苏里格致密气藏纳米增效剂的研制与应用

Research and application of nano synergis in Sulige tight gas reservoir

苏里格致密砂岩气藏属于低孔低渗储层,孔喉细小、排驱压力高、亲水性强,常规压裂液返排困难,水锁损害问题严重、气井产量受到极大影响。针对该类气藏储层地质特征,研制了一种“粒径小、性能强、低伤害、易携带”的纳米增效剂,通过进入微纳米孔道深部改善渗透率、降低界面张力和改变润湿性等机理提高气藏开发效果。现场试验过程中进一步优化压裂方法,首先是环空加砂注入,降低压裂液摩阻,增大压裂液的注入速度;其次在前置液阶段及携砂液前期差异化添加纳米增效剂,降低深部储层水锁、改善远井微裂缝等低孔喉区域渗流通道,增强远井区域的产能贡献率。结果表明,纳米增效压裂技术降低了液氮伴注比、改善了返排效果、缩短了建井周期、提高了单井产量。该技术的成功应用对致密气藏水力压裂具有积极的指导和借鉴意义,应用前景广阔。

The Sulige tight sandstone gas reservoir belongs to a low porosity and low permeability reservoir,with small pore throats,high displacement fracturing,and strong hydrophilicity.It is difficult for conventional fracturing fluid to flow back,causing serious water lock damage,and greatly affecting gas well production.A nano synergistic agent with small particle size,strong performance,low damage,and easy portability was prepared based on the geological characteristics of this type of gas reservoir.The mechanism of improving permeability,reducing interfacial tension,and changing wettability by entering the deep part of micro and nano pores enhances the development efficiency of gas reservoirs.During the on-site testing process,further optimization of the fracturing method is carried out,firstly by injecting sand into the annulus to reduce the frictional resistance of the fracturing fluid and increase the injection rate of the fracturing fluid.Secondly,in the pre fluid stage and the early stage of sand carrying fluid,nano synergistic agents are added differentially to reduce water lock in deep reservoirs,improve the flow channels in low pore throat areas such as micro fractures in far wells,and enhance the productivity contribution rate in far well areas.The results show that the nano enhanced fracturing technology reduces the liquid nitrogen injection ratio,improves the flowback effect,shortens the well construction cycle,and increases the single well production.The successful application of this technology has positive guidance and reference significance for hydraulic fracturing of tight gas reservoirs,and has broad application prospects.