西藏措勤盆地它日错地区下白垩统多尼组与郎山组烃源岩评价

Hydrocarbon Source Rocks Evaluation for The Langshan Formation and The Duoni Formation of Lower-Cretaceous In Taricuo Area, the Coqen Basin, Tibet

措勤盆地是青藏高原仅次于羌塘盆地的海相含油气盆地,具有良好的油气前景。根据野外对露头烃源岩的观察,结合样品室内分析结果,从有机质的丰度、类型、成熟度以及沉积特征等方面,对其进行了初步评价。结果表明,它日错地区的两套烃源岩,郎山组灰岩有机质丰度很低,以Ⅱ1型干酪根为主,处于成熟阶段;多尼组灰岩有机质丰度低,多为Ⅱ2-Ⅲ型干酪根,达到高成熟-过成熟阶段;总体而言,它日错地区烃源岩生油潜力很差。

Located in central Tibetan Plateau, the Coqen basin is the second largest marine hydrocarbon-bearing basin in Tibet Plateau, which has considerable oil prospect. According to the field outcrop investigation and laboratory analysis results of hydrocarbon source rocks samples, this paper conducts a preliminary evaluation of hydrocarbon source rocks, which is based on the organic matter abundance, organic matter type, organic matter maturity. The results show that total organic carbon（TOC） content in limestone of Langshan Formation is very low. The organic matters were composed of type Ⅱ1kerogen and have reached the mature stage. The argillaceous rocks of Duoni Formation contain low TOC and are composed mostly of type Ⅱ2-Ⅲ kerogen, which has reached the high mature to over mature stage. All in all, the hydrocarbon generation potential of hydrocarbon source rocks in Taricuo area is very bad.