Multi-Phase Flow Metering Using Dissimilar Flow Sensors: Theory and Field Trial Results

Abstract

This paper addresses a new approach to multi-phase flow metering. The Multi-Phase Flow Meter (MPFM) described combines dissimilar flow sensors to measure the flow rates of the gas and liquid components plus a microwave water content monitor to determine the oil and water fractions A brief review of the alternate technologies and approaches to multiphase metering is included as a basis for explanation of the design choices in this meter. The predicted performance of the meter is compared against field tests that were conducted to assess the performance of the meter. These tests covered a wide range of fluid properties, gas void fractions up to 97%, 0-100% water cut, and various installation geometries. The field tests support the predicted overall accuracy of 10% of the reading (2% of the full scale) for liquids and 10% of the reading (5% of the full scale) for the gas components of the flow. Introduction The measurement of oil, water and gas flow in the production operations is required to assist in the reservoir management, reservoir allocation, and fiscal metering. The traditional approach to measurements of the produced fluids has required separation and independent measurements of the oil, water, and gas. The separation and measurement approach has inaccuracies and requires operator attention and maintenance. In addition, in offshore and subsea facilities where space and weight is a major concern, the large size and weight of the conventional separators adds to the cost of facilities. A multi-phase measurement is the measurement of oil, water, and gas phases in a production stream without the separation of the phases before entering the meter. A compact, light weight, multi-phase flow meter which can operate in a wide range of flow regimes and changing fluid conditions has many applications in the production facilities on and offshore. The search for an affordable and field worthy multi-phase meter and the advantages that such meters bring to the field of measurement has been the subject of numerous papers. This paper addresses the development and testing, by Agar Corporation of a new approach to multi-phase flow metering which uses dissimilar flow sensors. To provide the background for the design choices which were made in the development of the Agar multi-phase meter, a brief review of the alternate technologies and approaches to multi-phase metering will follow. P. 85