大港探区古流体特征及其地质意义

位于黄骅凹陷的大港探区经历了加里东、海西、印支、燕山和喜山期构造热事件。古流体研究表明 ,本区有两期油气运移过程 ,分别与燕山期和喜山期的构造热事件相对应。两期油气运移过程具有不同的流体包裹体特征记录和明显差异的流体成分和物理化学性质。早期油气运移以形成液态烃有机包裹体为主 ,流体成分中有机组分含量 (质量分数 )偏低 ( 13 5 %～ 3 7 9% ) ,而无机组分含量(质量分数 )偏高 ( 62 0 %～ 85 9% )。晚期油气运移以形成气态烃和气液烃有机包裹体为主 ,流体成分中有机组分含量 (质量分数 )偏高 ( 3 4 6%～ 73 0 % ) ,而无机组分含量 (质量分数 )偏低 ( 2 6 6%～65 2 % )。早晚两期流体的形成温度、压力也具有一定的差异 ,晚期的温度和压力均大于早期。酸碱度和氧化还原电位具有较小差异 ,晚期略小于早期。流体包裹体特征、流体成分和物理化学性质均表明 ,本区具有两期油气运移和演化过程

THE FEATURES AND GEOLOGICAL SIGNIFICANCE OF THE PALEO-FLUID IN DAGANG EXPLORATION AREA

Dagang oil field is located in Huanghua basin, and has been undergone five stages of tectonic thermal events including Caledonian, Hereyhian, Indo China, Yanshanian and Himalayan events The research on paleo fluid shows that two stages of oil and gas migration were taken place in this area They are corresponding to Yanshanian and Himalayan tectonic thermal events respectively, and are called as early stage and late stage There are quite differences in the features of fluid inclusion, compositions and physico chemical properties between early stage and late stage The liquid hydrocarbon inclusion is dominent in fluid inclusions at the early stage, and the gas liquid hydrocarbon inclusion is major in fluid inclusions at the late stage The organic composition is smaller than inorganic composition in fluid inclusion at the early stage, but the organic composition is higher than inorganic composition in fluid inclusion at the late stage Temperature and pressure is very different in fluid inclusions between early and late stages The temperature is lower at the early stage than at the late stage The pressure is higher at late stage than at the early stage There are slight differences in the pH value and Eh value of fluid between early stage and late stage They are smaller at late stage than at early stage The above results indicate that two stages of oil gas migration exist in this area