Which method is NOT recommended to minimize the risk of shallow gas?

Using heavy drilling mud is not recommended specifically for the purpose of minimizing the risk of shallow gas. While heavy drilling mud has its own advantages, such as providing wellbore stability and controlling downhole pressures, it can sometimes mask the presence of shallow gas rather than mitigate it. Shallow gas can be a significant hazard during drilling operations, and the use of heavy mud does not address the need for careful monitoring and management of unexpected gas encounters.

On the other hand, drilling a pilot hole at a slow rate allows for better assessment and evaluation of subsurface conditions, including the identification of any shallow gas zones. Pumping out of the hole on trips helps to clear any gas accumulations that could pose a threat if encountered, thereby reducing the risk. Controlling the rate of penetration (ROP) is crucial in managing wellbore pressure and reducing the likelihood of gas influx, as it allows for better control over the drilling process and response to geological variations.

In summary, while heavy drilling mud serves several roles in well control, its use is not directly aimed at minimizing the risks associated with shallow gas, unlike the other methods presented.