Multiphase Virtual Flow Metering: A Step Change in Production Management

Abstract

Abstract A multiphase flowmeter capable of adapting to varying well conditions and providing reservoir transient data is an essential tool for reliable production planning and optimization. This is the main driver for the development of a multiphase virtual flow metering (VFM) module, which is intended to be an add-on to the traditional production management system, (PMS), and as a value addition for the operator. Current physical flow metering systems have certain limitations such as a need for extensive calibration, and high capital and maintenance costs. Also, simultaneous monitoring of every producing well can be cost-prohibitive; thus, making it difficult to determine the field production efficiently and accurately. Having limited real-time field data adds a high degree of unreliability to any simulator predictions. The PMS integrated multiphase VFM described in this paper has been designed to specifically address some of these concerns in a cost-effective manner. This VFM system operates on simulated data sets as well as live field data, which are obtained at a much higher frequency to capture even short-duration transients in the field. An additional advantage of this system is that it can be deployed individually for each well, which facilitates single-well production metering. The VFM module, based on the dynamic multiphase flow simulator, has been developed by one of the industry leaders in simulating transient behavior of flow from a reservoir through the pipeline system. Virtual results such as pressures, temperatures, and multiphase flow rates from a digital-twin of the field are used as base results to predict the field flow rates. These predicted flow rates are compared with real-time data from instruments along the well tubing at the bottom-hole and wellhead. The VFM module processes deviations between predicted and real-time data, adjusts for factors such as instrument sensitivities and field data quality, and corrects the virtual flow rates even further towards more accurate predictions. To validate and confirm this, the model also outputs the confidence rating associated with the improved predictions. These predicted results and associated confidence levels are the final outputs from the VFM system. When integrated with the PMS, this VFM module can also configure alerts to the user in the case of any sudden risks or unwanted transients arising from the reservoir such as water breakthrough in a gas well. Upgrading the PMS with the new VFM module will empower the operator with reliable and accurate flow predictions and help overcome the production flow rate uncertainty In addition to removing dependency on field instrumentation, this VFM module will facilitate improved field production forecasting, and can help lead to timely intervention in potential production-loss scenarios caused by unexpected transients.