An integrated software tool for oil well operators
The problem of mineral scaling is as old as the oil industry itself. Scale forms when concentrations of inorganic minerals reach supersaturation and precipitate out. Supersaturation is brought about by interactions between fluids with different temperatures, pressures and/or composition. The scale accumulates over time on the inner walls of pipes, pumps, valves and other equipment, restricting, and in extreme cases plugging, flow. The result is reduced production, increased risk of accidents and increased maintenance costs, mainly in the form of expensive workovers. The ARISSTON project, led by the National Centre for Scientific Research in Greece, sought to make some headway in dealing with mineral scaling. They developed a modular software tool addressing the critical physical and geochemical processes. Various pieces of existing code were combined, modified and harmonised into a single model for this specific application. The tool is the first of its kind with the ability to forecast the timing of scale formation. It even accounts for induction time, the lag between the point of supersaturation and precipitation. This was made possible by a series of experiments with radioactive tracers, both in the lab and in real oil wells, providing instantaneous feedback. Data was gathered for calcite and barium sulfate, two of the most common types of mineral scaling. Knowing when and where scaling will develop enables well operators to make better informed decisions about remediation measures. Squeeze treatment, the injection of chemical substances called inhibitors that retard or reverse scale accumulation, can be designed to be more effective. The ARISSTON project also compared the effectiveness of different kinds of inhibitors, establishing Minimum Inhibitor Concentrations. The ARISSTON tool was systematically assessed with real field data from the industrial members of the consortium with favorable results. Oil well operators should find the tool very useful.