青藏高原隆升对柴西南区岩性油藏形成的影响作用分析

详细分析了青藏高原隆升与柴达木盆地西南区岩性油藏形成过程之间的耦合关系,认为青藏高原隆升具有"早弱晚强"的构造活动特征;相对于构造圈闭而言,隆升I阶段更利于岩性圈闭的形成,岩性圈闭发育早而且多期次发育;3期原油充注分别对应于隆升I期的B阶段(E_3~2)、II期的C(N_2~1)阶段和E阶段(N_2~3),配合沸腾包裹体群的发现,说明该区油气成藏的动力主要来自于青藏高原隆升所产生的远程构造应力。高压系统内的烃源岩进行"突发式"排烃,经开启的断裂向常压系统内运移和聚集。青藏高原隆升晚期强烈构造活动是柴西南区岩性油藏形成的主要成因,可以判断在这种"自我封闭"的高原咸化湖盆内岩性油藏的富集主要受控于断裂输导体系。

The impact analysis of Tibetan Plateau uplifting to the forming of lithologicreservoirs in southwestern Qaidam Basin

The coupling relationship between Tibetan Plateau uplifting and the lithologic reservoirs formation of southwestern Qaidam Basin has been detailedly analysed on the base of previous researches. It is summarized that Tibetan Plateau develops weakly at the early time and strongly at the last stage. The lithologic traps develop more early and multiperiod than structural traps in uplift period I. The three oil filling respectively occur in the B stage of uplift period I(E32), C stage (N21) and E(N23) stage of uplift period II. Combining with the discovery of boihng inclusion, it is concluded that the remote tectonic stress of Tibetan uplifting is the main accumulation dynamics in study area. The hydrocarbon in high-pressured source rocks can be expelled abruptly, migrating along the opened fractures and accumulating in the normal-pressured system. The strong tectonic activity of Tibetan Plateau uplifting II period is the main cause for the forming of litologic reservoirs in southwestern Qaidam Basin. So, it is clearly that fracture of conducting system is the main controlling factor for accumulation regulation of litologic reservoirs in this kind of plateau saline lacustrine basin, which is characteristiced as a self-reclusive system.