A kinetic study of barium sulphate formation in presence of scale inhibitor in a flowing system

The formation of barium sulphate is a persistent problem affecting the oil and gas industry. Due to its high insolubility and resistance to chemical/mechanical treatment, it is difficult to remove when formed. Barium sulphate formation can be predicted using thermodynamic models; nevertheless it is imperative to understand the kinetics of barium sulphate in order to predict more accurately the rate at which these scales are being formed and to identify the correct remediation technique. Several research works have been conducted on the kinetics of barium sulphate both in bulk precipitation and on surface deposition; however these studies were often conducted in a closed system (e.g. bulk jar test) and measurements were taken off-line. In a closed system normally the saturation ratio decreases as function of the time as scaling occurs. In the current study an experimental set-up has been designed to study the kinetics of bulk and surface scaling processes in-situ, in an open system and measurements were taken in real-Time. This work presents a kinetic study of barium sulphate with the absence and presence of scale inhibitors (diethylene triamine penta methylene phosphonic Acid (DETMP) and poly-phosphino carboxylic acid (PPCA)) on bulk precipitation and surface deposition. In the study, a turbidity probe was used to follow the bulk precipitation, whereas surface deposition was assessed by analysing image taken of the stainless steel surface at different time intervals.