Deep water well restart has become a more common and challenging practice in the Gulf of Mexico. It is essential to have an optimized operation procedure in place which can lead to a safe and efficient restart. Transient well models are often developed for optimizing the restart procedure. Therefore, understanding the accuracy and capability of these models, validating and improving them against the field data are of great importance for the daily operations support and future project design.
This study evaluated the accuracy of a transient multiphase flow simulator in modeling a cold well restart, identified the critical operational risks during the restart and optimized the operations procedure for startup. The scope of the study included well conditions beginning from the steady state production condition prior to shut-in, 35 days of shut-in, operational preparations for the restart, and restart back to steady state conditions. The results were compared with the field data.
Accuracies of the simulation in terms of pressure and temperature at key locations were evaluated for both the steady state and transient process. The simulation results demonstrated agreement with the operational data during steady state. The transient process was also well reflected in the simulation. The pressure and flow rate matched the measured data closely. The only difference between the simulation and the field data was that the simulation indicated a slightly slower warm-up (i.e. the wells warmed up more quickly) potentially suggesting longer well cool down periods in the field. Based on the observations, the optimization of restart procedures were performed to reach the fastest restart within the system limitations and to control the restart slugging to the minimal level.
