PSI - Issue 36

328 Liubov Poberezhna et al. / Procedia Structural Integrity 36 (2022) 326–333 Liubov Poberezhna, Ihor Chudyk, Volodymyr Khomyn et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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have developed an eco-efficiency strategy to justify to entrepreneurs that resource-saving and environmentally friendly business not only has a positive impact on the environment but is also profitable and cost-effective.

Fig. 2. Diagram of the distribution of depreciation level of responsible metal structures of oil and gas companies.

Decommissioned oil and gas wells pose a danger to the environment, as they are a source of methane leaks, a gas that contributes to the formation of the greenhouse effect on the planet, as well as in the well due to the destruction of its walls can leak fluids and subsequent entry into aquifers. The object of the study was selected wells in the final stages of operation and decommissioning, which are potential pollutants. 2. Materials and Methods. The study of the environmental impact of decommissioned wells is a necessary step to assess the causal trends and identify the most dangerous environmental situations (Poberezhnyi et al. (2017), Boothroyd et al. (2017), Yatsyshym et al. (2019)). The final stage of the life cycle of oil and gas wells is characterized by increased risks of uncontrolled processes that can pose a danger to the environment. In the late and final stages, the equipment of oil and gas wells is not reliable enough, it can be damaged as a result of an aggressive environment, accompanied by the loss of its quality characteristics. Over time, cement bridges can collapse in wells, corrosion of the mouth equipment and the column itself (Poberezhny et al. (2018), Kryzhanivskyi et al. (2020)), which causes depressurization of the well. The consequence of this situation is uncontrolled pollution of formation waters, soils, and atmospheric air. Environmental threats to the environment from oil and gas leaks during the operation of deposits are theoretically less large-scale compared to possible leaks after the completion of well development. In addition, during the operation of the well, pollution can be prevented and eliminated by various known environmental measures, and the wells that are decommissioned in most cases have no control. Seismic movements can increase the flow of hydrocarbons into the well and provoke accidental oil and gas emissions. There are research data and there are real facts of hydrocarbons from the deep layers, which causes uncontrolled leakage of fluid or gas into the environment during the depressurization of the well structure. The location of wells in river floodplains increases the likelihood of hydrocarbon migration and pollution of the hydrosphere. Wells in which formation waters are corrosive is exposed to the formation of channels through which hydrocarbon leaks occur. Sometimes such situations are recorded in wells that are operated, not to mention after the operational period. Monitoring the condition of the cement ring, designed to seal the gap between the casing and the drilled rock, in most cases indicates its unsatisfactory condition. These « favourable » conditions for the manifestation