Use of Multiphase Meters in Process Control for Oil Field Well Testing: Novel Level Controls and Resulting Performance Enhancement

摘要

The objective of providing oil well testing capability meeting the accuracy, facility integration and safety needs of that asset's development team were achieved. Types of Multiphase meters are found to be fundamentally different in properties depending on the physical principals used by the meter's sensors. Venturi-type gamma densitometer multiphase meters are selected as most useful in process control. Reducing gas fraction in a multiphase meter is shown from several sources, to improve that meter's oil rate accuracy. Conventional and compact separation systems are very capable of flow conditioning fluids to a multiphase meter and provide considerable advantages to the facility. The GVF control system can be supplementary to existing level control. The supplementary nature of the GVF Setpoint Control system using a multiphase meter is easily retro-fitted to old existing facilities in which well test accuracy or level control is a problem. Simulation was used to determine that a multiphase meter's tested performance could be enhanced by feedback control, leveraging the meter's accurate GVF output into enhanced oil rate accuracy. The general concept of Separator Level Setpoint Control by GVF Feedback was shown to work well. Simulation showed unexpected benefits of slug control in addition to the expected enhancement of multiphase meter performance. Specific guidelines were provided in selection of multiphase meters for process control were provided. Nominal Settings for conventional and GVF PID control are recommended for the Base Cases with the caution that actual installed conditions must be evaluated with respect to this report prior to operation. Simple scaling rules for PID settings may apply for variations of system volume due to corrosion, retro-fit and swap out, all other parameters remaining constant. Simulation demonstrates that accidental loss of the GVF signal has no negative impact on conventional level control.