The RCB/Well Tractor combo was an ideal solution for this job for a number of reasons: the tractor provides weight on bit (WOB) and torque control, the RCB works with the well fluids, the attached modular bailers recover debris while milling and field engineers monitor real-time tool feedback from the surface. Welltec® performed detailed simulations to model the forces in the well based on provided information. Once the simulations determined the job was feasible, the tools were mobilized to the wellsite from nearby Houston.
During the operation, the Well Tractor® conveyed the toolstring to the target depth. After confirming the location via the surface readout, the Well Cleaner® RCB engaged the ball while the Well Tractor® provided approximately 1200 lbs of WOB, milling for 3.7 hours. The RCB dislodged the ball and milled the top section of the plug mandrel, thereby re-establishing communication within the well across the frac plug. The client was then able to treat the perforations in the lower zone.
The job was completed in under 12 hours with no incidents. Afterwards, the mill bit was found to be in good condition, and it is estimated that the entire plug could have been released within two hours of additional milling time if the client chose to continue milling.
Heavier alternatives would have required additional time for mobilization and setup and would have resulted in a greater cost to the client. Moreover, Welltec’s lightweight wireline solution reduced HSE risks onsite.