Abstract
Thermodynamic scale prediction and laboratorial kinetic study are two of the major scale risk assessment methods applied in the oil and gas industry. The scale prediction calculations provide the equilibrium state, in terms of saturation ratio or saturation index of water for different scale species and possibly the mass of each precipitated species in bulk precipitation. On the other hand, laboratorial kinetic method studies the rate of scale surface deposition under dynamic conditions.
In the work reported herein, dynamic loop tests were carried out to study the CaCO3 deposition rate at 150°C in three water compositions with the same saturation ratio. These three water compositions represent a wide range of water chemistries encountered in the oil and gas industry, i.e., high calcium and low bicarbonate concentrations, medium calcium and medium bicarbonate concentrations, and low calcium and high bicarbonate concentration.
This paper gives a comprehensive study of the kinetics of CaCO3 deposition considering the effects of calcium and bicarbonate concentrations. The study encompasses thermodynamics prediction, laboratory evaluation, scale formation mechanisms and inhibitor selection. It will contribute to understand both thermodynamic and kinetics of CaCO3 formation, and qualification of effective inhibitors for field application.
