热解升温速率对有机质生烃动力学参数的影响

Influence of Heating Rates on Kinetic Parameters of Hydrocarbon Generation from Organic Matter

摘要: 完成了不同类型有机质样品多条升温速率(10℃/min、20℃/min、30℃/min、40℃/min、50℃/min)的开放体系热解实验。采用不同升温速率组合(10℃/min~20℃/min~30℃/min、20℃/min~30℃/min~40℃/min、30℃/min ~40℃/min~50℃/min)实验数据标定了动力学模型参数。结果揭示：不同类型有机质的生烃过程均可用平行一级速率模型描述，其中I型有机质活化能分布范围相对较窄，以一个占主要部分的活化能为主，III型有机质活化能分布范围相对较宽。由慢速升温速率组合到快速升温速率组合实验数据获得的指前因子依次降低，平均活化能也依次减小。以3.3℃/Ma的地质升温速率外推表明，随升温速率的增加，动力学模型计算的地质Tmax依次降低，范围在30℃~40℃之间。对此，提出一种采用研究区烃源岩生烃数据或成熟度数据对不同动力学参数进行可靠性检验的方法，有助于选择合适的动力学参数，也可以进一步进行动力学参数敏感性分析及动力学模型的风险评价。

Abstract: Open system pyrolysis experiments with multiple heating rates (10˚C/min, 20˚C/min, 30˚C/min, 40˚C/min, 50˚C/min) of different types of organic matter samples have been accomplished. The kinetic model parameters can be calibrated by using the experimental data of different heating rates (10˚C/min-20˚C/min-30˚C/min, 20˚C/min-30˚C/min- 40˚C/min, 30˚C/min-40˚C/min-50˚C/min). Results show that the hydrocarbon processes of different types of organic matter can all be described by the parallel first-order rate model. Therein, the activation energy distribution range of type I organic matter is relatively narrow, distributed mainly in the major part of the activation energy. The activation energy distribution range of type III organic matter is relatively wide. The pre-exponential factor obtained by the experimental data, as well as the average activation energy, gradually decreased from slow heating rate combinations to fast heating rate combinations. Extrapolated by geological heating rate of 3.3˚C/Ma shows that with the heating rate increasing, the geological Tmax calculated by the kinetic model gradually decreases from 30˚C - 40˚C. Therefore, proposing a method using the source rock hydrocarbon data or maturity data of the study area to test the reliability of different kinetic parameters could contribute to select the appropriate kinetic parameters. It can also be used for further sensitivity analysis of the kinetic parameters and risk assessment of the kinetic model.