Centro Nacional de Investigaciones Científicas

Abstract

High Resolution Gas Chromatography fingeprint was obtained for 18 crude oil samples of two Cuban fields: 9 from Pina and 9 from Puerto Escondido. A 30 m x 0.25 mm internal diameter and 0.25 µm film thickness DB-1 (J&W) capillary column as well as a suitable temperature program and chromatographic software were used. By means of a wider view of sample fingerprints, small differences in composition were highlighted and proper peak ratios for polar plot to obtain each sample star diagram were allowed to select. Diagram comparison shows similarities and differences in composition within each field and between them. This technique is often used to obtain data for reservoir geochemistry studies because it is fast, confident and simple. The obtained average peak ratio differences for duplicated analysis of 2-5 % show good reproducibility according to those that have been reported. Higher differences up to 40 % in Puerto Escondido and between 10-41 % in Pina were obtained. These results show variations in chemical composition between the analyzed samples within the studied fields, in fact, lack of continuity for the fluids in them. Nevertheless, it was possible to group some samples from Puerto Escondido with an average difference for the selected peak ratios between 5-6 % and also lower than 5 %. The obtained results leave an open space to the interest in deepening the reservoir geochemistry studies in these reservoirs.