准噶尔盆地深部致密油藏形成条件与分布预测——以玛湖凹陷西斜坡风城组致密油为例

Forming conditions and distribution prediction of deep tight reservoir in Junggar Basin:a case study from tight reservoir of Fengcheng Formation in the west slope of Mahu sag

以准噶尔盆地玛湖凹陷西斜坡风城组致密油为研究对象,通过对烃源岩和储层系统分析,阐明深部致密油的形成条件,并预测致密油有利勘探区带。研究结果表明准噶尔盆地玛湖凹陷西斜坡深部具有很好的致密油形成条件:TOC分布在1.1%~2.0%,Ro分布在1.0%~1.6%,有效烃源岩厚度最大可达200 m;目前发现的油气主要分布在生烃强度大于250×104t/km2范围。储层控制了致密油的成藏门限,其储层有效孔隙度下限为2%;储层孔隙度和厚度控制了致密油藏的含油气性;深部储层范围(孔隙度≤10%)决定了致密油藏的边界。应用功能要素组合控藏模式"T-LDPS"对玛湖凹陷西斜坡深部有利勘探区带进行了预测,显示潜在勘探区域主要分布在风南7井区—夏72井区及其以南周边、百泉1井区以南和风城011井区以东。

Tight oil of Fengcheng Formation in west slope of Mahu sag is taken as a research subject.Through systematic analysis of source rock and reservoir,this study illustrates forming conditions of deep tight oil,and predicts favorable zone for tight oil exploration.The results show that favorable forming conditions of tight oil are discovered in the deep layer beneath the west slope of Mahu sag in Junggar Basin.TOC ranges from1.1% to 2.0%;Rovaries from1.0% to 1.6%;effective thickness of source rock is up to 200 m.Currently,discovered hydrocarbons are mainly distributed within the scope where hydrocarbon-generating strength is above 250×104t/km2.The reservoir controls hydrocarbon accumulation threshold of tight oil,where the lower limit of effective porosity is 2%;hydrocarbon properties of tight oil reservoir are controlled by porosity and thickness of reservoir;boundary of tight oil reservoir is determined by the scope of deep reservoir(porosity≤10%).The model of functional element(T-LDPS)was applied to predict favorable exploration areas in the west slope of Mahu sag,suggesting that potential exploration zone is distributed in the periphery to south of Well Fengnan 7-Well Xia 72,to south of Well Baiquan 1,and to east of Well Fengcheng 011.