A rapid measurement of : The DECPMG sequence |
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| Authors: | J Mitchell MD Hürlimann EJ Fordham |
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| Institution: | aDepartment of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, United Kingdom;bSchlumberger-Doll Research Center, 1 Hampshire Street, Cambridge, MA 02139-1578, USA;cSchlumberger Cambridge Research, High Cross, Madingley Road, Cambridge CB3 0HG, United Kingdom |
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| Abstract: | The Driven-Equilibrium Carr–Purcell Meiboom–Gill (DECPMG) pulse sequence is a rapid method for obtaining the average ratio of longitudinal to transverse relaxation times  T1/T2 as a function of T2. Since this is a one-dimensional experiment, the T1/T2T2 ratio can be acquired, potentially, in just two scans; the second scan being a reference CPMG measurement. Conventionally, T1/T2 is determined from a two-dimensional T1-T2 relaxation correlation experiment. The method described here offers a significant reduction in experimental time without a reduction in signal-to-noise. The T1/T2 ratio is useful for comparing the behaviour of liquids in porous media. Here we demonstrate the application of the DECPMG sequence to the study of oil-bearing rocks by differentiating oil or water saturated rock cores, and by observing the relative strengths of surface interaction for water in two types of rock by measuring T1/T2 as a function of magnetic field strength. |
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| Keywords: | Driven equilibrium T1/T2 Relaxation correlations Surface residency times Laplace transforms Reservoir rocks |
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