What is the average pore pressure gradient typically measured in psi/ft?

The average pore pressure gradient is generally accepted to be approximately 0.465 psi/ft in typical sedimentary basins. This value is derived from the Hydrostatic Pressure Gradient, which usually represents the pressure exerted by a column of water. In geological environments, pore pressures in the subsurface tend to increase with depth, and using the standard density of water (approximately 8.33 ppg or approximately 62.4 lb/ft³), you can calculate that the corresponding pressure gradient is around 0.433 psi/ft to 0.465 psi/ft, depending on local variations and fluid properties.

This value is crucial for well control, as it helps in understanding the balance between hydrostatic pressure and formation pressure, which in turn guides decisions regarding wellbore stability and the prevention of blowouts during drilling operations. The other values listed either exceed typical gradients or fall below average measurements expected in most drilling conditions, making them less applicable in standard practice.