陆东凹陷油气藏烃类组成非均质性及其意义

陆东凹陷原油和油砂抽提物中烃类的宏观组成存在着明显的非均质性。在高孔隙度(>15%)储层单元中,饱和烃的含量高,占总组成的含量均大于40%,而极性化合物则相对较低,一般不足40%;相反,在低孔隙度(<15%)储层单元中,饱和烃的含量明显降低,而极性化合物则显著增加。此外,陆东凹陷原油和油砂抽提物中烃类成熟度亦存在着非均质性:在高孔隙度储层中,原油和油砂烃类的成熟度参数高,而在低孔隙度储层中原油和油砂烃类的成熟度参数低。根据原油和油砂抽提物中烃类的宏观组成特征和成熟度参数的变化规律,提出了陆东凹陷油气聚集模式。

HYDROCARBON COMPOSITIONAL HETEROGENEITIES OF PETROLEUM RESERVIOIRS IN LUDONG DEPRESSION AND ITS GEOLOGICAL SIGNIFICANCE

The bulk composition (proportion of saturated hydrocarbons, aromatic hydrocarbons and polar compounds) of crude oils and oilsands in Ludong depression is fairly heterogeneous throughout the field. In high\|porosity sandstones(>15%), the proportion of saturated hydrocarbons amounts to about 50% of the total extract, which is also similar to the well\|head oils, where the low\|porosity(<10%) sandstones contain only 30% saturated hydrocarbons. The proportion of polar compounds reveals an opposite trend and changes from 30% to about 50% from the high\| to the low\|porosity areas. Likewise the mature parameters of crude oils and oilsands in Ludong depression reveal a wide range of variation. More mature residual oils in high\|porosity versus low mature residual oils in low\|porosity sandstones. The observed compositional variations between high and low porosity reservoirs in Ludong depression are most likely due to petroleum fluids derived from different stage of generation history in same source rocks.