Evaluating Scale Inhibitors to Prevent Calcite Deposition Under Turbulent Flow Using a Lab Setup

In the oil and gas industry, scale formation is a common issue. Specifically, oilfield production leads to production losses by creating pressure drops in the pipes or blocking oil and gas flow. Scale can also develop in the reservoir near the wellbore, resulting in a reduction of the Productivity Index, which measures the relationship between flow rate and pressure drop in the wellbore. Beyond the impact on production, scale incurs costs related to preventing and remediating deposits in pipes and valves. The most common type of scale in carbonate reservoirs is the calcium carbonate (CaCO₃) scale. In Pre-Salt oilfields in Brazil, calcium carbonate is a substantial challenge since the reservoir is extremely deep (over 7000 m), and all the wells present high pressure, high temperature, high carbon dioxide (CO₂), and calcium concentration. Although the thermodynamics of the equilibrium and the use of scale inhibitors are well known, there are still questions about the kinetics of the deposition and how it performs under different flow conditions. Following a literature review, there are limited investigations regarding assessing calcite scale formation under high shear and turbulent flow regimes. There is good evidence for the increased risk of scale formation under turbulent flow. Actual test methods do not achieve the high shear stresses experienced in actual field situations (high Reynolds number and shear stress). Based on that, testing scale inhibitor performance under turbulent conditions during qualification for field application can be game-changing to provide a more accurate dosage.