Field evaluation of a multiphase meter in well-testing operation

This paper describes the evaluation results on the measurement accuracy and long-term operation of a multiphase meter used for well testing. The test was conducted by Chevron at its Lost Hills field in California. After many years of development work, several multiphase meter manufacturers have begun to offer their meters commercially for production operation. In this paper, commercial multiphase meters are first briefly reviewed based on the methods that those meters use to handle the fluid flow. The multiphase meter selected for this application was manufactured by Accuflow Inc. It uses the compact separation approach in handling the oil/gas/water flowstream by first separating the gas from the liquid stream and then measuring the gas and oil/water separately. The Accuflow system was installed at a gauge station in January 1996. It was designed to test wells that have productions ranging approximately from 100 to 400 bbl of fluid per day, with a high water cut (40 to 90%), and up to 200 Mcf/D of gas. For accuracy testing, the multiphase meter was piped in series with a test separator at the gauge station. Production from selected wells, covering a wide range of flow rates, water cuts, and gas volume fractions, flowed through the multiphase meter first and then through the test separator, which enabled comparison of the new meter's performance and accuracy with an existing reference. Additional tests also were conducted to compare results with a test tank at the site. The paper also discusses other operational aspects of the multiphase meter such as equipment maintenance and sand accumulation. Overall, satisfactory performance of this multiphase meter was observed, and additional units have been installed at the Lost Hills field.