Changes

Normal reservoir pressure is the pressure in the reservoir fluids necessary to sustain a column of water to the surface.<ref name=pt03r19>Fertl, W. H., 1976, Abnormal formation pressures: New York, Elsevier Scientific Publishing Company, 382 p.</ref> Normal pressures range between 0.43 and 0.50 psi/ft. Normal drilling muds weigh about 9 ppg (pounds per gallon) and exert a bottom hole pressure of approximately 0.47 psi/ft of depth.

Normal reservoir pressure is the pressure in the reservoir fluids necessary to sustain a column of water to the surface.<ref name=pt03r19>Fertl, W. H., 1976, Abnormal formation pressures: New York, Elsevier Scientific Publishing Company, 382 p.</ref> Normal pressures range between 0.43 and 0.50 psi/ft. Normal drilling muds weigh about 9 ppg (pounds per gallon) and exert a bottom hole pressure of approximately 0.47 psi/ft of depth.

By convention in the petroleum industry, ''overpressure'' refers to pressures higher than normal that require heavy drilling mud to keep formation fluids from entering the borehole. Pressures lower than normal are called ''subnormal''.

By convention in the [[petroleum]] industry, ''overpressure'' refers to pressures higher than normal that require heavy drilling mud to keep formation fluids from entering the borehole. Pressures lower than normal are called ''subnormal''.

==Overpressured reservoirs==

==Overpressured reservoirs==