黏弹性表面活性剂压裂液流变性研究

Viscoelastic surfactant fracturing fluid rheology

鉴于早期VES压裂液在现场应用中存在的问题,制备了VES-SL黏弹性表面活性剂压裂液并研究了其流变性。VES-SL黏弹性表面活性剂由SL表面活性剂和助剂Ⅰ合成,SL表面活性剂烃基结构对VES-SL压裂液黏度的影响较小,SL表面活性剂的浓度较低时,VES-SL压裂液仍然保持较高的黏度,助剂Ⅰ的使用可以明显提高VES-SL压裂液的黏度,无机盐在一定浓度范围内对压裂液有增黏作用。VES-SL压裂液的抗热降解和剪切降解的能力强于HPG压裂液,且具有很好的流动性。实验结果表明,该压裂液黏度高、成本低,对岩心基质伤害率低,因此,其性能明显优于HPG压裂液。胜利油田营543区块现场试验效果对比表明,VES-SL压裂液的性能明显优于HPG压裂液,取得了良好的增油效果。

To solve the problems of VES fracturing fluids, VES-SL fracturing fluid was developed and its rheological property was studied. VES-SL system consists of two main components, SL surfactant and additive I. The viscosity of VES-SL fracturing fluid is less affected by the alkyl structure changes of the SL surfactant. At low concentrations, VES-SL system can still have a relatively high viscosity. The viscosity of VES-SL system can be improved by using additive Ⅰ, the inorganic salt is conductive to increasing the cohesiveness of fracturing fluid in a certain concentration. VES-SL system is superior to HPG fracturing fluid in antidegradation and shearing strength, and has better mobility. Experiments show that the VES-SL system exhibits a high viscosity, low cost, and low damage to core matrix. The field tests in Block Ying-543 in Shengli Oilfield reveal that the property of VES-SL system is better than that of HPG fracturing fluid. The system increases oil production.