Flow Regime Analyzer Based on Low- Field NuclearMagnetic Resonance and Field-Cycling Scheme for Fluid Contrast

LUCAS MATÍAS CERIONI, CRISTIAN SEBASTIÁN MORÉ, JULIA INÉS GARCÍA, DANIEL JOSÉ PUSIOL

Congreso; 18th ISMAR 2013/14th NMR Users Meeting; 2013

ISMAR

TH258: Flow Regime Analyzer Based on Low- Field NuclearMagnetic Resonance and Field-Cycling Scheme for Fluid Contrast 1;2_Lucas Matías Cerioni, 1Cristian Sebastián Moré, 1Julia Inés García, 1;2;3Daniel José Pusiol 1SPINLOCK SRL, Córdoba, Argentina, 2Argentinian National Research Council, 3Instituto de Física Enrique Gaviola, Ciudad Universitaria, Córdoba, Argentina The real-time determination of the flow regime and the composition of the complex fluid being extracted through the production line is today one of the main challenges in the oil industry. In this work we present a system, based on a Halbach magnet type, designed for determining in real-time, mean velocity and fraction of components of complex fluids directly in the production vein by means of low-field Nuclear Magnetic Resonance. This constitutes an extension and improvement of a previous work. The apparatus includes a main Halbach magnet of 35 cm in length, with a cylindrical region of interest (ROI) of 5 cm in diameter and 10 cm in length, allowing to measure in a 5 cm (2 inch) pipe. By means of a method based on the analysis of the early behavior of the echo amplitudes of a CPMG sequence and without applying any static or pulsed gradients, the cuts and mean velocity of oil and water mixtures were measured for flow-rates between 0.2 and 4 m3/h. Density contrast between oil and water phases with different longitudinal relaxation times T1 was accomplished varying the pre-polarization field. Unlike a previous work where the pre-polarization field of variable effective length was achieved by means of Halbach stacks with rotation capabilities, the prepolarization stage of 200 cm in lenght remains fixed, and an electromagnet of 30 cm in lenght before the main magnet provides the fluid contrast. A better contrast is achieved using a field-cycling type scheme on the pre-polarizing magnetic field, taking advantage of the greater difference in oil and water relaxation times at Larmor frequencies ranging in low-field values (kHz range). A theoretical modeling using adiabatic processes for the changes in the magnetic field experienced by the sample while flowing allows optimizing the contrast between the two phases. The experimental results are in agreement with the theoretical framework. ACKNOWLEDGMENTS: CONICET, FONTAR, SPINLOCK