低渗低压油藏真实岩心薄片微观水驱试验研究

Experimental Study of Microscopic Water Displacement in Low-permeability and Low-pressure Reservoirs by Using Sandstone Slice

利用真实岩心薄片水驱油试验,研究微观水驱油速度对低渗透油层水驱效果的影响以及水驱油过程中的油水运动分布特征。结果表明,剩余油饱和度和驱替效率与所处的微观模型位置有关,从微观模型的入口到出口,剩余油饱和度递增,驱油效率递减;随水驱油速度增加,驱油效率上升,当达到一定程度后,开始下降,说明存在一个最佳驱替速度,即临界驱替速度。储层束缚水主要以水膜形式附着在孔隙表面或充满于较小的孔隙中,而油则充满较大的孔隙;注入水的驱替速度较低时,在孔隙介质亲水性较强的条件下,注入水进入孔隙喉道时,是沿着岩石表面"爬行"进入的,注入水的前缘为一个凹形面。

A waterflooding experiment of sandstone slice was used to study oil displacement efficiency at different water-flooding speeds in low-permeability reservoirs,and distributional features of oil and water movement in the process of waterflooding.The test result shows that residual oil saturation and displacement efficiency have a relation with the location in the model,and residual oil saturation rises with the decrease of displacement efficiency from the entrance to the export in the model.Displacement efficiency rises with the injection speed increase at the beginning.Hereafter,displacement efficiency tends to stabilize and gradually reduces with the rising of water injection rate.This phenomenon shows that there is an optimum waterflooding speed,which is the critical ones.Bound water mainly attaches to the pore surface in the form of water film or in the smaller pores,while the oil is full of larger pores,When water injection rate is low,injected water enters the pore throat along the rock surface by crawling and the water front is a concave surface under the condition of strong hydrophilicity of porous media.