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.