Organic field deposits from distinct geographical regions were analysed using a wide range of analytical techniques, viz. for cation composition (EDAX), diffraction patterns (XRD), thermal profiling (DSC/TGA), naphthenic acid distribution using electrospray mass spectrometry (ESMS), nuclear magnetic resonance 1H NMR and solid state 13C NMR. Clear distinctions for end member soap types were observed with regard to the type and amount of cations, the naphthenic acid content, as well as their thermal behaviour. Specific soap samples were analysed along with their parent soap forming crude oils collected from the same field over a period of one year. The nature of two of these soap samples were found to be related to the particular chemical treatment on site. There were clearly observable differences in the final location within the surface facility, as well as the final composition (calcium content, acid distribution, presence of other chemical families) of these samples. These were suggested to be related also to crude oil chemistry changes and mitigation (chemical) strategies used. The implications of these new findings on the basic mechanisms of soap formation are discussed.

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