil-gas boreholes. Program-algorithmic means of numerical inversion of relative gain-phase characteristics in axis-symmetric models have been worked out. Algorithm of solving fast inverse problem is based on linear inversion and includes analysis of a matrix of sensitivities of the measured signals to model parameters. Inversion is accompanied by determination of areas of ambiguity of parameters recovery. High productivity of two-dimensional direct problem made possible realization of alternative approach to inversion based on plotting and analysis of all the ensemble of quasi-solutions of two-dimensional inverse problem. Elaborated algorithms give possibility to determine geo-electric parameters of penetration zone and the layer and estimate their inaccuracies. Experiments on recovery of electro-conductivity in typical models of collectors on synthetic and experimental data have been performed

Features of Direct Alkaline Processing of Rare-Metal Ores of the Tomtor Deposit

Исследовано прямое щелочное разложение редкометалльной томторской руды в различных условиях. Установлено, что попутные минералы (алюмофосфаты, карбонаты и сульфиды железа) разлагаются растворами гидроксида натрия и существенно снижают активность оборотного щелочного раствора. Предварительная обработка руды разбавленными отработанными щелочными растворами позволяет разложить алюмофосфаты с частичным переводом их в растворимые формы и устойчивые в щелочных растворах алюмосиликаты. Показано, что значительные колебания выхода в раствор редкоземельных металлов при последующем кислотном выщелачивании кеков щелочного вскрытия связаны с частичным окислением церия кислородом воздухаDirect alkaline decomposition of rare-metal Tomtor ore under various conditions has been studied. It has been established that associated minerals (aluminophosphates, iron carbonates and sulfides) are decomposed by sodium hydroxide solutions and significantly reduce the activity of the circulating alkaline solution. Pre-treatment of ore with dilute spent alkaline solutions makes it possible to decompose aluminophosphates with their partial conversion into soluble forms and aluminosilicates stable in alkaline solutions. It is shown that significant fluctuations in the release of rare- earth metals into solution during subsequent acid leaching of cakes from alkaline opening are associated with partial oxidation of cerium by atmospheric oxyge

Higher Mass-Independent Isotope Fractionation of Methylmercury in the Pelagic Food Web of Lake Baikal (Russia)

Mercury undergoes several transformations that influence its stable isotope composition during a number of environmental and biological processes. Measurements of Hg isotopic mass-dependent (MDF) and mass-independent fractionation (MIF) in food webs may therefore help to identify major sources and processes leading to significant bioaccumulation of methylmercury (MeHg). In this work, δ¹³C, δ¹⁵N, concentration of Hg species (MeHg, inorganic Hg), and stable isotopic composition of Hg were determined at different trophic levels of the remote and pristine Lake Baikal ecosystem. Muscle of seals and different fish as well as amphipods, zooplankton, and phytoplankton were specifically investigated. MDF during trophic transfer of MeHg leading to enrichment of heavier isotopes in the predators was clearly established by δ²⁰²Hg measurements in the pelagic prey–predator system (carnivorous sculpins and top-predator seals). Despite the low concentrations of Hg in the ecosystem, the pelagic food web reveals very high MIF Δ¹⁹⁹Hg (3.15–6.65‰) in comparison to coastal fish (0.26–1.65‰) and most previous studies in aquatic organisms. Trophic transfer does not influence MIF signature since similar Δ¹⁹⁹Hg was observed in sculpins (4.59 ± 0.55‰) and seal muscles (4.62 ± 0.60‰). The MIF is suggested to be mainly controlled by specific physical and biogeochemical characteristics of the water column. The higher level of MIF in pelagic fish of Lake Baikal is mainly due to the bioaccumulation of residual MeHg that is efficiently turned over and photodemethylated in deep oligotrophic and stationary (i.e., long residence time) freshwater columns