致密气藏压裂用防水锁剂的性能评价

Performance Evaluation of Anti-water Blocking Agent for Fracturing in Tight Gas Reservoirs

为了确保防水锁剂在低压强亲水致密气藏的水力压裂中发挥其应有的功能,需要评估其载体和使用环境对其性能的影响。研究了3种不同类型的防水锁剂——氟碳阴离子表面活性剂FCY137、氟碳非离子表面活性剂FCF102及纳米FC-ST降低表面张力和改变岩心润湿性能力,通过对比在不同黏度、APS加量、矿化度、pH值下溶液的性能,筛选出性能最佳的防水锁剂,并通过自吸实验、吸附性能实验、渗透率同比恢复实验评价了优选防水锁剂在压裂液体系中防水锁能力。研究结果表明,在室内常规条件下,氟碳阴离子表面活性剂FCY137、氟碳非离子表面活性剂FCF102及纳米FC-ST均能显著降低表面张力,增大接触角,有效降低毛管力。纳米FC-ST在破胶液黏度小于4 mPa·s、120℃以内、APS加量为0.5 g/L、矿化度为100 g/L以及pH≤11的情况下,能较好地保持性能稳定,满足常见低压强亲水致密气藏的普遍需求,综合性能优于氟碳阴离子表面活性剂FCY137和氟碳非离子表面活性剂FCF102。纳米FC-ST滑溜水体系可以显著降低毛管力,有效减少水的侵入;相较于普通助排剂,该体系能有效降低近井地带吸附量;该体系有50%以上的渗透率同比恢复率,相较于常规防水锁剂、助排剂,载体及环境因素对体系性能影响小,预防水锁性能显著。

For hydraulic fracturing in low-pressure strong hydrophilic tight gas reservoirs,it is necessary to evaluate the influence of the carrier and the usage environment on the performance of the anti-water blocking agent,and to make sure the anti-water blocking agent performs its proper function.Three different types of surfactants,including fluorocarbon anionic surfactant FCY137,fluorocarbon nonionic surfactant FCF102 and self-developed nano FC-ST,had been studied to reduce surface tension and change wettability.By comparing the performance of the solution under different viscosity,APS dosage,mineralization,and pH value,the best anti-water blocking agent were selected,and the waterproof locking capability was evaluated in fracturing fluid,through self-absorbing experiments,adsorption performance experiments sur factant and penetration rate recovery experiments.The results showed that the fluorocarbon anionic surfactant FCY137,fluorocarbon nonionic surfactant FCF102 and nano FC-ST could significantly reduce the surface tension,increase contact angle,effectively reduce the capillary force under the conventional indoor conditions.The nano-FC-ST could maintain stable performance in the fracturing gel-breaking fluid under the condition that the viscosity was less than 4 mPa·s,the temperature was below 120℃,APS dosage was 0.5 g/L,the mineralization of water was 1×10^(5) mg/L and pH value was lower than 11.The performances of the anti-water blocking agent nano surfactant FC-ST met the needs of common low-pressure strong hydrophilic tight gas reservoirs,and it was better than fluorocarbon anionic surfactant FCY137 and fluorocarbon nonionic surfactant FCF102.The slick water of nano FC-ST fracturing fluid could significantly reduce the capillary force,effectively reduce water intrusion,and reduce adsorption in the near well zone.It had a permeability recovery rate of more than 50%,compared with conventional anti-water blocking agent,cleanup additive,the performance was less affected by the carrier and the environment,the performance of the water blockage prevention was remarkable.