Field Tests Of The High Gas Volume Fraction Multiphase Meter

Abstract

Abstract Tests were conducted during November, 1995 by Agar Corporation, Conoco, Inc., and Amoco Corporation at the Conoco Multiphase Test Facility near Lafayette, Louisiana, to demonstrate the performance of a novel high gas volume fraction multiphase meter. This paper describes how the meter works, summarizes the results of these field tests and discusses the application of the meter. The high gas volume fraction meter (MPFM-400 Series) utilizes a Fluidic Flow Diverter (FFDTM) to divert most of the free gas in a multiphase stream around an MPFM-300 multiphase meter and into an ancillary gas measurement loop. The gas in the bypass loop is metered accurately and added to the oil, water, and gas measured by the multiphase meter. The result is a high void fraction multiphase meter which can accurately meter flow streams where the gas phase is a dominant component of the flow. This novel concept reduces the size and the cost of the multiphase meter while improving its capacity and accuracy. The field tests conducted at the Conoco Multiphase Test Facility have shown that the meter can handle flow conditions with the GOR of 20 to 90,000 SCF/BBL with very good accuracy. This paper describes the performance and accuracy of this new concept multiphase meter as demonstrated by the field tests. The MPFM-400 Series Meter has important applications for metering high GOR wells or wells with moderate GOR that are tested at low pressure. Introduction High gas to liquid ratio (GLR) production streams pose special problems to multiphase metering. These problems have been reviewed, and methods for partial separation to deal with high GLR streams have been presented previously. The need for high GLR capabilities of a multiphase meter is illustrated in Figure 1. The graph in Figure 1 shows a sample of well characteristics (gas to liquid ratios) from different production regions around the world. It should be noted that a significant percentage of the wells have gas fraction above the 90 to 95% gas volume fraction. The MPFM-400 ("High GVF Meter"), which can measure accurately with a GVF of 99.9%, is an extension of the MPFM-300 Series multiphase meter ("Multiphase Meter"), which is limited to an average GVF of 97.5%. The principles of the operation and performance of the Multiphase Meter have been described in detail in References 3, 4 and 5. The Multiphase Meter measures the total volume of the flowing stream utilizing a ruggedized PD (Positive Displacement) meter, a Venturi section to measure gas/liquid flow rates, and a Water Cut Monitor for determination of the water/liquid fraction. The outputs of these devices are fed into a computer which houses the proprietary data management software. The software is designed to provide flow rates of oil, water and gas phases in the multiphase stream. The High GVF Meter is designed to measure flow streams with very high GLR's accurately. Using the unique FFDTM, the meter routes varying amounts of the free gas in the inlet stream into the gas bypass loop as shown in Figure 2. This innovation allows the High GVF Meter to handle a much higher total rate of multiphase fluids. The unique design approach reduces the overall size of the equipment which would otherwise be required, and lowers the overall cost of the system. Figure 2 is a drawing of the High GVF Meter. The fluid stream enters the meter through the FFD which diverts a major portion of the free gas in the inlet stream to the gas bypass loop. The remaining fluids pass into the Multiphase Meter. The FFD device is a mechanical device with no moving parts that utilizes the difference in the flow momentum of the gas and liquid to operate as a fluidic diverter. The lower flow momentum of the gas causes the FFD to deflect most of the gas in the inlet stream to the gas bypass loop. The higher momentum of the remaining liquid/gas mixture in the stream induces continuation of the flow through the Multiphase Meter. P. 213