塔里木盆地塔中地区奥陶系碳酸盐岩礁滩复合体油气来源与运聚成藏研究

THE STUDY OF HYDROCARBON ORIGIN,TRANSPORT AND ACCUMULATION IN TAZHONG AREA,TARIM BASIN

近年来对塔里木盆地海相层系油气的勘探进展很快,在塔中地区围绕塔中I号坡折带有重要发现,特别是发现了上奥陶统碳酸盐岩礁滩复合体大面积富含油气。认为该区上奥陶统碳酸盐岩礁滩复合体储层存在多期油气运移聚集,包括晚加里东期油气的聚集、晚海西期古油藏油气的调整转移和直接从烃源岩生成油气的补充以及喜山期古油藏裂解天然气对早期油藏的气侵;塔中地区原油和凝析油主要来源于寒武系-下奥陶统烃源岩,上奥陶统中聚集的油气是沿断裂垂向运移与沿多套储层横向运移面来;塔中奥陶系油气藏之所以表现出外带为凝析气藏、内带为油藏的分布特征,主要与来源于外带下伏的的寒武系-下奥陶统古油藏的裂解气有关,也与I号坡折带北侧的良里塔格组斜坡相古油藏的裂解气有关,这些天然气沿I号坡折带向上运移,补充到位于I号坡折带附近的礁滩复合体油气藏中,并对原来的油藏产生气侵,气侵程度的不同,或者形成凝析气藏,或者仍然保持油藏。

The exploration of Tarim marine facies layer system developed quickly recent years. There are great discoveries at No. Ⅰ Faulted Slope Break in Tazhong area, especially the Upper Ordovician carbonate reef complex. The study finds that the Upper Ordovician carbonate reef complex has several stages of oil and gas migrate accumulation, including the accumulation, adjustment and transforming of Late Caledonian, also the oil supplement from hydrocarbon of Late Hercynian, the air cutting of paleo-oil hydrocarbon cracking to the early oil reservoir. The crude oil and condensate oil mainly came from Cambrian- Lower Ordovician, and the oil and gas mainly came from vertical and lateral the transformation through several reservoir. The Ordovician reservoir is condensate oil in outer belt and oil in inner belt, the reason is the gas was came from the cracking of paleo-oil of the underlying Cambrian- lower Ordovician and the northern No. Ⅰ Faulted Slope Break and migrate upward along the No. Ⅰ Faulted Slope Break, then accumulated in the reef complex reservoir, which caused the gas invasion to the previous oil reservoir. The different degrees of gas invasion induced the condensed reservoir and oil reservoir.