The Growth of Online Oil in Water Monitoring and Statoil's Experience on the Sleipner A Platform

Abstract

Abstract The increase in produced water has led to a growing need from E&P operators for better oil in water monitoring systems. Roxar has developed an inline and online oil-in-water monitor suitable for topside discharge and re-injection applications, based on ultrasonic technology. The first Roxar Oil-in-water monitor was installed in May 2006 on Statoil's Sleipner A platform in the North Sea. Statoil is using the monitor to measure overboard water discharge, ensuring that it meets environmental requirements and efficiently monitors the separation process. Immediately after installation, attempts were made to introduce increasing amounts of oil into the produced water stream to verify that the monitor registered oil concentration changes accordingly, which it did. Periods with distinctly higher concentration levels were also analyzed. The rapid change in water level in the separators corresponded to an increase in the oil-in-water concentration downstream. During the trial phase, reliability and robustness have been demonstrated, and this paper describes how the ultrasonic measurement techniques, combined with a novel reflector design, helps the operator obtain accurate oil concentration readings even during and after experiencing production instability. This paper presents results from the pilot, verifying the performance of online oil in water monitoring and its ability to operate at different concentrations. The pilot to date has confirmed the monitor's ability to provide accurate information to Statoil on the size distribution and concentration of oil and is already playing a key role in monitoring Statoil's overboard discharge and separation process.