元宝山洼陷储层原油特征及成藏期次分析

Characteristics and Migration History of Reservoir Fluids of Yuanbaoshan Sag

本文重点对元宝山洼陷下白垩统储层油气进行了油气包裹体和有机地球化学分析,结果表明白垩系现今储层原油至少为两期油气的混合物。第一期油气成藏发生在储层成岩作用晚期,油气成藏规模大。第二期油气成藏发生在成岩期后,与构造运动关系密切,成藏规模相对较小。储层自生伊利石K-Ar同位素测年结果表明,两期油气的成藏时间分别为90 Ma和100-104 Ma。储层原油的成熟度分析结果表明,元宝山洼陷现今储层主要为低成熟原油。

Hydrocarbon fluid inclusion and organic geochemistry analyses were carried out in the Low Cretaceous reservoir of Yuanbaoshan Sag. The results indicated that current-found crude oil in this Low Cretaceous reservoir was a mixture of oils from at least two filling stages. The first stage was found to be happened at the end of diagenesis processes with large oil filling scale and low oil maturity. The second stage, closely correlated with the tectonic cracks, was happened after diagenesis processes with small filling scale and high oil maturity. The isotopic dating results of K-Ar in authigenic illiten implicated that ages of the two oil filling stages were 100--104 Ma and 90 Ma, respectively. The crude oil maturity analysis confirmed that the majority of oil in the reservoir of Yuanbaoshan Sag is low maturity oil.