The corrosion of carbon steel downhole completion tubing at high temperature is one of the serious corrosion issues facing the oil and gas industry. Few corrosion inhibitor chemistries can protect downhole production tubing against corrosion, especially at high-temperature and high-pressure (HTHP) in high total dissolved solids (TDS) brine. The objective of this study was to develop a HTHP corrosion inhibitor abbreviated (NAM 9) for the protection of carbon steel at a temperature of up to 120°C for possible application in sweet gas wells. The new corrosion inhibitor formulation (NAM 9) was evaluated using the linear polarization resistance (LPR) technique, batch corrosion testing (drop and drip) and autoclave corrosion test. The LPR result shows that 10 ppm of NAM 9 drastically reduces the corrosion rate of C1018 steel from 214.4 mpy (5.44 mm/y) to 3.28 mpy (0.08 mm/y) giving an inhibition efficiency of 98.47 % at 70°C. The corrosion rate of the blank using autoclave corrosion testing at 120°C was 250.6 mpy (6.36 mm/y) and 30.3 mpy (0.77 mm/y) in the presence of 500 ppm of NAM 9, respectively. The results indicate that NAM 9 is a promising high-temperature corrosion inhibitor for downhole production tubing used in gas wells.
The corrosion of the internal surfaces of gas pipelines, especially at high temperatures, is one of the most serious corrosion issues facing the oil and gas industry. Produced oil and gas may contain some water mixed with brines and contain varying amounts of carbon dioxide (sweet gas), hydrogen sulfide (sour gas), and organic acids.1 All of these can affect the integrity of the low-carbon steel pipes. Internal corrosion of pipelines and other facilities made from low-carbon steel continues to represent a serious challenge for the oil and gas industry. Mitigating oil and gas production with chemical inhibitors is challenging when high temperature (>120 °C), high total dissolved solids (TDS) brines, and CO2 are present. The high temperatures associated with deep wells and thermal recovery methods demand an advancement in conventional inhibitor technologies. Traditional organic inhibitors struggle to protect carbon steel assets making them susceptible to localized corrosion in sweet environments. These environments require inhibitors with combined thermal stability and persistency to provide uniform filming and corrosion protection.2
