Changes

  | part    = Critical elements of the petroleum system

  | part    = Critical elements of the petroleum system

  | chapter = Formation fluid pressure and its application

  | chapter = Formation fluid pressure and its application

  | frompg  = 5-1

  | frompg  = 5-5

  | topg    = 5-64

  | topg    = 5-5

  | author  = Edward A. Beaumont, Forrest Fiedler

  | author  = Edward A. Beaumont, Forrest Fiedler

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch05/ch05.htm

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch05/ch05.htm

==Fluids==

==Fluids==

A fluid is “a substance (as a liquid or gas) tending to flow or conform to the outline of its container” (Webster, 1991). Thus, the explorationist should think of oil, gas, and water as fluids to understand their behavior in the subsurface. In this chapter, where the fluid state (liquid or gaseous) is important, the state (or phase) is specified.

A fluid is “a substance (as a liquid or gas) tending to flow or conform to the outline of its container.”<ref name=Webster_1979>Webster's New Twentieth Century Dictionary, Unabridged, 2nd ed., 1979: New York, Simon and Schuster, 2129 p.</ref> Thus, the explorationist should think of oil, gas, and water as fluids to understand their behavior in the subsurface. In this article, where the fluid state (liquid or gaseous) is important, the state (or phase) is specified.

==Fluid pressure==

==Fluid pressure==

==Hydrostatic pressure==

==Hydrostatic pressure==

Normal hydrostatic pressure is the sum of the accumulated weight of a column of water that rises uninterrupted directly to the surface of the earth. Normally pressured fluids have a great degree of continuity in the subsurface through interconnected pore systems. Abnormally pressured fluids can occur where fluids are completely isolated in containers (compartments) that are sealed on all sides.

Normal hydrostatic pressure is the sum of the accumulated weight of a column of water that rises uninterrupted directly to the surface of the earth. ''Normally pressured fluids'' have a great degree of continuity in the subsurface through interconnected [[pore systems]]. ''Abnormally pressured fluids'' can occur where fluids are completely isolated in containers (compartments) that are sealed on all sides.

==Hydrostatic mud pressure==

==Hydrostatic mud pressure==

The geological definition of “hydrostatic” differs from the engineering definition. Engineers use “hydrostatic” to refer to the pressure exerted by the mud column in a borehole at a given depth. Hydrostatic mud pressures are found on DST (drill-stem test) reports and on scout ticket reports of DSTs.

The geological definition of “hydrostatic” differs from the engineering definition. Engineers use “hydrostatic” to refer to the pressure exerted by the mud column in a borehole at a given depth. Hydrostatic mud pressures are found on [[Drill stem testing|DST (drill-stem test)]] reports and on [[scout ticket]] reports of DSTs.

==Properties of hydrostatic pressure==

==Properties of hydrostatic pressure==

Normal hydrostatic pressure has the following properties:<ref name=ch05r5>Dahlberg, E., C., 1994, Applied Hydrodynamics in Petroleum Exploration, 2nd ed.: New York, Springer-Verlag, 295 p. Excellent subsurface fluid pressure reference. Covers hydrodynamic and static fluids.</ref>

Normal hydrostatic pressure has the following properties:<ref name=ch05r5>Dahlberg, E. C., 1994, Applied Hydrodynamics in Petroleum Exploration, 2nd ed.: New York, Springer-Verlag, 295 p.</ref>

* Amount of pressure increases with depth.

* Amount of pressure increases with depth.

==Static vs. dynamic fluids==

==Static vs. dynamic fluids==

[[file:formation-fluid-pressure-and-its-application_fig5-1.png|thumb|{{figure number|1}}See text for explanation.]]

[[file:formation-fluid-pressure-and-its-application_fig5-1.png|thumb|300px|{{figure number|1}}Balanced and unbalanced pressures.]]

Fluid pressure is nondirectional if the fluid is static. If a pressure imbalance exists in any direction, the fluid moves in the direction of lower fluid pressure. The diagrams in [[:file:formation-fluid-pressure-and-its-application_fig5-1.png|Figure 1]] illustrate balanced and unbalanced pressures.

Fluid pressure is nondirectional if the fluid is static. If a pressure imbalance exists in any direction, the fluid moves in the direction of lower fluid pressure. The diagrams in [[:file:formation-fluid-pressure-and-its-application_fig5-1.png|Figure 1]] illustrate balanced and unbalanced pressures.

==See also==

==See also==

* [[Geostatic and lithostatic pressure]]

* [[Geostatic and lithostatic pressure]]

* [[Normal hydrostatic pressure gradients]]

* [[Normal hydrostatic pressure gradients]]

[[Category:Critical elements of the petroleum system]]  

[[Category:Critical elements of the petroleum system]]  

[[Category:Formation fluid pressure and its application]]

[[Category:Formation fluid pressure and its application]]