Extending Virtual Metering to Provide Real Time Exception Based Analytics for Optimizing Well Management and Chemical Injection

Abstract

Shell Malaysia Upstream operations offshore Sabah and Sarawak in the South China Sea have been utilizing a data driven Virtual Flow Metering System to provide gas production estimates in real time for close to a decade. More recently, the analytics aspect of the system is helping to detect liquid loading in gas wells, support Exception Based Surveillance (EBS) and optimize chemical injection. In the absence of multiphase flow meters, a Virtual Flow Metering System may be used for well by well production rate estimation. This has been implemented for the oil wells in a deepwater facility in Sabah, enabling onshore production support teams to monitor production from each well in real time. It is a cost effective approach to project delivery while enabling safe and reliable production. Production estimation by the Virtual Flow Metering System is derived from data driven models built using a series of well tests. These models are updated as often as well tests are performed and compared to the export meter to constantly validate the accuracy of the well-by-well production estimates. For superior wells and reservoir management and to maintain asset integrity, exception based surveillance (EBS) is required. A large number of complex EBS requirements are being monitored in real time, using the signal processing and pattern detection capability of the Virtual Flow Metering System as the calculation engine. The intent of the EBS system is to alert onshore operations when a user defined operating limit is exceeded to facilitate actions to be taken in a timely manner. Some examples of EBS implementation are for sand detection and the quality of injected water and gas. Additionally, the EBS system is being used to detect liquid loading in mature Sarawak gas fields, leveraging on recent best practices reported elsewhere within the Group. More recently, this Virtual Flow Metering System usage has been extended to provide Real Time corrosion inhibitor flow monitoring with the aim to track injection rates and keep injection on target, while minimizing excess chemical costs. Within days of the deployment of this real time surveillance tool, high injection alerts detected have resulted in significant savings. Over the same period, detection of low injection has allowed faster adjustments to increase injection and thus minimize corrosion effects to the pipelines.