Flow conditions at gas production facilities are usually not the steady and undisturbed conditions which have been used during research to derive orifice coefficients or during meter calibrations. Wellhead pressures and flows are often transient in nature and can vary over a wide range in relatively short periods of time. Flow measurements at typical production installations are subject to more difficult transient conditions than in many other measurement situations. If these dynamic conditions are not taken into account and controlled in the meter installation design and instrumentation implementation, then the transients can lead to significant errors in measured flows.

A research program for transient effects on electronic flow measurement (EFM) has been planned as a part of the Gas Research Institute's (GRI) metering research effort at SwRI. The objectives of the research program include the development of design and installation guidelines for minimizing EFM susceptibility to transient-induced errors. The successful metering system will result from specific recommendations for piping arrangements, gage lines, transducers, and signal processing specified for given transient conditions. This paper describes the transient-induced errors affecting both the primary and secondary orifice metering elements, and discusses the requirements to account for and minimize these errors. Past research work has defined the errors caused by pulsations and some transients, and has addressed the question of what is required to eliminate such errors. Combining this information with additional data to be developed during the planned research will lead to a description of an EFM system to minimize errors in transient flow measurement situations.

You can access this article if you purchase or spend a download.