Maturity of oils

The objectives of this study are to illustrate, in terms of commercial PVT data, and Slope Factors (SF) summarizing the compositional information therein, three fundamental processes affecting the make-up of petroleums the maturation of oil, its modification by the admixture of gas and gas-condensate, and the generation of gas-condensates by evaporative fractionation as a consequence of gas addition. 

George, S.C., Ruble, T.E., Dutkiewicz, A., Eadington, P.J. (2002) Reply to comment by Oxtoby on Assessing the maturity of oil trapped in fluid inclusions using molecular geochemistry data and visually-determined fluorescence colours . Applied Geochemistry, 17,1375-1378. 

Introduction and commercial application Investment opportunities in the exploration and production (E P) sector of oil and gas business are abundant. Despite areas such as the North Sea, Gulf of Mexico and the North Slope in Alaska being mature areas, there are still many new fields under development in those regions, and new areas of business interest are opening up in South America, Africa and South East Asia. Some fields which have a production history of decades are being redeveloped, such as the Pedernales Field in Venezuela. 

It will be seen that (1) the acidity decreases during the maturing of the plant (2) as in all the cases previously considered, oil of geranium becomes ricber in esters during vegetation (3) tbe proportion of total alcohol increases slightly and the quantity of free alcohol decreases, but not to an extent corresponding with the increase of esters, so that in the course of esterification, which takes place in this case without dehydration, a small quantity of alcohol is produced. 

The inorganic materials are sometimes even capable of hindering derivatisation, as shown in the chromatogram of Figure 11.4, which was obtained from a mature linseed oil paint sample containing high amounts of sulfates only underivatised acids are observed. The pyrolyser was a CDS Pyroprobe 5000 series (CDS Analytical Inc, Oxford, USA) pyrolyser interface 180°C transfer line 300°C valve oven 290°C. Pyrolysis was performed in the presence of HMDS at 600°C. 

Figure 11.4 Chromatogram relative to a mature linseed oil paint sample containing a high amount of sulfates, obtained by pyrolysis/silylation with a resistively heated filament pyrolyser at 600° C...

Virgin olive oil contains considerable amounts of simple phenols that have a great effect on the stability/sensory and nutritional characteristics of the product. Some of the most representative are hydroxytyrosol (3,4-dihydroxyphenylethanol) and tyrosol (4-hydroxyphenylethanol) however, phenolic compounds are removed when the oil is refined (Tovar and others 2001). The phenolic content of virgin olive oil is influenced by the variety, location, degree of ripeness, and type of oil extraction procedure used, and that is why hydroxytyrosol can be considered as an indicator of maturation for olives (Esti and others 1998). Hydroxytyrosol concentrations are correlated with the stability of the oil, whereas those of tyrosol are not (Visioli and Galli 1998). 

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