What happens to the SIDPP when the well is shut in and gas migrates up the annulus?

When the well is shut in and gas migrates up the annulus, the Shut-In Drill Pipe Pressure (SIDPP) increases. This increase occurs because the gas migrating into the annulus creates additional pressure within the confined space. As gas rises, it expands due to the decrease in hydrostatic pressure in the wellbore associated with the shut-in conditions.

Since the gas has a lower density than the surrounding fluid, its presence will lead to a pressure build-up. This is particularly influenced by the height of the gas column that is rising in the annulus, and it continues to exert pressure on the fluid in the drill pipe. Therefore, the overall impact of gas migration when the well is shut in is to result in an increase in SIDPP. This understanding is crucial for well control operations, as an increase in pressure can indicate that gas is moving, which might necessitate further intervention or monitoring to prevent any potentially hazardous situations.