二连盆地乌里雅斯太凹陷南洼槽油气运移特征

Petroleum Migration of South Trough in Wuliyastai Sag, Erlian Basin

在油气藏的形成过程中,油气运移始终起着重要的作用,乌里雅斯太凹陷南洼槽整体上断层规模小、延伸距离短。受湖底扇沉积环境的制约,砂体横向连通性差,不整合成为优势运移通道,油气沿着由高孔渗砂体一次生断层-不整合面构成的输导体系进行运移。该凹陷地层压力系数基本在1.0左右,具静压系统,且纵向上为统一压力系统。平面上较强的孔隙流体动力场控制油气运移方向,油气藏发育主要在能量相对较低的低压和现今油势低值区内。

Hydrocarbon migration always plays an important role in process of oil-gas accumulation. The south trough in Wuliyastai sag is characterized by small-sized and short-extending faults, poor plane connectivity of sandbodies under the control of sedimentary environment of subla-custrine fan. So unconformity could be its dominant channel for hydrocarbon migration, and the hydrocarbons probably migrate along the conducting system composed of high porosity-permeability sand body-secondary fault-unconformity. The sag has been found to possess static pressure system, vertically unified pressure system with formation pressure factor of about 1.0, horizontally more intensive pore fluid dynamic field to control oil-gas migration directions. The study suggests that the oil-gas reservoirs are mainly formed in low pressure areas with relative low energy.