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  | isbn    = 0891816607

  | isbn    = 0891816607

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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''.