海拉尔盆地贝尔凹陷原油芳烃化合物组成和分布特征

Composition and distribution of aromatic hydrocarbons of crude oils in the Buir Sag,Hailar Basin

通过色谱—质谱分析,对海拉尔盆地贝尔凹陷35个原油样品进行聚类分析,将之分成4类。Ⅰ类原油是贝尔凹陷原油主体,占分析样品的77%,特点是菲系列含量高,平均值为64.7%,三芳甾类化合物和三芴类化合物含量次之,分别为11.42%和11.81%。Ⅱ类原油为高三芳甾类原油,三芳甾类化合物占芳烃化合物的53.9%,是该类原油的主要成份,菲系列化合物含量较低,为32.5%,萘系列含量和三芴化合物含量最低,分别为0.6%和3.54%。Ⅲ类原油为高菲系列和高萤蒽含量原油,菲系列为64%,萤蒽含量高达11%,是其它原油的16倍以上。Ⅳ类原油具有高萘、高三芴化合物和低菲系列化合物的特点,分别占原油芳烃馏分的30%、32%和26%,三芳甾类化合物含量低,占3.6%。这充分说明海拉尔盆地烃源岩沉积期间有不同的沉积环境,原油有不同的生烃母质。Ⅱ类原油以藻类为主要生烃母质,Ⅲ类原油以高等植物为主,Ⅰ类原油介于Ⅱ类和Ⅲ类原油之间,为混合型生烃母质。Ⅳ原油沉积环境和前三类原油明显不同,为咸水强还原湖相沉积环境。

Through gas chromatographic-mass spectrometric （GC-MS）analyses,35 crude oil samples from the Buir Sag,Hailar Basin were performed cluster analysis. The results revealed that the crude oils in the sag could be divided into four types. The type Ⅰ oil showed the phenanthrene series being the highest and the average value being 64.7% , the triaromatic steroid and fluorene, dibenzofuran, dibenzothiophene series being higher, with an average value being 11.42 % and 11.81% respectively. It was majority of the crude oils in the sag,and occupied 77% of the crude oil samples. The type Ⅱ oil was high triaromatic steroid series oil. Its triaromatic steroid series occupied 53.9% of the aromatic hydrocarbons compound,which was primary component of this kind of oils, with lower phenanthrene series content （the average value being 32.5% ） ,the naphthalene series and the fluorene, dibenzofuran, dibenzothiophene series being the lowest（the average value being 0. 6% and 3.5% respectively）. The type Ⅲ oil showed the high phenanthrene series and fluoranthene. Its phenanthrene series was 64% ,and the fluoranthene content reached 11% ,which was 16 times of other oils mentioned above. The type Ⅳ oil showed the highest naphthalene series,the high fluorene,dibenzofuran, dibenzothiophene series and low phenanthrene series,with average value being 30% ,32% and 26% respectively. Its triaromatie steroid series was lower,with average value being 3.6%. This study sufficiently illustrated the source rocks having varied depositional environments during the rock deposition and the crude oil possessing different hydrocarbon-generating precursors. The precursors of type Ⅱ and type Ⅲ oils were algae and higher plant for chief respectively,and the precursor of type Ⅰ oil was mixed by ones of the types Ⅱ and Ⅲ. Different from the above three crude oils, the depositional environment of type IV crude oil was salty and strong reductional lacustrine.