PSI - Issue 36

Teodoziia Yatsyshyn et al. / Procedia Structural Integrity 36 (2022) 362–369 Teodoziia Yatsyshyn, Myroslava Polutrenko, Lubomyr Poberezhny et al./ Structural Integrity Procedia 00 (2021) 000 – 000 3

364

The causes of the above-mentioned environmental risks in the construction of wells are due to the imperfection of construction technologies; non-compliance with technology regulations, as well as operational unreliability and imperfection of structures and equipment. The operation of oil and gas complex very often violates the equilibrium of natural geological systems – activates earthquake activity which may lead to calamities. Extracting hydrocarbon raw materials from the earth depths may provoke local earthquakes of considerable destruction power. There are some well-known historic facts – huge earthquakes close to oil and gas deposits in Rocky mountains (USA) and gas deposits in Uzbekistan and also local of 4 points of local intensity that took place in march 1986 at Khrestyshchen gas-condensate deposit in Ukraine (Shkitsa et al. (2018)). Another factor that relates to both man-made and natural risk is the increase in seismic activity in regions where no such events have been observed before and the increase in seismic activity in seismically active areas of Fig. 2 (Sejsmomonitoring (2021)).

Fig. 2. Seismic activity as of 13.10.2021.

With such phenomena, uncontrolled flows of hydrocarbons and the appearance of griffins and oil and gas fountains can occur. If insufficient attention is paid to preventing and preventing the occurrence of extreme conditions, then the likelihood of complications and accidents increases sharply. The risk factors that must be taken into account and create conditions for their prevention at the stages of the life cycle of the oil and gas well shows on the Table 2 (Shkitsa et al. (2018)). At all the stages of a well's life cycle there exist different factors that influence the rate of ecological hazard. A set of factors reflecting technical conditions of the equipment is worth mentioning (high quality, wearing out). The equipment used at all the stages of life cycle of an oil and gas well is being under aggressive influence. The study of technical indices of the equipment is very important for evaluation of its reliability, especially if the terms of operation are higher than the standards. In cases like this the intensity of hardware faults increases and so does the level of environmental risk. The probability of failure-free operation of equipment is defined by the formula (Vengertsev (2005)):

       T t Ф P t 0 ,  

(1)

where P (t) – is failure-free performance of the equipment under study; T 0 – average time between failures; t – working life of the equipment under study; Ф – Laplace's function; σ – mean square deviation of working life. Most oil and gas equipment, especially in the late stages of operation, exceeds the terms of their standard operation and the risks of environmentally hazardous phenomena increase. Thus, environmental risk assessment takes into account the factors inherent in specific operating conditions that may cause an adverse effect. Hence the need to use systematic analysis to assess the multifactorial risks of oil and gas facilities, including oil and gas wells during the life cycle. Sophisticated systems such as “ oil and gas facilities - the environment ” require reliable and timely forecasts to