Corrosivity of Oxygen Scavenger in a Sea Water Environment

摘要

Sodium bisulfite (SBS) oxygen scavenger is being applied in several sea water flood injection systems in the Gulf of Mexico. High corrosion rates (CRs) were observed in one particular field during periods when oxygen scavenger injection rates were elevated. In an effort to establish a safe operating concentration for oxygen scavenger, testing was conducted over a range of conditions to determine the corrosivity of the oxygen scavenger in seawater. Initial test work identified corrosion rate spikes upon injection of SBS in the laboratory and all subsequent work was designed to determine the mechanism generating these corrosion spikes. Scavenger performance was studied with and without the presence of oxygen. Parameters included in this study were SBS concentration, tetrakis-hydroxymethyl-phosphonium (THPS) concentration, temperature, and pH. Electrolyte simulation software was used to determine the dominant aqueous reactions that may contribute to the corrosive environment. This paper outlines the test protocols and results of the lab tests as well as the aqueous modeling. According to the test results and aqueous simulations, the field dose rate of 49 ppm SBS appears to be safe with respect to corrosivity and effective at eliminating the dissolved oxygen.