Characterization of Crude Oil and Condensate by Time-Resolved Laser Fluorescence Microscopy--Preliminary Study: ABSTRACT

Abstract

To determine the type and maturity of normal and biodegraded crude oil and condensates, 13 samples from diverse types of Tertiary and Cretaceous reservoirs from Alabama, California, Texas, and Venezuela were characterized utilizing pulsed laser fluorescence microscopy (developed by Borst for coal characterization). Parameters such as fluorescence lifetime in nanoseconds (ns) for three resolved fluorophores and percent contribution of each fluorophore were correlated with organic geochemical and bulk chemical data on crude oils and condensates. The fluorescence lifetime (ns) of the intermediate component has been correlated with ratios of aromatics to the heterocomponents (fluorescence emitters). This relationship, when compared with the ratio of aromatics to asphaltenes (fluorescence quenchers), revealed characteristic distribution of oils derived from two different reservoirs: (1) marine source-derived oil from Lovetts Creek field (Smackover), Alabama, and (2) terrestrial source-derived oil from Charamousca field (Wilcox), south Texas. These data are supported by geochemical fingerprinting. The above-mentioned ratios and the ratios of the fluorescence lifetimes of two individual fluorophores also show characteristic patterns for biodegraded (alteration in reservoir) and nonbiodegraded crude oils from the Wilcox, Duval County, south Texas, and the Oficina reservoir, Venezuela. These ratios also suggest the possible maturity of two biodegraded crude oils from the Wilcox,more » south Texas, that coincides with the results of a biomarker study. The above parameters indicate the similarity in origin of two crude oils and one condensate from the Travis Peak Formation, Chapel Hill field, east Texas.« less