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The strip of Pand north of heavy crude oil represents the main source of Cuban hydrocarbons. About the reservoirs several thickness of clayey sediments are reported. Such sequences of these rocks characterize the base of Vega Alta formation providing a sealing character. Recently scanning electron microscopy with X ray microanalysis have been used as part of a methodology of analysis, developed for clayey seal rock characterization in thouse strip of land. This methodology consisted on the integration of the morphological and chemical information. These techniques were applied to drilling cores and outcrop samples. The results of the analysis allowed to get information about the nature of the seal rocks, which is important aspect to take into account for the hydrocarbon exploration. With the application of these techniques, clays belonging to the complex mixture illite, smectite were determined. The spectra obtained by x-ray fluorescence, corresponding to clayey rocks. The chemical composition evidence the nature of these rocks, where the major elements are silicon, aluminum, calcium and magnesium. These studies allowed a better characterization of the oil seal, and allowed more detailed studies, not only in the strip of land north and also in other areas, aspect which is the main objective of the present research. [ABSTRACT FROM AUTHOR]

The north fringe of heavy crude represents the main source of Cuban hydrocarbons. Gas and oil seals of Cuban Northern Province are represented by a series of orogenic formations consisting mainly of terrigenous rocks with clay components. For seal quality evaluation of these formations, petrography and mineralogical characterization are essential. The primary sealing elements of Cuban northern province are clays, which are defined as the fundamental object of this research. They are distinguished by having a lower crystallinity than carbonates, effect that is caused by crystal imperfections: crystallite size, structural disorder and stress, while carbonates have a chemical composition that includes a smaller number of chemicals that showing clays. For this characterisation it was applied the infrared spectroscopy and x ray diffraction techniques. For this purpose samples were taken from clays and carbonate rocks of drill cores and geological outcrops. The application of these techniques allowed the determination of the composition of the rocks, characterized by the complex mixture of: illite, smectite, chlorite and hydromica (hydromuscovite) accompanied by their respective interlayereds. [ABSTRACT FROM AUTHOR]