柴西地区古流体势场演化对油气成藏的控制作用

古流体势分析是油气成藏研究和盆地、区带含油气评价的基础。综合考虑时间和埋深对孔隙演化的影响,采用孔隙度双元函数模型计算了柴西地区的地层古埋深,应用改进的Phillipone法对地层古压力进行了计算,在此基础上恢复了研究区的古流体势,分析成藏期古流体势对油气运聚成藏的控制作用,探讨柴西地区油气成藏的特点和规律。分析结果表明,柴西地区古流体势场对油气成藏的控制作用明显,在主要成藏期(上油砂山组沉积末期、狮子沟组沉积末期)油气藏基本位于流体势相对较低的区域内,高势区也有油气藏分布,但都是封闭及保存条件好的岩性等原生油气藏。

Control of palaeo-fluid potential evolution over accumulation of oil and gas in western Qaidam Basin

Analysis of palaeo-fluid potential is the basic work of the study of petroleum accumulation and the assessment of basin. The age and the depth of the stratum have an influence on the evolution of the porosity. So they are taken into account to solve the restoration of palaeo-burial depth. Palaeogeopressure was solved using the modified method of Phillipone. And palaeo-fluid potential of stratum was calculated. The control of palaeo-fluid potential over petroleum migration and accumulation and the characteristics of petroleum distribution were discussed. The results show that in the middle of Miocene epoch and the late of Pliocene epoch, hydrocarbon pools usually lie in the areas, which have lower fluid potential. But the areas with high potential have pools, which are lithologic hydrocarbon reservoirs and other pools with better conservation and seals.