Spectroscopic determination of naphthenic acid composition from various calcium naphthenates field deposits

Mohammed Murtala Ahmed, K. S. Sorbie

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Naphthenate formation in oil production systems has been recognised for some times as a troublesome and potentially expensive flow assurance problem. The production of biodegraded or higher TAN (total acid number) crude oils together with the changes in both chemical and physical properties during production operations may trigger naphthenate formation. These naphthenate deposits may form as either a soft emulsion type sodium naphthenate or as a hard solid deposit of calcium naphthenate. Within the Flow Assurance and Scale Team (FAST) at Heriot-Watt, we have carried out an extensive series of naphthenic acid extraction and characterization experiments on a range of field sodium and calcium naphthenates samples from around the world. In particular, we have analysed these samples using the negative ion mass spectroscopic techniques, ESMS and APCI-MS. In this paper, we present results of naphthenate extract analyses for calcium naphthenate field deposits from the North Sea and Asia. Some of the samples analysed show the presence of both lower and higher molecular weight naphthenic acids in the spectra, whilst others showed mostly the presence of higher molecular weight naphthenic acids with minor traces of lower molecular weight species. Results from this work have now shed more light on the naphthenic acid composition in different field calcium naphthenates, which has been a topic of debate for some time. Results are also presented from novel re-precipitation experiments using the naphthenic acid extract and synthetic brine. Both APCI-MS and ESEM/EDAX data are presented for these laboratory formed precipitates. These results lead to some clear conclusions on the final composition of calcium naphthenate deposits. Copyright 2009, Society of Petroleum Engineers.

    Original languageEnglish
    Title of host publicationProceedings - International Symposium on Oilfield Chemistry 2009
    Pages595-604
    Number of pages10
    Volume2
    Publication statusPublished - 2009
    EventInternational Symposium on Oilfield Chemistry 2009 - The Woodlands, TX, United States
    Duration: 20 Apr 200922 Apr 2009

    Conference

    ConferenceInternational Symposium on Oilfield Chemistry 2009
    CountryUnited States
    CityThe Woodlands, TX
    Period20/04/0922/04/09

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  • Cite this

    Ahmed, M. M., & Sorbie, K. S. (2009). Spectroscopic determination of naphthenic acid composition from various calcium naphthenates field deposits. In Proceedings - International Symposium on Oilfield Chemistry 2009 (Vol. 2, pp. 595-604)