It is widely known that the drilling fluid´s primary function is to keep well control and prevent an influx of formation fluid to the well causing a blowout. The mud also prevents loss to the formation by keeping the hydrostatical pressure. Not a big issue in the top sections of the well. As we approach the reservoir, however, the consequences of a loss to the formation is critical. The permeability is reduced, and the danger of emulsion is lurking in the dark.
What do you do when you run into a casing connection that is impossible to break out? Do you send a man into the red zone with a reciprocator saw while the string is in the elevator? Or are you willing to spend some time rigging up a belt tong to assist where your roughneck or casing tongs were not able to deliver the required torque?
Hopefully not. We have safer and more efficient ways of handling P&A jobs with obstinate connections.