准噶尔盆地西北缘超剥带圈闭含油性量化评价

Quantitative assessment on trap oil-bearing property in ultra-denudation zones at the northwestern margin of Junggar Basin

准噶尔盆地西北缘超剥带圈闭总体上具有分布广、埋藏浅、圈-源距离较远、圈闭含油性差异大等特点。圈闭含油性主要受控于断层-砂体(断-砂)输导体系的输导性能、油气运移距离、储-盖物性差等因素。其中,断层、砂体的输导性能分别可用断层启闭指数、砂体输导指数进行表征,油气运移距离可用圈-源平面距离表征,圈闭储集性能可用遮盖层与储集层孔隙度差值进行表征。圈闭是否含油取决于断层-砂体输导指数是否超过临界值,圈闭含油程度与断层-砂体输导指数、圈闭储-盖孔隙度差呈较好正相关关系,而与圈-源平面距离呈负相关关系。在圈闭含油性与单因素关系分析基础上,通过多因素综合,建立了超剥带圈闭含油性多参数拟合关系式,应用结果表明,该拟合关系式预测值与实际值吻合度较高,可用来对准噶尔盆地西北缘超剥带圈闭含油性进行量化评价。

The traps in the ultra-denudation zones at the northwestern margin of Junggar Basin are characterized by wide distribution,shallow buried depth,long trap-source distance,large differences in trap oil-bearing property and etc.Trap oil-bearing property is mainly controlled by the migrating capability of fault-sand transport system,hydrocarbon migration distance,poor reservoir-cap physical properties and other factors.Among them,the fault-sand transport performance can be expressed by fault open-closure index and sand transport index.The hydrocarbon migration distance can be expressed by trap-source plane distance,and trap reserving performance can be characterized by the difference in reservoir porosity between reservoir and cap rock.Whether the trap contains oil or not depends on whether the fault-sand transport index exceeds critical value.The trap oil-bearing degree has a favorable positive correlation with fault-sand transport index and trap reservoir-cap porosity difference,but shows a negative correlation with trapsource plane distance.Through analyzing the relationship between trap oil-bearing property and single factors,multiple factors are combined to establish the multi-parameter fitting relation of trap oil-bearing property in ultra-denudation zones.The application results show that the predicted value of such fitting relation is highly consistent with the true value,so that this relation can be used for quantitative assessment on the trap oil-bearing property in ultra-denudation zones at the northwestern margin of Junggar Basin.