hydrostatic pressure — Oil & Gas Glossary
The pressure at any point in a column of fluid caused by the weight of fluid above that point. Controlling the hydrostatic pressure of a mud column is a critical part of mud engineering. Mud weight must be monitored and adjusted to always stay within the limits imposed by the drilling situation. Sufficient hydrostatic pressure (mud weight) is necessary to
Detailed Explanation
prevent an influx of fluids from downhole, but excessive pressure must also be avoided to prevent creation of hydraulic fractures in the formation, which would cause lost circulation. Hydrostatic pressure is calculated from mud weight and true vertical depth as follows:Hydrostatic pressure, psi = 0.052 x Mud Weight, lbm/gal x True Vertical Depth, ft. (To convert to SI units, 1.0 psi = 6.9 kPa.)