Hydrocarbon Accumulation Condition and Main Controlling Factors of Chang-6 Reservoir in Zibei Area of Ordos Basin

Tectonic characteristics,distribution of sedimentary facies and sandstone distribution of Chang-6 member in Yanchang Formation of Zibei area,Odors Basin were analyzed.Hydrocarbon accumulation conditions of Chang-6 reservoir were investigated in terms of hydrocarbon source rock,reservoir,caprock,etc.Reservoir type,main controlling factor and accumulation period were discussed.The results show that Chang-6 member has a good assemblage of sourcereservoir-caprock in Zibei area,and is controlled by sedimentary microfacies and reservoir physical property;petroleum in Chang-6 member is reserved in channel sandbody of Chang-61,Chang-62,Chang-63 members,and reservoir type is lithologic trap;the main controlling factors of reservoir in Chang-6 member include main distributary channel,reservoir physical property andits anisotropy,distribution of petroleum;distribution of homogenization temperature of petroleum inclusion in Chang-6 member is bimodal shape with the values of 100 ℃-110 ℃ and 130 ℃-140℃;hydrocarbon accumulation period is obtained by the combination of thermal evolution history and homogenization temperatures of fluid inclusion,and petroleum generated by hydrocarbon source rock of Chang-7 member migrates in Early Cretaceous,and accumulates in oil layer group of Chang-6 member,and then Chang-6 member reservoir forms.