| Kinetic modeling of the hydrocarbons generation from organic matter's cracking is a useful method in reconstructing the history of petroleum generation in a basin. The kinetic models commonly used are proposed that the reactions of hydrocarbon generation from kerogen are parallel and independent. They should have the same exponential parameter, but distinguish themselves with different reaction energies. Because of the complexity of the mechanism of the real reactions, the exponential parameters are only an adjust factors without any physical chemistry significances.The progress of kinetic models of hydrocarbons generation promotes the technique to accurately simulate the stable carbon isotope ratio of methane. Kinetics could model the stable carbon isotope ratio of methane in the geological history. Therefore, it could help to assess how and when a gas accumulating. Up to date, Cramer model and Tang model are two models that are accepted in the world. In this Dissertation, those two models are implemented and their characters are analyzed. Also, the kinetics simulation of the stable carbon isotope ratios of other heavy gaseous components in confined system is made out. The usage of it, accompany with that of methane, could give much more accurate result in rebuilding the formation of a gas, especially a gas in a complex geological surrounding.The characters and quality of natural gases is changeful in many geological progresses, including primary migration, diffusion, water washing, bacterial activity. That made the formation information of natural gases changeable too. So, to analyze the formation of a gas should take into consideration of all those factors. In this paper, the quality and characters of the lost gas during the second processes are kinetically modeled.The modeling results based on pyrolysis experiments of Upper Paleozoic coal showed that gases in Upper Paleozoic reservoir are derived from those coals with a long time cracking history. In Ordovician reservoir, 70% of gases are from Low Paleozoic marine organic matter, and about 30% are coal-formed gas. During long time diffusion from the formation of coal-formed gas, about 30% gases rich in methane have escaped through the cap rocks, therefore, the gases left in reservoir became wet with much more heavy gaseous components. But the variance in the stable carbon isotope ratios of gas in reservoir is very inconspicuous. During water washing, about 10% coaled-gas has been lost with much more heavy gaseous components. Also, the modified characters of leaving parts are inconspicuous too. The primary migration of gases from source rock to reservoir rock makes more heavy gaseous parts leaving in the coal, because of the preferential adsorption of the coal for heavy gaseous components than for methane.Modeling results including stable carbon isotope ratios of both methane and ethane showed that gases in Kela 2 gas field are accumulated from coal burial to the end of KuqaIIIstage of Cenozoic. The earlier gas generated from coal before the formation of Kela 2 structure was adsorbed in the coal measures. The accumulation of gases finished at the end of Kuqa stage (2 Ma B.P.), because of strong structural deformation of Kuqa depression, which made some faults cut off the thick salt cap rocks.The primary migration of gases from source rock to reservoir rock in these two basins showed different degree in depleting of heavy gaseous components because of the different maturity of their mother rocks.
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