Nimets N. Improving the environmental safety of returning oilfield produced water to the bowels of oil-and-gas condensate fields with iodine extraction

Thesis for scientific degree of candidate of technical science on specialty 21.06.01 – «Ecological safety». – Scientific-research institution «Ukrainian scientific-research institute of ecological problems», Kharkiv, 2019 The thesis is devoted to improving the environmental safety of the return of oilfield produced water to the bowels of oil-and-gas fields with the removal of iron compounds and the extraction of iodine by ozonation. Based on an experimental analysis of the component chemical composition of the oilfield produced water of a number of domestic deposits, the scientific justification of their compatibility with oilfield produced water, an increase in environmental safety is assessed when they return to the bowels. Installed are those domestic oil-and-gas condensate fields, which can be the raw material base for iodine production. During the research, regularities were found for the removal of iron compounds in the sediment and the extraction of iodine from produced water by ozonation, by studying the transition of Fe2+ ions to Fe3+ ions and the degree of iodine formation from the molar ionic ratio ratio of reactants, processing time, mineralization, acidity, iodide concentration ions, bromide ions, phase contact surfaces. It has been theoretically substantiated and experimentally confirmed that environmental safety is improved when iron compounds are removed and iodine is obtained from the oilfield produced water and returned by the use of ozonized air with a low ozone concentration. Express test methods have been developed for the analysis of iron, sulfate, and iodine ions, which provide water quality control and increase environmental safety when returning ozonated oilfield produced water to the bowels. Improved environmental safety has been proved and the economic efficiency of the return of oilfield produced water with iodine production has been estimated by reducing the possible emissions of harmful substances into the environment during hydrocarbon production from oil-and-gas condensate fields. A water treatment technology has been developed with preliminary removal of iron compounds and iodine extraction, which increases the environmental safety of returning oilfield produced water to the bowels. The economic effect expected from the introduction of the proposed technology for the return of oilfield produced water into the subsoil with the production of iodine by ozonation in only one Medvedovsky gas condensate field is $ 2.6 million. Keywords: increase, return, oilfield produced water, subsoil, oil-and-gas condensate fields, ecology, safety, ozonation, iron ions, implementation, economic effect