济阳坳陷东营凹陷沙三中亚段流体包裹体古流体势场恢复

Reconstruction of the paleo-fluid potential field of Es^3 in the Dongying Sag of the Jiyang Depression with systematic fluid inclusion analysis

通过对东营凹陷沙三中亚段砂岩储层中376块流体包裹体样品的系统分析,将研究区的油气充注划分为3个期次,并确定出3期油气充注发生的时间。运用流体包裹体PVT热动力学模拟的方法,获得了3个充注期的古压力演化,结合本区平面和剖面上现今地层压力的分布,确定了沙三中亚段油气藏可视为处于同一个含油气压力系统中。在此基础上,利用流体包裹体所获得的参数恢复了沙三中亚段3期古油水势场的演化,并分析了其分布特征,探讨了油气充注期中的有利油气聚集区。认为东营凹陷油气藏的分布与古流体势的演化有密切的联系,3期油气充注时期古油势控制成藏的阀值分别为7,10.5和22 kJ/kg,利津洼陷北坡和牛庄洼陷南坡是第一期有利的油气低势聚集带,围绕牛庄洼陷和利津洼陷这两大高油势中心的周边区域为第二期有利油气成藏带,第三期油气有利成藏带逐渐扩展到民丰和博兴两大洼陷周缘区域。

Based on the analyses of 376 samples of fluid inclusions from the middle Es3 in the Dongying sag, hydrocarbon charging in the study area was divided into three different stages with exact time. The evolution of pa- leo-formation pressure during these three charging stages was obtained through PVT thermodynamic modeling of the fluid inclusions. The results in combination with the plane and sectional views of current pressure distribution reveal that the hydrocarbon reservoirs in Es3 belong to the same pressure system. The evolution of paleo-fluid po- tential fields in Es3 during these three stages were reconstructed with the parameters obtained from fluid inclusion analysis and their distribution features were analyzed. The favorable areas for hydrocarbon accumulation during these three periods of hydrocarbon charging were discussed. It is believed that the reservoir distribution in the Dongying sag was closely related to the evolution of paleo-fluid potential, and the thresholds of paleo-fluid potential controlling hydrocarbon accumulation in these three charging periods were 7 kJ/kg, 10.5 kJ/kg and 22 kJ/kg respectively. The northern slope of the Lijin subsag and the southern slope of the Niuzhuang subsag were the favorable areas for hydrocarbon accumulation during the first period of hydrocarbon charging ; the surrounding areas of the Lijin and the Niuzhuang subsags （high oil potential centrers） were the favorable areas during the second period of hydrocarbon charging;while the surrounding areas of the Minfeng and the Boxing subsags were the faorable areas during the third period of hydrocarbon charging.