Hydrocarbon accumulation stages and their timing in multicyclical superimposed basins —a case study of the Upper Paleozoic in the eastern Linqing Depression,the Bohai Bay Basin

doi:10.11743/ogg20110304

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Hydrocarbon accumulation stages and their timing in multicyclical superimposed basins —a case study of the Upper Paleozoic in the eastern Linqing Depression,the Bohai Bay Basin
Vol. 32, Issue 3, Pages: 333-341(2011)
Online First：28 June 2011，

Published：2011
DOI： 10.11743/ogg20110304
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DOI：

Hydrocarbon accumulation stages and their timing in multicyclical superimposed basins —a case study of the Upper Paleozoic in the eastern Linqing Depression,the Bohai Bay Basin[J]. 2011, 32(3): 333-341. DOI： 10.11743/ogg20110304.

摘要

勘探实践表明，多旋回叠合盆地油气成藏过程的复杂性极大地影响了油气勘探进程。对渤海湾盆地临清坳陷东部上古生界石炭-二叠系烃源岩生烃史进行模拟的结果表明，该盆地分别在中-晚三叠世、晚白垩世、古近纪和新近纪—第四纪发生了4次生烃过程，且第一次生烃量小、可忽略不计，第二次生烃量也不大，主要生烃高峰期发生在新生代；而6口井76块流体包裹体样品的系统分析成果揭示，上古生界分别在晚侏罗世—早白垩世、古近纪和新近纪—第四纪发生了3期以天然气充注为主的油气成藏过程，第一期成藏发生在141.9~95.7 Ma，第二期成藏发生在51.0~33.1 Ma，第三期成藏发生在19.7~0 Ma，且每期成藏均起始于叠合盆地拗陷阶段，终止于构造抬升阶段。储层有机包裹体观测表明，第一期充注油气几乎全被破坏成残留沥青，第二期和第三期充注的油气有可能在以北西向断裂分隔的中央洼陷上古生界地层-构造圈闭聚集成藏而成为潜在的勘探目标。

Abstract

Complexity of hydrocarbon accumulation process is a major factor influencing petroleum exploration in a multicyclical superimposed basin.Modeling of hydrocarbon generation in the PermoCarboniferoussource rocks in the Linqing Depression

the Bohai Bay Basin reveals that four stages of hydrocarbon generation occurred in the middlelate Triassic

the late Cretaceous

the Paleogene

and the NeogeneQuaternary

respectively.The volume of hydrocarbons generated in the first stage was very small and that generated in the second stage is insignificant too.The peak hydrocarbon generation occurred in the Cenozoic.Systematic analyses of fluid inclusions from 76 samples of six wells show that three stages of hydrocarbon accumulations dominated by gas charging events occurred in the late Jurassicearlier Cretaceous (141.9-95.7Ma)

the Paleogene (51.0-33.1Ma)

and the NeogeneQuaternary (19.7-0Ma)

respectively.All the hydrocarbon charging events initiated during the depression of the superimposed basin and terminated during its uplifting.The hydrocarbons charged in the first stage were almost completely destroyed and turned into bitumen

while the hydrocarbons charged in the second and third stages might accumulate in the Upper Paleozoic stratigraphicstructural traps in the central sags compartmentalized by the NWtrending faults.These traps might be favorable exploration targets.