鄂尔多斯盆地西北部延长组下部幕式成藏特征  

Episodic migration and accumulation of hydrocarbon in lower Yanchang Formation of the northwestern Ordos Basin

作　　者：李元昊[1,2] 刘池洋[1] 王秀娟[2] 独育国[2] 

机构地区：[1]西北大学地质系,陕西西安710069 [2]中国石油长庆油田公司勘探开发研究院,陕西西安710021

出　　处：《石油学报》2009年第1期61-67,共7页Acta Petrolei Sinica

基　　金：国家重点基础研究发展规划(973)项目(2003CB214607);长江学者和创新团队发展计划项目(IRT0559)联合资助

摘　　要：鄂尔多斯盆地延长组长7段优质烃源岩在大量生烃时产生较强的异常高压,在盆地西北部长7段与下部长8段地层之间存在10MPa以上的过剩压力差,这成为石油向下运移的主要动力。岩心、薄片和成像测井资料表明,超压导致源岩及其下部地层发生流体压裂,流体以混相通过裂隙快速排出。在长7段烃源岩和长8段、长9段储层中发现的沸腾油气包裹体,是油气幕式排烃、幕式充注的直接证据。包裹体均一温度表明,鄂尔多斯盆地西北部主要发生了两次大规模的幕式充注过程,主要成藏时期为早白垩世早期—早白垩世中期。The high-quality source rock of Chang 7 Member in Ordos Basin produced abnormal high pressure during the main period of hydrocarbon generation. There are about 10MPa differential overpressure between Chang 7 Member and Chang 8 Member, which was the main dynamic force for oil migration to the lower reservoirs. Overpressure can result in the hydraulic fracturing in source rock and its underlying strata. Many hydraulic fractures were founded in the cores, thin section and FMI data. Mixed phase fluid of hydrocarbon and water were expulsed quickly along fractures. The boiling oil and gas inclusions were founded in the source rock of Chang 7 Member and the reservoirs of Chang 8 Member and Chang 9 Member, which indicated the episodic expulsion and migration of oil and gas. According to the homogenization temperature of organic inclusion, it is suggested that oil and gas in the northwestern Ordos Basin has been mainly charged in twice episodes. The period of hydrocarbon accumulation was from the early to the middle of Early Cretaceous.

关 键 词：鄂尔多斯盆地 延长组 幕式成藏 流体压裂 沸腾油气包裹体 成藏期 

分 类 号：TE112.3[石油与天然气工程—油气勘探]