Performance Test of a High Gas Volume Fraction Multiphase Meter in a Producing Field
Authors: Ngai Charles C. , Brown Michael D. , Mehdizadeh Parviz 
Published: December 2007

A high gas volume fraction multiphase meter was installed and tested in PanCanadian Petroleum Ltd. Rockyford Battery. The performance testing was conducted from June 1996 to September 1996. This paper describes the multiphase meter, the battery well test facilities and test results of a high gas volume fraction multiphase meter in a producing field.

An Agar 2 inch MPFM-401-20-20 multiphase meter was installed in series with an existing well test facility. Live production fluids flowed through the testing meter into a well test separator. The two phase well test separator is equipped with an orifice meter for measuring the gas rate and a coriolis mass meter and net oil computer for measuring the oil and water rates. This test facility has a history of accurate measurement and proration factors. For this reason its data are used as standards of measurement for the multiphase meter. Over 50 well tests from 7 producing wells were measured with a water oil ratio (WOR) range from 0–96.2% and a gas oil ratio (GOR) range from 41 to 284 m3/m3 Maximum average gas volume fraction encountered in these tests was 96.9%.

Test results showed excellent agreement between the multiphase meter and the well test facility. The MPFM-401-20-20 met all its manufacturer's specified accuracies. The meter has also shown its real time diagnostic capability for producing wells. It demonstrated the flow characteristics of a horizontal well at different draw downs. The real time data collected were analyzed and used to optimize the well and troubleshoot the artificial lift equipment.

Introduction

Considering the challenge of measuring wide variation of production flow characteristics, densities, water oil ratios, and gas liquid ratios, accurate measurement of multiphase flows has always been a challenge in production operations. In addition, there are fiscal requirements of dealing with production allocation, royalty, and taxation. Due to these issues considerable resources have been dedicated to ensure the measurement accuracy. While conventional separators can be designed to provide the measurement accuracy, they have their limitations. Size and weight (and hence costs) of the equipment could dictate their applications. Besides, much of production operations are geared towards production optimization through automation and real time data management. The need for a high gas liquid ratio (GLR) multiphase meter has been demonstrated. This along with the proven multiphase pumping technology, provides new application opportunities for multiphase productions.

PanCanadian invested in a number of multiphase metering initiatives three years ago and the performance tests that formed the basis for this paper were a result of one of these initiatives.

The multiphase meter selected for the field test was an Agar MPFM-401-20-20 meter. Description of the MPFM-401 and its evaluation in a flow loop has been previously reported. PanCanadian field tests were conducted in a producing field equipped with a conventional well test separator. The basis for the selection of the test sites were:

Accuracy of the Field Test Facility. Since the MPFM-401 measurement results were to compare with the test facility data, it is very important that the system has a proven accuracy and repeatability.

Flow Characteristics. Preferably the selected site has production wells with a wide range of flow rates, gas oil ratio, water oil ratio that can cover the full range of the multiphase meter.

Operators Receptiveness. The buy in of operators is very important.

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