Upstream facilities often collect streams from a variety of wells with varying percentages of hydrocarbon liquids, gas and water. These multiphase flows can be divided into components by gravity separators, where gas is taken off the top, and oil and water are separated by density and drawn from the side and bottom.
“But we need to know more about what is coming out of a field,” said Nunzio Bonavita, business development manager, Measurement Products, ABB S.p.A., to attendees of his session, “Enhanced Multiphase Flow Measurement by VIS – Vega Isokinetic Samping,” today at ABB Automation & Power World in Houston. “Test separators are capital-intensive and expensive to operate, and they do not lend themselves to real-time, continuous operation when they have to be shared among wells.”
A multiphase meter can measure the flow of each component, and continuous monitoring can allow users to verify well operation, monitor and optimize production, allocate flows from different wells to different owners, and test wells to identify their production potential. But conventional solutions use radioactive sources and have limitations on the gas volume fraction (GVF) they can handle accurately.
ABB recently formed a joint venture with TEA Sistemi, a University of Pisa spin-off that pioneered multiphase flowmeters based on isokinetic sampling, to design and manufacture a refined version of the Vega isokinetic sampling (VIS) multiphase flowmeter.
No gamma rays needed
The resulting new ABB VIS Multi-Phase Flow Meters are compact, mount directly in the pipeline, can be used both onshore and offshore, and are “the only meters on the market fully based on isokinetic sampling, which extracts a representative sample of the flow, separates it into its constituent parts, measures their flows and reconstructs the global composition,” said Bonavita. The meter relies on first principles and is designed to work without field correlations or calibration.
The meter also uses only conventional pressure, temperature and flow instrumentation (by ABB), with no other analyzer or radioactive components, so maintenance requires no specialized training or qualifications. “Gamma ray-free technology removes issues in importation, maintenance, transportation and customs,” Bonavita said.
The ABB VIS is a refinement of the original Vega, which has been installed in 44 locations since 2002 in sizes from 2 in. to 16 in. The redesign reduces size and weight (by 50% in the 10-in. size) by moving the valves and gas flowmeter inside the casing. The resulting “unique and patented” meter is “tailored for wet gas with GVF greater than 80%,” Bonavita said. “Other meters can’t do GVF so high,” and the meter offers “very high accuracy, even at GVF greater than 95%,” he said. The ABB VIS accuracy is “up to 10 times better than competitors at high GVF.”
The meter is suitable for mobile applications in well field testing, for aging reservoirs where GVF tends to increase, and for oil wells in gas lift operation where large amounts of gas are extracted together with the liquid phase. Also, “in gas storage facilities, it can detect water during gas extraction,” said Bonavita, eliminating the need to treat all extracted gas for potential liquid contamination.
ABB’s Multi-Phase Flow Meter has no size limitations, and can be applied to all the usual pipe dimensions. The design can be customized to allow gas turndown ratio up to 100:1 with no loss of accuracy.