This paper describes how Brunei Shell Petroleum Co Sdn Bhd (BSP) uses cross validated and reconciled real time production data across large offshore and onshore production networks to support more proactive day-to-day oil and gas production surveillance and management. Examples are presented of the gathering network surveillance systems for the extensive BSP East and Darat Production Assets.

In modern oil fields, there is an abundance of instrumentation distributed over often large geographical areas. The production network ranges from the individual wellheads, to production manifolds, test and bulk separators, past surge vessels and export pumps, to crude dehydration tanks at a central crude terminal or to the gas compressors and gas export points. At least the initial parts of the production gathering network at the wells will have multiphase flow with uncertain and variable oil, water and gas proportions. Normally the most downstream flow meters are well calibrated with good calibration records, but the actual accuracy of the majority of the flow meters upstream will be uncertain, and they will not be nominally designed to handle multiphase fluids or mixtures of fluids with varying densities. Conventionally, it is regarded to be problematic to track production variations in real time across the network back to the source wells. This is due to issues with metering multiphase flows and assumed uncertain transport delays.

It is shown here that it is now practical to track in real time production rates across large production networks, working back from the most downstream, well metered, points to the individual bulk separator units or production platforms or the wells themselves. Indeed, it is possible to obtain a consistent, real-time reconciled view of the current production rates across these larger production networks. This allows more accurate surveillance of production from the wells, early detection of measurement issues and quicker responses to system upsets. Various common blockers to real time network wide production flow surveillance are addressed, including noisy meters, storage tanks, on-off pumps and hard-to-measure multiphase flows from the wells. The work reported may be seen as a "top-down" approach that complements the existing metering systems, integrating the data to "make the best of" all available metering and instrumentation. An example shows how better metering and instrumentation, virtual metering and real time data analysis are combined to detect and correct significant discrepancies.

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