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1、四川叠合盆地油气富集原因剖析刘树根孙玮I,王国芝韩克猷2,李智武邓宾冉波I雍自权I徐国盛I袁海锋1(1•油气藏地质及开发工程国家重点实验室(成都理工大学),成都610059;2.屮国石汕西南汕气地质勘探开发研究院,成都610051)[摘要]通过总结和综合分析"U川叠合盆地油气富集的控制因素一一原始生桂条件、古油藏发育特征、保存条件、构造特征以及油气成藏等多方面资料,结果表明四川叠合盆地冇7套坯源岩,除上三叠统须家河组和上二叠统龙潭组外均为汕系坯源岩,总成烧潜量达4263.1X1012m曾形成过多个层位的古汕
2、藏,且古汕藏曾经历过深埋藏过程。深埋高温作用使得四川盆地内海相地层小一切能住成天然气的有机质均充分而完全地转化成犬然气,致使有机质成气率极高。盆地内的保存条件优越,特别是中下三叠统膏盐岩盖层是重耍的区域盖层,封盖性强,致使其下的油气不易逸散。盆山结构是控制油气富集的另一重要因素,突变型盆山结构在盆地内的变形弱,保存条件未遭人规模破坏,有利于喜马拉雅期构造变动时汕气的保存和聚集;渐变型盆山结构在盆地内的变形较强,构造变化人,保存条件被不同程度地破坏,不利于喜马拉雅期构造变动时油气的保存。因此四川叠合盆地油气富集的主要
3、原因(一级控制因素)是桂源充足和保存条件佳。除四川盆地外的广大南方地区,桂源仍较充足,但已剥蚀掉中下三叠统膏盐岩区域盖层的地区,其保存条件较差,不易形成大规模的常规油气聚集。[关键词]四川亞合盆地;汕气富集;保存条件;盆山结构AnalysisofcausesofoilandgasaccumulationinsuperimposedSichuanBasinofChinaLIUShu-gen1,SUNWei1,WANGGuo-zhi1,HANKe-you2,LIZhi-wu1,DENGBin1,RANBo1,YONGZ
4、i-quan1,XUGuo-shcng1,YUANHai-fcng11.StateKeyLaboratoryofOilandGasResei^oirGeologyandExploitation,ChengduUniversity^ofTechnology,Chengdu610059,China;2.Exploration&ProductionResearchInstituteofPetroChinaOilandGasfieldCompany,Chengdu610051,ChinaAbstract:Thispaper
5、analyzesthecontrollingfactorsofaccumulatinghydrocarbonacrossthesuperimposedSichuanBasinexperiencedmultitectonics,includingtheoriginalhydrocarbon-generatingconditions,developingcharacteristicsofpaleo-reservoirs,preservationconditionsandstructuresetc.Theresultsh
6、owsthattherearesevensetsofsourcerocksinSichuanBasin.TheyareallsourcerockspronetoproduceoilexceptUpperPermianLongtanFormationandUpperTriassicXujiaheFormation.Thetotalpotentialhydrocarbongenerationinthebasinis4.2631X10'mwithpaleo-reservoirsoccurredinmultiplelay
7、ers・Deepburialresultedinthethermalcrackingofoiltonaturalgas.Preservationconditionsarefavorable,inparticular,thatoftheLowerTriassicgypsumasanimportantregionalcaprock.Anotherimportantfactorcontrollingoilandgasaccumulationisthebasin-mountainstructure・Thesuddenlyd
8、eformedbasin-mountainstructurehasweakdeformationinthebasin,andthepreservationconditionsarcnotdestroyed.ThisisfavorableforthepreservationandaccumulationofoilandgasinHimalayanepoch・O