基于格子Boltzmann方法的油水两相流动规律

Oil-water two-phase flow rule based on lattice Boltzmann method

 吴子森 董平川 雷刚 杨书 曹耐 李玉丹

 （中国石油大学（北京）石油工程教育部重点实验室，北京102249）

 (MOE Key Laboratory of Petroleum Engineering, China University of Petroleum, Beijing 102249, China)

 文中采用随机生长四参数生成法，对储层岩石的二维微观孔隙结构进行了重构。基于格子Boltzmann方法，从孔隙尺度模拟了多孔介质中的油水两相流动，对不同驱替时刻多孔介质内流体分布进行了模拟，得到了油水两相相对渗透率曲线和油水压汞曲线，并分析了π准数（界面张力与压力梯度比值）对油水两相流动的影响。研究结果表明：润湿相（水相）沿着大孔道的中轴部位驱替非润湿相（原油），在小孔道残余部分原油，而随着水驱过程的继续进行，小孔道中的油也逐渐被驱替出来；随着含水饱和度的增加，油相相对渗透率逐渐下降，水相相对渗透率逐渐增加。当π准数减小时，油水两相相对渗透率值均增大，其中油相相对渗透率值增大幅度较水相相对渗透率值增大幅度更大，可通过提高驱动压力梯度或者降低界面张力提高采收率。

 In order to study the distribution characteristics of pore structure of the reservoir, the 2D micro-structure of porous media were reconstructed by the multi-parameter random generation growth method. According to lattice Boltzmann method (LBM), oil-water two-phase flow was simulated in the porous media by the pore scale. The distribution of these two-phase fluids existed in porous media was studied at different time. Additionally, the relative permeability curve and capillary pressure curve were proposed respectively, and the influence of the value of π(the ratio of interfacial tension to driving pressure gradient) on oil-water two-phase flow was studied. The calculated results show that the wetting phase (water phase) displaces the non wetting phase (oil phase) along the center of the large pore, and the residual oil stays in tiny channel. The oil phase in the tiny channel will be also displaced as the process of water-flooding continues. With the increase of water saturation, the relative permeability of water phase increases, however the relative permeability of oil phase decreases. Both water phase relative permeability and oil phase relative permeability increase with the decrease of the value of π; the increased value of oil phase relative permeability is greater than that of water phase. As the result, the oil recovery can be enhanced by improving the driving pressure gradient or reducing the interfacial tension.

10.6056/dkyqt201603014