The viscous fingering phenomenon occurring in immiscible displacement in a horizontal channel is focused on by using the lattice Boltzmann method （LBM）. The gravity is considered by imposing perpendicularly to the fluid flowing direction. The role of the viscosity ratio between displaced fluid and displacing fluid and surface wettability are analyzed by comparing the final finger pattern and discussing the displacement efficiency in terms of two parameters, the breakthrough time and areal sweep efficiency. The analytical results reveal that under the effect of gravity, the finger pattern is unsymmetrical to the central line of the channel, and the increasing of viscosity ratio of immiscible fluid enhances the finger growth; as a result, the displacement efficiency decreases. Besides, the influende of surface wettability on the fluid behavior is also studied with consideration of gravity, and it is found out that the finger growth is enhanced when the channel surface is non-wetting for displacing fluid, and the finger formation is suspended when the channel surface is wetting for displacing fluid.%采用格子Boltzmann方法（LBM）研究了水平通道内非混相驱替过程中的黏性指进现象.考察流动方向与重力方向垂直时,驱替和被驱替流体间黏度比及壁面可润湿性的影响,比较了不同条件下的指进前缘形状,并利用突破时间和面积扫掠效率分析了驱替效率.研究表明,在重力的影响下,指进前缘形状关于水平通道的中心线是非对称的.随着非混相流体间黏度比的增大,指进现象也随之增强,导致驱替效率降低.当驱替流体不易润湿通道壁面时,指进现象被强化;当驱替流体易于润湿通道壁面时,指进现象则被抑制.
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