特低渗透砂岩大型露头模型单相渗流特征实验

An experimental study on single-phase seepage characteristics with a large-scale model made of ultra-low permeability sandstone outcrops

应用电阻率测井的电极系测量原理,建立了一套测量平板模型平面流场的方法。同时利用特低渗透天然砂岩露头制作大型平板模型,进行了特低渗储层单相渗流实验。实验测定了平板模型单相渗流曲线,平面压力梯度场以及流场。利用压力梯度场和平行岩样非线性渗流曲线将模型渗流区域划分为不流动区、非线性渗流区和拟线性渗流区。研究表明,特低渗透多孔介质在平面渗流过程中存在非线性,平板模型视渗透率随着注采压差的增大而增加,模型平面流场存在未波及区域,提高平板模型注采压差后,平面渗流区域随之改变,流场中未波及区域消失。

On the basis of the electrode-system measurement principle of resistivity logging,a method to measure the flow field of a flat model was established.A single-phase seepage experiment on ultra-low permeability reservoirs was performed with a large-scale flat model made of ultra-low permeability sandstone outcrops.The experiment measured single-phase seepage curves,the pressure gradient field and the flow field of the flat model.Seepage areas of the flat model were divided into immobile,no-linear and quasi-linear seepage areas by using the pressure gradient field and no-linear seepage curves of small rock samples.The result shows that the flat seepage in ultra-low permeability porous media is no-linear and the apparent permeability of the flat model increases with increasing the injection/production drawdown.There is an unswept area in the plane flow field,the plane seepage area changes with increasing the injection/production drawdown of the flat model,and consequently the unswept area in the flow field will disappear.