稠油重力泄水微观可视化实验研究

Microscopic Visual Experiment Study of Heavy Oil Gravity Drainage

辽河油田重力泄水辅助蒸汽驱已取得显著开发效果,但开发过程中冷凝水的泄水规律尚不明确。采用玻璃刻蚀的均质和非均质可视岩心进行模拟实验,在2块玻璃中间形成一个由孔隙和喉道组成的水平油藏模型。通过图像采集系统采集驱油过程图像并转化为计算机数值信号,对比重力泄水前后的图像,并通过实验数据分析岩心的均质性、压差对泄水规律的影响。结果表明,重力泄水过程中,冷凝水并非均匀下泄,而是沿着一定的泄水通道下泄。泄水通道形成前期,瞬时泄水量随压差的变化不明显;中期瞬时泄水量随压差增加而增大;后期趋于稳定。均质岩心泄水通道形成的时间较非均质岩心提前;泄水通道形成后,压差对非均质岩心瞬时泄水量的影响大于均质岩心。

Gravity draining assisted steam flooding conducted by Liaohe oilfield had made significant development effect. The drain- ing law of condensed water was unclear during the development. It was simulated by using homogeneous and heterogeneous visual cores with glass etching. In the middle of two piece of glass, a horizontal reservoir which was composed of pore and throat formed. The images before and after gravity draining which were transformed into computer numerical signal by image acquisition system were contrasted. The effect of core homogeneity and differential pressure on draining law was analyzed through experiment data. The results showed that the condensed water did not drain evenly, but discharged along a certain draining channel. The instanta- neous quantity of draining water with the changes of differential pressure was not obvious in the early of forming draining channel. It increased with increasing differential pressure during the medium-term, and that was stable at the late stage. The formation of drainage channel in homogeneous cores was earlier than that in heterogeneous cores. The effect of differential pressure on instanta- neous quantity of draining water in heterogeneous cores was bigger than that in homogeneous cores after the draining channel formed.