表面活性剂降低注水井注入压力室内实验研究

Laborotary Experiment of water injection pressure decreasing by surfactant

针对外围油田部分注水井注入压力高、注水驱替效率低及套损井不断增加等情况,开展了表面活性剂降低注水井注入压力室内实验研究。室内实验表明,55℃表面活性剂体系油水界面张力达到10^(-2)mN/m数量级,且具有较好的界面张力稳定性。岩心驱油降压模拟实验表明,表面活性剂体系驱替0.5倍孔隙体积(PV),后续水驱替压力下降48％左右。注入表面活性剂体系后,油水界面张力降低,残余油饱和度下降,水相相对渗透率上升,注入压力下降。

Aiming at the problem of high water injection pressure and low displacement efficiency, laboratory research on decreasing injection pressure by surfactant has been in process. Laboratory experimental results indicated that the interfa-cial tension between oil and water were below 10-2mN/m at 55℃ and the stability was satisfactory. Core simulation experiments showed that the pressure of water drive could decrease by 48% after surfactant drive (0.5 PV) . Principle is that in-terfacial tension between oil and water decreases, which cause residual oil saturation to drop down, the relatively permeability of water phase go up, thus leads to deelining water injection pressure.