Wax precipitation from North Sea crude oils. 2. Solid-phase content as function of temperature determined by pulsed NMR

W.B. Pedersen, A.B. Hansen, E. Larsen, A.B. Nielsen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    A simple, low-resolution pulsed NMR method was applied for determining the amount of solid phase at different temperatures in 17 crude oils of different origins. Protons present in the oils were excited by a pulse of radio frequency radiation. After the pulse, the decay in magnetization was characterized by its signal amplitude obtained 10 and 70 μs after the pulse. The first signal was proportional to the number of protons in the solid and liquid phases, and the latter signal was proportional to the number of protons in the liquid phase. The NMR signals were calibrated against samples of polyethylene dispersed in a wax-free oil. For most of the oils investigated, except for some biodegraded and asphaltenic oils, the NMR estimated solid-phase content at-40 °C correlated well with the amount of wax determined by acetone precipitation at-25 °C. This pulsed NMR method was demonstrated to be capable of determining the temperature dependence of the solid-phase content of crude oils during a single working day.
    Original languageEnglish
    JournalEnergy and Fuels
    Volume5
    Issue number6
    Pages (from-to)908-913
    ISSN0887-0624
    DOIs
    Publication statusPublished - 1991

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