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Oilfield Glossary
Oilfield Glossary
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polarization time

1. n. [Formation Evaluation]
The time allotted for the alignment of hydrogen atoms with the static magnetic field during a nuclear magnetic resonance (NMR) measurement. The alignment of hydrogen atoms follows an exponential rule such that after a polarization time PT the percentage aligned is 100*(1 ? e-PT/T1) where T1 is their longitudinal relaxation time. An infinite polarization time is therefore needed to align every hydrogen atom, but 95% are aligned after a time of 3*T1. Typical polarization times for a standard NMR log are between 1 and 4 s.