准噶尔盆地东部石炭系烃源岩演化模拟

Simulation of source rock evolution in Carboniferous,eastern Junggar Basin

利用TSM盆地模拟软件,对准噶尔盆地东部石炭系烃源岩的埋藏史、热演化史和生烃史进行分析。结果表明,研究区的沉降中心从侏罗纪到新生代存在由南向北迁移,而后又南移的跷跷板过程。南部的吉木萨尔凹陷内巴塔玛依内山组烃源岩有2个关键的生烃期:侏罗纪末,该烃源岩的镜质体反射率(Ro)分布在0.6%～1.3%之间,新生代中晚期之后,Ro分布在1%～2%之间;北部五彩湾凹陷内滴水泉组烃源岩的关键生烃期为白垩纪末期,Ro大部分在0.7%～1.5%之间,处于生烃高峰期;北部石钱滩凹陷石钱滩组烃源岩白垩纪末则刚进入生烃门限,演化程度低。另外,生烃强度从层位上看,滴水泉组和巴山组相对较大,可达200 mg/g,而石钱滩组较小,最高只有40 mg/g。

The histories of bury,thermal evolution and hydrocarbon generation of Carboniferous source rocks in the east of the Junggar Basin were studied by means of the TSM basin stimulation software.It was concluded that the depocenter of the study area transferred from the south to the north and then back to the south from Jurassic to Cenozoic.In the Jimsar Sag in the south of the basin,the source rocks in the Batamayineishan Formation gave birth to hydrocarbon during 2 key periods： 1） the end of Jurassic when the Ro of source rocks ranged from 0.6% to 1.3%;2） after the middle and late Cenozoic when the Ro of source rocks ranged from 1% to 2%.In the Wucaiwan Sag in the north of the basin,the source rocks in the Dishuiquan Formation generated hydrocarbon mainly at the end of Cretaceous when Ro ranged from 0.7% to 1.5%,indicating a large amount of hydrocarbon.In the Shiqiantan Sag in the north,the source rocks in the Shiqiantan Formation entered the threshold for hydrocarbon generation at the end of Cretaceous and the evolution degree was low.The hydrocarbon intensities of the Dishuiquan and Bashan Formations were higher,amounting to 200 mg/g,while the highest value of the Shiqiantan Formation was only 40 mg/g.