Abstract
Internal corrosion related failures in oil and gas gathering systems are increasing, especially in conditions categorized as “low risk” by computer modeling. Such systems usually exhibit, low pressure, low temperature sweet gas production, and relatively low total dissolved solid content waters. The failure rate is commonly influenced by two major factors; 1) undiagnosed microbiologically influenced corrosion (MIC) mechanisms, and 2) the unappreciated impact of corrosive chemical biocides used to treat sessile and planktonic bacteria. Low velocity gas gathering systems are particularly difficult to treat for MIC as a result of pigging challenges and the tendency for corrosive biocides to concentrate in the water phase over time. Here we report a new water soluble quaternary ammonium compound, didecyldimethylammonium bicarbonate/carbonate (DDABC), that acts as an MIC corrosion control agent against common oilfield bacteria. At the proper dilution, DDABC also acts as a thin film forming anodic inhibitor on steel. Supporting lab and field tests indicate this inhibitor is effective in competitive evaluations against glutaraldehyde, THPS, and quaternary ammonium chloride based agents. In a field trial reported herein, DDABC reduced the failure rate of a 1,653 km low velocity gas gathering field to approximately one-sixth the original rate in a 20 month field trial.
