纳米二氧化硅增强胍胶压裂液性能研究

Effect of nano-silica on the performance of guar gum fracturing fluids

为提高压裂液性能,适应复杂油气藏的开发需求,往往采用改性稠化剂、温度稳定剂和新型交联剂来实现,但是这些方法目前对压裂液的性能提升已达到极限,本文采用纳米杂化的方式来提升压裂液综合性能。考察了纳米二氧化硅加入到胍胶压裂液中对其耐温性能、携砂性能、破胶性能和伤害程度的影响。结果表明,在相同的胍胶浓度下,在压裂液中加入3 000 mg/L的纳米SiO_(2)能使硼交联剂的用量减少0.05%,而压裂液冻胶黏度却提高了76 mPa·s。纳米SiO_(2)杂化压裂液相比于空白压裂液的耐受温度提高了20℃,在压裂液基液和冻胶中的沉降速度都明显变慢,说明纳米SiO_(2)增强了压裂液的黏弹性能,即增强了压裂液的携砂性能;杂化压裂液破胶后的黏度、表面张力和残渣含量都符合"水基压裂液通用技术指标";并且纳米SiO_(2)的加入能减小压裂液对岩心和支撑剂充填层导流能力的伤害。纳米SiO_(2)杂化胍胶压裂液满足现场施工和低伤害的要求。

In order to improve the performance of fracturing fluid and adapt to the development requirements of complex oil and gas reservoirs,the modified densifier,temperature stabilizer and new crosslinker are often adopted,but these methods have reached the limit of the performance of fracturing fluid at present.Using the nano-hybrid method to improve the comprehensive performance of the fracturing fluid.The effect of nano SiO_(2) on the temperature resistance,sand carrying property,gel breaking property and damage degree of guar gum fracturing fluid was investigated.The results show that with the same densifier concentration,the addition of 3 000 mg/L nano-SiO_(2) in the fracturing fluid can reduce the amount of boron crosslinker by 0.05%,while the viscosity of the fracturing fluid is increased by 76 mPa·s.Compared with the pristine fracturing fluid,the tolerance temperature of the nano-SiO_(2) hybrid fracturing fluid increased by 20 ℃,and the static settlement velocity in the base fluid of the fracturing fluid and the gel was slowed obviously,indicating that the nano-SiO_(2) enhanced the viscoelastic properties of the fracturing fluid,that is,the sand carrying performance of the fracturing fluid was enhanced.The gel breaking liquid viscosity,surface tension and residue content of the hybrids fracturing fluid are all conform to the general technical index of water base fracturing fluid,and the addition of nano-SiO_(2) can reduce the damage of fracturing fluid to the conductivity of core and proppant filling layer.Nano-SiO_(2) hybrid guar gum fracturing fluid meets the requirements of site construction and low damage.