原油和烃源岩中三、四金刚烷类化合物的绝对定量与热演化研究

Absolute quantitative analysis and thermal evolution of trimantanes and tetramantanes in crude oil and source rock

金刚烷类化合物独特的稳定性使其在评价高–过成熟油气的成熟度和来源等方面具有较大的应用前景。单、双金刚烷类化合物的易挥发性会影响其定量结果,而三、四金刚烷类化合物具有更强的稳定性,可以弥补单、双金刚烷类化合物的不足。三、四金刚烷类化合物在原油和烃源岩中的浓度普遍较低且缺乏绝对定量检测方法,极大地阻碍了三、四金刚烷类化合物的定量分析与应用研究。本研究通过人工高温熟化原油、柱层析除去芳烃类杂质干扰和气相制备色谱提纯等过程,得到了3种三金刚烷类化合物(三金刚烷、9-甲基三金刚烷和9,15-二甲基三金刚烷),建立了一套能够高效识别三、四金刚烷类化合物的气相色谱质谱–质谱(GC-MS-MS)绝对定量检测方法。原油和干酪根的黄金管封闭体系热模拟实验结果表明,三、四金刚烷类化合物产率分别在Easy Ro为3.1%、3.7%(原油)和3.1%、4.0%(干酪根)达到最大,而后开始裂解。根据金刚烷类化合物的裂解演化规律构建了2类三金刚烷类指标,有效拓宽了金刚烷类指标在指示成熟度方面的应用范围。

The unique stability of diamondoids makes them have great application prospects in terms of maturity and as a source of high-over-mature oil and gas. At present, the focus of research is mainly on adamantanes and diamantanes, but the volatile properties of these compounds will affect the accuracy of their quantitative results. The triamantanes and tetramantanes have stronger stability, which can make up for the shortcomings of the adamantanes and diamantanes. However, due to the low contents of triamantanes and tetramantanes in crude oil/source rocks and the lack of an absolute quantitative detection method, the quantitative analysis and application of triamantanes and tetramantanes have been greatly hindered. In this study, through artificial high-temperature maturation of crude oil, removal of aromatic impurities by column chromatography, and purification by gas preparative chromatography, three compounds of triamantanes (T, 9-MT and 9,15-DMT) were obtained, and a set of GC-MS-MS absolute quantitative detection methods that can efficiently identify tri- and tetramantane compounds was established. The results of thermal simulation experiments on the closed system of gold tubes of crude oil and kerogen showed that the formation and evolution of triamantanes and tetramantanes reached their maximum at Easy Ro=3.1% and 3.7% (crude oil) and 3.1% and 4.0% (kerogen), respectively, and then began to crack. Two triamantane indices were constructed according to the cracking evolution of diamondoids, which effectively broadened the application range of diamondoid indices for indicating maturity.