应用流体包裹体研究油气成藏期次——以柴达木盆地南八仙油田第三系储层为例

储层中的流体包裹体是储层成岩过程被自生矿物晶格所捕获而形成的油气水包裹体 ,它们记录了油气水充注储层时的组成、性质以及物理化学条件。不同自生矿物或不同期次的胶结矿物捕获的包裹体 ,其组成和物理化学性质不同 ,这些特征是油气藏形成演化历史的直接标志。柴达木盆地南八仙油田是一个侏罗系生烃、第三系储集的成藏系统。文章通过包裹体类型、成岩矿物期次、烃类包裹体成分以及均一化温度和盐度等分析 ,证明南八仙油田上第三系与下第三系有着不同的油气注入和成藏期次 :下第三系的油气藏为两期充注的结果 ,而上第三系油气藏则主要为一期成藏。结合区域构造演化史以及南八仙第三系埋藏史和古地温资料推断 ,南八仙油田下第三系油气藏形成的地质时期为渐新世和上新世 ,上第三系油气成藏的地质时期为上新世。

APPLICATION OF FLUID INCLUSIONS TO DETERMINATION OF THE TIMES AND STAGES OF HYDROCARBON RESERVOIR FILLING:A CASE STUDY OF NANBAXIAN OILFIELD IN THE QAIDAM BASIN

Fluid inclusions in the reservoir authigenic minerals provide a direct insight on the filling history of the fluids to the reservoirs. This article describes the characteristics of the fluid inclusions in the Tertiary reservoirs of Nanbaxian oilfield in the Chaidamu basin, including the occurrence in the authigenic minerals, the fluorescence, the homogenization temperature, and the gross hydrocarbon composition. The differences of these aspects between the inclusions in the Eogene reservoirs and in the Neogene reservoirs suggest the differences in the filling and entrapment history of the hydrocarbon into the two reservoirs of the Eogene and the Neogene systems. Combining with the conclusion of the basin evolution, we deduce that the filling and entrapping stages of petroleum to the Eogene reservoirs were during the Oligocene Epoch and during the Pliocene Epoch, while the filling stage of petroleum to the Neogene reservoirs was during the Pliocene Epoch.