深层油气中三金刚烷类化合物的形成与演化

Due to stable chemical structure, diamondoids have wide prospects of application in petroleum geochemistry field. But the adamantanes are easily volatile, which seriously affects their wide application, especially for source rock samples. Triamantanes, with high boiling point, can make up for the defects of adamantanes. However, the contents of triamantanes in geophere are very lower, which makes their quantitative detection more difficult and results in few researches on triamantanes. A great deal of researches have been carried on adamantanes and diamantanes and a systematic understanding on them has been obtained. But it is still not clear for the formation and evolution of triamantanes in oil and gas, seriously influencing their application. In this project, a new quantitative detection method for triamantanes in crude oils using highly sensitive and selective gas chromatography- triple quadrupole mass spectrometry (GC-MS-MS) would be established through optimizing the instrument runtime parameters to obtain maximum selectivity and sensitivity for target analytes. Combined with pyrolysis simulation of crude oils/ source rocks, the formation and evolution of triamantanes would be revealed. Further, the triamantanes in typical highly mature crude oil samples of deep layers from different basins would be identified and the application of triamantane indices could be discussed. Hence, this study could deepen the understanding on the formation and evolution of triamantanes and provide reliable experimental evidences and scientific theory bases for the construction and application of triamantane indices.

金刚烷类化合物具有稳定的化学结构，在油气地球化学领域有着广阔的应用前景。然而，由于单金刚烷类化合物的易挥发性，严重影响其广泛应用，特别是对于烃源岩样品。三金刚烷类化合物具有较高的沸点，可以很好地弥补单金刚烷类的缺陷，但由于它在地质体中的含量非常低，定量检测难度较大，因此相关研究非常少。前人对单、双金刚烷类化合物已经进行了大量研究并取得了系统认识，但是对三金刚烷类化合物的形成与演化的认识尚不清楚，影响相关应用。本项目拟利用具有高灵敏度高选择性的色谱-质谱-质谱仪，通过优化仪器参数，建立一套适用于三金刚烷类化合物的定量检测方法；结合原油/烃源岩热模拟实验，揭示三金刚烷类化合物的形成和演化规律；选取不同盆地典型深层高熟原油样品，探究三金刚烷指标的应用。因此，本研究可以更好的认识三金刚烷类化合物的形成与演化机理，为三金刚烷指标的构建与应用提供可靠的实验依据和科学的理论基础。

金刚烷类化合物独特的稳定性使其在指示高-过成熟油气成熟度和来源方面具有很大的应用前景。目前研究重点主要以单、双金刚烷类化合物为主, 但是单、双金刚烷类化合物易挥发的特性会影响其定量研究结果的准确性。而三、四金刚烷类化合物相对单、双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。但是, 由于三、四金刚烷类化合物在原油/烃源岩中含量较低且绝对定量检测方法缺乏, 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, 得到了三金刚烷类的三种化合物(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GC-MS-MS绝对定量检测方法; 同时通过开展原油和干酪根的黄金管封闭体系热模拟实验, 明确了原油和烃源岩中三、四金刚烷类化合物的生成演化规律, 三、四金刚烷类化合物产率分别在3.1%Easy Ro、3.7%Easy Ro(原油)和3.1%Easy Ro、4.0%Easy Ro(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两类三金刚烷类指标, 有效拓宽了金刚烷类指标在指示成熟度方面的应用范围。