免钻桥塞在致密气藏储层改造中的适应性评价

Feasibility evaluation of drill-free bridge plug in stimulation of tight gas reservoirs

可钻式复合桥塞内通径小,压后需磨铣桥塞,连续油管钻塞费用高、作业周期长,严重影响了水平井的投产进度。大通径免钻桥塞内通径大、压裂球可溶,现场实施简便、经济可靠。结合区域储层流体特征,开展压裂球的室内溶蚀评价实验,压裂球在清水中不溶蚀,在压裂液和返排液中易溶蚀,温度越高溶蚀越快。根据室内实验结果,优化桥塞泵送工艺,采用活性水泵送桥塞,再采用清水作隔离液,控制可溶球的溶蚀速度。将大通径免钻桥塞应用在松辽盆地凝析气藏水平井X井的6段压裂中,累计泵入液体4 760 m^3,支撑剂354 m^3,顺利完成了水平井各段的储层改造。现场试验表明,大通径桥塞工具坐封可靠,压后返排中压裂球溶蚀彻底,满足压裂施工要求,能大幅缩短水平井投产周期,在致密气藏储层改造中具有良好的推广价值。

The drillable composite bridge plug with the characteristic of small diameter needs bridge plug milling using coiled tubing after the fracturing,which seriously affects the production schedule of the horizontal well due to the high cost and long operation period.The large-bore drill-free bridge plug has a large drift diameter and dissoluble fracturing ball,featuring with simple onsite application,cost effectiveness and reliability.Based on the fluid characteristics of the regional reservoir,indoor corrosion evaluation experiment of fracturing balls was carried out The fracturing ball do not dissolve in the clear water,and is easily dissolved in the fracturing fluid and the flowback fluid and higher temperature results in faster dissolution.According to the results of laboratory experiments above,the bridge plug pumping process was optimized.Active water is used to pump the bridge plug,and the clear water is used as the isolation fluid to control the dissolution rate of the dissoluble ball.The large-bore drill-free bridge plug was applied to the six-stage horizontal well fracturing of Well X in the condensate gas reservoir in South of Songliao,with the cumulative pumping liquid of 4 760 m^3 and the proppant of 354 m^3,resulting in successful stimulation of each stage of the horizontal well.Field tests show that the large-bore bridge plug tool is reliable,and the fracturing ball indicated by flowback is completely dissolved,which meets the requirements of fracturing operation,and can greatly shorten the putting-to-production time of horizontal well,presenting a good promotion prospect in the stimulation of tight gas reservoirs.