摘要
用TSQ－70 GC／MS／MS色质仪分析了珠江口盆地100余个原油和生油岩样品，发现部分原油样品具有异常丰富的ααα-C29甾烷（20S）异构体。国内外许多学者认为甾烷ααα-C29 20S／（20S＋20R）值是最有效的成熟度指标，只与成熟度有关，其热成熟平衡值为0．50－0．55。珠江口盆地有部分油样甾烷ααα-C29 20S／（20S＋20R）值异常之高，最高达0．67，已超过其热平衡值，已超过了当地成熟、过成熟生油岩样品值。确认油源之后，发现离生油凹陷越远，运移距离越大的原油，其甾烷ααα-C29 20S／（20S＋20R）值越大。因此，ααα-C29 20S（20S＋20R）不仅与成熟度有关，还与运移距离有关。
More than 100 crude oil and source rock samples in Pearl River Mouth Basin were analysized by TSQ-70 GC/MS/MS mass spectrometer.Abnormally abundant ααα-C_(29) sterane (20S) isomer were found in some samples.It is believed that the parameter of ααα-C_(29) sterane 20S/(20S+20R) is the most effective maturity index and only related to maturity.Its thermal equilibrium value is about 0.50— 0.55. However,some crudes in Pearl River Mouth Basin have abnormally high values of ααα-C_(29) sterane 20S/ (20S+20R) ,with the maximium about 0.67 which exceeded the thermal equilibrium value and the values of matured or over matured source rocks.After the verification of oil source,it has found that the longer the distance from the oil generation sag,the longer the crudes migrated,and the bigger the ααα-C_(29) sterane 20S/(20S+20R) values.Thus,ααα-C_(29) sterane 20S/(20S+20R) values are not only related to maturity,but also related to the distance of migration.
出处
《中国海上油气（地质）》
1991年第5期19-24,共6页
China Offshore Oil and Gas(Geology)
