Corrosion study of degradable plugs for non-return valves in simulated production water

CERE S.; BERTOLDI F.; FERNANDINO D.; TANO DE LA HOZ M.F.

Congreso; LATINCORR & INTERCORR; 2023

Non-return valves are used to avoid the reverse flow of the water used for injection in the oil and gas industry, thus avoiding any negative effects that this could generate in terms of process and mechanical failures. Usually, these valves are covered with a plug to prevent fouling of the tube before reaching its final position in the well. This plug is ejected from the valve after the tubing string is placed at the required depth in the injection well. Once it is expelled, it remains in one of the sections of the packing system in the well. In order to avoid the possible clogging of the tube with the plug once it has been expelled, the use of degradable plugs is desirable. The development and application of dissolvable magnesium alloys is a relatively new technology in the oil and gas industry.The objective of this work is to study the degradability of a magnesium alloy plug used in the oil and gas industry in natural and simulated production water. Mg alloy stoppers were immersed in simulated fluid and submitted to weight loss assays, where pH and temperature were controlled throughout the experiments. Also, polarization curves, electrochemistry impedance spectroscopy, and Raman spectroscopy (to determine surface composition after immersion) were measured. Degradation was very noticeable after 24 hours of immersion, and high corrosion rates were determined. Surface compounds were mainly related to magnesium oxides and hydroxides.