中—新生代大陆边缘盆地海相烃源岩生烃特征

近年来,中—新生代大陆边缘盆地海相烃源岩的成因类型研究取得了新的进展,根据生源构成和沉积环境将大陆边缘盆地海相烃源岩划分为海相内源型、海相陆源型和混合生源型3种成因类型。在大陆边缘盆地海相烃源岩成因类型划分的基础上,利用生烃模拟实验研究了海相烃源岩的生烃特征,发现不同成因类型海相烃源岩的生烃特征存在显著差异:海相陆源型烃源岩具有生烃活化能分布较为分散、生烃门限温度低、主生烃期温度范围宽、生烃转化率曲线平缓,无明显的生烃高峰期的特征;而海相内源型烃源岩则具有活化能分布较为集中、生烃门限温度高、主生烃期温度范围窄、生烃转化率曲线较陡峭、有明显生烃转化高峰的特征;海相混合生源型烃源岩的生烃特征介于上述2种海相烃源岩之间。显微组分组成的差异是造成不同成因类型海相烃源岩生烃特征不同的根本原因。

The hydrocarbon generation characteristic of marine source rock in Meso-Cenozoic continental marginal basins

New progress on the study of genetic types for marine source rocks in Mesozoic-Cenozoic continental marginal basins has been achieved in recent years. The sources of marine source rocks in continental marginal basins can be divided into three types according to their source compositions and sedimentary environments, i.e., marine endogenous type, marine terrigenous type and mixed type. Based on the classification of genetic type for marine source rocks in continental marginal basins, the hydrocarbon generating characteristics of marine source rocks were studied by means of hydrocarbon generating simulation experiment. On this basis, it has been found that a significant difference exists in hydrocarbon generating characteristics among various genetic types of marine source rocks:The marine terrigenous type is characterized by the dispersedly distributed hydrocarbon generating activation energy, low-temperature threshold for hydrocarbon generation, wide temperature range in the main hydrocarbon-generating period, gentle conversion rate curve and lack of an obvious peak hydrocarbon-generating period. The marine endogenous type has the characteristics of intensively distributed activation energy, high-temperature threshold, the narrow temperature range in the main hydrocarbon-generating period, steep conversion rate curve and an obvious peak hydrocarbon generation period. The hydrocarbon generating characteristics of the mixed type are moderate as compared with above two types of marine source rocks. The basic reason for causing different hydrocarbon generating characteristics of various marine source rocks is attributed to the different composition of macerals.