Corrosion Challenges on Electrical Submersible Pump Wells in the North Kuwait Field

Oil production in North Kuwait (NK) asset highly relies on artificial lift systems. The predominant method of artificial lift in NK is electrical submersible pump (ESP). Corrosion is one of the major issues for wells equipped with ESP in NK field. Over 20% of the all pulled ESPs in 2019 and 2020 in NK field were due to corrosion of the completion or the ESP string. With an increase in ESP population in NK, a proactive corrosion mitigation is essential to reduce the number of ESP wells requiring workover. Historic data of the pulled ESPs in NK revealed that most of the corrosion cases were found in the tubing as opposed to the ESP components. Although there are multiple factors that can cause corrosion in NK, the driving force was identified to be the presence of CO2 (sweet corrosion). Corrosion rates have been enhanced by other factors such as stray current and galvanic couples. In this paper, multiple methods have been suggested to minimize and prevent the corrosion issue such as selecting the optimal completion and ESP metallurgy (ex. corrosion resistant alloy), installing internally glass reinforced epoxy lined carbon steel tubing, and installing a sacrificial anode whenever applicable.

Improving the Corrosion Resistance of API X56 and API X70 Pipeline Steels by Hot Dip Aluminization

The external surface of the pipeline steels can be protected from corrosion by cathodic protection and a suitable coating system. But to protect the internal surface of steel pipelines from corrosion is always a challenge. In the current study, a protective aluminum coating was applied on the internal surface of steel pipeline grades API X56 and API X70 by hot dip aluminization process to minimize the cost of inhibitors. The steel substrates were dipped in the hot aluminum bath, whose temperature was maintained at 720 °C, for three different dipping times (5, 7.5 and 10 minutes) and then permitted to cool to room temperature. The coated specimens were characterized in terms of their structure and composition by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM micrographs analysis reveal that the hot dip aluminized specimens gave an unwavering and well adherent interface which is essential for corrosion resistance of the substrates. The corrosion behavior was evaluated by weight loss method in case of sweet corrosion (in 1.0 % NaCl + CO2 environment) and, by electrochemical potentiodynamic polarization tests for marine corrosion (in 3.5% NaCl environment). The sweet corrosion rates showed severe material loss (14.17 mpy for API X56 and 6.6 mpy in case of API X70) of uncoated samples as compared to the aluminized samples which showed no corrosion at all even after one week due to the passive layer of Al2O3. Whereas the marine corrosion of aluminized specimens was also reduced to 0.11 mpy (coated specimens) from 0.57 mpy (uncoated specimens).