Determination of Kinetic Parameters of Arrhenius Equation for Oil and Gas Generation Reactions by Hydrous Pyrolysis Method in Oil Shale Samples Containing Type II Kerogen in Lorestan Sargelu Formation

In this research, type-II kerogen-bearing oil shale samples from the Sargelu Formation in the GhaliKuhArea (Lorestan, Iran) weresubjected to hydrous pyrolysis to determine the kinetic parameters of the Arrhenius equation by studying the kineticsof the hydrocarbon generation reaction in the region. In order to perform the hydrous pyrolysis tests on the samples, atemperature- and pressure-adjustable apparatus was designed and manufactured. Given the requirement of particular geochemical properties prior to the hydrous pyrolysis, the undisturbed samples were initially subjected to Rock-Eval analysis to identify immature samples with appropriate organic matter (OM) content for the hydrous pyrolysis experiments.The hydrous pyrolysis experiments were performed on 50-g rock samples at six temperatures (250, 270, 290, 310, 330 and 350°C) for 72 h. Upon the analysis, the generated amounts of oil and gas at each temperature were obtained in milligrams, with the highest amount of oil production being 739 mg at 330°C. The conversion yields were calculated based on the oil and gas generation stats and the reaction rate constant for both oil and gas generation reactions. For this purpose, the reaction rate constant was plotted against the inverse of temperature to evaluate the values of the kinetic indices of the Arrhenius equation for the oil and gas generation reactions; these were 40.75 kcal/mol and 1.03×1014 time units, for the oil generation reaction, and 40.77 kcal/mol and9.54×1013time units, for the gas generation reaction. The graph of the gas-oil ratio versus the total conversion yield indicated a decrease in the ratio as the reaction proceeded with increasing the temperature.In general, the kinetic indices can be used to study the kinetic model of the Sargelu Formation in terms of maturity, history of hydrocarbon generation, etc. In this respect, the topic is highlypractical and important in the field of hydrocarbon generation kinetics.