Pore pressure gradient

Pore pressure gradient is a dimensional petrophysical term used by drilling engineers and mud engineers during the design of drilling programs for drilling (constructing) oil and gas wells into the earth. It is the pressure gradient inside the pore space of the rock column from the surface of the ground down to the total depth (TD), as compared to the pressure gradient of seawater in deep water. Pore pressure gradient is a dimensional petrophysical term used by drilling engineers and mud engineers during the design of drilling programs for drilling (constructing) oil and gas wells into the earth. It is the pressure gradient inside the pore space of the rock column from the surface of the ground down to the total depth (TD), as compared to the pressure gradient of seawater in deep water. Whereas in 'pure math,' the gradient of a scalar function expressed by the math notation grad(f) may not have physical units associated with it; in drilling engineering the pore pressure gradient is usually expressed in API-type International Association of Drilling Contractors (IADC) physical units of measurement, namely 'psi per foot.' In the well-known formula taught in almost all petroleum engineering courses worldwide, the mud weight (MW) is expressed in pounds per U.S. gallon, and the true vertical depth (TVD) is expressed in feet, and 0.052 is a commonly used conversion constant that can be derived by dimensional analysis: 1 p s i f t × 1 f t 12 i n × 1 l b / i n 2 1 p s i × 231 i n 3 1 U S G a l = 19.25000000 l b / g a l {displaystyle mathrm {{frac {1;psi}{ft}} imes {frac {1;ft}{12;in}} imes {frac {1;lb/in^{2}}{1;psi}} imes {frac {231;in^{3}}{1;US;Gal}}=19.25000000;lb/gal} }