利用粘土电解膨效应改善油藏渗透特性

为了在修复粘土伤害、改善油藏渗透特性中应用直流电场,用粘土膨胀实验及填砂岩心渗流实验研究了直流电场作用下蒙脱石、高岭石、伊利石的电解膨效应及含蒙脱石的石英砂填砂岩心的渗透率变化规律。实验结果表明,粘土的膨胀性越强,其电解膨效应越明显;粘土电解膨率随着电场强度E的增加而增加,E>2V/m后趋于稳定;外加直流电场能够提高填砂岩心的渗透率,渗透率因子随E的增加而增加,E>12V/m时其增幅较小。利用外加直流电场下粘土的电解膨效应可以修复或者防止粘土的膨胀伤害、改善油藏渗透特性,该方法对于膨胀性粘土含量高、粘土膨胀伤害严重的油藏效果更明显。

Reservoir Permeability of Fossil Oil is Improved by Electrical Shrinking Effect of Clay

In order to apply the direct current electric field to the repair of damage caused by clay swelling and to the improvement of permeation in reservoir,the electric shrinkage effect of montmorillonite,kaolinite and illite and the rule of permeability variation in quartz sandpack containing montmorillonite under the direct current electric field were studied by experiments of clay swelling and seepage in sandpack.The experimental results indicate that the electric shrinkage effect of clay is more obvious with the increase of expandability of clay;the electric shrinkage rate of clay increases with the increase of electric field strength E and its increment is little when E was more than 2V/m;After exerting the direct current electric field,the permeability of sandpack increases and the permeability factor of the sandpack increases with the increase of E and does not increase again when E is higher than 12V/m.Utilizing the electric shrinkage feature of clay can rebuild or protect the damage of clay swelling and improve the permeation feature of reservoir.The method,applying the electric shrinkage effect of clay to improving the permeation feature of reservoir,has a more positive effect on the reservoir with more swelling clay and more severe damage of clay swelling.