Paper 3. Genetic Similarity of Natural Systems and Region Boundaries. The present paper (the concluding one in a series) deals with one important application of generalizations of the relationships between the compositional patterns of conative* hydrocarbon systems and their formation conditions [i, 2]. We are referring to those properties of natural hydrocarbon systems (NHCSs) that are genetic characteristics and permit establishment of similarities or differences in the sources and formation conditions for specific systems (primarily petroleum systems). This in turn permits establishment of the patterns of NHCS distribution over geochemical regions. The practical value of identifying genetic traits and regional boundaries goes far beyond intellectual and theoretical problems. Establishment of the true boundaries (whose coincidence with administrative boundaries is far from consistent) of lands containing genetically similar NHCS facilitates optimization of the construction of expensive oil and gas processing, collection, and grading systems, of trends and scales in refinery expansion, and of strategy and tactics for seeking new fields and even new regions. This approach to the principles of NHCS classification is prompting a broad range of new basic research on the chemistry, geochemistry, and geophysics of natural systems and proved and putative oil and gas provinces, as well as optimum ways to provide consumers with fuel and feedstocks for organic synthesis. The choice of genetic similarity criteria should naturally rest on definite fundamental concepts regarding the origin of NHCS. The biogenetic concept, which is dominant in world science and practice, has dictated that such criteria be sought in hereditary similarity of oil and gas components, with a presumed biogenic conservatism. Many such criteria have been proposed. Most important are so-called chemofossils, i.e., by Hunt's definition [3], "organic compounds whose carbon structure or backbone was formed in living organisms and is distinguished by rather high stability, so that they can be recognized as ancient remnants in petroleum or organic matter." Hunt considers typical chemofossils, e.g., porphyrins, which have a closed bridge structure made up of four pyrrole rings and a strong ability to form complexes. It is porphyrin derivatives in magnesium complex form that are incorporated intothe chlorophyll of green plants and in divalent iron-complex-form that serve as components of hemoglobin and cytochrome. However, much that pertains to this presumed chemofossil has gone unremarked. First of all, remnants of porphyrin iron or magnesium complexes have not been found in any petroleum; only vanadium and nickel complexes have been detected. In 1967, Hodgson and Baker [4] published data on porphyrin formation under the action of an electrical discharge (lightening model) in a gas mixture (paleoatmosphere model). These researchers detected porphyrins in the organic portion of the Orgueil meteorite [5]. There is other evidence supporting possible abiogenic synthesis for both porphyrins and other compounds that have been confidently classified as chemofossils [6], e.g., isoprenoids. Adamantane derivatives have been treated as chemofossils, but it has been reported that adamantane could not be produced from biogenic precursors [7]. One publication [8] lists the presence of iodine as an indicator of the organic origin of petroleum; it was probably assumed that this element did not exist prior to the development of life on Earth and could not exist outside biomass.
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Jan 1, 1992
N G Evdokimova + 3
Open Access