鄂尔多斯盆地东南部延长组致密油成藏条件及主控因素

Tight oil reservoir formation conditions and main controlling factors of Yanchang Formation in southeastern Ordos Basin

鄂尔多斯盆地东南部延长组致密油成藏条件研究程度较低,致密油勘探未取得大的突破。为了评价盆地东南部延长组致密油的勘探前景,通过对沉积、储层、盖层、油气运移等方面的研究,深入分析了盆地东南部延长组致密油成藏条件。研究结果表明盆地东南部延长组长7段优质烃源岩大面积分布,延长组储层致密,源储配置好,具有形成致密油的良好地质条件。长6、长7、长8油层组是鄂尔多斯盆地东南部延长组致密油主力勘探层系。延长组致密油藏的形成和富集主要受沉积微相、优质储层的控制。通过包裹体测温、盆地热史、伊利石测年、饱和压力等多种方法确定的致密油藏主成藏期为早白垩世,致密油成藏期受中生代晚期构造热事件的控制,具有晚期成藏的特点。

No breakthrough has been made in tight oil exploration of the Yanchang Formation in southeastern Ordos Basin be-cause of the low level of research on tight oil accumulation conditions .In order to evaluate tight oil exploration prospect of the Yanchang Formation,we studied in-detail the tight oil accumulation conditions in the study area studying respects of sedimen-tary microfacies,reservoir rock,cap rock and hydrocarbon migration.The high quality source rocks of Chang 7（7th Member of the Yanchang Fm）are widely developed in the southeast region of the basin .The reservoir of the Yanchang Formation is tight . The favorable source-reservoir combination provided good geological conditions for tight oil accumulation .The Chang 6, Chang 7 and Chang 8（the 6th,7th and 8th Members of the Yanchang Fm）intervals are the main targets for exploration of tight oil in the Yanchang Formaiton in the study area .Tight oil reservoir formation and enrichment are controlled by sedimentary microfacies and quality reservoirs.Based on the study of inclusions temperature,thermal history,illite dating,saturation pressure and other methods ,the tight oil accumulation period in Yanchang Formation is set at the Early Cretaceous and was controlled by the Late Mesozoic tectonic thermal event , thus tight oil accumulation occurred in late stage .