Changes

If purely hydrodynamic in origin, the fluid contact tilt can be extrapolated across the field as a flat plane that intersects the contact elevation in a minimum of three control wells. Regional fluid pressure data can be used to extrapolate the fluid contacts from the contacts measured in one or two wells. Only corrected [[Pressure transient testing#Pressure buildup tests|shut-in pressure]]s unaffected by nearby production should be used for this evaluation.

If purely hydrodynamic in origin, the fluid contact tilt can be extrapolated across the field as a flat plane that intersects the contact elevation in a minimum of three control wells. Regional fluid pressure data can be used to extrapolate the fluid contacts from the contacts measured in one or two wells. Only corrected [[Pressure transient testing#Pressure buildup tests|shut-in pressure]]s unaffected by nearby production should be used for this evaluation.

Hydrodynamic potential (''h'') is usually measured as the elevation to which water would rise in an open borehole, called the ''potentiometric elevation''. It is calculated from the reservoir pressure by the following relationship:

Hydrodynamic potential (''h'') is usually measured as the elevation to which water would rise in an open borehole, called the ''potentiometric elevation''. It is calculated from the reservoir pressure by the following relationship (Equation 1):

:<math>h = P/(\rho_{\rm w} \times C) + (E_{\rm m} - E_{\rm r}) </math> (Equation 1)

:<math>h = P/(\rho_{\rm w} \times C) + (E_{\rm m} - E_{\rm r}) </math>

where

where

* ''E''_r = reference elevation (not subsurface depth)

* ''E''_r = reference elevation (not subsurface depth)

Potentiometric elevations are mapped and contoured to determine the change in potentiometric elevation per unit distance, called the ''potentiometric gradient''. The hydrodynamic tilt of a fluid contact can be estimated from the potentiometric gradient and fluid densities by the following relationship:<ref name=pt06r56>Hubbert, M. K., 1953, [http://archives.datapages.com/data/bulletns/1953-56/data/pg/0037/0008/1950/1954.htm Entrapment of petroleum under hydrodynamic conditions]: AAPG Bulletin, v. 37, p. 1954–2026.</ref><ref name=pt06r21>Dahlberg, E. C., 1982, Applied Hydrodynamics in Petroleum Exploration: New York, Springer Verlag, 161 p.</ref>

Potentiometric elevations are mapped and contoured to determine the change in potentiometric elevation per unit distance, called the ''potentiometric gradient''. The hydrodynamic tilt of a fluid contact can be estimated from the potentiometric gradient and fluid densities by the following relationship<ref name=pt06r56>Hubbert, M. K., 1953, [http://archives.datapages.com/data/bulletns/1953-56/data/pg/0037/0008/1950/1954.htm Entrapment of petroleum under hydrodynamic conditions]: AAPG Bulletin, v. 37, p. 1954–2026.</ref><ref name=pt06r21>Dahlberg, E. C., 1982, Applied Hydrodynamics in Petroleum Exploration: New York, Springer Verlag, 161 p.</ref> (Equation 2):

 

:<math>\text{Hydrocarbon tilt} = \rho_{w}/(\rho_{w} - \rho_{h}) \times \text{potentiometric gradient}</math>

:<math>h_{\rm A}  = 2369/0.433 - 5160 = 311 \mbox{ ft}</math>

:<math>h_{\rm A}  = 2369/0.433 - 5160 = 311 \mbox{ ft}</math>