油气超长运移距离  

Ultra-long distance migration of hydrocarbon

作　　者：朱光有[1] 杨海军[2] 张斌[1] 苏劲[1] 张超[2] 张科[2] 刘永福[2] 卢玉红[2] 

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油塔里木油田勘探开发研究院,库尔勒841000

出　　处：《岩石学报》2013年第9期3192-3212,共21页Acta Petrologica Sinica

基　　金：国家油气专项(2008ZX05004-003);中国石油科技研究项目联合资助

摘　　要：塔里木盆地塔北地区广泛分布着来自于库车坳陷的陆相油气,其运移距离超过100km,是一个比较典型的油气超长距离运移实例。本文在结合油气勘探基础资料的基础上,通过对出油井的详细地球化学研究,综合油气运移条件的分析,探讨了油气超长运移的地质条件与动力机制。研究认为,在哈拉哈塘和英买力南部地区白垩系砂岩储层中发现的油气来源于北部库车坳陷的三叠系湖相烃源岩,成藏时间在5~3Ma;油气主要通过断裂沟通不整合面以及白垩系巴西改组的砂体进行长距离侧向运移,运移的直线距离达到110~130km。研究发现,库车坳陷三叠系优质烃源岩短期内快速熟化并高效排烃,为油气长距离运移提供了充沛的油源和驱动力条件;白垩系巴西改组油层在致密顶底板岩层的封堵约束作用下,油气沿着宽缓斜坡上大面积分布的连通砂体呈面状发生长距离运移,沿途缺少大型圈闭拦截和聚油,油气损失相对较少,所以油气在通畅的运移道路上持续向南推进,这是该区油气发生超长运移的主要动力机制。超长的运移距离,与该区低幅度宽缓的斜坡构造背景和良好的输导通道密切相关,因此,在已发现白垩系出油井点以南更远地区还将不断会有陆相油的新发现;在油气运移经过的地区,白垩系内只要存在圈闭,均可形成油藏,因此,低幅度构造圈闭与岩性地层圈闭所形成的中小型油气田群将作为今后勘探的主要目标。Terrestrial oil and gas generated in the Kuqa depression is widely distributed in the Tabei area, Tarim basin. It＇ s a typical example for ultra-long distance migration of hydrocarbon more than 100km. Through detailed analysis of geochemical characteristics of oil from production wells, combined the hydrocarbon exploration data with migration conditions, the geological characters and dynamic mechanism of ultra-long distance migration of hydrocarbon is discussed. The study shows that oil and gas found in Cretaceous sandstone reservoirs located in Halahatang and southern of Yingmaili area were generated from Triassic lacustrine source rocks in Kuqa depression, accumulated during 5 ~ 3Ma. Hydrocarbon laterally migrated long distances along unconformities and sand bodies of Baxigai Formation of Cretaceous, the straight-line migration distance reached 110 ~ 130km. High speed maturation of Triassic source rocks in the Kuqa depression and high effectively expulsion of hydrocarbon provided sufficient hydrocarbon and driving force for long distance migration. Constrained by the tight roof and floor strata, hydrocarbon in the oil-bearing sand of Baxigai Formation of Cretaceous planar migrated long distance along pervasively distributed sand bodies in the broad slope. Lack of large scale traps along the pathways resulted in low loss of hydrocarbon during migration, thus hydrocarbon could migrated southward for long distance, this is the major dynamic mechanism for ultra-long distance migration. The ultra-long migrating distance of hydrocarbon in this area is related with low amplitude slope structural background and well developed migrating pathway, it could be inferred there will be more Terrestrial oil and gas discovered in south of oil production wells in Cretaceous reservoirs. Hydrocarbon fluids could be captured in any Cretaceous traps distributed along the migrating pathway, it is suggested middle-small scale oil and gas fields reserved in the low amplitude structural traps and stratigraphic traps would be the major

关 键 词：运移距离 输导条件 油气二次运移 陆相原油 白垩系 库车坳陷 塔里木盆地 

分 类 号：P618.130.8[天文地球—矿床学]