A prediction model of the shortest drilling time for horizontal section in extended-reach well

Drilling the horizontal extended-reach well (ERW) with the shortest time is of great significance for drilling safety, efficiency and economic benefits. Moreover, the reservoir damage can be reduced or eliminated only when the well's horizontal section is drilled fast enough. In this paper, considering the effects of horizontal well's extension ability on the rate of penetration (ROP) and tripping in/out velocity, a prediction model of the shortest drilling time for horizontal section in ERW is established. The horizontal ERW Z-42 is analyzed, predicting its shortest drilling time in horizontal section. Results show that the predicted shortest drilling time is mainly dependent on its maximum ROP and maximum tripping in/out velocity in horizontal section. Specifically, the maximum ROP must satisfy four constraints, and the predicted maximum tripping in/out velocity must meet three constraints. Moreover, the predicted shortest time of drilling process in horizontal section is very close to the actual time in Z-42 well. In addition, the actual ROP and tripping in/out velocity in horizontal section should be as close as possible but strictly less than the predicted maximum ROP and maximum tripping in/out velocity to avoid drilling hazards. The shortest drilling time is not fixed and can be predicted in real time. Furthermore, in order to reduce the drilling time, it is necessary to reduce the times of tripping as much as possible to shorten the total drilling time of horizontal section. The model provides a practical tool to predict the shortest drilling time for horizontal section in ERW.