低频波强化泡沫微观驱油特征

Characteristics of microscopic oil displacement under low-frequency wave excitation by foam flooding

为探究低频波激励下泡沫对水驱残余油的驱替特征,基于微观非均质模型,开展了低频波激励下泡沫驱油实验,剖析了低频波强化泡沫驱油的机理及效果。研究结果表明:低频波通过提高泡沫稳定性、形成局部压力扰动、降低壁面吸附力等作用提高泡沫波及系数和驱油效果,且低频波激励下泡沫驱微观驱油效率提高6.78%。与单一泡沫驱相比,低频波激励下泡沫驱替柱状残余油的方式是泡沫沿着孔隙壁面逐渐向孔隙另一侧通过“层层剥离—少量乳化—稳定运移”实现残余油的有效驱替,提高了原油脱离基质壁面及孔隙喉道的速度。对于盲端残余油,低频波激励下增加了泡沫在盲端入口处的扰动,改变了泡沫在盲端局部处的流动方向,为泡沫流入盲端创造了有利条件;对于连片残余油,低频波减缓了泡沫驱替过程中的突进现象,提高了泡沫在小孔隙中的有效波及和驱替效果。

To investigate the characteristics about the displacement of residual oil by foams after water flooding under low-frequency wave excitation,a foam-facilitated oil displacement experiment under low-frequency wave excitation was performed based on the microscopic inhomogeneous model,and the mechanism and effect of foam-facilitated oil displacement reinforced by low-frequency wave were analyzed.The results show that the low-frequency wave improves the sweep coefficient and oil displacement effect of foam flooding by improving the foam stability,creating local pressure disturbance,and reducing the wall adsorption capability,and the microscopic oil displacement efficiency is increased by 6.78%under the low-frequency wave excitation.Compared with single foam flooding,the way for the displacement of column residual oil by foams under low-frequency wave excitation is that foams gradually move along the pore wall to the other side of the pore to achieve the effective displacement of residual oil through layer stripping,a small amount of emulsification and stable transportation,which improves the speed of crude oil migration from the matrix wall and the pore throat.For the residual oil at the blind end,the low-frequency wave excitation increases the foam disturbance at the entrance to the blind end,changes the flow direction of foams at the blind end,and creates favorable conditions for the foam flow into the blind end;for the continuous flake residual oil,the low-frequency wave slows down the abrupt advance in the foam flooding process,and improves the sweep efficiency and displacement effect of foam flooding in the small pore space.