深层页岩气井投产初期能量充足,大多采用套管快速排液,当井口压力降至带压作业能力范围内或气井出现携液困难时再下入油管生产,油管下入时机、下入深度及油管尺寸等参数设计基本依据作业进度或现场经验而定。目前,下入时机对气井产能的影响鲜有研究材料供参考,因此,基于川南深层页岩气在套管生产阶段的53井次井筒动态监测资料,优选了井筒压降计算模型。通过分析气井生命周期内井筒流型、井底流动压力、临界携液能力的变化规律,确定油管最佳下入时机;基于探明的不同油管深度下的井筒压降变化规律,提出了以井筒最小压降为目标的油管最优下入深度;综合携液、压力损耗敏感性研究,得到最优管柱尺寸。结果表明：川南深层页岩气井在井口压力降至15~25 MPa时,为油管最佳下入时机,油管最优下深井斜介于70°~85°,最优管径为62 mm。该设计在现场应用良好,通过油管参数设定,气井压降速度降低了50 %,单位压降产量增长2倍,对有效地指导川南深层页岩气水平井油管设计及实施具有重要意义。

At the early stage of production, deep shale gas wells in southern Sichuan have sufficient energy. Most of the wells use casing to discharge fluid quickly. When the wellhead pressure drops to the capacity of the pressurized operation or the gas well is difficult to carry fluid, tubing production is run. The tubing installation time typically depends on the wellhead pressure drawdown to the capability of the snubbing unit or the onset time of liquid loading. Tubing depth and diameter are commonly determined based on the production progress according to operators’ field experience. So far, the influence between the tubing installation time and gas well deliverability is still unclear. Based on the well performance monitoring data of 53 times of deep shale gas wells in Southern Sichuan at the casing production stage, the calculation model of wellbore pressure drop and the variation law of wellbore flow pattern are analyzed, besides, the bottom hole flow pressure and critical liquid carrying capacity is also determined the best running time of tubing. In this work, the variation of wellbore pressure drop under different tubing depth is analyzed, and a method to determine the optimal tubing running depth is proposed by aiming at minimizing wellbore pressure drop. Finally, the optimal string size is obtained, and field verification is carried out based on the sensitivity analysis of liquid carrying and pressure loss. The results suggested that the optimum tubing installation time is when wellhead pressure drops to 15~25 MPa. The proper tubing depth is at 70° to 85° of well deviation and the suitable tubing inner diameter is 62 mm. By running tubing in time, the pressure drop rate of the gas well is reduced by 50 %, and the unit pressure drop production is increased by twice times, which effectively guides the tubing design and implementation of deep shale gas horizontal wells in Southern Sichuan.