Development of Experimental Model of Magnetic Resonance Multiphase Flowmeter, 15-9045

Principle Investigators
Derwin King
Qingwen Ni
Armando De Los Santos

Inclusive Dates: 10/01/98 - Current

Background - This project addresses the development of magnetic resonance (MR) as a new technology for on-line oil, water, and gas multiphase flow measurement. Improved multiphase flowmeters are needed worldwide as the oil and gas industry expands into more and deeper subsea regions and operates in more marginal fields. Present multiphase flowmeters, usually based on gamma ray or dielectric constant technologies, are not sufficiently accurate for the wide range of variable flows and composition encountered. Magnetic resonance is one of the few methods that can potentially provide direct quantitative and separate measurements of the flow rates of gas, oil, and water phase fractions. No commercial multiphase flowmeter based on MR technology has been successfully developed despite efforts by several organizations. Concepts recently developed by the team members are based on the use of electron paramagnetic resonance (EPR) for the oil fraction measurement and NMR for the gas and total liquid flow rates. This technology may provide the necessary breakthrough. Patent applications have been filed for international coverage.

Approach - This project, intended to develop and verify critical components and to demonstrate the concept’s feasibility in the laboratory, includes development of an experimental model of the flowmeter for laboratory testing. The effort also includes the determination of NMR and EPR properties of a wide range of crude oil samples and the development and testing of critical flowmeter components. These components include a special in-line NMR sensor to provide separate measurements of the liquid and gas velocities and flow rates and an in-line EPR sensor to measure the fraction of oil in flowing oil-water fluids. Designs are being optimized for the multiphase flowmeter application. Other major elements of the proposed system include a pre-polarization magnet, pressure and temperature sensors, a flow mixer, modifications of existing software to accommodate the multiphase signal processing, and interfaces to allow existing laboratory apparatus to be used to obtain signals from the special sensors. The experimental system will use one-inch (nominal) diameter pipe and be suitable for pressures to ten atmospheres. The initial MR laboratory tests will demonstrate the feasibility and determine any major limitations of the MR technology for this application. Subsequent tests on the SwRI hydrate flow loop will assess the absolute accuracy of this technique and experimental model over a wide range of flow rates and compositions.

Accomplishments - The NMR and EPR sensor and associated system requirements have been determined and most of the detail designs completed. The NMR sensor has been assembled for use with an existing NMR laboratory system, while final assembly of the EPR sensor and associated electronics is underway. EPR and NMR data have been obtained on the properties of a wide range of crude oils. All tested oils show properties consistent with both NMR and EPR measurement in a multiphase flowmeter. Experimental NMR measurements have been made using oil-water mixtures, and the proposed methods for fraction measurements were verified under flowing conditions. The complete instrument is now scheduled for completion in 1999 and performance verified in early 2000.

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