Application of nonaqueous titration to nitrogen functionality analysis for sedimentary bitumens and a crude oil

Abstract

Nonaqueous titration was used for the analysis of nitrogen functionality in bitumen (solvent extract) from Neogene marine sediments and a crude oil from the Akita Basin, NE Japan. The nitrogen in bitumen or crude oil was divided into strongly basic nitrogen (SBN; pyridinic-N), weakly basic nitrogen (WBN; mostly amide-N) and nonbasic nitrogen (NBN; pyrrolic-and nonreactive-N). High SBN/bitumen-N ratio occurred in the sediment samples that were presumably deposited under high organic flux, suggesting that the abundance ratio relates to paleoproductivity. The SBN/bitumen-N (or SBN/oil-N) ratio was higher in American and Japanese crude oils than in bitumens. The difference is attributed to either their maturity difference or the fractionation during petroleum migration.