Purpose This study aimed to perform a systematic review to analyse the seasonal concentration and ecological risk assessment of heavy metals (HMs) in seawater and sediment samples collected from the coastline of Jam city in Bushehr, Iran. Methods A total of 96 sediment and seawater samples were collected from 16 sampling stations during the spring, summer, autumn, and winter of 2017. Then, the concentrations of Pb, Ni, Cd, Cr, Cu, Zn, and Fe were determined. Finally, the pollution load index (PLI), ecological risk (Er), and environmental risk (RI) were calculated to assess the HM ecological risk. ResultsThe results showed that the mean concentrations of HMs were lower than the maximum acceptable concentration by SQG and NOAA. In addition, the PLI assessed a low pollution load level in the region. The ER and RI results also showed that the region was at low risk, and the metal risk was classified as Cd > Cu > Pb > Ni > Zn > Cr. In some samples, the mean concentrations of HM were found to be higher with a statistically significant difference (P˂0.05). The results also showed that sediments were engaging in a moderate Er by Cd. Conclusions Generally, the rapid growth of urbanization, as well as industrial and human activities, along this coastline and area has increased the pollutants dumped into the seawater and sediments. Thus, it is necessary to take regular monitoring programs and develop better management strategies to minimize the amount of HMs entering into this coastal area.

Wellbore integrity during the full life cycle of a well has always been a focus of the petroleum industry, particularly during extreme drilling conditions and throughout complex well operations. Pumping compound fluids during hydraulic fracturing operations affects stresses on all tubular components, which can lead to component failure. During casing and tubing design, expected stresses are determined. This includes kick tolerance, drilling and production operations, and complete wellbore evacuation. However, a series of tubular failures indicates a more detailed analysis is necessary to help prevent well integrity loss. This paper presents selected case studies of tubing failure during the hydraulic fracturing process. A transient program is used to determine the precise magnitude of stress on both the tubular and the connection. The analysis results are provided and discussed in detail. It is concluded that high localized dogleg severity and the sequence of fluids in the wellbore should be studied carefully because the stress on the tubing changes with the position of fluids and fluid density.

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