When does the bottom hole pressure (BHP) reach its highest point with gas cut mud?

The bottom hole pressure (BHP) reaches its highest point when the gas reaches the surface because, at that moment, the hydrostatic pressure exerted by the drilling fluid is at its maximum without the interference of the gas. When gas cuts through the mud and it subsequently rises to the surface, it creates a reduction in the hydrostatic weight of the fluid column, temporarily altering the pressure dynamics.

Once the gas escapes to the surface, the system stabilizes, and the BHP reflects the full hydrostatic pressure of the drilling fluid column above the gas. Therefore, the condition of gas being at the surface allows the BHP to return to its highest potential based on the fully accounted column of fluid without dilution by gas.

In this scenario, the moment the gas reaches the surface is critical, as it influences the pressure readings and operational decisions during drilling.