青藏措勤盆地下白垩统活动热流体与油气成藏  

Active thermal fluids and the Lower Cretaceous hydrocarbon accumulation in the Cuoqin Basin,Tibet

作　　者：吴悠[1] 陈红汉[1,2] 肖秋苟[3] 耿峰[1] 

机构地区：[1]中国地质大学资源学院,湖北武汉430074 [2]中国科学院地质与地球物理研究所兰州油气资源研究中心,甘肃兰州730000 [3]中国石化勘探南方分公司,四川成都610041

出　　处：《石油学报》2011年第4期621-628,共8页Acta Petrolei Sinica

基　　金：教育部科学技术重点项目(No.106113)资助

摘　　要：对26块流体包裹体样品系统分析表明,青藏高原措勤盆地下白垩统郎山组、多尼组存在大量沥青及有机包裹体,证实盆地内曾发生过大规模的油气生成、运移和聚集过程。测温结果显示,研究区存在5幕热流体活动,且均与油气运聚有关,其中以第2幕—第5幕的大量天然气运聚为主。结合盆地热演化史和沉积埋藏史,确定措勤盆地下白垩统有3期热流体充注,其时间分别为距今124.1-101.5Ma、距今96.4-89.9Ma和距今80.4-63.1Ma,其中第1期和第2期是研究区油气的主要运聚时期。措勤盆地在构造作用影响下流体活动频繁,后期高温热流体活动促进了盆地内烃源岩的热演化,但也使古油藏遭到强烈破坏,油气散失严重。由此认为,措勤盆地油气勘探应以寻找晚期形成的新生界油藏或者中生界保存条件相对较好的油藏、天然气藏为主。Fluid flow has a significant impact on the hydrocarbon accumulation and preservation under the plateau-formed background.The present paper revealed a relationship between active thermal fluids and the Lower Cretaceous hydrocarbon accumulation in the Cuoqin Basin by systematically analyzing 26 samples of fluid inclusions.The result indicated that there were plenty of bitumen and organic fluid inclusions in the Cretaceous Langshan（K1l） and Duoni（K1d） formations of the Cuoqin Basin,confirming occurrences of large-scale hydrocarbon generation,migration and accumulation within the basin.The homogenized temperature of saline aqueous inclusions indicated that there existed five episodes of thermal fluid activities in the study area and they were all related to hydrocarbon migration and accumulation,which were statistically dominated by the 2 to 5 episodes.Based on homogenized temperatures and combined with thermal and burial histories of this sedimentary basin,three hydrocarbon charges were determined to occur in 124.1-101.5 Ma,96.4-89.9 Ma and 80.4-63.1 Ma,respectively,among which the critical moment for hydrocarbon migration and accumulation occurred in the first and second episodes.There were frequent activities of fluid flow in the Cuoqin Basin during Early Cretaceous due to the effect of tectonic movements,and later hydrothermal fluids accelerated the thermal evolution of source rocks,leading to the loss of hydrocarbons and the destruction of paleo-oil reservoirs.It was,therefore,suggested that hydrocarbon resources accumulated in Late Cenozoic or Mesozoic oil-gas reservoirs that were comparatively well preserved would be the major target for oil and gas exploration in this basin.

关 键 词：措勤盆地 下白垩统 活动热流体 油气成藏 流体包裹体 

分 类 号：TE112[石油与天然气工程—油气勘探]