The Use of Inhibition Kinetics and NMR Spectroscopy in Thermal Stability Study of Scale Inhibitors

摘要

As the oil and gas industry is making firm stride in deepwater exploration and development, possible thermal degradation of scale inhibitor molecules poses a great challenge for scaling control and flow assurance for high temperature reservoirs. Although extensive research has been conducted to test thermal stability of scale inhibitors, little work has been devoted to study the thermodynamics/kinetics of thermal degradation of scale inhibitors. In this work a novel and efficient testing approach based on inhibition kinetics has been developed and successfully applied to determine the fraction of the initial inhibitor molecules in preheated samples of scale inhibitors with various generic chemistries. Moreover, for the first time, we have modeled the kinetics of inhibitor thermal degradation based on the integrated first-order rate equation and Arrhenius equation, with good agreements between the model predictions and experimental data. The preheated scale inhibitors have been analyzed by nuclear magnetic resonance (NMR) spectroscopy for organic compound characterization. Our results and predictions based on inhibition testing assay are consistent with the ~(31)P/~1H NMR analyses. This work has enabled an in- depth understanding of the time and temperature dependence of thermal degradation of scale inhibitors, and facilitates the rational selection and deployment of scale inhibitors for high temperature oil and gas production.