适用于致密砂岩储层的多功能表面活性剂驱油压裂液体系

Multifunction surfactant oil-displacing fracturing fluid system suitable for tight sandstone reservoirs

针对鄂尔多斯盆地某致密砂岩油田储层物性差、压裂液返排率低、存在水锁及水敏伤害等问题,以复合黏弹性表面活性剂CNT-3和多功能表面活性剂CZPJ-1为主要处理剂,并添加相关助剂,研制出了一套适用于致密砂岩储层的多功能表面活性剂驱油压裂液体系,室内对压裂液体系的综合性能进行了评价。结果表明:该压裂液体系具有良好的耐温抗剪切性能,在90℃、170 s^-1条件下剪切100 min后,黏度仍能保持在50 mPa·s左右;体系还具有良好的携砂性能和破胶性能;破胶液对储层天然岩心的渗透率伤害率为7%左右,具有低伤害特性;另外,破胶液还能通过降低油水界面张力和改变岩石表面润湿性等作用来提高致密砂岩储层的渗吸驱油效果,进一步提高压裂施工改造的效果。A-1井的矿场试验结果表明,其压后的产油量是使用常规胍胶压裂液的邻井A-2井的4倍左右,取得了明显的压裂增产效果。

In view of some problems such as poor physical properties, low fracturing fluid return rate, water locking and water sensitivity damage in the tight sandstone oilfield of Ordos Basin, a set of multifunctional surfactant oil-displacing fracturing fluid system was developed for the tight sandstone reservoirs with the composite viscoelastic Surfactant CNT-3 and multifunctional Surfactant CZPJ-1 as the main processing agent and with the help of the related auxiliaries. The comprehensive performance of the fracturing fluid system was evaluated indoors. The results show that the fracturing fluid system has good temperature resistance and shear resistance. After cutting 100 min at 90 ℃ and 170 s^-1, the viscosity can still remain around 50 mPa·s;the system also has good sand carrying property and gel breaking property;The damage rate of the gel breaking solution to the natural core’s permeability of the reservoir is about 7%, which has pretty lower damage characteristic;in addition, the gel breaking fluid can improve the effects of the imbibition and displacement of the tight sandstone reservoir by reducing the oil-water interfacial tension and changing the wettability of the rock surface, and further improve the effects of the fracturing construction and reconstruction. The field test results of Well A-1 show that the oil production after the fracturing is about 4 times than that of Well A-2-the adjacent well stimulated by the conventional guanidine fracturing fluid, that’s to say the effect of the fractured stimulation is pretty obvious.