表面活性剂对长庆超低渗砂岩油藏化学渗吸的影响

Effect of Surfactants on Chemical Imbibition in Changqing Ultra-low Permeability Sandstone Reservoir

以长庆油田超低渗储层Y284区块为研究对象,通过静态渗吸、油水界面张力、润湿性以及油水黏度比测量等实验,研究了表面活性剂性能对化学渗吸采收率的影响。结果表明:在超低渗Y284砂岩储层中,阴离子型表面活性剂的渗吸效果最好,并且阴离子亲油基碳链长度的增加可以增强渗吸作用;溶液p H大于两性离子等电点时,甜菜碱型表面活性剂可促进渗吸作用;阳离子表面活性剂不适用于砂岩油藏的化学渗吸采油中;当界面张力处于10-1m N/m数量级时,界面张力下降,渗吸采收率升高,当界面张力处于10-2m N/m数量级时,界面张力上升,渗吸采收率升高;表面活性剂可以改善岩石表面润湿性,增强渗吸作用;给出了油砂静态渗吸的毛管数表达式,润湿相黏度的适当增加或非湿相黏度的降低有利于毛管数的增加,可以增大渗吸采收率。

Taking Y284 Block in the low-permeability reservoir of Changqing Oilfield as the object of the study,with the help of the experiments on imbibition,interfacial tension,wettability and oil-water viscosity ratio,the effect of surfactant performance on chemical imbibition recovery was studied. The achievements show that in ultralow permeability sandstone reservoir,the anionic surfactants have the best imbibition effect,and the increase of the lipophilic group carbon number can enhance the imbibition recovery. When the pH value of the solution is greater than the zwitterionic isoelectric point,betaine surfactants can promote the imbibition. Cationic surfactants are not suitable for chemical imbibition in sandstone reservoirs. The imbibition recovery rises when the interfacial tension decreases at the interfacial tension of 10^-1 m N/m level,the imbibition recovery increases when the interfacial tension rises at the interfacial tension of 10^-2 m N/m level. Surfactant improves the wettability of rock and enhance the imbibition capability. The expression of the capillary number for the oil sand imbibition of is given. The appropriate increase of wetting phase viscosity or the decrease of non-wetting phase viscosity are favorable for increasing capillary number and increasing the imbibition recovery.