Comparative studies of crude oils from some selected oil fields in Ghana using spectroscopic techniques

Laser-induced fluorescence (LIF), Energy Dispersive X-ray Fluorescence (ED-XRF) and Non-destructive Gamma spectroscopic (NDGS) techniques are the modern spectroscopic techniques used in analysing crude oil samples around the world because of their advantages. There is currently no information on the use of these techniques for the characterisation of crude oils from oil fields in Ghana. This study explored the use of these spectroscopic techniques for characterisation of crude oils from Jubilee, Tweneboa Enyenra Ntomme (TEN) and Saltpond oil fields. LIF, ED-XRF and NDGS techniques were applied on four crude oil samples obtained from these oil fields. Fluorescence spectra obtained, using a continuous wave 405 nm laser as the excitation source, revealed five (5) peak wavelengths after deconvolution. Using Principal Component Analysis (PCA), Hierarchical Clustering Analysis (HCA), and Linear Discriminant Analysis (LDA), the crude oil samples were classified accurately. Using the fluorescence spectra from the ED-XRF sulphur concentrations in the crude oil samples were determined. Based on their Sulphur concentrations, the four crude oil samples were characterised as sweet oils. NDGS was able to identify naturally occurring radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K. Thus, it is feasible to use LIF, EDXRF and NDGS as simple and straightforward spectrochemical techniques to characterise crude oils from Ghana's oil fields effectively. (author)