Understanding Thermal Stability and Inhibition Effectiveness of Corrosion Inhibitors at High Temperatures

摘要

As oil and gas production moves to more challenging high temperature and high pressure conditions, using corrosion inhibitors (CIs) to mitigate carbon steel corrosion becomes more difficult for two main reasons. One reason is that the chemicals are susceptible to thermal degradation at high temperatures. This can lead to loss of inhibition performance and possibly precipitation which can block injection equipment. The other main reason is that satisfactory inhibition performance is typically only achieved by significantly higher chemical dosage at high temperatures compared to dosages at lower temperature. The effectiveness of CIs typically decreases as temperature increases. To maintain a satisfying performance, the required quantity of chemical may be too high to be economical or the high quantity could exceed designed injection capability. Recent efforts to address these two concerns for high temperature Cl development are demonstrated in this communication. The comparison of chemical inhibitors' performance before and after thermal aging is used to evaluate the thermal stability limit of each intermediate. Through a systematic performance evaluation at different inhibitor concentrations, accurate estimation on thermal stability limit and thermal degradation kinetics can be obtained by comparing aged and as received inhibitor intermediates. Furthermore, the effectiveness of CIs at high temperature were investigated and compared among different inhibitor groups, such as imidozolines, quaternary amines, and phosphate ester compounds. Overall the thermal stability and effectiveness of Cl intermediates are combined to determine their suitability for high temperature applications.