Study of surface deposition and bulk scaling kinetics in oilfield conditions using an in-situ flow rig

Scale management is often a complex mixture of prediction, inhibition and sometimes removal strategies. Recent investigations have shown that crystals formed on the surface are not always the result of a secondary deposition process after the precipitation mechanism which occurs in the bulk solution, in contrast to popular thinking. This study assesses CaCO₃ scale precipitation and deposition in-situ and in real-time measured in a once-through flow rig that allows for consideration and assessment of various scaling indices, temperatures, flow velocities, inhibitor concentrations and different surface treatments. In this first paper, the in-situ flow rig has been designed to combine measurement of turbidity in the bulk solution and real-time visualization of scale build-up on the surface. The kinetics of CaCO₃ formation is evaluated from image analysis; the surface coverage, number of particles and average size of the particles with time are assessed. Three brines with different saturation ratios at different temperatures are tested. The results show the variation in their respective turbidity, surface coverage, number of particles, average particle size and distribution with time. The facility allows for a mechanistic understanding of scale build up on the surfaces in flowing conditions and improvement on the understanding of both bulk precipitation and surface deposition scaling kinetics.