Predicting Carbonate Scale in Oil Producers From High-Temperature Reservoirs

Abstract

Summary Calcium carbonate (CaCO3) scale is a common problem in the oil industry, leading to reduced well performance and obstruction of safety valves. Recent field experiences indicate that scaling may be a problem at lower saturation ratio (SR) than earlier anticipated. In a high-pressure, high-temperature scale cell, crystal growth in synthetic formation water has been studied. Induction times and growth rates have been determined by use of a microscope cell. The results have been interpreted by use of nucleation theory. The findings indicate that wells may be safely operated at SR below 2.5 at 85°C. At higher temperature, crystal growth is less dependent on SR and the temperature dominates the system. Care should therefore be taken when operating wells at temperatures greater than 100°C.