海相碳酸盐岩烃源岩热解动力学研究:全岩和干酪根的对比

Kinetic simulating experiment on marine carbonate source rocks: Comparison of source rocks with isolated kerogens

我国海相碳酸盐岩地层分布广泛,厚度巨大,经历的地质历史较长,特点是有机质丰度低,多处于高过成熟阶段。碳酸盐岩烃源岩评价对我国的油气资源评价与勘探至关重要。用生烃动力学方法来研究碳酸盐岩生油气过程是一个值得探索的研究方向。本文通过生烃动力学热模拟实验,求取了碳酸盐岩全岩和其干酪根不同烃类组分(甲烷、C2～C5气态烃)的生成动力学参数并进行对比。结果表明,在生烃动力学热解实验中,全岩和其干酪根具有相似的动力学参数,采用烃源岩应该比干酪根更符合实际,但是干酪根样品可以测得更为详细的实验数据,因此可以根据样品的情况,选择合理且易行的实验条件。在此基础上,以本文得到的参数作为参照指标,用动力学方法外推到地质实际中,可准确地提出适合我国的碳酸盐岩生烃定量模型,能为碳酸盐岩的资源评估等方面给出定量数值,从而为有效烃源岩的定量评价提供一种新的方法和途径。

The thick marine carbonate rocks spread widely in China. It is characterized by low TOC, high maturity and long geological history. The evaluation of marine carbonate source rocks is very important to the assessment and exploration of oil and gas resources in China. Hydrocarbon-generating kinetics provides a new method for quantitatively evaluating the effective source rocks. The aim of this work is to determine the kinetic parameters of hydrocarbon generation from the marine carbonate source rocks. The results shows that the marine carbonate source rocks and the isolated kerogens exhibit very similar kinetic parameters. It is suggested that the kinetic parameters of kerogen degradation measured on the whole rock give meaningful results, but more detailed data are obtained using kerogen concentrates. Whether kerogen isolation is necessary should depend on the basic geochemical data of the study sample. It is indicated that use of the results of this study can quantitatively model the generation of oil and gas and examine the natural evolution of hydrocarbon of marine carbonate source rocks via extrapolation of laboratory kinetic data obtained from high, fast heating rates to very low, geological heating ones. The results of this study also provide a new method for evaluating marine carbonate source rocks.