Calibrating and operating Coriolis flow meters with respect to process effects

Abstract

The temperature, pressure and viscosity of produced oil from a reservoir can differ considerably from standard calibration laboratory conditions. The standard practice for calibrating flow meters for the oil & gas industry has been to match the fluid viscosity and, if possible, the fluid temperature and pressure. However, matching all parameters is seldom possible due to the limitations set by the calibration facilities. As such, the parameter that is most often matched is the fluid viscosity. A limitation of the above approach is that temperature and pressure variations are known to influence properties, other than fluid viscosity, that may also be critical to the overall measurement uncertainty.To address this, NEL have built and commissioned a fully accredited elevated pressure and temperature (EPAT) liquid flow facility. This facility has been used to investigate the performance of flow meters at elevated pressures and temperatures. It also allows for liquid flow calibrations to be completed close to service conditions. This work will provide traceable data on the performance of Coriolis flow meters when operated at elevated pressures and temperatures. This data can then be used to update the Coriolis ISO standard 10790. At present, the latest revision in 2015 includes little practical guidance for the operation of Coriolis meters at elevated pressures, temperatures and viscosities.Unfortunately, the methodology for calibrating and operating Coriolis meters at elevated conditions appears fragmented.The purpose of this paper will be to highlight the influence of elevated temperatures, pressures and viscosities and to provide the end user with the correct methodology for calibrating Coriolis meters for these conditions. The paper will also highlight the requirement for the ISO standard 10790 to be updated given the current knowledge level.