页岩气井出砂主控因素分析及防治对策

Analysis of Main Control Factors of Sand Production in Shale Gas Wells and Countermeasures

随着地层压力逐渐降低,川渝地区页岩气田加密调整时,压裂返排出现支撑剂回流、返吐现象,一方面降低支撑裂缝的导流能力,另一方面支撑剂进入地面给设备带来冲刷损坏。为从源头上控制地层出砂,开展主控因素分析,为页岩气井立体防砂措施提供参考依据。通过改善支撑剂的铺置剖面,增加压裂液粘度、优化单段射孔簇数、加入纤维等优化措施,有效降低支撑剂回流风险。并对放喷测试制度进行优化调整,采用由小到大的油嘴顺序进行放喷。并针对不同程度出砂气井,形成“一井一策”差异化治理措施,提出旋流过滤式除砂器工艺,除砂器纵向上整体采用“内窄外宽”设计,有效避免堵塞缝腔,对粒径≥0.6 mm粉砂除砂效率达到98%。

With the gradual decrease of formation pressure,proppant backflow and regurgitation occur during the infill adjustment of shale gas fields in Sichuan and Chongqing areas,which on the one hand reduces the conductivity of propped fractures,and on the other hand,proppant enters the ground and brings scouring damage to equipment.In order to control the formation sand production from the source,analyze the main control factors and provide reference for the three-dimensional sand control measures of shale gas wells.By improving the laying profile of proppant,increasing the viscosity of fracturing fluid,optimizing the number of single-stage perforation clusters,adding fibers and other optimization measures,the risk of proppant backflow is effectively reduced;The blowout test system is optimized and adjusted,and the blowout is carried out in order of nozzles from small to large;Aiming at gas wells with different degrees of sand production,a differentiated treatment measure of“one well and one strategy”is formed,and a Swirl filter desander process is put forward.The desander is designed as a whole with“narrow inside and wide outside”in the longitudinal direction,which effectively avoids blocking the fracture cavity,and the desanding efficiency of silty sand with particle size≥0.6 mm reaches 98%.