NMR-Responsive Paramagnetic [M-EDTA] (M = Fe3+, Mn2+, Cu2+) Complexes to Differentiate T2-Distribution Signals of Crude Oil and Brine

Safyan A. Khan, Shahid Ali*, Zain H. Yamani, Syed R. Hussaini, Julian Eastoe, Asad M. Khan, Sadaf Sarfraz

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

1 Citation (Scopus)
32 Downloads (Pure)


Nuclear magnetic resonance (NMR) well logging tools are being commercially utilized for the characterization of various fluids confined within reservoir rocks. Conventional NMR T2-distribution measurements are unable to quantify the actual fractions of crude oil and brine simultaneously present in the reservoir rocks. Herein, we reported NMR-responsive paramagnetic [M-EDTA] (M = Fe3+, Mn2+, Cu2+) complexes having the capability to differentiate NMR T2-distribution signals coming from crude oil and brine by accelerating the water (1H) relaxation. The formation of these [Fe-EDTA]-, [Mn-EDTA]2-, and [Cu-EDTA]2- complexes was explored by UV-visible spectroscopy, and their chemical stability in brine solution was monitored by measuring the change in percent transmittance and backscattering intensities with time. Spin-spin (T2) relaxation signals and T2-distribution spectra of various carbonate and sand packs were recorded. The separation of NMR T2-distribution signals was achieved using the optimized concentration of synthesized paramagnetic complexes. The separation of NMR T2-distribution signals with the optimum concentration of complexes and their long-term chemical stability in a brine solution suggest them to be commercially reliable contrast agents for the characterization of various rock fluids confined in oil reservoirs.

Original languageEnglish
Article number12
Pages (from-to)12278-12285
Number of pages8
JournalEnergy and Fuels
Early online date12 Nov 2019
Publication statusPublished - 19 Dec 2019


  • lipids
  • solution chemistry
  • ions
  • petrochemicals
  • transition metals

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