表面活性剂对致密砂岩储层自发渗吸驱油的影响

自发渗吸驱油是致密砂岩油藏比较重要的一种采油方式。为了研究表面活性剂对长庆油田致密砂岩储层渗吸效果的影响,采用核磁共振技术,根据天然岩心在地层水和表面活性剂中的自发渗吸实验,研究了不同润湿性岩心自发渗吸的特点,以及表面活性剂对中性润湿砂岩渗吸结果的影响。实验结果表明:强水润湿砂岩的渗吸采出程度为60%左右,而中性润湿砂岩的渗吸采出程度只有33%左右;表面活性剂的加入能够有效提高中性润湿砂岩的渗吸采出程度,0.05%HYZ-5的效果最好。通过岩心驱替实验评价了HYZ-5表面活性剂对中性致密砂岩周期注水采收率的影响,可以看出HYZ-5可以显著提高周期注水的采收率。现场试验证明,A井采用周期注水,注入HYZ-5表面活性剂溶液渗吸驱油后,取得了明显的增产效果,说明表面活性剂可以提高致密砂岩储层的自发渗吸驱油效率。

Influence of surfactant on spontaneous imbibition in tight sandstone reservoir and its application

Spontaneous imbibition is an important method for oil recovery in tight sandstone reservoirs.In order to study the effect of surfactants on spontaneous imbibition in tight sandstone reservoir of Changqing Oilfield,various methods including NMR testing,imbibition experiments of natural cores samples immersed in water formation or surfactant,the imbibition with different wettability characteristic and the effect of surfactant on the moderate-wet sandstone reservoir were studied.The results show that the total recovery ratio of water-wet sandstone is about 60％,whilst that of moderate-wet sandstone is 33％.The addition of 0.05％ HYZ-5 favorably improves the degree of imbibition of moderate-wet sandstone.Additionally,the effect of surfactant HYZ-5 on the oil recovery rate during cyclic water injection in moderate-wet and tight reservoir was evaluated,a significant improvement of the recovery rate was observed.Furthermore,the field test proved the efficiency of spontaneous imbibition as well as oil displacement in tight sandstone reservoir.