准噶尔盆地车排子凸起稀、稠油反序分布成因探讨

A discussion on the genesis of light and heavy oil distribution of inverted sequences in the Chepaizi Uplift,the Junggar Basin

沈扬 李茂榕

Shen Yang Li Maorong

原油密度分布大都有下稀上稠、心稀边稠的特征,而位于准噶尔盆地西部隆起车排子凸起的原油分布却有上稀下稠的特征.通过油源对比及区域构造、烃源岩演化和保存条件的研究认为,该区有二叠系、侏罗系两个层系、多种类型烃源岩的油源供给,具有多个生、排烃高峰期.多期构造与沉积造就了不同封盖能力的盖层.多期成藏以及各成藏期不同的保存条件是形成车排子凸起稀、稠油反序分布的重要原因,晚期注入和一定的保存条件是形成该凸起新近系沙湾组稀油油藏的必要条件.勘探中应考虑"稠油之上有稀油"的可能性.

It is generally believed that light oil is often found at the lower part or the central of an oil pool while heavy oil is more often located at the upper part or the periphery.However,the oil density distribution in the Chepaizi Uplift of Junggar basin proves otherwise:light oil is on top of heavy oil.Oil-source correlation and research on the regional structures,source rock evolution and preservation conditions indicate that multiple types of the Permian and Jurassic source rocks have generated and expulsed hydrocarbon sin several stages in the study area.Multiphase structural activities and sedimentation formed cap rocks of different sealing capacities.It is multiphase reservoiring and different sealing conditions in each reservoirng phase that caused the inverted sequence of light and heavy oil in the Chepaizi uplift.And later injection and certain preservation conditions are consi-dered necessary for forming light oil pool in the Neogene Shawan Formation of the uplift.It is suggested that exploration of the area shall take the possibility of "light oil on top of heavy oil" into consideration.

10.11743/ogg20080110