鄂尔多斯盆地陇东地区长7页岩油成藏期次及时期确定

Determination of Accumulation Stages and Periods of Chang 7 Shale Oil in Longdong Area

为了明确鄂尔多斯盆地陇东地区长7页岩油成藏期次及时期,利用流体包裹体荧光观察、荧光光谱定量化描述、均一温度投点等方法,对该地区长7储层流体包裹体进行了系统分析。研究表明:陇东地区长7储层见发蓝绿色、绿色、黄绿色3种荧光颜色的油包裹体,其中广泛发育蓝绿色和黄绿色两种荧光颜色油包裹体。根据λmax与QF535的相关关系特征,识别出研究区共有三幕油气充注,同时在井中观察到少量的沥青存在,说明有一部分早期充注的油遭受到破坏。综合分析认为陇东地区长7页岩油共发生了三期成藏,第一期油气充注发生在早白垩世初期137~139 Ma期间,第二期油气充注发生早白垩世晚期121~123 Ma期间,第三期油气充注发生中白垩世初期107~S109 Ma期间,其中第三期油气充注对储层贡献度最大。该成藏期次拟定为该地区页岩油勘探开发提供了理论依据。

In order to make clear the accumulation period and time of Chang 7 shale oil in Longdong area of Ordos Basin,this study systematically analyzed the fluid inclusions of Chang 7 reservoir in this area by means of fluorescence observation,quantitative description of fluorescence spectrum and homogenization temperature point.The results show that there are three kinds of fluorescent oil inclusions in Chang 7 reservoir in Longdong area,including blue-green,green and yellow green,in which two kinds of fluorescent oil inclusions are widely developed.According to the correlation betweenλMax and QF535,three charging periods are identified in the study area,and a small amount of asphalt is observed in the well,which indicates that there are some early charging periods The oil is damaged.Comprehensive analysis shows that chang7 shale oil in Longdong area has three stages of reservoir formation,the first stage of oil and gas charging occurred during 137-139 MA in the early Cretaceous,the second stage during 121-123 MA in the late Early Cretaceous,and the third stage during 107-109 MA in the early Middle Cretaceous.The third stage of oil and gas charging has the largest contribution to the reservoir.This study provides a theoretical basis for shale oil exploration and development in this area.