准噶尔盆地西北缘烃源灶迁移演化及其对油气藏的定位作用

Oil accumulation related to migration of source kitchens in northwestern margin structural belt,Junggar Basin

根据油气源对比、成藏期次及烃源灶迁移演化分析认为,3套烃源灶的迁移演化控制了准噶尔盆地西北缘现今油气的分布:佳木河组气源灶早期生成的天然气没有保存下来,现今气源灶的位置控制了气藏的分布;风城组烃源灶在玛湖凹陷中心已处于过成熟阶段,只有灶缘还在生成油气,控制了其贡献的油气藏也主要分布在西北缘两翼;乌尔禾组烃源灶成熟演化总体相对滞后,凹陷中部仍处于大量生油气阶段,来源于该套烃源灶的油气藏也主要分布在西北缘地区的中部。单个烃源灶在不同地质时期供烃强度不同,多个烃源灶在同一地质时期供烃强度也不同,所以在西北缘不同地区形成了不同的烃源灶供烃模式,控制了油气藏的分布格局。

According to the analyses of hydrocarbon-source correlation, hydrocarbon accumulation periods and source kitchen migration, the present hydrocarbon distributions in the northwestern margin of the Junggar Basin are controlled by three sets of source kitchen migration. The natural gas which generated during the early stage from source kitchens in the Jiamuhe Formation has not been preserved, and the present location of source kitch- ens controls reservoir distribution. The source kitchens in Fengcheng Formation at the centre of the Mahu Sag can not generate gas since they are over-matured. Only the source kitchens at the margin of the sag can generate hy- drocarbon and control the location of oils generated from them. The source kitchens in Wuerhe Formation can still generate oil and gas in the center of the sag and also control the location of oil generated from them. Because of the different hydrocarbon-generation intensity for the same source kitchen during different geological periods and different source kitchens at the same geological period, different hydrocarbon supply modes develop and control the location of hydrocarbon in the northwestern margin of Junggar Basin.