塔里木盆地震旦系石油地质特征及勘探方向

通过对塔里木盆地周边露头剖面及盆内钻井震旦系石油地质特征分析,认为震旦系顶部白云岩受岩溶作用发育溶蚀孔(洞)缝,储集空间主要为角砾间孔、溶蚀孔(洞)及裂缝;南华—震旦系泥质岩类和下寒武统泥岩、泥灰岩为震旦系的有效烃源岩;同时,下寒武统泥岩及泥灰岩直接覆于震旦系白云岩储集层之上,可作为良好盖层,与震旦系白云岩储集层形成良好储盖组合;震旦系油气成藏史分析表明顶部白云岩具有多期油气充注条件,在古隆起斜坡区可能保存原生古油藏。在此认识基础上,结合区带评价分析,提出塔东低凸起北斜坡、塔中低凸起北翼及柯坪-巴楚隆起等震旦系为有利勘探方向。

Petroleum Geologic Characteristics and Hydrocarbon Exploration objectives of Sinian in Tarim Basin

This paper analyzes the petroleum geologic characteristics of the outcrop sections around Tarim basin and the Sinian in wells in this basin. It is recognized that dolomite in top of Sinian develops solution pores, vugs and fractures caused by karstification, and the reservoir pore space also contains inter-rubble pores. The effective source rocks of Sinian are argiloid of Nanhua-Sinian, mudstone and muddy limestone of Lower Cambrian which directly overlaps the Sinian dolomite reservoir as a good cap rock, forming a good reservoircap rock assemblage. The analysis of the Sinian petroleum accumulation history indicates that its top dolomite is of multistage oil-gas charging conditions, and the primary paleo-reservoir could be preserved in the paleo-uplift slope area. On this basis, integrated with regional tectonic zone evaluation, it is proposed that the Sinian strata of north slope in Tadong low swell, north side in Tazhong low swell and Keping-Bachu uplift will be favorable objectives for hydrocarbon exploration.