Total Scanning Fluorescence Characteristics of Coals and Implication to Coal Rank Evaluation

Total Scanning Fluorescence (TSF), as a kind of new fluorescence technique, has great significance and wide application in identifying hydrocarbon inclusions of reservoirs, hydrocarbon migration pathways and palaeo-current oil-water interfaces. Total scanning fluorescence (TSF) is characterized by high efficiency, requiring low sample amount and high accuracy. Vitrinite reflectance (Ro) is one of significant parameters for determining coal ranks, it cannot only reflect coalification features, but also provide a favorable indicator for coal ranks. In order to establish a relationship between vitrinite reflectance (Ro) and the characteristic parameters derived from total scanning fluorescence (TSF), fourteen coal samples (coal powder without separating macerals) collected from Qinshui basin and Huaibei coalfield are tested by TSF technique and vitrinite reflectance (oil immersion), respectively. It shows that TSF parameters are related to vitrinite reflectance value, although TSF parameters and fluorescence intensity of coals differ in Qinshui basin and Huaibei coalfield. Research indicates that more factors should be taken into consideration for coal sample TSF testing in the future so as to obtain an empirical formula relationship between Ro and TSF parameters. 1. Introduction to Total Scanning Fluorescence (TSF) Technique Fluorescence spectroscopy is a technique that has had wide application in characterizing hydrocarbon mixtures. Ultraviolet (UV) fluorescence is inherently more selective for aromatic compounds than conventional absorption measurements and at least an order of magnitude more sensitive. Fluorescence methods are particularly useful for the detection and measurement of organic compounds containing one or more aromatic functional groups. Since all oils contain a significant amount of aromatic compounds, with one to four (or more) aromatic rings and their alkylated analogues, oils exhibit distinctive fluorescence “fingerprints.” These “fingerprints,” used in conjunction with other analyses, can provide significant information for typing oils, shale extracts, and sea bottom sediment extracts [1]. Fluorescence analysis technique is significant in identifying hydrocarbon inclusion, hydrocarbon migration pathway, and palaeocurrent water-oil interface [2–4]. It includes three items, quantitative grain fluorescence (QGF), quantitative grain fluorescence-extract (QGF-E), and total scanning fluorescence (TSF). TSF technique is used in this study. TSF which developed from 1980s, was used to test aromatic hydrocarbon and concentration. This method of