Automated Analytical Method To Determine Solution Alkalinity of Oilfield Brine in the Presence of Weak Organic Acids

Abstract

Oilfield produced brine can cause significant corrosion and mineral scaling issues to the production system and the environment. Solution alkalinity is an important parameter dictating the corrosion and scaling threat of oilfield brine. However, it remains an ongoing challenge to accurately measure oilfield brine alkalinity, especially in the presence of weak organic acids, such as carboxylic acids. The conventional titration method for oilfield alkalinity measurement does not consider the impact of organic acid on alkalinity, leading to an erroneous measurement result. In this study, an analytical method was presented to simultaneously measure total alkalinity and weak organic acid (acetic acid) concentrations of the brine via an automated titration approach. It shows that the automated method substantially outperformed the conventional method in terms of accurately measuring both solution alkalinity and organic acid concentration with one titration effort. The automated analytical method is considerably robust and is not highly sensitive to the introduction of random error. Modeling calculation shows that the automated analytical method exceeds the conventional method in determining solution alkalinity with an enhanced accuracy for scale threat predictions. This is the first study to report such an accurate and convenient analytical method to measure solution alkalinity and organic acid concentrations for oilfield produced brine. Given the accuracy and convenience of this reported analytical method, it can find wide industrial applications within oilfield and beyond, including corrosion and scaling control, water resource management, and environmental pollution control.