准噶尔盆地南缘中西段油气成藏研究进展及下组合勘探方向

Research Advances in Pool Formation and Exploration in the Lower Play,Southern Margin of Jungaar Basin

准噶尔盆地南缘自南向北发育三排构造带,垂向上划分3个油气成藏组合,随高探1井勘探重大突破,下组合成藏问题受到关注。本文在综合前人研究成果的基础上,通过对南缘燕山期古构造分析、各类型原油在不同构造带和不同成藏组合的分布以及燕山期古构造与烃源岩生油时间的匹配分析,预测下组合勘探方向。(1)燕山期形成了三排构造带下组合的构造雏形,喜山构造运动对燕山古构造进行了加强,喜山期构造运动强化了燕山期古构造并形成了中、上组合构造体。(2)准南发育4套有效烃源岩,其中二叠系烃源岩、中下侏罗统烃源岩以及白垩系烃源岩发育于准南中-西段,古近系烃源岩发育于准南西段。(3)南缘中-西段烃源岩生烃时间与古构造演化过程匹配程度高,南缘西段中下侏罗统烃源岩生油时间与燕山期古构造活动时间一致,有利于在下组合形成油气藏。(4)南缘中段二叠系和中下侏罗统烃源岩生油时间与第一排构造带燕山期古构造匹配较好,有利于在下组合形成油气藏,上盘地层油气较为富集。根据烃源岩展布规律及古构造演化,第二排构造带下组合可作为油气勘探的重点领域,准南西段第二排构造带下组合最具勘探潜力。

Three structural belts in area and three plays in vertical are identified in the souther margin of Jungaar Basin.With an exciting exploration result form lower play in well Gaotan-1,the lower play attracts much attention as a main exploration target.Based on numerous prevous research results about oil pool formation,this study has objective to predict exploration from analysis of Yanshannian paleostucture,of distribution of discovered different types oil in structural belts and plays,and comparison between oil generation time and Yanshannian paleostucture formation time.The results are:(1)The paleostructure miniature of three structural belts as tectonic body of lower play was formed during Yanshan movement,and enhanced by Himalaya movement.The tectonic body of middle and upper plays was also formed during Himalaya movement.(2)In west segment of the southern margin,the oil generation time of Jurassic source rock is matching well with the formation time of Yanshannian paleostructure,and favorizes pool's formation.The lower play in the second structural belt is favorable for exploration.(3)In the first structural belt of the middle segment of the southern margin,the oil generation time of Permian and Jurassic source rocks is fairly matching with the formation time of Yanshannian paleostructure.Exploration should focus on target well preserved and on Triassic or Permian layers in the hanging wall of thrusted fault.The seal capacity of the thrusted fault should be evaluated for exploration in the footwall.(4)From distribution of discovered oil in the plays,it is inferred that the lower play in the second and third structural belt could capture oil generated by Jurassic source rock,and the second structural belt is favorasble for exploration.