Cristin-resultat-ID: 1917359
Sist endret: 21. juni 2021, 14:45
Resultat
Vitenskapelig foredrag
2021

New NMR approaches on the quantification of wax-inhibitor interactions in crude oils

Bidragsytere:
  • George Claudiu Savulescu
  • Sebastien Charles Simon
  • Geir Sørland og
  • Gisle Øye

Presentasjon

Navn på arrangementet: The 21st International Conference on Petroleum Phase Behavior and Fouling
Sted: Online conference
Dato fra: 7. juni 2021
Dato til: 9. juni 2021

Om resultatet

Vitenskapelig foredrag
Publiseringsår: 2021

Beskrivelse Beskrivelse

Tittel

New NMR approaches on the quantification of wax-inhibitor interactions in crude oils

Sammendrag

Wax crystallization at low temperature is one of the main problems affecting flow assurance during oil production. Wax inhibitors, such as pour point depressants (PPDs) and crude oil components, such as asphaltenes are estimated to impact wax precipitation, by both co-crystallization and the formation of complexes with waxes [1] [2]. Low field nuclear magnetic resonance (LF-NMR) methods have rarely been implemented for the analysis of wax precipitation in crude oil in spite of very promising results. Previous advances established a method to observe the phase change of wax from liquid to solid during cooling in toluene-based systems with PPDs and asphaltenes [3] [4]. Another recent breakthrough was the development of an algorithm to calculate the amount of precipitated wax at each temperature, following LF-NMR experiments. This study builds on previous findings and presents an improved method focused on the measurement of relaxation times which characterize the mobility of wax, asphaltene and PPD molecules. As a dispersion forms at low temperature due to wax precipitation, liquid wax molecules become trapped in the pores and interact with the species of solids in dispersion. We aim to determine and quantify such interactions (wax-wax, wax-asphaltene and wax-PPD interactions) as a function of temperature. Our method firstly shows the effect of wax concentration on the wax appearance temperature and on the percentage of precipitated wax at each temperature, which both display quasi-linear increases when wax concentration increases. The level of interaction of solid waxes with liquid waxes is also demonstrated to be quasi-proportional to the wax concentration in the system, reaching a maximum at higher temperatures for higher wax concentrations, during cooling. In systems with asphaltenes, the presence of asphaltene nanoaggregates above the wax appearance temperature has been for the first time detected with LF-NMR, with our new algorithm. The impact of these nanoaggregates on the precipitated wax dispersion at low temperatures is initially qualitatively observed. Starting from this qualitative remark, we created a method to quantify interactions which demonstrates a proportional correlation of the asphaltene concentration with the intensity of interactions between solids in dispersion and liquid wax. This emphasizes the active impact of asphaltene molecules on wax crystal formation and consequently, on the pattern of wax precipitation. For example, the addition of high concentration asphaltene to wax systems increase the wax precipitation rate. Our study aims to be a starting point for the analysis of wax precipitation behavior in the presence of PPDs and asphaltenes in real crude oil systems. The understanding and subsequent control of this behavior can provide the ground for the creation of more sustainable, more efficient flow assurance methods.

Bidragsytere

George-Claudiu Savulescu

Bidragsyterens navn vises på dette resultatet som George Claudiu Savulescu
  • Tilknyttet:
    Forfatter
    ved Institutt for kjemisk prosessteknologi ved Norges teknisk-naturvitenskapelige universitet

Sebastien Charles Roger Simon

Bidragsyterens navn vises på dette resultatet som Sebastien Charles Simon
  • Tilknyttet:
    Forfatter
    ved Institutt for kjemisk prosessteknologi ved Norges teknisk-naturvitenskapelige universitet

Geir Humborstad Sørland

Bidragsyterens navn vises på dette resultatet som Geir Sørland
  • Tilknyttet:
    Forfatter
    ved Institutt for kjemisk prosessteknologi ved Norges teknisk-naturvitenskapelige universitet
  • Tilknyttet:
    Forfatter
    ved Anvendt Teknologi AS

Gisle Øye

  • Tilknyttet:
    Forfatter
    ved Institutt for kjemisk prosessteknologi ved Norges teknisk-naturvitenskapelige universitet
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